阅读说明：本技术 电动机驱动系统 (Motor drive system ) 是由 李学俊 于 2019-08-13 设计创作，主要内容包括：公开了一种电动机驱动系统。本发明一实施例的系统,包括：速度控制部,根据电动机的速度指令与所述电动机的反馈速度之间的差异,通过应用比例增益和第一积分增益的比例积分控制来输出电流指令；速度指令生成部,使用所述速度指令的振幅和速度控制带宽为频率的正弦函数来输出所述速度指令；以及增益变更部,调节所述比例增益和所述第一积分增益,以使所述速度指令与所述反馈速度之间的相位差实质上变为π/4。(A motor drive system is disclosed. The system of an embodiment of the present invention includes: a speed control section that outputs a current command by proportional-integral control applying a proportional gain and a first integral gain, according to a difference between a speed command of a motor and a feedback speed of the motor; a speed command generating unit that outputs the speed command using a sine function having a frequency of an amplitude and a speed control bandwidth of the speed command; and a gain changing unit that adjusts the proportional gain and the first integral gain so that a phase difference between the speed command and the feedback speed becomes substantially pi/4.)

1. An electric motor drive system, comprising:

a speed control section that outputs a current command by proportional-integral control applying a proportional gain and a first integral gain, according to a difference between a speed command of a motor and a feedback speed of the motor;

a speed command generating unit that outputs the speed command using a sine function having a frequency of an amplitude and a speed control bandwidth of the speed command; and

and a gain changing unit that adjusts the proportional gain and the first integral gain so that a phase difference between the speed command and the feedback speed becomes substantially pi/4.

2. The motor drive system according to claim 1,

when a velocity command as a sine wave is applied to the velocity control unit, the velocity control bandwidth is a frequency at which the phase delay of the feedback velocity becomes substantially pi/4.

3. The motor drive system according to claim 1,

the gain changing unit includes:

a phase changing unit that outputs a first signal of a virtual d-axis and a second signal of a virtual q-axis having a phase delay of-pi/2 from the first signal and being an orthogonal component, based on the feedback speed and the speed control bandwidth;

a first integration unit that outputs a phase angle for rotation conversion in accordance with the speed control bandwidth;

a rotation conversion unit that performs rotation conversion on the first signal and the second signal using the phase angle, and outputs a third signal and a fourth signal that are direct currents; and

and an integration control unit that performs integration control of the third signal and the fourth signal by applying a second integration gain for speed control gain adjustment, and outputs a variation amount for the speed control adjustment gain.

4. The motor drive system according to claim 3,

the phase changing unit includes a second-order generalized integrator, which is SOGI.

5. The motor drive system according to claim 3,

the integration control unit includes:

an error determination section that determines an error between the third signal and the fourth signal;

an integral gain applying section that applies the second integral gain to the error; and

a second integration unit that outputs the change amount by integrating the output of the integral gain application unit.

6. The motor drive system according to claim 1, further comprising:

a first switching unit that switches between the speed control unit and the speed command generation unit;

a second switching unit that switches between the speed control unit and the gain changing unit; and

and a control part for outputting a control signal for controlling the connection or disconnection of the first switch part and the second switch part.

7. The motor drive system according to claim 3,

the proportional gain isThe first integral gain is

Wherein, T_ratedIs the rated torque, ω, of the motor_{rm_rated}Is a rated speed of the motor, K is an adjustment gain of the speed control unit, and Δ K is the variation amountIn addition, K_scIs the second integral gain of the second signal component,is the third signal of the first signal and the second signal,is the fourth signal.

8. An electric motor drive system, comprising:

a speed control section that outputs a current command by proportional-integral control applying a proportional gain and a first integral gain, according to a difference between a speed command of a motor and a feedback speed of the motor;

a speed command generating unit that outputs the speed command using a sine function having a frequency of an amplitude and a speed control bandwidth of the speed command; and

a gain changing unit that adjusts the proportional gain and the first integral gain so that the magnitude of the feedback speed becomes substantially the magnitude of the speed command

9. The motor drive system according to claim 8,

the velocity control bandwidth is a bandwidth in which the magnitude of the feedback velocity becomes substantially the velocity command when the velocity command is applied to the velocity control unit as a sine waveOf (c) is detected.

10. The motor drive system according to claim 8,

the gain changing unit includes:

a phase changing unit that outputs a first signal of a virtual d-axis and a second signal of a virtual q-axis having a phase delay of-pi/2 from the first signal and being an orthogonal component, based on the feedback speed and the speed control bandwidth;

a first integration unit that outputs a phase angle for rotation conversion in accordance with the speed control bandwidth;

a rotation conversion unit that performs rotation conversion on the first signal and the second signal using the phase angle, respectively, and outputs a third signal and a fourth signal that are direct currents;

a first multiplier for outputting a product of the third signal and a third signal;

a second multiplier for outputting a product of the fourth signal and a fourth signal;

an adder for adding outputs of the first multiplier and the second multiplier; and

an integral control part for applying a second integral gain for speed control gain adjustment to sum the outputs of the addersIntegral control is performed to output a variation amount for the speed control adjustment gain, where ω is_mIs the amplitude of the velocity command.

11. The motor drive system according to claim 10,

the phase changing unit includes a SOGI.

12. The motor drive system according to claim 10,

the integration control unit includes:

an error determination unit for determining the output of the adder and the output of the adderThe error between;

an integral gain applying section that applies the second integral gain to the error; and

a second integration unit that outputs the change amount by integrating the output of the integral gain application unit.

13. The motor drive system of claim 8, further comprising:

a first switching unit that switches between the speed control unit and the speed command generation unit;

a second switching unit that switches between the speed control unit and the gain changing unit; and

and a control part for outputting a control signal for controlling the connection or disconnection of the first switch part and the second switch part.

14. The motor drive system according to claim 10,

the proportional gain isThe first integral gain is

Wherein, T_ratedIs the rated torque, ω, of the motor_{rm_rated}Is a rated speed of the motor, K is an adjustment gain of the speed control unit, and Δ K is the variation amountIn addition, K_scIs the second integral gain of the second signal component,is the output of the adder.

Technical Field

The present invention relates to a motor drive system.

Background

With the development of power semiconductor technology, a Variable Voltage Variable Frequency (VVVF) power supply can be relatively easily realized by using a power element that can be switched at high speed. VVVF is mainly used in a voltage-source inverter that is a variable-voltage source that generates ac by using a dc voltage as an input. Such voltage-type inverters are mainly used in Energy Storage Systems (ESS), photovoltaic inverters (PV inverters) and motor drive technologies.

When the motor is driven, the rotational speed of the motor is determined by the load torque, and therefore when the speed of the motor is to be controlled, it is necessary to control the torque of the motor in the speed control system.

In a speed control system for a motor using a voltage-type inverter, a speed controller is generally constituted by a simple proportional-integral unit, and the total proportional-integral gain of the proportional-integral unit requires the entire inertia information of a motor drive system.

In the conventional system, the gain of the speed controller depends on the inertia as a mechanical constant, and in the case where the information of the system constant is incorrect, the speed controller cannot satisfy the designed control bandwidth, and thus the performance of the speed control may be deteriorated.

In general, in the case of driving a motor using an inverter, inertia, which is a mechanical constant, is information that is difficult to obtain, and in order to obtain the information, the following process is required: the user obtains inertia information by directly measuring the speed and the torque by the measuring instrument, or a process for inertia estimation needs to be additionally added to the inverter operation or the like. However, since the motor needs to operate stably, it is difficult to obtain accurate inertia information at the initial stage of the operation of the motor.

Disclosure of Invention

Problems to be solved by the invention

The invention provides a motor drive system which can simply set a proportional-integral gain without using inertia information.

Means for solving the problems

In order to solve the above technical problem, a motor driving system according to an embodiment of the present invention may include: a speed control section that outputs a current command by proportional-integral control applying a proportional gain and a first integral gain, according to a difference between a speed command of a motor and a feedback speed of the motor; a speed command generating unit that outputs the speed command using a sine function having a frequency of an amplitude and a speed control bandwidth of the speed command; and a gain changing unit that adjusts the proportional gain and the first integral gain so that a phase difference between the speed command and the feedback speed becomes substantially pi/4.

In an embodiment of the present invention, the velocity control bandwidth may be a frequency at which a phase delay of the feedback velocity becomes substantially pi/4 when a velocity command as a sine wave is applied to the velocity control section.

In an embodiment of the present invention, the gain changing unit may include: a phase changing unit that outputs a first signal of a virtual d-axis and a second signal of a virtual q-axis having a phase delay of-pi/2 from the first signal and being an orthogonal component, based on the feedback speed and the speed control bandwidth; a first integration unit that outputs a phase angle for rotation conversion in accordance with the speed control bandwidth; a rotation conversion unit that performs rotation conversion on the first signal and the second signal using the phase angle, respectively, and outputs a third signal and a fourth signal that are direct currents; and an integration control unit that performs integration control of the third signal and the fourth signal by applying a second integration gain for speed control gain adjustment, and outputs a variation amount for the speed control adjustment gain.

In an embodiment of the invention, the phase altering unit may include a Second Order Generalized Integrator (SOGI).

In an embodiment of the present invention, the integration control section may include: an error determination section that determines an error between the third signal and the fourth signal; an integral gain applying section that applies the second integral gain to the error; and a second integration unit that outputs the change amount by integrating the output of the integral gain application unit.

The system according to an embodiment of the present invention may further include: a first switching unit that switches between the speed control unit and the speed command generation unit; a second switching unit that switches between the speed control unit and the gain changing unit; and a control unit that outputs a control signal for controlling the first and second switching units to be turned on or off.

In an embodiment of the present invention, the proportional gain may beThe first integral gain may beAt this time, T_ratedMay be the rated torque, ω, of the motor_{rm_rated}May be a rated speed of the motor, K may be an adjustment gain of the speed control section, and Δ K may be the amount of change andin addition, K_scIt may be the second integral gain that is,it may be the third signal that is,may be the fourth signal.

In order to solve the above-mentioned problems, a motor drive system according to an embodiment of the present invention may include: a speed control section that outputs a current command by proportional-integral control applying a proportional gain and a first integral gain, according to a difference between a speed command of a motor and a feedback speed of the motor; a speed command generating unit that outputs the speed command using a sine function having a frequency of an amplitude and a speed control bandwidth of the speed command; and a gain changing unit for adjusting the ratioA gain and the first integral gain so that the magnitude of the feedback speed becomes substantially the magnitude of the speed command

In an embodiment of the present invention, when a velocity command as a sine wave is applied to the velocity control unit, the velocity control bandwidth may be such that the magnitude of the feedback velocity substantially becomes the velocity commandOf (c) is detected.

In an embodiment of the present invention, the gain changing unit may include: a phase changing unit that outputs a first signal of a virtual d-axis and a second signal of a virtual q-axis having a phase delay of-pi/2 from the first signal and being an orthogonal component, based on the feedback speed and the speed control bandwidth; a first integration unit that outputs a phase angle for rotation conversion in accordance with the speed control bandwidth; a rotation conversion unit that performs rotation conversion on the first signal and the second signal using the phase angle, and outputs a third signal and a fourth signal that are direct currents; a first multiplier for outputting a product of the third signal and a third signal; a second multiplier for outputting a product of the fourth signal and a fourth signal; an adder for adding outputs of the first multiplier and the second multiplier; and an integral control section for applying a second integral gain for speed control gain adjustment to sum outputs of the addersIntegral control is performed to output a variation amount for the speed control adjustment gain, where ω is_mIs the amplitude of the velocity command.

In an embodiment of the invention, the phase changing unit may include an SOGI.

In an embodiment of the present invention, the integration control section may include: an error determination part for determining the additionOutput of a method and a method as describedThe error between; an integral gain applying section that applies the second integral gain to the error; and a second integration unit that outputs the change amount by integrating the output of the integral gain application unit.

The system according to an embodiment of the present invention may further include: a first switching unit that switches between the speed control unit and the speed command generation unit; a second switching unit that switches between the speed control unit and the gain changing unit; and a control unit that outputs a control signal for controlling the first and second switching units to be turned on or off.

In an embodiment of the present invention, the proportional gain may beThe first integral gain may beAt this time, T_ratedMay be the rated torque, ω, of the motor_{rm_rated}May be a rated speed of the motor, K may be an adjustment gain of the speed control section, and Δ K may be the amount of change andin addition, K_scIt may be the second integral gain that is,may be the output of the adder.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention as described above sets the speed control gain, not by an additional measurement or estimation process, but by simply adjusting the speed control adjustment gain according to the nameplate value of the motor, thereby setting the optimum gain.

Drawings

Fig. 1 is a configuration diagram of a general motor speed control system.

Fig. 2 is a detailed configuration diagram of the speed control unit of fig. 1.

Fig. 3 is a configuration diagram of a motor drive system according to an embodiment of the present invention.

Fig. 4 is a detailed configuration diagram of the speed command generating unit of fig. 3.

Fig. 5 is a detailed configuration diagram of a first embodiment of the gain changing section of fig. 3.

Fig. 6 is a detailed configuration diagram of a second embodiment of the gain changing section of fig. 3.

Detailed Description

In order to fully understand the constitution and effect of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various forms and may be variously modified. However, the description of the present embodiments is intended to provide a complete disclosure of the invention, and to fully disclose the scope of the invention to those skilled in the art to which the invention pertains. In the drawings, the size of constituent elements is exaggerated for convenience of explanation, and the scale of constituent elements may be exaggerated or reduced.

The terms "first", "second", and the like may be used to describe various constituent elements, but these constituent elements should not be limited to the above terms. The above terms may be used only to distinguish one constituent element from another constituent element. For example, a "first constituent element" may be named a "second constituent element", and similarly, a "second constituent element" may also be named a "first constituent element", without departing from the scope of the present invention. Furthermore, unless the context clearly dictates otherwise, expressions in the singular include expressions in the plural. Unless otherwise defined, terms used in the embodiments of the present invention may be construed as meanings well known to those skilled in the art.

Hereinafter, a conventional motor driving system will be described with reference to fig. 1 and 2, and a motor driving system according to an embodiment of the present invention will be described with reference to fig. 3 to 6.

Fig. 1 is a configuration diagram of a general motor speed control system.

In order to follow the speed command of the motor 200The speed control unit 110 measures the speed ω using the synchronous angular and speed detector (position sensor) 160 or the position estimator_rmAnd is used for control, and outputs a synchronous coordinate system current command based on a difference between the speed command and the measured speed

In order to follow the synchronous coordinate system d and q-axis current commands output from the speed control unit 110The current control unit 120 measures d-and q-axis currents of the motor 200And is used for control, and outputs d and q-axis voltage commands of the synchronous coordinate system based on the difference between the current command and the measured current

At this time, the current command can be usedThe measured current can be represented byIs represented by a vector of (a).

The coordinate conversion unit 130 converts the synchronous coordinate system d and q-axis physical quantities into abc physical quantities, and the coordinate conversion unit 170 converts the abc physical quantities into synchronous coordinate system d and q-axis physical quantities.

To be input to the coordinate conversion section 130Is changed intoThe following equation is used. In the following, the following description is given,

[ equation 1]

Angle θ used in equation 1 above_eIs an electrical angle detected by the synchronous angle and velocity detector 160.

In addition, i is input to the coordinate conversion unit 170_abcsIs changed intoThe following equation is used. Wherein the content of the first and second substances,

[ equation 2]

Angle θ used in equation 2 above_eIs an electrical angle detected by the synchronous angle and velocity detector 160.

PWM control unit 140 commands abc phase voltageChange to proper pole voltage commandPulse Width Modulation (PWM) is performed. Wherein the content of the first and second substances,

inverter 150 instructs the voltage of the voltage generated by PWM control unit 140Synthesizing into an electrode voltage. Pole voltage commandSynthesized by the inverter 150 to the actual pole voltage v_abcn. At this time, the process of the present invention,

the synchronous angle and speed detector 160 is a position sensor/position estimator such as an encoder or a resolver, and detects a synchronous angle and speed to detect a mechanical speed ω used by the speed control unit 110_rmAnd an electrical angle theta for coordinate conversion used in the coordinate conversion sections 130, 170_e。

Fig. 2 is a detailed configuration diagram of the speed control unit 110 of fig. 1.

Speed command of motorAnd measuring the velocity omega_rmError between by proportional gain of K_pProportional controller 111 and integral gain of K_iThe sum 114 of the values after the integral controllers 112, 113 is used as a torque commandThe torque command is output and converted into d-axis and q-axis current commands in a synchronous coordinate system by the conversion unit 115And output.

In the configuration of the speed control unit 110 described above, the proportional-integral gain is set through the following procedure.

If the influence caused by the friction force is neglected in the general inertia system mechanical equation, it can be expressed as follows.

[ equation 3]

Wherein, T_eIs the torque applied to the motor, and J represents the inertia of the motor.

The transfer function of the proportional-integral speed controller can be expressed as follows.

[ equation 4]

At this time, K_pIs the proportional gain, K_iIs the integral gain.

When it is assumed that the dynamic characteristics of current control unit 120 are sufficiently faster than speed control unit 110, the gain of current control unit 120 is approximated to 1, and the ideal case where the torque of motor 200 determined by the output current of inverter 150 follows the torque command well is assumedIn this case, the speed control system can be expressed by the following equation.

[ equation 5]

In order to solve equation 5 above, the velocity response to the velocity command can be expressed by the following transfer function.

[ equation 6]

When the bandwidth of the speed control part 110 is ω_scAnd designed to be over-attenuated, the proportional gain and the integral gain can be obtained by the following equation 7.

[ equation 7]

K_p＝Jω_sc

As described above, it was confirmed that the gain of the speed control unit 110 depends on the inertia, which is a mechanical constant of the motor drive system. Therefore, when the information of the system is not correct, the speed control portion 110 cannot satisfy the designed control bandwidth, and there is a problem in that the performance of the speed control is deteriorated.

In general, in the case of driving a motor using an inverter, inertia, which is a mechanical constant, is information that is difficult to obtain. To obtain this information, the following procedure is required: the user directly measures the speed, the torque, and the like by the measuring instrument, or, a process for estimating the inertia needs to be additionally attached to the inverter action. However, in order to perform such an operation, the motor 200 needs to be stably operated to some extent, and it is difficult to perform such an operation at the initial stage of the operation.

In addition, in the case where there is no inertia information, the gain of the speed control unit needs to be set by the user while directly and manually measuring the speed, the torque, and the like by the measuring instrument. Therefore, the gain is important to be able to control the speed, but there is a problem that it is difficult to easily set the gain.

To solve such a problem, the present invention provides a gain setting based on inertia obtained using a control settling time (settling time) so that a user can easily set a gain of speed control without additional inertia information. In addition, a method is provided for automatically adjusting the speed control gain based on such gain settings. Thus, the present invention stably drives the motor.

First, a method for setting a speed control gain according to the present invention will be described.

Under the assumption that the inertia of the load is constant, the torque can be determined by the following equation.

[ equation 8]

When a rated torque T is to be applied_ratedAt the time of reaching the rated speed omega_{rm_rated}Is defined as a stabilization time t_sThe inertia of the system can be determined by equation 9.

[ equation 9]

Considering the transfer function of equation 6 above, the time t will be stabilized_sIs defined as follows.

[ equation 10]

In the above equation 10, K represents the adjustment gain of the speed control section, ω_scIndicating the bandwidth of the speed control section. According to an embodiment of the present invention, the user can easily change the gain of the speed control section by adjusting the adjustment gain K of the speed control section.

On the other hand, the inertia is obtained by substituting the stable time of equation 10 into equation 9, as shown in the following equation.

[ equation 11]

When the inertia of equation 11 above is substituted into the gain of the velocity control section of equation 7, the gain of the velocity control section may be defined as follows.

[ equation 12]

K_i＝0.2·K_p·ω_sc

In the above equation 12, K_pDenotes the proportional gain, K_iRepresenting the integral gain.

In general, the bandwidth of the speed control portion is a value given by the bandwidth of the current control portion, and the initial value of K, which is the adjustment gain of the speed control portion, can be found by considering the attenuation rate of the system. Therefore, the user can simply configure the motor drive system by changing K in the bandwidth of a given speed control section.

Fig. 3 is a configuration diagram of a motor drive system according to an embodiment of the present invention.

As shown in the drawing, the motor drive system 1 according to the embodiment of the present invention may include a speed control unit 11, a current control unit 12, a first conversion unit 13, a PWM control unit 14, an inverter 15, a detection unit 16, a second conversion unit 17, a control unit 20, a first switching unit 30, a second switching unit 35, a speed command generation unit 40, and a gain change unit 50.

The operations of speed control unit 11, current control unit 12, first conversion unit 13, PWM control unit 14, inverter 15, detection unit 16, and second conversion unit 17 are the same as those described with reference to fig. 1.

The speed control part 11 can be based on the speed command of the motor 2With the actual speed ω of the motor 2 detected by the detecting section 16_rmThe difference between the two, output the d and q axis current commands of the synchronous coordinate system

The current control unit 12 can control the current command according to the d-axis and q-axis current commands of the synchronous coordinate systemD-and q-axis measuring currents in a synchronous coordinate system with the motor 2The difference between the two signals is used for outputting d-axis and q-axis voltage commands of the synchronous coordinate system

The first conversion unit 13 can use equation 1Is converted intoIn addition, the second conversion unit 17 can use equation 2 to convert i_abcsIs converted into

PWM control unit 14 may command the abc phase voltagesChange to appropriate pole voltage commandAnd performs Pulse Width Modulation (PWM), the inverter 15 can instruct the voltage of the voltage formed by the PWM control section 14Synthesizing into an electrode voltage.

The detection unit 16 can detect the synchronous angle and speed of the motor 2 and supply the detected angle and speed to the speed control unit 11, the first conversion unit 13, the second conversion unit 17, and the gain change unit 50.

The speed command generating portion 40 may generate a speed command for adjusting the gain of the speed control portion 11.

The gain changing section 50 may receive the speed detected by the detecting section 16, and may change K, which is the adjustment gain of the speed control section 10.

The first switch unit 30 and the second switch unit 35 are turned on or off according to the control flag FlagSC of the control unit 20, and when the first switch unit 30 and the second switch unit 35 are turned on, the gain of the speed control unit 10 can be adjusted and outputted, and when the first switch unit 30 and the second switch unit 35 are turned off, the gain of the speed control unit 10 can be outputted in the same manner as in the conventional manner of fig. 1.

Specifically, when flag sc is off, the speed command for driving the motor is input to the speed control unit 11, and when flag sc is on, the speed command generated by the speed command generation unit 40 is input to the speed control unit 11.

When flag sc is off, Δ K for adjusting the gain of speed control unit 11 becomes 0, and the gain of speed control unit 11 is not changed, but when flag sc is on, Δ K is output from gain changing unit 50, and the gain of speed control unit 11 can be changed.

That is, when the flag sc as the control signal supplied from the control unit 20 is on, the speed command generating unit 40 generates a speed command for adjusting the gain of the speed control unit 11, and the speed command may be applied to the speed control unit 11. The adjustment gain change amount Δ K of the speed control unit 11 may be obtained using the speed (feedback speed) of the motor 2 fed back from the detection unit 16, and Δ K may be used to change the gain of the speed control unit 11.

Fig. 4 is a detailed configuration diagram of the speed command generating unit of fig. 3.

In the velocity command generating unit according to the embodiment of the present invention, the amplitude ω of the velocity command is set to_mAnd sine function-sin ω_sct may be multiplied by the multiplier 41 and output as a speed command.

At this time, the sine function sin ω is multiplied_scthe purpose of t is to make the magnitude ω of the speed command_mVibrating with a sine function, the frequency of which may be ω, which is the control bandwidth set by the speed control unit 11_sc. The speed command may be expressed as the following equation.

[ equation 13]

That is, the speed command may be generated to have ω_mThe amplitude of (a) is a sine wave.

On the other hand, in the case where a sine wave command is applied, the speed control bandwidth of the speed control portion 11 can be defined as a frequency at which the phase delay of the feedback speed is pi/4. Therefore, in the case where the sine wave command of equation 13 is applied, the feedback speed can be defined as equation 14.

[ equation 14]

At this time, ω_fbRepresenting the amplitude of the feedback velocity.

As shown in equation 14, the gain change unit 50 can obtain the adjustment gain K of the speed control unit 11 in which the phase difference between the speed command and the feedback speed is pi/4.

Fig. 5 is a detailed configuration diagram of a first embodiment of the gain changing section of fig. 3.

As shown in the drawing, the gain change section 50 of the first embodiment of the present invention may include a phase change section 51, a first integration section 52, a rotation conversion section 53, an error determination section 54, an integral gain application section 55, and a second integration section 56.

The phase changing unit 51 can receive the feedback speed and the set control bandwidth and output a first signal of a virtual d-axisAnd a second signal having a phase delay of-pi/2 compared with the first signal and having an imaginary q-axis as a quadrature componentIn this case, the phase changer 51 may be, for example, a Second Order Generalized Integrator (SOGI). When a sine wave is applied, the SOGI outputs a signal having a phase delay of-pi/2 and being a quadrature component.

The signal output from the phase changing unit 51 is expressed by the following equation.

[ equation 15]

In the embodiment of the present invention, the configuration of the phase changing unit 51 is described as, for example, SOGI, but various circuits may be used to obtain the output signal of expression 15.

As described above, the imaginary d and q-axis signals, which are sine wave ac signals, can be converted into dc components by rotation conversion.

The first signal and the second signal of imaginary d and q axes, which are sine wave ac signals, can be converted into dc components by rotation conversion, and equation 15 is expressed in terms of angles as follows.

[ equation 16]

The first integrating section 52 can output the rotation angle of the sine wave command by integrating the control bandwidth. This is expressed as follows.

[ equation 17]

θ_sc＝∫ω_scdt＝ω_sct

When the rotation conversion is defined as equation 18 and applied to the alternating current signal of equation 16, it may be converted into a direct current signal as shown in equation 19 and the same as the output of the phase converting part 53. That is, as an output signal of the phase changing section 51Can be converted into

[ equation 18]

[ equation 19]

Referring to equation 19 above, it can be confirmed that the converted DC signal has a phase delay of π/4Have the same value. In other words, as the output signal of the phase converting section 53The same value indicates that the phase delay between the feedback speed and the command speed is pi/4. Therefore, if the gain of the speed control section 11 is adjusted so thatHaving the same speed, the speed control portion 11 satisfies a given speed control bandwidth, thereby performing automatic adjustment.

In one embodiment of the invention, integral control may be used to adjust the speed control gain. It can be expressed as equation 20.

[ equation 20]

At this time, K_scThe integral gain for the speed control gain adjustment is indicated. As shown in equation 20 above, the speed control adjustment gain variation Δ K may be generated by integral control such thatHave the same value. This can be achieved by the error determination section 54, the integral gain application section 55, and the integration section 56.

That is, the error determination section 54 determines two direct current signals of the rotation conversion section 53Andthe integral gain applying section 55 applies the integral gain K_scApplied to the error, and integrated by the second integrating section 56, the variation Δ K of the speed control adjustment gain can be output.

The speed control unit 11 in fig. 3 may receive the change Δ K in the speed control adjustment gain generated as described above again and change the proportional-integral gain as shown in equation 21.

[ equation 21]

On the other hand, in an embodiment of the present invention, the speed control bandwidth may also be defined such that the magnitude of the feedback speed becomes commanded when a sine wave command is appliedOf (c) is detected. Therefore, when the sine wave command of equation 13 is applied, the feedback speed can be defined as equation 22.

[ equation 22]

ω_rm＝-ω_fbsin(ω_sct-φ_fb)

In equation 22, φ_fbThe phase delay representing the velocity of the feedback is taken as ω which is the magnitude of the velocity of the feedback_fbBecome commanded when speed control bandwidth is satisfiedI.e. its size becomes

When the feedback velocity of equation 22 is taken as a virtual d-axis signal and the quadrature component having a phase delay of-pi/2 compared to the velocity is taken as a virtual q-axis signal, it can also be expressed as equation 23.

[ equation 23]

Imaginary d-axis and q-axis signals, which are sine wave ac signals, can be converted into dc components through rotation conversion. Equation 23 is expressed in terms as follows.

[ equation 24]

If the rotation conversion is applied to the ac signal of the above equation 24, the ac signal can be converted into a dc signal as shown in equation 25.

[ equation 25]

From the above equation 25, ω_fbCan be obtained as shown in equation 26.

[ equation 26]

That is, since in Δ K satisfying the speed control bandwidth, ω is_fbBecome intoUnder this condition, equation 27 can be written.

[ equation 27]

That is, when the gain of the speed control section 11 is adjusted so thatAndhaving the same value, the speed control portion 11 satisfies a given speed control bandwidth, thereby being able to perform automatic adjustment. Also, in an embodiment of the present invention, the speed control gain may be adjusted using integral control, and may be expressed as equation 28.

[ equation 28]

The above process is illustrated by fig. 6. Fig. 6 is a detailed configuration diagram of a second embodiment of the gain changing section of fig. 3.

As shown in the drawing, the gain change section 50 of the second embodiment of the present invention may include a phase change section 61, a first integration section 62, a rotation conversion section 63, a first multiplier 64, a second multiplier 65, an adder 66, an error determination section 67, an integral gain application section 68, and a second integration section 69.

In one embodiment of FIG. 6, ω_rmIs the feedback speed, ω, of the motor_scIs a preset speed control bandwidth.

The phase changing unit 61 may change the feedback speed ω of the motor 2_rmAnd speed control bandwidth omega_scAs an input, and can output a signal with a phase delay of-pi/2 when a sine wave is applied. That is, in the second embodiment of the present invention, when the speed control bandwidth is defined such that the magnitude of the feedback speed becomes commanded when a sine wave command is appliedIn the case of the frequency of (3), the phase changing unit 61 may change the phase and output the phase as in expression 24.

The rotation converting section 63 may receive the phase angle θ integrating the speed control bandwidth by the first integrating section 62_scAnd may pass through a phase angle θ_scThe output of the phase changing section 61 is rotationally converted. The output of the rotation converter 63 is shown in equation 25 as the output signal of the phase changer 1Can be converted into

The first multiplier 64 and the second multiplier 65 may output separatelyAndadder 66 may output asOf the sum of the first and second multipliers 64 and 65

Then, the error determination section 67 determines the output of the adder 66 andthe integral gain applying section 68 applies the integral gain K to the error_scApplied to the error, and integrated by the second integrating section 69, thereby being able to output Δ K as the amount of change in the speed control adjustment gain.

The speed control unit 11 may receive Δ K, which is the amount of change in the adjustment gain of the speed control, and may change the proportional-integral gain as shown in equation 21.

In the past, the gain of the speed control section was set by the speed and torque measured by the measuring instrument or was hard to realize by the additional inertia estimation, but unlike this, according to an embodiment of the present invention, the speed control gain can be set by simply adjusting the speed control adjustment gain according to the nameplate value of the motor without the need for an additional measurement or estimation process.

That is, the present invention can easily set the speed control gain when the user initially drives the motor by using the gain obtained by the control settling time. In addition, the present invention can set an optimal speed control gain by automatically adjusting the speed control gain without additional inertia estimation or measurement.

While embodiments of the invention have been described above, this is by way of example only, and it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof. Therefore, the true technical scope of the present invention should be determined by the appended claims.