阅读说明：本技术 控制装置、控制方法以及无刷电机 (Control device, control method, and brushless motor ) 是由 东海林元广 高野幸寿 绀谷幸生 星野丰彦 三上均 于 2020-03-10 设计创作，主要内容包括：本发明提供控制装置、控制方法以及无刷电机。控制装置具有控制部,所述控制部通过矢量控制来控制施加到无刷电机的多个相的各相的电压、电流,所述矢量控制在对转子的旋转进行控制时,利用以q轴电流为主的旋转控制来进行,在接收到停止的指令信号时,利用以d轴电流为主的励磁固定控制来进行。所述控制部在所述励磁固定控制中,抑制分别构成多个半桥电路的高侧开关元件和低侧开关元件均被设定为断开的死区时间的影响来控制该无刷电机,所述多个半桥电路与所述无刷电机的所述多个相的各相对应地设置,对该各相提供电压、电流。(The invention provides a control device, a control method and a brushless motor. The control device includes a control unit that controls a voltage and a current applied to each of a plurality of phases of the brushless motor by vector control that is performed by rotation control mainly based on a q-axis current when controlling rotation of the rotor and by excitation fixation control mainly based on a d-axis current when receiving a stop command signal. The control unit controls the brushless motor by suppressing an influence of dead time during which both a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits are set to be off in the excitation fixing control, the plurality of half-bridge circuits being provided corresponding to each of the plurality of phases of the brushless motor and supplying a voltage and a current to each of the phases.)

1. A control device, wherein,

the control device includes a control unit that controls a voltage and a current applied to each of a plurality of phases of the brushless motor by vector control that is performed by rotation control mainly based on a q-axis current when controlling rotation of a rotor and by excitation fixation control mainly based on a d-axis current when receiving a stop command signal,

the control unit controls the brushless motor by suppressing an influence of dead time during which both a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits are set to be off in the excitation fixing control, the plurality of half-bridge circuits being provided corresponding to each of the plurality of phases of the brushless motor and supplying a voltage and a current to each of the phases.

2. The control device according to claim 1,

the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor,

the control unit sets the following electrical angle when aligning the position of the rotor of the brushless motor with an initial position of the electrical angle in vector control in the excitation fixation control: the electrical angle is set to avoid an electrical angle at which a voltage applied to any of the plurality of phases of the brushless motor becomes a voltage near a zero crossing, and the electrical angle corresponding to the position of the rotor is calculated based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor.

3. The control device according to claim 1,

the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor,

the control unit sets an electrical angle of a voltage having a maximum absolute value at a time when the position of the rotor of the brushless motor is aligned with an initial position of the electrical angle in vector control in the excitation fixation control, and calculates the electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor.

4. The control device according to claim 3,

the control unit resets an electrical angle that is closest to the electrical angle in a direction opposite to the rotational direction of the rotor and at which a voltage of any one of the plurality of phases becomes a voltage having a maximum absolute value when the rotation amount of the rotation information acquired from the acquisition unit becomes equal to or greater than a predetermined amount when the rotor is rotated by the set electrical angle, and performs initial position alignment.

5. The control device according to any one of claims 2 to 4,

the control unit returns the position of the rotor to a position before the initial position alignment is performed after the initial position alignment is completed.

6. The control device according to claim 1,

the control unit sets, in the excitation fixation control, a voltage to be applied to each of the plurality of phases of the brushless motor to a voltage obtained by correcting a voltage in the rotation control.

7. The control device according to claim 6,

the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor,

when the rotor is stopped, the control unit corrects the electrical angle in accordance with a deviation between a position of the rotor obtained from the rotation information acquired by the acquisition unit and a commanded electrical angle.

8. The control device according to claim 7,

the control unit reduces the d-axis current if a deviation between a position of the rotor obtained from the rotation information acquired by the acquisition unit and a commanded electrical angle is equal to or smaller than a predetermined range, and increases the d-axis current if the deviation between the position of the rotor and the commanded electrical angle exceeds the predetermined range, when the rotor is stopped by the excitation fixing control.

9. The control device according to claim 6,

the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor,

the control unit reduces the d-axis current if a deviation between a position of the rotor obtained from the rotation information acquired by the acquisition unit and a commanded electrical angle is equal to or smaller than a predetermined range, and increases the d-axis current if the deviation between the position of the rotor and the commanded electrical angle exceeds the predetermined range, when the rotor is stopped by the excitation fixing control.

10. A control device, wherein,

the control device includes a control unit that controls a voltage and a current applied to each of a plurality of phases of the brushless motor by vector control that is performed by rotation control mainly based on a q-axis current when controlling rotation of a rotor and by excitation fixation control mainly based on a d-axis current when receiving a stop command signal,

the control unit controls the brushless motor by correcting a target voltage applied to each of the phases of the brushless motor, while suppressing an influence of a dead time during which both a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits, which supply a voltage and a current to each of the phases, are set to be off.

11. A control device, comprising:

an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of a rotor of the brushless motor; and

a control unit that controls a voltage and a current applied to each of a plurality of phases of the brushless motor by vector control performed by rotation control mainly based on a q-axis current when controlling rotation of a rotor and by excitation fixation control mainly based on a d-axis current when receiving a stop command signal,

the control unit controls the brushless motor by correcting a target voltage applied to each of the plurality of phases of the brushless motor when a rotation speed of the rotor obtained from the rotation information obtained by the obtaining unit is equal to or less than a predetermined rotation speed or less than the predetermined rotation speed.

12. A brushless motor, comprising:

the control device according to any one of claims 1 to 11;

a rotor; and

and a plurality of coils arranged around the rotor in correspondence with the plurality of voltages and currents applied thereto, the plurality of coils being controlled by the control device.

13. A control method, wherein,

the voltage and current applied to each of a plurality of phases of the brushless motor are controlled by vector control which is performed by rotation control mainly based on q-axis current when controlling the rotation of the rotor and by excitation fixation control mainly based on d-axis current when receiving a stop command signal,

in the excitation fixing control, the brushless motor is controlled while suppressing an influence of dead time during which both of a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits provided corresponding to the respective phases of the brushless motor are set to be off, and a voltage and a current are supplied to the respective phases.

Technical Field

The present disclosure relates to a control device, a control method, and a brushless motor.

Background

Japanese patent application laid-open No. 2017-22867 describes a motor driving method including the steps of: setting energization, namely, before the motor is started, utilizing two-phase energization to generate a fixed magnetic field for a certain time, and positioning the rotor at a position deviated from a zero crossing point by 30 degrees; starting energization of 1-phase 180 ° energization, that is, energization is performed by selecting a section further one section ahead in the traveling direction from a set theoretical stop position from the 1-phase 60 ° bipolar rectangular wave energization pattern; and completing start-up energization by detecting a zero-crossing point of a position advanced by a phase difference of 90 ° from a theoretical stop position of the rotor, and then performing the 1-phase 60 ° bipolar rectangular wave energization by zero-crossing point detection of each phase difference of 60 °.

Japanese patent application laid-open No. 2014-217113 describes a motor drive device including: an inverter having a plurality of switching elements, the inverter outputting drive power to the motor by turning on and off the switching elements; and a control unit that turns a rotor of the motor to an initial position by PWM-controlling the switching elements so that a predetermined excitation current flows through the phase windings of the motor, the control unit switching the initial position of the rotor for each start of the motor.

Japanese patent application laid-open No. 2018-98915 discloses a method for correcting an excitation position error of a motor, including: a correction coefficient A is multiplied by a 1 st or 2 nd measurement value measured when an offset error occurs for each energization pattern at the time of position detection of permanent magnet excitation, to obtain a correction value corrected for the offset error, and position estimation of permanent magnet excitation is performed based on the correction value.

In addition, in the brushless motor control device, the voltage and current applied to the motor are controlled by controlling on/off of the high-side switching element and the low-side switching element of the half-bridge circuit. At this time, due to the dead time for preventing the simultaneous turn-on of the high-side switching device and the low-side switching device, there is a possibility that an error occurs in the voltage and current applied to the brushless motor, and an error in the position control of the brushless motor, an increase in the consumption current, an increase in the speed variation, and the like occur.

Disclosure of Invention

An object of the present disclosure is to provide a brushless motor control device, a brushless motor control method, and a brushless motor in which the influence of a dead time is suppressed.

According to the 1 st aspect of the present disclosure, there is provided a control device including a control unit that controls a voltage and a current applied to each of a plurality of phases of a brushless motor by vector control performed by rotation control mainly based on a q-axis current when controlling rotation of a rotor, and by excitation fixed control mainly based on a d-axis current when receiving a stop command signal, wherein the control unit controls the brushless motor by suppressing an influence of a dead time during which both a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits are set to be off in the excitation fixed control, and wherein the plurality of half-bridge circuits are provided in correspondence with each of the plurality of phases of the brushless motor and supply the voltage and the current to the each of the phases.

According to the 2 nd aspect of the present disclosure, the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor, and the control unit sets the following electrical angle when aligning a position of the rotor of the brushless motor with an initial position of the electrical angle in vector control in the excitation fixing control: the electrical angle is set to avoid an electrical angle at which a voltage applied to any of the plurality of phases of the brushless motor becomes a voltage near a zero crossing, and the electrical angle corresponding to the position of the rotor is calculated based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor.

According to claim 3 of the present disclosure, the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor, and the control unit sets an electrical angle of a voltage that maximizes an absolute value of a voltage applied to any one of the plurality of phases of the brushless motor when aligning a position of the rotor of the brushless motor with an initial position of the electrical angle in vector control in the excitation fixing control, and calculates the electrical angle corresponding to the position of the rotor based on the rotation information acquired by the acquisition unit, thereby controlling the brushless motor.

According to the 4 th aspect of the present disclosure, when the rotor is rotated by the set electrical angle, and the rotation amount of the rotation information acquired from the acquisition unit is equal to or greater than a predetermined amount, the control unit resets the electrical angle that is closest to the electrical angle in a direction opposite to the rotation direction of the rotor and is a voltage at which the absolute value of the voltage of any of the plurality of phases is maximum, and performs initial position alignment.

According to claim 5 of the present disclosure, the control unit returns the position of the rotor to the position before the initial position alignment is performed after the initial position alignment is completed.

According to claim 6 of the present disclosure, in the excitation fixing control, the control unit sets a voltage applied to each of the plurality of phases of the brushless motor to a voltage corrected in the rotation control.

According to claim 7 of the present disclosure, the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor, and the control unit corrects the electrical angle in accordance with a deviation between a position of the rotor obtained from the rotation information acquired by the acquisition unit and a commanded electrical angle when the rotor is stopped.

According to the 8 th aspect of the present disclosure, when the rotor is stopped by the excitation fixing control, the control unit decreases the d-axis current if a deviation between a position of the rotor obtained from the rotation information acquired by the acquisition unit and a commanded electrical angle is equal to or smaller than a predetermined range or is smaller than a predetermined range, and increases the d-axis current if the deviation between the position of the rotor and the commanded electrical angle exceeds the predetermined range.

According to a 9 th aspect of the present disclosure, the control device includes an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of the rotor of the brushless motor, and the control unit decreases the d-axis current if a deviation between a position of the rotor and a commanded electrical angle obtained from the rotation information acquired by the acquisition unit is equal to or smaller than a predetermined range or is smaller than a predetermined range and increases the d-axis current if the deviation between the position of the rotor and the commanded electrical angle exceeds the predetermined range when the rotor is stopped by the excitation fixing control.

According to a 10 th aspect of the present disclosure, there is provided a control device including a control unit that controls a voltage and a current applied to each of a plurality of phases of a brushless motor by vector control performed by rotation control mainly based on a q-axis current when controlling rotation of a rotor and by excitation fixed control mainly based on a d-axis current when receiving a stop command signal, wherein the control unit controls the brushless motor by correcting a target voltage applied to each of the plurality of phases of the brushless motor by suppressing an influence of a dead time during which both a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits are set to be off, the plurality of half-bridge circuits supplying the voltage and the current to each of the phases.

According to an 11 th aspect of the present disclosure, there is provided a control device having:

an acquisition unit that acquires rotation information indicating a rotation amount and a rotation direction of a rotor of the brushless motor; and

a control unit that controls a voltage and a current applied to each of a plurality of phases of the brushless motor by vector control performed by rotation control mainly based on a q-axis current when controlling rotation of a rotor and by excitation fixation control mainly based on a d-axis current when receiving a stop command signal,

the control unit controls the brushless motor by correcting a target voltage applied to each of the plurality of phases of the brushless motor when a rotation speed of the rotor obtained from the rotation information obtained by the obtaining unit is equal to or less than a predetermined rotation speed or less than the predetermined rotation speed.

According to a 12 th aspect of the present disclosure, there is provided a brushless motor having: the control device; a rotor; and a plurality of coils arranged around the rotor in correspondence with a plurality of voltages and currents applied thereto, the plurality of coils being controlled by the control device.

According to a 13 th aspect of the present disclosure, there is provided a control method, wherein,

the voltage and current applied to each of a plurality of phases of the brushless motor are controlled by vector control which is performed by rotation control mainly based on q-axis current when controlling the rotation of the rotor and by excitation fixation control mainly based on d-axis current when receiving a stop command signal,

in the excitation fixing control, the brushless motor is controlled while suppressing an influence of dead time during which both of a high-side switching element and a low-side switching element constituting a plurality of half-bridge circuits provided corresponding to the respective phases of the brushless motor are set to be off, and a voltage and a current are supplied to the respective phases.

(Effect)

According to the above aspects 1, 10, and 13, the influence of the dead time can be suppressed.

According to the above-described aspect 2, it is possible to suppress the occurrence of an error in the initial position alignment of the brushless motor, as compared with the case where the initial position alignment of the brushless motor is performed without limiting the electrical angle.

According to the above aspect 3, the occurrence of errors can be further suppressed as compared with the case where the electrical angle of the voltage that maximizes the absolute value is not set.

According to the above-described aspect 4, the amount of rotation of the rotor in the initial position alignment can be reduced as compared with the case where the closest electrical angle is not set.

According to the above-described aspect 5, the operation can be resumed from the position at which the rotor is stopped, as compared with the case where the position is not returned.

According to the 6 th aspect, it is possible to suppress generation of an error in initial position alignment of the brushless motor, as compared with a case where no voltage is corrected.

According to the 7 th aspect, the accuracy of the position control of the rotor is improved as compared with the case where the electrical angle is not corrected.

According to the above aspects 8 and 9, the power consumption can be suppressed while maintaining the positional accuracy of the rotor.

According to the above-described aspect 11, the calculation load of the control device can be reduced as compared with the case where the correction is performed without depending on the rotation speed.

According to the 12 th aspect, a brushless motor in which the influence of the dead time is suppressed can be provided.

Drawings

Fig. 1 is a diagram showing an example of the overall configuration of a brushless motor to which embodiment 1 is applied.

Fig. 2 is a diagram showing an example of the structure of the motor.

Fig. 3 is a diagram showing an example of 3-phase currents flowing through the coils of the stator.

Fig. 4 is a diagram showing a state where a rotor rotates in a motor. (a) The state where the current of the electrical angle 0 ° in fig. 3 flows, (b) is the state where the rotor starts rotating, and (c) is the state where the rotor starts rotating.

Fig. 5 is a diagram illustrating a motor driver unit that applies voltages to respective phases of a motor in a motor control device.

Fig. 6 is a diagram showing an example of a relationship among a target voltage set for each phase of the motor, a current flowing through each phase of the motor, and a rotation amount of a rotating shaft of the motor. (a) The target voltage is set for each phase of the motor, (b) the current flowing through each phase of the motor, and (c) the rotation amount of the rotating shaft of the motor.

Fig. 7 is a diagram showing a hardware configuration of the motor control device.

Fig. 8 is a diagram showing an example of a functional configuration of a motor control device to which embodiment 1 is applied.

Fig. 9 is a diagram illustrating initial position alignment in embodiment 1. (a) The current flowing through each phase of the motor, (b) the d-axis current, and (c) the position of the rotor.

Fig. 10 is a diagram illustrating initial position alignment in embodiment 3. (a) The current flowing through each phase of the motor, (b) the d-axis current, and (c) the position of the rotor.

Fig. 11 is a diagram showing an example of a functional configuration of a motor control device to which embodiment 4 is applied.

Fig. 12 is a diagram showing a waveform of the target voltage supplied from the coordinate conversion section and a waveform of the correction voltage corrected by the dead time correction section. (a) Is the waveform of the target voltage supplied from the coordinate conversion unit, and (b) is the waveform of the correction voltage corrected by the dead time correction unit.

Fig. 13 is a diagram showing an example of a relationship among the correction voltage set for each phase of the motor, the current flowing through each phase of the motor, and the rotation amount of the rotating shaft of the motor. (a) The correction voltage is set for each phase of the motor, (b) is a current flowing through each phase of the motor, and (c) is a rotation amount of a rotating shaft of the motor.

Fig. 14 is a diagram showing a timing chart for controlling the rotation of the motor by applying the motor control device of embodiment 4.

Fig. 15 is a diagram showing an example of a functional configuration of a motor control device to which embodiment 5 is applied.

Fig. 16 is a diagram showing an example of a functional configuration of a motor control device to which embodiment 6 is applied.

Fig. 17 is a diagram showing an example of a functional configuration of a motor control device to which embodiment 7 is applied.

Fig. 18 is a diagram showing a timing chart for controlling the rotation of the motor by applying the motor control device of embodiment 7.

Fig. 19 is a diagram showing an example of a functional configuration of a motor control device to which embodiment 8 is applied.

Fig. 20 is a diagram showing a timing chart for controlling the rotation of the motor by applying the motor control device of embodiment 8.

Detailed Description

Embodiments of the present disclosure are described in detail below with reference to the drawings.

The brushless motor is as follows: a permanent magnet is used as a rotor (also referred to as a rotor) and a plurality of coils arranged around the rotor are used as stators (also referred to as stators), and a rotating magnetic field is generated by changing the current flowing through each coil to rotate the rotor. The brushless motor may have a structure in which a rotor is disposed around a stator. Here, the brushless motor is described as having a stator disposed around a rotor.

[ embodiment 1 ]

Fig. 1 is a diagram showing an example of the overall configuration of a brushless motor 1 to which embodiment 1 is applied.

The brushless motor 1 includes a motor 10, an encoder 20, and a motor control device 30. The motor 10 has a rotor, a stator, and a rotating shaft. The rotating shaft is fixed to the rotor and rotates together with the rotor. A load 2 is mounted on the rotating shaft. The load 2 is a mechanical element such as a gear, a cam, and a roller, and rotates together with the rotating shaft to transmit power. The encoder 20 is a device that outputs a rotation signal indicating a rotation direction and a rotation amount of the rotor.

The encoder 20 is, for example, a transmissive optical encoder, and includes a disk having a slit, a light source, and a light receiving sensor. The circular plate has slits arranged at equal intervals along the circumference. In the encoder 20, light from the light source passes through the slit of the circular plate and is received by the light receiving sensor. That is, the disk rotates together with the rotor, and the light receiving sensor receives light passing through the slit of the disk in a pulse shape. By providing a dual-system slit array (referred to as a channel) of the a-phase and the B-phase, the pulse that rises first out of the a-phase pulse and the B-phase pulse indicates the rotation direction, and the number of pulses per unit time indicates the rotation amount. Here, the rotation signal indicating the rotation direction and the rotation amount, which is the output of the encoder 20, is an example of the rotation information.

The motor control device 30 is a computer that controls the rotation of the motor 10 (specifically, the rotation of the rotor) using the rotation signal output from the encoder 20.

Fig. 2 is a diagram illustrating an example of the structure of the motor 10.

The motor 10 has a rotor 11, a stator 12, and a rotary shaft 14. A rotation shaft 14 is fixed to the rotor 11. The rotor 11 is a permanent magnet having 1 set of magnetic poles (N pole and S pole). The stator 12 has 3 coils 13 (described as coils 13u, 13v, and 13w when they are distinguished from each other). The coils 13 are arranged at positions shifted by 120 ° from each other in the direction from the rotation axis 14 toward the coils 13. One end of the winding of each coil 13 is connected to a motor driver (motor driver 311 in fig. 5) described later, and the other ends are connected to each other.

Hereinafter, for convenience of explanation, a direction in which the coil 13u is disposed with the rotation axis 14 as the center is described as a direction of 0 ° (also referred to as an upward direction), an opposite side thereof is described as a direction of 180 ° (also referred to as a downward direction), and a direction closer to the coil 13w among directions forming an angle of 90 ° with respect to these directions is described as a direction of 270 ° (also referred to as a leftward direction) and a direction closer to the coil 13v is described as a direction of 90 ° (also referred to as a rightward direction). In this case, the coil 13u is arranged in the direction of 270 °, the coil 13v is arranged in the direction of 30 °, and the coil 13w is arranged in the direction of 150 °. The motor 10 is a 3-phase motor as follows: the rotor 11 is rotated by passing currents of 3 phases (U-phase, V-phase, W-phase) shifted by 120 ° in phase through the 3 coils 13.

Here, in the motor 10, the rotor 11 is a permanent magnet having 1 set of magnetic poles as an example, but the rotor 11 may be a permanent magnet having a plurality of sets of magnetic poles. Similarly, the stator 12 has 3 coils 13, but may have coils exceeding 3 times 3.

Fig. 3 is a diagram showing an example of 3-phase current flowing through the coil 13 of the stator 12. In fig. 3, the vertical axis represents the current (a), and the horizontal axis represents the electrical angle (°). The electrical angle is a phase (position in a cycle) when 1 cycle of the sine wave current is set to 360 ° (2 pi radians). Here, the electrical angle is an electrical angle with respect to the d-axis direction in the vector control. The d-axis direction is a direction in which the N-pole of the rotor 11 faces.

In this example, the U-phase current (current flowing in the coil 13U) is "-F1" at an electrical angle of 0 °, 0 "at 90 °, F1" at 180 °, 0 "at 270 °, and" -F1 "again at 360 °. The V-phase current (current flowing in the coil 13V) is "0" at an electrical angle of 30 °, "-F1" at 120 °, "0" at 210 °, "F1" at 300 °, and "0" again at 390 °. The W-phase current (current flowing in the coil 13W) is "F1" at an electrical angle of 60 °, "0" at 150 °, "-F1" at 240 °, "0" at 330 °, and "F1" again at 450 °.

Fig. 4 is a diagram showing a state where the rotor 11 rotates in the motor 10. Fig. 4 (a) shows a state where the current of the electrical angle 0 ° in fig. 3 flows, fig. 4 (b) shows a state where the rotor 11 starts rotating, and fig. 4 (c) shows a state where the rotor 11 starts rotating. In fig. 4 (a), the N pole of the rotor 11 is oriented in the 0 ° direction of the motor 10 defined in fig. 2, and the S pole is oriented in the 180 ° direction of the motor 10.

As shown in fig. 4 (a), when the current of 90 ° in electrical angle in fig. 3 flows through the coil 13, the current flows through the V-phase and the W-phase. Then, a current of the V-phase flows through the coil 13V, and a current of the W-phase flows through the coil 13W. Since the current of the U-phase is "0", no current flows through the coil 13U. Therefore, a magnetic field is formed in which the 270 ° side of the motor 10 is the N-pole and the 90 ° side is the S-pole. Then, as shown in fig. 4 (b), the N pole of the rotor 11 is attracted by the S pole of the formed magnetic field, and the S pole of the rotor 11 is attracted by the N pole of the formed magnetic field. Thereby, the rotor 11 starts to rotate in the clockwise direction. The clockwise direction referred to herein is a direction from the coil 13u to the coil 13w through the coil 13v (a direction in which the angle of the direction shown in fig. 2 gradually increases). Then, as shown in fig. 4 (c), when the rotor 11 starts to rotate and the electric angle changes as shown in fig. 3, and the current flowing through the coil 13 changes, the N-pole and S-pole of the magnetic field formed by the current also rotate clockwise. The rotating magnetic field is described as a rotating magnetic field. Then, the N-pole and the S-pole of the rotor 11 are attracted to and rotate by the S-pole and the N-pole of the rotating magnetic field, respectively. That is, a rotating magnetic field is formed by the current flowing through the coil 13, and the N-pole and the S-pole of the rotor 11 are continuously attracted by the rotating magnetic field, respectively, whereby the rotor 11 of the motor 10 rotates. That is, the motor 10 rotates. The current flowing through the coil 13 is controlled by the motor control device 30.

As described above, when the motor 10 includes the rotor 11 including 1 set of magnetic poles and 3 coils 13 through which 3-phase current flows, the position of the rotor 11 matches the electrical angle.

Fig. 5 is a diagram illustrating the motor driver 311 (see fig. 8 described later) that applies voltages to the respective phases of the motor 10 in the motor control device 30. Here, a PWM conversion section 317 (see fig. 8 described later) that supplies a pulse Width modulation signal (hereinafter, referred to as a PWM (pulse Width modulation) signal) to the motor 10, the encoder 20, and the motor driver section 311 is also shown. The PWM signal is a pulse signal that repeatedly turns on and off a voltage, and a voltage corresponding to the pulse width of the on state is applied.

The motor driver portion 311 includes half-bridge circuits 40 (described as half-bridge circuits 40U, 40V, and 40W) that supply voltages to the U-phase, V-phase, and W-phase of the motor 10, respectively. Each half-bridge circuit 40 has a p-channel FET41 and an n-channel FET42 connected in series. A connection point between the p-channel FET41 and the n-channel FET42 (a connection point between the drain side of the p-channel FET41 and the drain side of the n-channel FET42) in each half bridge circuit 40 is connected to each of the motors 10. That is, the connection point of the half-bridge circuit 40U is connected to U of the motor 10, the connection point of the half-bridge circuit 40V is connected to V of the motor 10, and the connection point of the half-bridge circuit 40W is connected to W of the motor 10. Further, a feedback diode 43 is connected in parallel to the p-channel FET41, and a feedback diode 44 is connected in parallel to the n-channel FET 42. The source side of the p-channel FET41 is connected to a power supply, and the source side of the n-channel FET42 is grounded via a resistor R. The current i (in the case of being distinguished from each other, the currents iu, iv, iw.) flowing through each half bridge circuit 40 is detected by the resistor R. Further, feedback diodes 43 and 44 are provided to feed back the energy accumulated in the coil 13 connected to the half-bridge circuit 40 to the power supply. The p-channel FET41 is an example of a high-side switching element, and the n-channel FET42 is an example of a low-side switching element.

The PWM conversion section 317 supplies PWM signals to the gate of the p-channel FET41 and the gate of the n-channel FET42 in each half bridge circuit 40. That is, the PWM converter 317 applies a voltage VH (described as voltages VHu, VHv, and VHw.) as a PWM signal to the gate of the p-channel FET41 and applies a voltage VL (described as voltages VLu, VLv, and VLw.) as a PWM signal to the gate of the n-channel FET 42. The p-channel FET41 and the n-channel FET42 in each half-bridge circuit 40 are set on/off by the supplied PWM signal. Then, a voltage is applied to each phase of the motor 10 by the turned-on p-channel FET41 and n-channel FET42, and a current flows through the coil 13 of the stator 12. In addition, the ratio (duty ratio) of the on period and the off period is switched and set for each half-bridge circuit 40, and thereby a sinusoidal current shown in fig. 3 flows in each phase of the motor 10 as an average value. For example, when the p-channel FET41 of the half-bridge circuit 40u is turned on and the n-channel FET42 of the half-bridge circuit 40v is turned on, a current flows through the p-channel FET41 of the half-bridge circuit 40u, the coil 13v, and the n-channel FET42 of the half-bridge circuit 40 v. At this time, a current flows from one end portion to the other end portion in the coil 13u, and a current flows from the other end portion to the one end portion in the coil 13 v. Here, as for the current flowing through the coil 13, the current flowing from one end portion to the other end portion is positive, and the current flowing from the other end portion to the one end portion is negative.

In the half-bridge circuit 40, when the p-channel FET41 and the n-channel FET42 connected in series are turned on at the same time, current flows from the power supply to the half-bridge circuit 40 to the ground. This current is sometimes referred to as a through current. Therefore, in order to suppress simultaneous on (through current flowing) of the p-channel FET41 and the n-channel FET42, a period during which both the p-channel FET41 and the n-channel FET42 are off, that is, a so-called dead time, is provided between a period during which the p-channel FET41 is on and a period during which the n-channel FET42 is on.

Fig. 6 is a diagram showing an example of the relationship among the target voltages (Vv, Vu, Vw) set for the respective phases of the motor 10, the currents flowing through the respective phases of the motor 10, and the amount of rotation of the rotary shaft 14 of the motor 10. Fig. 6 (a) shows target voltages set for the respective phases of the motor 10, fig. 6 (b) shows currents flowing through the respective phases of the motor 10, and fig. 6 (c) shows the amount of rotation of the rotary shaft 14 of the motor 10. Here, the horizontal axis represents time. In addition, the chain line in fig. 6 (c) shows an ideal case where the rotation amount of the rotary shaft 14 of the motor 10 changes in proportion to time.

Target voltages (Vv, Vu, Vw) set for the respective phases of the motor 10 shown in fig. 6 (a) are set in a stepwise manner so as to be able to approximate a sine wave. That is, the motor driver 311 gradually changes the voltages applied to the U-phase, V-phase, and W-phase of the motor 10 with time. As a result, current flows through the U-phase, V-phase, and W-phase of the motor 10, and the rotor 11 of the motor 10 rotates. However, the current flowing through each phase (U, V, W) of the motor 10 shown in fig. 6 (b) is not approximately sinusoidal. In particular, in fig. 6 (b), the sinusoidal wave has a large deviation between a portion where target voltage Vw crosses 0V (described as α), a portion where target voltage Vu crosses 0V (described as β), and a portion where target voltage Vv crosses 0V (described as γ) in fig. 6 (a).

Therefore, as shown in fig. 6 (c), the rotation amount of the rotary shaft 14 is deviated from the ideal rotation amount of the rotary shaft 14 shown by the chain line. In particular, in fig. 6 (c), the sinusoidal wave has a large deviation between a portion where target voltage Vw crosses 0V (described as α), a portion where target voltage Vu crosses 0V (described as β), and a portion where target voltage Vv crosses 0V (described as γ) in fig. 6 (a). In addition, a case where the target voltage crosses 0V or a case where the current crosses 0A may be described as a zero crossing.

As described above, as shown in fig. 6 (a), even if the target voltages set for the respective phases of the motor 10 are set in a stepwise manner so as to approximate a sine wave, no current that approximates a sine wave flows through the respective phases of the motor 10. Therefore, in the motor 10, an error may occur in the position control of the rotor 11, or power consumption may increase or the rotation speed of the rotor 11 may fluctuate because the rotor 11 is not at a predetermined position. This condition arises due to the dead time preventing simultaneous turn-on of the high-side switching element (p-channel FET41) and the low-side switching element (n-channel FET 42).

Fig. 7 is a diagram showing a hardware configuration of motor control device 30. The motor control device 30 includes a CPU 31, a ROM 32, a RAM 33, an input/output interface (hereinafter, referred to as input/output IF)) 34, a communication interface (hereinafter, referred to as communication IF)) 35, and a bus 36. The CPU 31, ROM 32, RAM 33, input/output IF 34, and communication IF 35 are connected via a bus 36. Although not shown, motor control device 30 may include an HDD. The HDD is also connected to the bus 36.

The input/output IF 34 is connected to the motor driver portion 311. The motor driver 311 is connected to the motor 10. The input/output IF 34 is connected to the encoder 20. The communication IF 35 is connected to another control device (or CPU) not shown. The portion surrounded by the broken line is an example of the control unit.

After the power is turned on, the CPU 31 reads out the programs and data stored in the ROM 32 (or HDD), develops the programs and data into a state executable on the RAM 33, and writes the programs and data into the RAM 33. The program is then executed. With the execution of the program, data is exchanged with the RAM 33, the input/output IF 34, the communication IF 35, and the like.

The input/output IF 34 supplies a voltage to each phase of the motor 10 via the motor driver unit 311, and acquires pulses of the a and B phases from the encoder 20. The communication IF 35 obtains a command for starting/stopping rotation of the motor 10 and a command (sometimes described as a command value) related to control of the rotation speed, the stop position, and the like from another control device. The communication IF 35 outputs information (sometimes described as data) on the rotation start/rotation stop state of the motor 10 and the state of the rotation speed, the stop position, and the like to other control devices.

The ROM 32 (or HDD) is, for example, an EPROM, an EEPROM, a flash memory, or the like, and stores a program, and data such as initial values of constants and variables used in the program. The RAM 33 may be a rewritable nonvolatile memory such as a flash memory.

Fig. 8 is a diagram showing an example of a functional configuration to which motor control device 30 according to embodiment 1 is applied. The motor control device 30 includes a timer control unit 301, an instruction signal acquisition unit 302, a target speed setting unit 303, an encoder output acquisition unit 304, a rotational speed calculation unit 305, a speed control unit 306, a position control unit 307, a PWM conversion unit 317, a current detection unit 312, a current conversion unit 313, a q-axis current control unit 314, a d-axis current control unit 315, a coordinate conversion unit 316, a control switching unit 320, a 1 st switching unit 321, a 2 nd switching unit 322, a 3 rd switching unit 323, and a 4 th switching unit 324. Further, the respective parts such as the timer control part 301 are described as functional parts.

The brushless motor 1 is controlled by rotation control for rotating the rotor 11 at a predetermined rotation speed, and excitation fixation control for starting rotation of the brushless motor 1 when the power is turned on or for setting the rotor 11 at a stop position. In particular, the brushless motor 1 does not have a sensor that detects the position of the rotor 11 (here, the direction in which the N-pole of the rotor 11 faces). Therefore, after the power is turned on, the position of the rotor 11 is made to coincide with the controlled electrical angle by the excitation fixing control. This is described as initial position alignment. After the initial position alignment, rotation control is performed to control rotation of the rotor 11 of the motor 10. Further, the excitation fixing control is also performed when the rotor 11 is stopped after the rotation. That is, the brushless motor 1 is controlled by switching the rotation control and the excitation fixing control. The excitation fixing control is to fix the rotor 11 at a position specified in an electrical angle, specifically, a magnetic field (referred to as excitation) formed by flowing a current through the coil 13 of the stator 12 to fix the position of the rotor 11 at a predetermined position.

In the vector control, excitation fixing control is performed by specifying an electrical angle, and setting the q-axis current to "0" a and setting the d-axis current. The rotation control is performed by setting a q-axis current. In addition, the d-axis current may be set in the rotation control. The q-axis current leads the d-axis current by 90 deg. phase.

Here, the control switching unit 320 switches the 1 st switching unit 321, the 2 nd switching unit 322, the 3 rd switching unit 323, and the 4 th switching unit 324 based on the instruction signal acquired by the instruction signal acquiring unit 302, thereby switching the rotation control and the excitation fixing control. In fig. 8, the control performed by the control switching unit 320 is indicated by a broken line, and a constant set in the case of the excitation fixing control, here, a constant in the case of the initial position alignment, is described. First, a functional unit for performing rotation control will be described below.

The timer control unit 301 generates a signal of a predetermined period and supplies the signal to the instruction signal acquisition unit 302 and the encoder output acquisition unit 304. An instruction signal for instructing the rotation direction and the rotation speed or the rotation position (the position for stopping the rotor 11) is input from another control device to the instruction signal acquisition unit 302, and the instruction signal acquisition unit 302 acquires the instruction signal input during the period from the time when the signal is supplied from the timer control unit 301 to the time when the next signal is supplied. The other control device mentioned here is, for example, a device that controls the operation of the load 2.

The instruction signal acquisition unit 302 supplies the acquired instruction signal indicating the rotational speed to the target speed setting unit 303, and supplies the acquired instruction signal indicating the position of the rotor 11 to the position control unit 307 via the 1 st switching unit 321. The obtained instruction signal indicating the d-axis current (to be described later) is supplied to the d-axis current control unit 315 via the 3 rd switching unit 323. The obtained instruction signal indicating the electrical angle Φ e is supplied to the coordinate conversion unit 316 via the 4 th switching unit 324.

The target speed setting unit 303 sets the rotation speed indicated by the instruction signal supplied from the instruction signal acquiring unit 302 as the target speed, and supplies the set target speed to the speed control unit 306.

The encoder output acquisition unit 304 receives the rotation signals (a-phase pulse and B-phase pulse) output from the encoder 20 shown in fig. 5, and the encoder output acquisition unit 304 acquires the rotation signal input during a period from when the signal is supplied from the timer control unit 301 to when the next signal is supplied, and supplies the acquired rotation signal to the rotation speed calculation unit 305 and the position control unit 307. The encoder output acquisition unit 304 supplies the acquired rotation signal to the coordinate conversion unit 316 via the 4 th switching unit 324. The encoder output acquisition unit 304 is an example of an acquisition unit that acquires the rotation information output by the encoder 20.

The rotation speed calculation unit 305 calculates the rotation speed of the rotor 11 using the rotation signal supplied from the encoder output acquisition unit 304. The rotation speed calculation unit 305 calculates the rotation speed from, for example, the number of pulses per unit time indicated by the rotation signal. The calculated rotational speed corresponds to a measured value of the current rotational speed of the rotor 11. The rotation speed calculation section 305 supplies the calculated rotation speed to the speed control section 306.

The speed control unit 306 performs speed control so that the rotation speed of the rotor 11 supplied from the rotation speed calculation unit 305 approaches the target speed set by the target speed setting unit 303. The speed control unit 306 performs speed control by using a PI (Proportional-Integral) control method, which is one of feedback control, for example.

The speed control unit 306 supplies a command value (a value corresponding to the calculated rotation speed and target speed) of the q-axis current among the 2-axis currents (d-axis current and q-axis current) obtained by converting the 3-phase current flowing through each coil 13 to the q-axis current control unit 314 described later via the 2 nd switching unit 322, and causes the q-axis current control unit 314 to perform control so that the value (iq described later) obtained by converting the measured current flowing through each coil 13 into the q-axis current approaches the command value, thereby causing the rotation speed to approach the target speed.

The position control unit 307 performs position control for bringing the position of the rotor 11 close to the target position by using a method such as P (Proportional) control, using the position of the rotor 11 indicated by the instruction signal supplied via the 1 st switching unit 321 as the target position. At the time of the rotation control, the initial position of the rotor 11 has been detected. The position control unit 307 detects the current position of the rotor 11 based on the detected initial position and the rotation direction and the rotation amount indicated by the rotation signal supplied from the encoder output acquisition unit 304.

The position control unit 307 calculates an error between the rotational position (the position at which the rotor 11 is stopped) indicated by the instruction signal supplied from the instruction signal acquisition unit 302 via the 1 st switching unit 321 and the detected current position of the rotor 11. The position control unit 307 repeatedly supplies the calculated error to the speed control unit 306, and causes the speed control unit 306 to control the speed to "0" if the error is "0", for example, thereby stopping the rotor 11 at the rotational position.

The current detection unit 312 obtains the 3-phase currents iu, iv, and iw flowing through the half-bridge circuits 40u, 40v, and 40w of the motor driver unit 311 shown in fig. 5, respectively, and supplies the currents to the current conversion unit 313. Then, the current converter 313 converts the 3-phase currents iu, iv, iw into 2-phase currents i α, i β orthogonal to the fixed coordinates by clark conversion. The current conversion unit 313 then obtains a d-axis current id and a q-axis current iq by converting the fixed coordinates of the currents i α and i β into rotational coordinates by park transformation. The current conversion unit 313 supplies the q-axis current iq thus obtained to the q-axis current control unit 314 via the 2 nd switching unit 322, and supplies the d-axis current id to the d-axis current control unit 315 via the 3 rd switching unit 323.

The q-axis current control unit 314 performs control to make the q-axis current iq supplied from the current conversion unit 313 close to the command value of the q-axis current supplied from the speed control unit 306, using, for example, a PI control method. The q-axis current control unit 314 supplies a command value of the q-axis voltage Vq obtained from the q-axis current iq and the command value thereof to the coordinate conversion unit 316. The d-axis current control unit 315 performs control to make the d-axis current id supplied from the current conversion unit 313 close to a command value of the d-axis current supplied from another control device via the 3 rd switching unit 323, for example, by using a PI control method. The d-axis current control unit 315 supplies a command value Vd of the d-axis voltage obtained from the d-axis current id and the command value thereof to the coordinate conversion unit 316.

When the initial position of the rotor 11 is detected, the coordinate conversion unit 316 obtains the current electrical angle from the initial position of the rotor 11 and the rotation direction and the rotation amount indicated by the rotation signal supplied from the encoder output acquisition unit 304. The coordinate conversion unit 316 converts the command value of the q-axis voltage supplied from the q-axis current control unit 314 and the command value of the d-axis voltage supplied from the d-axis current control unit 315 into coordinates of target voltage values (Vu, Vv, Vw) of the respective phases (U-phase, V-phase, W-phase) by space vector conversion using the obtained electrical angle.

The PWM conversion section 317 converts the voltage value coordinates of the 3-phase into a voltage signal serving as a PWM signal, and supplies the voltage signal to the motor driver section 311.

Next, a functional unit that performs excitation fixing control during initial position alignment will be described. Hereinafter, the rotation control will be described in comparison with the above. As described above, the control switching unit 320 controls the 1 st switching unit 321, the 2 nd switching unit 322, the 3 rd switching unit 323, and the 4 th switching unit 324 to switch information supplied to the functional units downstream of the respective switching units between the rotation control and the excitation fixing control.

The control switching unit 320 controls the 1 st switching unit 321 to supply the instruction signal indicating the position of the rotor 11 acquired by the instruction signal acquiring unit 302 to the downstream position control unit 307 in the case of the rotation control, and to supply the position acquired by the instruction signal acquiring unit 302 to the downstream position control unit 307 as the target position of the initial position of the rotor 11 in the case of the excitation fixing control in the initial position detection.

The control switching unit 320 controls the 2 nd switching unit 322 to supply the command value of the q-axis current from the speed control unit 306 and the q-axis current iq from the current conversion unit 313 to the downstream q-axis current control unit 314 in the case of the rotation control, and to supply the command value of the q-axis current whose current value is set to "0" a to the downstream q-axis current control unit 314 in the case of the excitation fixing control in the initial position detection.

The control switching unit 320 controls the 3 rd switching unit 323 to supply the command value of the d-axis current from another control device and the d-axis current id from the current conversion unit 313 to the downstream d-axis current control unit 315 in the case of the rotation control, and to supply the command value of the d-axis current set to a predetermined value (here, "X" a) to the downstream d-axis current control unit 315 in the case of the excitation fixing control in the initial position detection.

The control switching unit 320 controls the 4 th switching unit 324 to supply the rotation signal from the encoder output acquisition unit 304 to the downstream coordinate conversion unit 316 in the case of the rotation control, and to supply the command value for gradually changing the electrical angle to the downstream coordinate conversion unit 316 in the case of the excitation fixing control in the initial position detection.

The instruction signal acquisition unit 302 is realized by the communication IF 35 in fig. 7, the PWM conversion unit 317, the encoder output acquisition unit 304, and the current detection unit 312 are realized by the input/output IF in fig. 7, and the functional units other than the motor driver unit 311 are realized by the CPU 31, the ROM 32, and the RAM 33 in fig. 7. The portion surrounded by the broken line is an example of the control unit.

(initial position alignment of rotor 11 based on excitation fixing control)

Next, the initial position alignment of the rotor 11 in embodiment 1 will be described.

The encoder 20 included in the brushless motor 1 supplies rotation signals (a phase and B phase) to the motor control device 30. The rotation direction and the rotation speed of the rotary shaft 14 of the motor 10 are known from the rotation signals (phase a and phase B). However, as described above, the position of the rotor 11 in the motor 10 is unknown at the time of power-on. Therefore, when the power is turned on, motor control device 30 matches the position of rotor 11 with the electrical angle for control in order to control the rotation of motor 10. This is the initial position alignment.

The initial position alignment is performed as follows: the coil 13 of the stator 12 shown in fig. 2 is supplied with current to form a magnetic field, and the rotor 11 is stopped at a predetermined position. That is, an electrical angle is specified, and a current corresponding to the electrical angle is caused to flow through the coil 13, thereby forming a magnetic field (excitation) by the stator 12. Then, the rotor 11 is rotated to a position specified in an electrical angle and stopped, thereby making the position of the rotor 11 coincide with the electrical angle for control. However, when the electrical angle at which the initial position alignment is performed is specified to be near the zero crossing of the voltage, as shown in fig. 6, an error is likely to occur in the current flowing through the coil 13. Therefore, an error is likely to occur in the stop position of the rotor 11. That is, the initial position alignment generates a deviation. When the initial position alignment is deviated, an error occurs in the position control of the rotor 11 during the driving of the motor 10, and there is a possibility that an increase in power consumption and a variation in the rotation speed occur.

Therefore, in embodiment 1, the electrical angle specified for initial position alignment is specified while avoiding the vicinity of the zero crossing. This suppresses variation in initial position alignment due to the influence of the dead time.

Fig. 9 is a diagram illustrating initial position alignment in embodiment 1. Fig. 9 (a) shows currents flowing through the respective phases of the motor 10, fig. 9 (b) shows a d-axis current, and fig. 9 (c) shows a position of the rotor 11. In fig. 9 (a), the vertical axis represents current (a) and the horizontal axis represents electrical angle (degree), in fig. 9 (b), the vertical axis represents d-axis current (a) and the horizontal axis represents time, and in fig. 9 (c), the vertical axis represents position (degree) of the rotor and the horizontal axis represents time. On the horizontal axes of (a) and (b) in fig. 9, time passes at times t0, t1, t2, and ….

As described above, the initial position alignment of the rotor 11 based on the excitation fixing control is performed by setting the d-axis current. When the initial position alignment is performed, first, an electrical angle to be set is specified for the rotor 11 by another control device. Hereinafter, the electrical angle of the rotor 11 set by another control device is described as a command electrical angle. When the motor control device 30 obtains a command electrical angle from another control device, current is caused to flow through the coil 13 of the stator 12 in order to set the rotor 11 at the position of the command electrical angle. At this time, the command electrical angle is set so as to avoid the electrical angle of the portion surrounded by the broken line shown in fig. 9 (a). The electrical angle to be avoided is an electrical angle in the vicinity of the zero crossing in any of the U phase, the V phase, and the W phase.

At time t0 shown in fig. 9 (b) and (c), the position of the rotor 11 before the initial alignment is set to 180 °, for example. The command electrical angle for stopping the rotor 11 from another control device is set to 0 °. However, when the power is turned on, motor control device 30 does not recognize the position of rotor 11. When the command electrical angle is 0 °, as shown in fig. 9 (a), the currents of any of the U-phase, V-phase, and W-phase are not located near the zero crossing. That is, the command electrical angle 0 ° is an electrical angle avoiding an electrical angle near the zero crossing.

Then, at time t1, motor control device 30 starts to flow a d-axis current for setting the rotation speed of rotor 11. Here, the d-axis current is "X" A. Then, the position of the rotor 11 is rotated from 180 ° toward 0 ° by a magnetic field formed by the d-axis current of "X" a. When the position of the rotor 11 reaches 0 ° at time t2, the rotation is stopped and fixed. Then, as shown in fig. 9 (a), at time t3, the d-axis current is 0. In addition, time t1 < time t2 ≦ time t 3. Further, motor control device 30 calculates the position (0 °) of rotor 11 as an electrical angle (0 °) for control.

Even when the rotor 11 has 4 poles, 6 poles, 8 poles, or the like other than 2 poles, or when the number of coils 13 of the stator 12 is 6, 9, 12, or the like other than 3, the position of the rotor 11 is fixed (fixed by excitation) at a position corresponding to the command electrical angle.

In the above-described initial position alignment, whether or not the rotor 11 has been fixed at the position 0 ° may be determined based on the elapse of a preset time (here, t2-t1) from the time t1 at which the d-axis current starts to flow, or may be determined based on the detection of the stop of rotation based on the amount of rotation of the rotor 11 output from the encoder 20.

After the initial position alignment of the rotor 11 is completed, the motor control device 30 may rotate in the reverse direction in accordance with the rotation amount of the rotor 11 during the initial position alignment period (the time from time t1 to time t 2) acquired from the encoder 20, and return the rotor 11 to the position at the time of power-on (before the initial position alignment is performed). At this time, the electrical angle of the position at the time of power-on of the rotor 11 (before initial position alignment is performed) is calculated from the command electrical angle and the rotation amount of the rotor 11.

As described above, in embodiment 1, the command electrical angle is set so as to avoid the electrical angle at which the current of any of the U-phase, V-phase, and W-phase is near the zero crossing. For example, as shown in fig. 9 (a), the electrical angles 30 °, 90 °, 150 °, 210 °, 270 °, and 330 ° in the d-axis current are electrical angles that cause the current of any one of the U-phase, V-phase, and W-phase to cross zero. Therefore, the command electrical angle may be set while avoiding the electrical angles in the vicinity thereof.

In addition, the vicinity of the zero crossing refers to a range of, for example, less than ± 10 ° with respect to the electrical angle such that the zero crossing.

[ 2 nd embodiment ]

In embodiment 1, the command electrical angle is set so as to avoid the electrical angle at which any of the U-phase, V-phase, and W-phase currents is near the zero crossing, and the initial position alignment is performed. In embodiment 2, as the command electrical angle, an electrical angle at which the absolute value of any of the currents in the U-phase, the V-phase, and the W-phase becomes maximum is set as the command electrical angle, and initial position alignment is performed (see fig. 10 (a) to be described later). The other structures are the same as those of embodiment 1, and therefore, the description thereof is omitted.

As shown in fig. 9 (a), for the electrical angle at which the absolute value of any of the currents in the U-phase, V-phase, and W-phase becomes maximum, the U-phase current is 0 ° at the negative side, the W-phase current is 60 ° at the positive side, the V-phase current is 120 ° at the negative side, the U-phase current is 180 ° at the positive side, the W-phase current is 240 ° at the negative side, and the V-phase current is 300 ° at the positive side. If the electrical angle is the same, the current of the phase other than the phase having the largest absolute value is not in the vicinity of the zero crossing.

[ embodiment 3 ]

In embodiment 2, the command electrical angle is set and the rotor 11 is fixed to the electrical angle by excitation. In embodiment 3, the amount of rotation of the rotor 11 in the initial position alignment is reduced. The other structures are the same as those of embodiment 1, and therefore, the description thereof is omitted.

Fig. 10 is a diagram illustrating initial position alignment in embodiment 3. Fig. 10 (a) shows currents flowing through the respective phases of the motor 10, fig. 10 (b) shows a d-axis current, and fig. 10 (c) shows a position of the rotor 11. In fig. 10 (a), the vertical axis represents current (a) and the horizontal axis represents electrical angle (°), in fig. 10 (b), the vertical axis represents d-axis current (a) and the horizontal axis represents time, and in fig. 10 (c), the vertical axis represents position (°) of the rotor and the horizontal axis represents time. The times t0, t1, t2, and … assigned to the horizontal axes of (b) and (c) in fig. 10 are different from the times t0, t1, t2, and … assigned to the horizontal axes of (b) and (c) in fig. 9.

Here, the position of the rotor 11 before the initial position alignment is performed (time t0) is set to 140 °. The command electrical angle is set to 0 °. As shown in fig. 10 (a), the command electrical angle 0 ° is an electrical angle at which the U-phase current is maximized on the negative side (absolute value).

Then, at time t1, motor control device 30 starts to flow a d-axis current for setting the rotation speed of rotor 11. Here, the d-axis current is "X" A. Then, the rotor 11 starts to rotate toward the position 0 °. In this case, the rotor 11 needs to be rotated 140 °. Here, the electrical angle shown in fig. 10 (a) is the same as the position of the rotor 11. Therefore, as can be seen from fig. 10 (a), the electrical angle 120 ° at which the absolute value of the V-phase current is maximized is closest to the position 140 ° in the direction from the position 140 ° to the position 0 °. However, when the power is turned on, the motor control device 30 does not recognize the position of the rotor 11, and thus gradually rotates the rotor 11 toward the command electrical angle of 0 °.

When detecting that the rotation amount of the rotor 11 is 60 ° or more based on the rotation information from the encoder 20, the motor control device 30 resets 60 ° obtained by adding 60 ° to the command electrical angle 0 ° to a new command electrical angle. At this time, the position of the rotor 11 is 80 °. However, the command electrical angle 60 ° is on the same side as the previous command electrical angle 0 °. Therefore, the rotor 11 is rotated in the same direction as before, but toward the command electrical angle of 60 °. Therefore, when detecting that the rotor 11 is rotated in the same direction even if the command electrical angle is reset based on the rotation information from the encoder 20, the motor control device 30 resets the command electrical angle 120 ° obtained by adding 60 ° to the command electrical angle 60 ° to a new command electrical angle. At this time, the position of the rotor 11 is shifted to a side further smaller than 80 °. Therefore, the command electrical angle of 120 ° is in a direction from the position of the rotor 11 toward the reverse rotation. Therefore, the rotor 11 is oriented toward the command electrical angle of 120 °, and starts to rotate in the opposite direction to that before. And is fixed at a position of 120 ° in the command electrical angle by excitation. That is, the initial position alignment is performed at a position (120 ° in this example) closest to a position (140 ° in this example) at the time of power-on of the rotor 11 (before the initial position alignment is performed). Further, the motor control device 30 calculates the position of the rotor 11 as an electrical angle for control.

That is, in the case of 3 phases, as shown in fig. 10 (a), the electrical angle at which the absolute value of each phase current is maximized is set to an interval of 60 °. Therefore, when the rotor 11 is rotated toward the command electrical angle, the rotor 11 is rotated by 60 ° or more, and the initial position alignment of the rotor 11 is performed beyond the closest electrical angle at which the absolute value of the current is maximized. Therefore, when rotor 11 rotates more than 60 °, motor control device 30 decreases the command electrical angle by 60 ° based on the rotation information from encoder 20. Then, it is determined whether the rotation direction of the rotor 11 is reversed. In the case where the rotation direction of the rotor 11 is the same, that is, the rotation direction is not reversed, the command electrical angle is further reduced by 60 °. On the other hand, when the rotation direction is reversed, the position of the rotor 11 is fixed to the command electrical angle while maintaining the command electrical angle. In this case, the rotor 11 is fixed at an electrical angle that is closest to the initial position of the rotor 11 and maximizes the absolute value of the current. When the power is turned on, the encoder 20 does not recognize the position of the rotor 11 when the power is turned on, but detects the rotation speed and the rotation direction of the rotor 11.

This suppresses the load 2 connected to the rotor 11 from largely deviating from the state before the alignment.

The above description is a case where the command electrical angle is smaller than the position of the rotor 11 at the time of power-on (before initial position alignment). Conversely, when the command electrical angle is larger than the position of the rotor 11 at the time of power-on (before initial position alignment), the rotation direction is reversed.

The above 60 ° is a case where the rotor 11 has 1 set of magnetic poles, the stator 12 is 3, and the motor 10 is driven by 3 phases. In the case of another configuration, the values may be set in accordance with the configuration. The 60 ° is an example of a predetermined amount of the rotation information.

[ 4 th embodiment ]

In embodiments 1 to 3, in the initial position alignment of the rotor 11 based on the excitation fixing control, the influence of the dead time for preventing the simultaneous turn-on of the high-side switching element (p-channel FET41) and the low-side switching element (n-channel FET42) is suppressed. In embodiment 4, a dead time correction unit 318 is provided between the coordinate conversion unit 316 and the PWM conversion unit 317 in fig. 8, and the voltage waveforms (Vu, Vv, Vw) of the respective phases output from the coordinate conversion unit 316 are corrected and supplied to the PWM conversion unit 317, thereby suppressing the influence of the dead time in the rotation control and the excitation fixing control.

Fig. 11 is a diagram showing an example of a functional configuration to which motor control device 30A according to embodiment 4 is applied. In addition to the configuration shown in fig. 8 to which motor control device 30 according to embodiment 1 is applied, motor control device 30A includes dead time correction unit 318 between coordinate conversion unit 316 and PWM conversion unit 317. The other structures are the same as those of embodiment 1, and therefore, the description thereof is omitted.

The dead time correction section 318 corrects the voltages Vu, Vv, Vw supplied from the coordinate conversion section 316, and supplies the corrected voltages Vu ', Vv ', Vw ' to the PWM conversion section 317. The dead time correction unit 318 is supplied with a signal relating to the electrical angle Φ e input to the coordinate conversion unit 316.

Fig. 12 is a diagram showing the waveform of the target voltage supplied from the coordinate conversion unit 316 and the waveform of the correction voltage corrected by the dead time correction unit 318. Fig. 12 (a) shows waveforms of the target voltages (Vu, Vv, Vw) supplied from the coordinate conversion unit 316, and fig. 12 (b) shows waveforms of the corrected voltages (Vu ', Vv ', Vw ') corrected by the dead time correction unit 318. In fig. 12 (a) and (b), the vertical axis represents voltage (V) and the horizontal axis represents electrical angle (degree). Fig. 12 (a) and (b) show one of the 3 phases.

The waveforms (Vu ', Vv ', Vw ') of the corrected voltages corrected by the dead time correction unit 318 shown in fig. 12 (b) are waveforms obtained by dividing the waveforms of the target voltages (Vu, Vv, Vw) shown in fig. 12 (a) by the voltage 0V and shifting the waveforms to the + side and the-side. This makes the absolute value of the voltage near the zero crossing particularly large. Thereby, the influence of the dead time is suppressed.

Fig. 13 is a diagram showing an example of the relationship among the correction voltages (Vu ', Vv ', Vw ') set for the respective phases of the motor 10, the currents flowing through the respective phases of the motor 10, and the amount of rotation of the rotary shaft 14 of the motor 10. Fig. 13 (a) shows correction voltages (Vu ', Vv ', Vw ') set for respective phases (U-phase, V-phase, W-phase) of the motor 10, fig. 13 (b) shows currents flowing through the respective phases (U-phase, V-phase, W-phase) of the motor 10, and fig. 13 (c) shows the rotation amount of the rotating shaft 14 of the motor 10. Here, the horizontal axis represents time. In addition, the chain line in (c) of fig. 13 shows an ideal case where the rotation amount of the rotary shaft 14 of the motor 10 changes in proportion to time.

As shown in fig. 12 (b), the correction voltages set for the respective phases (U-phase, V-phase, W-phase) of the motor 10 shown in fig. 13 (a) are near the zero crossing, and the voltages are shifted toward the + side and the-side. That is, the voltage waveform near the zero crossing is different from the voltage waveform when the dead time correction is not performed as shown in fig. 6 (a). Accordingly, the current flowing through each phase (U-phase, V-phase, W-phase) of the motor 10 with respect to the target voltage shown in fig. 13 (b) is approximately sinusoidal. That is, in fig. 13 (b), the deviation from the sine wave is suppressed in the portion α where voltage Vw crosses 0V, the portion β where voltage Vu crosses 0V, and the portion γ where voltage Vv crosses 0V in fig. 6 (a).

Therefore, as shown in fig. 13 (c), the rotation amount of the rotary shaft 14 is suppressed from being deviated from the ideal rotation amount of the rotary shaft 14 shown by the chain line. That is, the dead time correction unit 318 is provided to correct the target voltages Vu, Vv, Vw supplied from the coordinate conversion unit 316 to the correction voltages Vu ', Vv ', Vw ', thereby suppressing the possibility of an error in the position control of the rotor 11 due to the dead time, an increase in power consumption due to the rotor 11 not being at a predetermined position, or a variation in the rotational speed of the rotor 11.

Fig. 14 is a diagram showing a timing chart for controlling the rotation of the motor 10 by applying the motor control device 30A of embodiment 4. The horizontal axis represents time, and it is assumed that time passes in the order of time points a, b, c, and …. Here, assuming that the initial position alignment of the rotor 11 by the excitation fixing control described in embodiment 1 is completed, the start of rotation of the motor 10 (motor ON) is instructed by another control device at time a. In fig. 14, a command speed for instructing the rotation speed of the rotor 11 from another control device, a motor ON signal for instructing the start of rotation of the motor 10, a position error of the rotor 11, a motor STOP (STOP) signal for instructing the STOP of the motor 10, a target q-axis current, a target d-axis current, and an electrical angle Φ e of the motor 10 are described from the upper side.

The motor 10 is controlled to rotate by a motor ON signal instructed from other control means. On the other hand, the other control device instructs the command speed to be set to "0", and the motor 10 is stopped. At this time, the speed control section 306 supplies the motor STOP signal to the coordinate conversion section 316. That is, the motor 10 is stopped by the excitation control in which the command speed is set to "0" and the q-axis current is set to "0" A, d and the axis current is set to "X" a. The command speed of "0" is an example of the command signal for stopping, and the command speed set to "0" by the other control device is an example of the command speed for receiving the stop.

When the rotation of the motor 10 is instructed by the motor ON signal at time a, the command speed is set to gradually increase from "0". Immediately after time a, the position error of the rotor 11 becomes insufficient rotation that rotates slower than the command speed. The position error is reduced along with the rotation of the rotor 11. At this time, the target q-axis current is set to be large, so that the rotation speed is controlled to be increased to easily reach the command speed. Therefore, when the command speed approaches the time point b at which the command speed is set to a constant value, the vehicle is over-rotated faster than the command speed. In addition, the target d-axis current is set to "0" a.

When the command speed at time b is set to a constant value, the control is performed such that the target q-axis current is reduced and the over-rotation easily reaches the command speed.

At time c, the position error is "0", and the rotor 11 rotates at the command speed. Also, the target q-axis current is maintained at a constant value so that the rotor 11 maintains rotation at the command speed.

At time d, the command speed is set to gradually decrease toward the stopped state from time e. Then, the position error of the rotor 11 becomes excessive rotation once, and then becomes insufficient rotation again. At this time, in order to suppress the excessive rotation, the target q-axis current is once set to the minus side and then set to the plus side again.

When the command speed is "0" at time e, the target q-axis current is set to "0" a, and the target d-axis current becomes a preset value. That is, excitation fixing control is performed. Here, the position error of the rotor 11 is stopped from the state of insufficient rotation and fixed at the preset electrical angle Φ e.

When the command speed is set to be gradually increased again at time f, the rotation of the rotor 11 is started in the same manner as at time a. Since the time f to the time k is the same as the time a to the time k, the description thereof is omitted.

As described above, the rotation of the rotor 11 is controlled by the command speed. Here, as shown from time a to time b, the target q-axis current is adjusted in accordance with the position error of the rotor 11, so that the rotation speed of the rotor 11 is controlled to quickly converge to the command speed. Although the time for the rotational speed of the rotor 11 to converge to the command speed is long, the target q-axis current may be set to a constant value.

[ 5 th embodiment ]

In embodiment 4, the dead time correction unit 318 always corrects the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to a correction voltage (Vu ', Vv ', Vw ') and supplies the correction voltage to the PWM conversion unit 317. In embodiment 5, the dead time correction unit 318 corrects the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to the correction voltage (Vu ', Vv', Vw ') and supplies the corrected voltage (Vu', Vv ', Vw') to the PWM conversion unit 317 only when the motor STOP signal is supplied.

Fig. 15 is a diagram showing an example of a functional configuration of motor control device 30B to which embodiment 5 is applied. In addition to the configuration shown in fig. 11 to which motor control device 30A according to embodiment 4 is applied, motor control device 30B supplies a motor STOP signal from speed control unit 306 to dead time correction unit 318. The other structures are the same as those of embodiment 4, and therefore, the description thereof is omitted.

Thus, in the case of the rotation control, the dead time correction unit 318 does not correct the voltage, and supplies the target voltages (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to the PWM conversion unit 317. When the motor STOP signal is supplied from the speed control unit 306, the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 is corrected to the correction voltage (Vu ', Vv ', Vw ') and supplied to the PWM conversion unit 317. Thereby, the load of the CPU 31 in the motor control device 30 is reduced. That is, when the dead time correction is performed regardless of the presence or absence of the motor STOP signal, the correction voltages (Vu ', Vv ', Vw ') are generated following the temporal change of the target voltages (Vu, Vv, Vw). However, when the motor 10 to which the motor STOP signal is supplied is stopped, the target voltages (Vu, Vv, Vw) are fixed, and therefore, the correction to the correction voltages (Vu ', Vv ', Vw ') is easy. That is, the dead time correction can be performed without using the expensive CPU 31 operating at high speed.

[ 6 th embodiment ]

In embodiment 5, only when the motor STOP signal is supplied, the dead time correction unit 318 corrects the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to a correction voltage (Vu ', Vv ', Vw ') and supplies the correction voltage to the PWM conversion unit 317. In embodiment 6, the dead time correction unit 318 corrects the voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to a voltage (Vu ', Vv ', Vw ') and supplies the voltage to the PWM conversion unit 317 only when the rotation speed of the motor 10 is equal to or less than a predetermined speed.

Fig. 16 is a diagram showing an example of a functional configuration to which motor control device 30C according to embodiment 6 is applied. In addition to the configuration shown in fig. 15 to which motor control device 30B according to embodiment 5 is applied, motor control device 30C includes rotation speed determination unit 308. The rotation speed determination unit 308 supplies a rotation speed signal indicating that the rotation speed (here, R.) of the rotor 11 supplied from the rotation speed calculation unit 305 is equal to or less than a predetermined rotation speed (here, Rth.) (R ≦ Rth) to the dead time correction unit 318. The dead time correction unit 318 corrects the target voltages (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to correction voltages (Vu ', Vv', Vw ') and supplies the correction voltages (Vu', Vv ', Vw') to the PWM conversion unit 317 only when the rotation speed signal is supplied. In addition, the rotational speed signal may also be provided in case the rotational speed (R) of the rotor 11 is less than a predetermined rotational speed (Rth) (R < Rth).

Thus, when the rotation speed (R) of the rotor 11 exceeds the predetermined rotation speed (Rth), the dead time correction unit 318 does not correct the voltage, but supplies the target voltages (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 to the PWM conversion unit 317. When the rotation speed (R) of the rotor 11 is equal to or less than a predetermined rotation speed (Rth) or less, the target voltage (Vu, Vv, Vw) supplied from the coordinate conversion unit 316 is corrected to a correction voltage (Vu ', Vv ', Vw ') and supplied to the PWM conversion unit 317. Thereby, the load of the CPU 31 in the motor control device 30C is reduced. That is, when the rotation speed is low, the temporal change of the target voltage (Vu, Vv, Vw) is slow as compared with when it is high. Therefore, if the temporal change of the target voltage (Vu, Vv, Vw) is slow, it is easy to correct to the correction voltage (Vu ', Vv ', Vw '). That is, the CPU 31 can correct the dead time without using an expensive CPU that operates at high speed.

[ 7 th embodiment ]

In embodiment 4, the rotor 11 is fixed at a position of a preset electrical angle Φ e in a stopped state. However, the stop position may be different from the set position of the electrical angle Φ e due to the influence of the load 2 and the like. In embodiment 7, when the position where the rotor 11 stops is different from the position of the electrical angle Φ e, the electrical angle is corrected.

Fig. 17 is a diagram showing an example of a functional configuration to which motor control device 30D according to embodiment 7 is applied. In addition to the configuration shown in fig. 11 to which the motor control device 30A according to embodiment 4 is applied, the motor control device 30D includes a correction electrical angle calculation unit 309. When there is a deviation (Δ Φ e.) in the stop position of the rotor 11 obtained from the encoder output acquisition unit 304, the corrected electrical angle calculation unit 309 supplies a corrected electrical angle Φ e' obtained by correcting the deviation (Δ Φ e) — Δ Φ e) to the dead time correction unit 318. Then, the dead time correction unit 318 replaces the electrical angle with the corrected electrical angle Φ e'.

Fig. 18 is a diagram showing a timing chart for controlling the rotation of the motor 10 by applying the motor control device 30D according to embodiment 7. The horizontal axis is time. The timing chart of fig. 18 is the same as the timing chart of fig. 14 except for the time e and the time f. Therefore, the time e and the time f will be explained, and the explanation of the other parts will be omitted. Here, a time e1 is set between the time e and the time f.

When the command speed becomes "0" at time e, the rotor 11 shifts to a stopped state. Thus, it is assumed that the position at which the rotor 11 stops is deviated from the specified position by the electrical angle Δ Φ e. That is, the electrical angle of the stop position produces an error of Δ Φ e. Therefore, the corrected electrical angle calculation unit 309 calculates the electrical angle Φ e 'obtained by correcting the electrical angle Φ e by- Δ Φ e, and supplies the electrical angle Φ e' to the dead time correction unit 318. Thereby, the electrical angle Φ e is corrected to the electrical angle Φ e', and the influence on the subsequent rotation control of the rotor 11 is suppressed. When the rotation control is performed from the time point f in a state where the stop position has an error, the control is performed in a state where the position of the rotor 11 has an error.

[ 8 th embodiment ]

In embodiments 5 to 7, the d-axis current continues to flow in the stopped state of the rotor 11. However, if the stopped state of the rotor 11 is maintained, the d-axis current does not need to be continuously supplied. In embodiment 8, the d-axis current is reduced after the rotor 11 is brought into a stopped state.

Fig. 19 is a diagram showing an example of a functional configuration of a motor control device 30E to which embodiment 8 is applied. In addition to the configuration shown in fig. 11 to which the motor control device 30A according to embodiment 4 is applied, the motor control device 30E includes a d-axis current adjustment unit 310. The d-axis current adjusting section 310 is supplied with the d-axis current via the 3 rd switching section 323 and is supplied with the electrical angle Φ e via the 4 th switching section 324. Therefore, when the position of the rotor 11 in the stopped state is at the position specified by the electrical angle Φ e, the reduced d-axis current is supplied to the dead time correction unit 318. The case where the position of the rotor 11 is at the position specified by the electrical angle Φ e includes the case where the position error is less than or equal to a predetermined range or less than a predetermined range.

Fig. 20 is a diagram showing a timing chart for controlling the rotation of the motor 10 by applying the motor control device 30E of embodiment 8. The horizontal axis is time. The timing chart of fig. 20 is the same as the timing chart of fig. 14 except for the time between time e and time f and the time between time j and time k. Therefore, description will be given between the time e and the time f and between the time j and the time k, and description of the other parts will be omitted. Here, the times e1, e2, e3, and e4 are provided between the time e and the time f, and the times j1 and j2 are provided between the time j and the time k.

When the command speed becomes "0" at time e, the rotor 11 shifts to a stopped state. At time e1, since the rotor 11 has a positional error, the d-axis current adjustment unit 310 maintains the d-axis current that has caused the rotor 11 to transition to the stopped state. At time e2, when the position error becomes equal to or smaller than a predetermined range or less, the d-axis current adjustment unit 310 gradually decreases (reduces) the d-axis current. However, when the position error exceeds or exceeds a predetermined range at time e3, the d-axis current adjustment unit 310 gradually increases (increases) the d-axis current. Thereby, the position error is reduced. Then, at time e4, the d-axis current adjustment unit 310 maintains the d-axis current at this time.

Similarly, when the command speed becomes "0" at time j, the rotor 11 also shifts to the stopped state. At time j1, when the position error of the rotor 11 becomes equal to or smaller than a predetermined range or less, the d-axis current adjustment unit 310 gradually decreases (reduces) the d-axis current. At this time, since no position error occurs at time j2, the d-axis current adjustment unit 310 sets the d-axis current to "0" a.

As described above, the d-axis current adjustment unit 310 changes the d-axis current in accordance with the positional error (the deviation of the electrical angle Φ e) of the rotor 11 when the rotor 11 is brought into the stopped state. For example, if the position error of the rotor 11 is equal to or smaller than a predetermined range, the d-axis current adjustment unit 310 may set the d-axis current to "0" a. Further, if the position error of the rotor 11 in the stopped state exceeds a predetermined range or becomes equal to or more than a predetermined range, the d-axis current may be increased to reduce the position error of the rotor 11. Further, if the position error of the rotor 11 is equal to or smaller than a predetermined range or less than a predetermined range, the d-axis current may be further reduced from the d-axis current at the time of transition to the stopped state. This suppresses the current consumption of motor control device 30. The predetermined range of the position error does not necessarily have to be "0", and means an allowable error range.

Several of the above-described embodiments 5 to 8 may be combined and used.