阅读说明：本技术 旋转电机的控制装置 (Control device for rotating electric machine ) 是由 北川润 森辰也 家造坊勋 泽田诚晋 久保建太 于 2019-06-04 设计创作，主要内容包括：本发明提供一种旋转电机的控制装置,能降低磁极位置(旋转角度)的推定延迟,并且能抑制推定用电压指令所引起的开关频率的高频化。旋转电机的控制装置(10)基于电压指令与载波的比较结果,使逆变器(2)所具有的开关元件导通关断并将电压施加到绕组,在固定于绕组的静止坐标系上,生成预先设定的周期的推定用电压指令,生成与推定用电压指令的周期相同周期的载波,从电流的检测值中提取推定用电压指令的周期的频率分量,并基于频率分量来推定旋转角度(θ)。(The invention provides a control device for a rotating electrical machine, which can reduce the estimation delay of a magnetic pole position (rotation angle) and can inhibit the high frequency of a switching frequency caused by a voltage command for estimation. A control device (10) for a rotating electrical machine turns on and off switching elements of an inverter (2) based on a comparison result between a voltage command and a carrier wave, applies a voltage to a winding, generates an estimation voltage command having a predetermined period in a stationary coordinate system fixed to the winding, generates a carrier wave having the same period as the period of the estimation voltage command, extracts a frequency component of the period of the estimation voltage command from a detected value of a current, and estimates a rotation angle (theta) based on the frequency component.)

1. A control device for a rotating electrical machine that controls the rotating electrical machine having a rotor with saliency via an inverter, the control device comprising:

a current detection unit that detects a current flowing through a winding provided in a stator of the rotating electric machine;

an angle estimation unit that estimates a rotation angle of the rotor based on a detected value of the current;

a current control unit that calculates a drive voltage command for driving the rotating electric machine based on a detected value of the current;

an estimation command generating unit that generates an estimation voltage command;

a voltage command calculation unit that calculates a voltage command by adding the estimation voltage command to the drive voltage command;

a carrier generation unit that generates a carrier; and

a voltage applying unit that turns on and off a switching element included in the inverter and applies a voltage to the winding based on a result of comparison between the voltage command and the carrier,

the estimation command generating unit generates the estimation voltage command in a predetermined cycle in a stationary coordinate system fixed to the winding,

the carrier generation unit generates the carrier having the same period as the period of the estimation voltage command,

the angle estimation unit extracts a frequency component of a cycle of the estimation voltage command from a detected value of the current, and estimates the rotation angle based on the frequency component.

2. The control device of a rotating electric machine according to claim 1,

the winding is a winding of three phases,

the carrier generation unit generates 3 carriers corresponding to each of three phases, 3 carriers having a phase difference of 1/3 cycles of a period in which the carriers are provided between phases,

the estimation command generating unit generates 3 estimation voltage commands corresponding to each of three phases, and the 3 estimation voltage commands have a phase difference of 1/3 cycles of a cycle in which the estimation voltage commands are provided between phases.

3. The control device of a rotating electric machine according to claim 1 or 2,

the carrier generation unit generates a 1.5-cycle triangular wave that ends at the peak of the valley from the peak of the peak or ends at the peak of the peak from the peak of the valley as the carrier of 1 cycle.

4. The control device of the rotating electric machine according to any one of claims 1 to 3,

the current detection unit detects a current at least 2 times in 1 cycle of the carrier wave.

5. The control device of the rotating electric machine according to any one of claims 1 to 4,

a current sensor is provided in a series circuit of the switching element on the positive side and the switching element on the negative side of the inverter,

the current detection unit detects the current based on an output signal of the current sensor when the positive-side switching element or the negative-side switching element is turned on.

6. The control device of the rotating electric machine according to any one of claims 1 to 5,

the winding is a winding of three phases,

the estimation command generating unit generates 3 estimation voltage commands corresponding to each of three phases, 3 of the estimation voltage commands having a phase difference of 1/3 cycles of a cycle in which the estimation voltage commands are provided between phases,

in 3 divided periods obtained by equally dividing 1 cycle of the voltage command for estimation into 3, values of at least 2 divided periods of the voltage command for estimation of each phase are different from each other.

7. The control device of the rotating electric machine according to any one of claims 1 to 6,

the frequency of the cycle of the estimation voltage command is 18000Hz or more.

Technical Field

The present application relates to a control device for a rotating electric machine.

Background

For fine control of the rotating electrical machine, a control device is required that controls power supply to the winding based on magnetic pole position information (rotation angle information) of a rotor of the rotating electrical machine. Conventionally, magnetic pole position information of a rotor is acquired by a rotation sensor attached to a rotating electric machine. However, the installation of the rotation sensor requires a large number of disadvantages, including a cost increase, a space for installation, and measures for preventing an abnormality in the rotation sensor. Therefore, many sensorless magnetic pole position estimation methods have been proposed to estimate magnetic pole position information of the rotor without providing a rotation sensor.

The sensorless magnetic pole position estimation method is roughly classified into 2 methods. The 1 st estimation method is an induced voltage method of estimating a magnetic pole position of a rotor by estimating an induced voltage of a rotating electrical machine. The induced voltage method can estimate the magnetic pole position with high accuracy when the rotating electrical machine is rotating to the extent that induced voltage is generated, but it is difficult to estimate the magnetic pole position in a region where the number of revolutions is low where induced voltage is not generated or hardly generated.

The 2 nd estimation method is a high-frequency superposition method for estimating the magnetic pole position of the rotor using the saliency of the rotating electrical machine. In the high-frequency superimposing method, a high-frequency voltage for estimating the magnetic pole position is superimposed on the rotating electric machine, and the magnetic pole position is estimated from the amplitude change of the current due to the position dependency of the inductance. Therefore, the present invention can be used in a region where the rotation speed is low.

However, in the high-frequency superimposing method using the saliency, since a high-frequency voltage is applied to estimate the magnetic pole position, there is a problem that noise corresponding to the frequency of the high-frequency voltage is generated. For example, in patent document 1, a high-frequency voltage based on a dq axis (alternating-current voltage) that rotates in synchronization with the rotation of a rotor is used for position estimation control. In this embodiment, since a high-frequency voltage having a period equal to the period (1 triangular wave) of the carrier wave (carrier wave) is used, it is easy to increase the frequency of the high-frequency voltage. That is, by setting the frequency of the high-frequency voltage to be outside the human audible range, noise can be reduced.

In patent document 2, a UVW axis-based high-frequency voltage is used for position estimation control. In this embodiment, a voltage vector rotating at a fixed cycle is applied to a UVW axis coordinate system which is a stationary coordinate system fixed to a stator winding of a rotating electrical machine, and a magnetic pole position is directly estimated by utilizing that a high-frequency current amplitude responding thereto has a position dependency similar to that of an inductor. Therefore, as in the case of the 1 st estimation method, PID control of the position error is not required, and no response delay occurs at the time of estimation.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-

Patent document 2: japanese patent No. 6203435

Disclosure of Invention

Technical problem to be solved by the invention

However, in patent document 1 using a dq-axis-based high-frequency voltage, an observer including PID control using an error Δ θ between an actual rotor position and an estimated position is used for estimating a magnetic pole position. That is, the error Δ θ is fed back and integrated to update the latest estimated position. Thus, the position can be estimated only with a response not higher than the response frequency of the feedback set by the PID control gain. Further, the responsiveness of the magnetic pole position estimation must be lower than the responsiveness of the current control, and the position estimation cannot be made highly responsive.

In contrast, the position estimation device as disclosed in patent document 2 uses a high-frequency voltage based on the UVW axis of the rotating electrical machine. As shown in a waveform diagram of a voltage command (high-frequency voltage command) for position estimation shown in fig. 6 of patent document 2, 3 carriers of triangular waves are necessary to generate a high-frequency voltage. This is because, when the half cycle of the triangular wave is set to 1 section, the output voltage of the PWM inverter changes only 1 time during the half cycle. That is, when the 1 cycle of the high-frequency voltage is 360 °, in order to generate a high-frequency voltage of three-phase alternating current in which each phase is shifted by 120 °, the high-frequency voltage must be set so as to be shifted by 2 intervals between phases and to have 1 cycle in 6 intervals. If the simplest rectangular wave is used to represent the high frequency waveform, the rise and fall are repeated every 180 °. If a phase difference of 120 ° is set between phases, the rise of each phase becomes a phase difference of 120 ° between phases, and the rise of a certain phase and the fall of a different phase become a phase difference of 60 °.

Therefore, the technique of patent document 2 requires division of 1 cycle of the high-frequency voltage into 6 segments at 60 °, and 6 intervals. Therefore, if 1 segment is a half cycle of the triangular carrier, a carrier of 3 cycles is required for 1 cycle of the high-frequency voltage. Compared with the method of patent document 1, the carrier wave (triangular wave) required for 1 cycle of the high-frequency voltage is 3 times, and the number of switching times is also 3 times. That is, in the technique of patent document 2, if the frequency of the high-frequency voltage is increased in order to reduce noise caused by the application of the high-frequency voltage, the switching frequency per unit time of the high-frequency voltage based on the UVW axis becomes larger than that of the high-frequency voltage based on the dq axis, and the switching loss and the electromagnetic noise increase. The switching loss is an energy loss generated when the switching element of the inverter is switched, and the loss increases in proportion to the number of switching times, and is important from the viewpoint of energy saving. In addition, since the frequency of noise increases and the magnitude of noise increases as the number of switching times per unit time, that is, the switching frequency increases, electromagnetic noise is important from the viewpoint of EMI (electromagnetic interference). That is, it is important to reduce the switching frequency.

Therefore, in the dq-axis reference high-frequency voltage of patent document 1, the increase in switching frequency due to the high-frequency voltage can be suppressed, but the position estimation response is poor, and in the UVW-axis reference high-frequency voltage of patent document 2, the position estimation response can be improved, but the switching frequency due to the high-frequency voltage increases. Therefore, the two technologies have advantages and disadvantages, and the advantages and the disadvantages have a trade-off relation.

Therefore, it is desirable to obtain a control device for a rotating electrical machine that can reduce delay in estimation of a magnetic pole position (rotation angle) and suppress increase in switching frequency due to an estimation voltage command.

Means for solving the problems

A control device for a rotating electrical machine according to the present application is a control device for a rotating electrical machine that controls a rotating electrical machine having a rotor with saliency via an inverter, and includes:

a current detection unit that detects a current flowing through a winding provided in a stator of the rotating electric machine;

an angle estimation unit that estimates a rotation angle of the rotor based on a detected value of the current;

a current control unit that calculates a drive voltage command for driving the rotating electric machine based on a detected value of the current;

an estimation command generating unit that generates an estimation voltage command;

a voltage command calculation unit that calculates a voltage command by adding the estimation voltage command to the drive voltage command;

a carrier generation unit that generates a carrier; and

a voltage applying unit that turns on and off a switching element included in the inverter and applies a voltage to the winding based on a result of comparison between the voltage command and the carrier,

the estimation command generating unit generates the estimation voltage command in a predetermined cycle in a stationary coordinate system fixed to the winding,

the carrier generation unit generates the carrier having the same period as the period of the estimation voltage command,

the angle estimation unit extracts a frequency component of a cycle of the estimation voltage command from a detected value of the current, and estimates the rotation angle based on the frequency component.

Effects of the invention

According to the control device for a rotating electrical machine of the present application, the cycle of the estimation voltage command is set to be the same as the cycle of the carrier wave, and therefore the number of times of switching per 1 cycle of the estimation voltage command can be reduced. This reduces switching loss and electromagnetic noise generated by switching. Further, since the estimation voltage command is generated on the stationary coordinate system fixed to the winding, it is possible to extract the frequency component of the cycle of the estimation voltage command from the detected value of the current by utilizing the magnetic pole position dependency of the inductance of the rotor having the saliency, directly estimate the rotation angle based on the frequency component, and reduce the estimation delay.

Drawings

Fig. 1 is a schematic configuration diagram of a rotating electric machine, an inverter, and a rotating electric machine control device according to embodiment 1.

Fig. 2 is a schematic block diagram of a control device for a rotating electric machine according to embodiment 1.

Fig. 3 is a hardware configuration diagram of a control device for a rotating electric machine according to embodiment 1.

Fig. 4 is a timing chart of the three-phase estimation voltage command according to embodiment 1.

Fig. 5 is a timing chart of three-phase carriers according to embodiment 1.

Fig. 6 is a timing chart for explaining generation of a PWM control signal by comparison of the estimation voltage command and the carrier wave according to embodiment 1.

Fig. 7 is a timing chart for explaining the operation of the estimation voltage command, the carrier wave, and the detected value of the current according to embodiment 1.

Fig. 8 is a schematic block diagram of the angle estimation unit according to embodiment 1.

Fig. 9 is a timing chart for explaining the operation of the U-phase estimation voltage command and the detected values of the carrier wave and the current in accordance with embodiment 1.

Fig. 10 is a timing chart of the three-phase estimation voltage command according to embodiment 2.

Fig. 11 is a timing chart for explaining an operation of setting a phase of a detected value of a current with respect to an estimation voltage command and a carrier wave according to embodiment 2.

Fig. 12 is a timing chart for explaining an operation of setting the phase of the detected value of the current with respect to the estimation voltage command and the carrier wave according to embodiment 2.

Fig. 13 is a timing chart for explaining an operation of setting the phase of the detected value of the current with respect to the estimation voltage command and the carrier wave according to embodiment 2.

Fig. 14 is a timing chart for explaining generation of a PWM control signal by comparison of the estimation voltage command and the carrier wave according to embodiment 3.

Fig. 15 is a timing chart for explaining the operation of the estimation voltage command, the carrier wave, and the detected value of the current according to embodiment 3.

Fig. 16 is a timing chart for explaining the operation of the U-phase estimation voltage command and the detected values of the carrier wave and the current according to embodiment 3.

Detailed Description

1. Embodiment mode 1

A control device 10 for a rotating electrical machine according to embodiment 1 (hereinafter simply referred to as a control device 10) will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of a rotating electric machine 1, an inverter 2, and a control device 10 according to the present embodiment.

1-1. rotating electrical machine

The rotating electrical machine 1 is a permanent magnet synchronous rotating electrical machine, and has a stator provided with three-phase windings Cu, Cv, and Cw of U-phase, V-phase, and W-phase, and a rotor provided with permanent magnets. Three-phase windings Cu, Cv and Cw are arranged for star connection. Further, the three-phase windings may be connected in a delta connection. The rotor has saliency, and the d-axis inductance is different from the q-axis inductance. For example, an embedded magnet synchronous rotating electrical machine in which a permanent magnet is embedded inside a rotor is provided.

1-2 inverter

The inverter 2 has a plurality of switching elements and performs dc/ac conversion between the dc power supply 25 and the three-phase winding. The inverter 2 is provided with 3 sets of series circuits in which a positive-side switching element 22a connected to the positive side of the dc power supply 25 and a negative-side switching element 22b connected to the negative side of the dc power supply 25 are connected in series, corresponding to the windings of the three phases. The inverter 2 includes three positive-side switching elements 22a and three negative-side switching elements 22b, and a total of 6 switching elements. The connection point at which the positive-side switching element 22a and the negative-side switching element 22b are connected in series is connected to the winding of the corresponding phase.

As the switching element, an IGBT (Insulated Gate Bipolar Transistor) having a diode 23 connected in reverse parallel, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) having a function of a diode connected in reverse parallel, or the like is used. The gate terminal of each switching element is connected to the control device 10. Each switching element is turned on and off by PWM control signals Swu, SWv, and SWv output from the control device 10.

The filter capacitor 24 is connected between the positive side and the negative side of the inverter 2. The voltage sensor 3 outputs an electric signal corresponding to the dc voltage of the dc power supply 25. The output signal of the current sensor 3 is input to the control device 10.

The inverter 2 is provided with a current sensor 4 for detecting a current flowing through the winding. In the present embodiment, the current sensor 4 is provided in a series circuit of the positive-side switching element 22a and the negative-side switching element 22 b. In this example, the shunt resistors 4U, 4V, and 4W are connected in series to the negative electrode side of the negative-electrode-side switching element 22b in the series circuit of each phase. The potential difference between both ends of the shunt resistors 4U, 4V, and 4W of each phase is input to the control device 10. The shunt resistors 4U, 4V, and 4W may be connected in series to the positive electrode side of the positive electrode side switching element 22a in the series circuit of each phase. Alternatively, the current sensor 4 may be a hall element or the like provided on a wire of each phase connecting a series circuit of switching elements and a winding.

A chargeable and dischargeable power storage device (for example, a lithium ion battery, a nickel hydride battery, or an electric double layer capacitor) is used as dc power supply 25. The DC power supply 25 may be provided with a DC-DC converter, which is a DC power converter for boosting or reducing a DC voltage.

1-3. control device

The control device 10 controls the rotating electrical machine 1 via the inverter 2. As shown in fig. 2, the control device 10 includes a current detection unit 31, an angle estimation unit 32, a voltage detection unit 33, a current control unit 34, an estimation instruction generation unit 35, a voltage instruction calculation unit 36, a carrier generation unit 37, a voltage application unit 38, and the like, which will be described later. Each function of the control device 10 is realized by a processing circuit provided in the control device 10. Specifically, as shown in fig. 3, the control device 10 includes, as Processing circuits, an arithmetic Processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 that exchanges data with the arithmetic Processing device 90, an input circuit 92 that inputs an external signal to the arithmetic Processing device 90, an output circuit 93 that outputs a signal from the arithmetic Processing device 90 to the outside, and the like.

The arithmetic processing device 90 may include an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, various Signal processing circuits, and the like. Further, the arithmetic processing device 90 may be provided with a plurality of arithmetic processing devices of the same type or different types to share and execute the respective processes. The storage device 91 may include a RAM (Random Access Memory) configured to be able to Read and write data from and to the arithmetic processing device 90, a ROM (Read Only Memory) configured to be able to Read data from the arithmetic processing device 90, and the like. The input circuit 92 is connected to various sensors and switches such as the voltage sensor 3 and the current sensor 4, and includes an a/D converter and the like that inputs output signals of these sensors and switches to the arithmetic processing device 90. The output circuit 93 is connected to an electrical load such as a gate drive circuit for driving the switching elements to be turned on and off, and includes a drive circuit for outputting a control signal from the arithmetic processing unit 90 to the electrical load.

The functions of the control units 31 to 38 and the like in fig. 2 included in the control device 10 are realized by the arithmetic processing device 90 executing software (program) stored in the storage device 91 such as ROM and cooperating with other hardware of the control device 10 such as the storage device 91, the input circuit 92, and the output circuit 93. The setting data used by the control units 31 to 38 and the like are stored in the storage device 91 such as a ROM as a part of software (program). Hereinafter, each function of the control device 10 will be described in detail.

1-3-1. each detecting part

The voltage detection unit 33 detects the power supply voltage VDC of the dc power supply 25. In the present embodiment, the voltage detection unit 33 detects the power supply voltage VDC based on the output signal of the voltage sensor 3.

The current detection unit 31 detects winding currents Iu, Iv, and Iw flowing through the three-phase windings. In the present embodiment, the current detection unit 31 detects the currents Iu, Iv, and Iw flowing from the inverter 2 through the windings Cu, Cv, and Cw of the respective phases based on the output signal of the current sensor 4.

In the present embodiment, the current sensor 4 is provided on the negative side of the negative-side switching element 22b in the series circuit of each phase, and it is necessary to detect a current at a timing when the negative-side switching element 22b is turned on and a current flows through the current sensor 4. Therefore, for each phase, when the negative-side switching element 22b is turned on, the current detection unit 31 detects a current based on the output signal of the current sensor. In the present embodiment, the current detection unit 31 detects the currents Iu, Iv, and Iw of the respective phases based on the output signals of the current sensors 4 of the respective phases at the peaks of the carrier of the respective phases. Further, the current detection may be performed with a delay of several μ s to several tens of μ s from the peak due to the influence of ringing caused by switching and the processing procedure of the arithmetic processing device 90.

In the case where the current sensor 4 is provided on the positive side of the positive-side switching element 22a in the series circuit of each phase, the current detection unit 31 may detect the current based on the output signal of the current sensor when the positive-side switching element 22a is turned on for each phase, and the current detection unit 31 may detect the currents Iu, Iv, Iw for each phase based on the output signal of the current sensor 4 for each phase at the peak of the valley of the carrier wave for each phase.

1-3-2. current control part

The current control unit 34 calculates a drive voltage command for driving the rotating electric machine 1 based on the detected value of the current. The current control unit 34 includes a current command calculation unit 34a, a current coordinate conversion unit 34b, a feedback control unit 34c, and a voltage coordinate conversion unit 34 d.

The current reference calculation unit 34a calculates a current reference Id _ ref for the d-axis and a current reference Iq _ ref for the q-axis. For calculation of the dq-axis current references Id _ ref and Iq _ ref, known current vector control methods such as maximum torque current control, field weakening control, and Id-0 control are used.

The current coordinate conversion unit 34b performs three-phase two-phase conversion and rotational coordinate conversion on the three-phase current detection values Iu, Iv, Iw based on the magnetic pole position θ estimated by the angle estimation unit 32 described later, and calculates the d-axis current detection value Id and the q-axis current detection value Iq. Here, the d-axis is defined as the direction (magnetic pole position) of the N-pole of the permanent magnet provided to the rotor, and the q-axis is defined as the direction that is advanced by 90 ° (pi/2) of the electrical angle from the d-axis.

The feedback control unit 34c calculates current deviations between the current references Id _ ref and Iq _ ref of the dq axis and the current detection values Id and Iq of the dq axis, and performs control calculation such as PID control based on the current deviations to calculate the drive voltage references Vd _ ref of the d axis and the drive voltage references Vq _ ref of the q axis.

The voltage coordinate conversion unit 34d performs fixed coordinate conversion and two-phase and three-phase conversion on the dq-axis drive voltage commands Vd _ ref and Vq _ ref based on the magnetic pole position θ to calculate a U-phase drive voltage command Vu _ ref, a V-phase drive voltage command Vv _ ref, and a W-phase drive voltage command Vw _ ref. The main components of the three-phase drive voltage commands Vu _ ref, Vv _ ref, and Vw _ ref are three-phase ac voltages (sine waves) for driving the rotating electric machine 1, and are referred to as fundamental waves. The fundamental wave has the same period as the electrical angle 1 period of the rotating electrical machine.

1-3-3 estimation instruction generating part

The estimation command generating unit 35 generates an estimation voltage command of a preset period Th in a stationary coordinate system fixed to the winding. The frequency fh of the cycle Th of the estimation voltage command is higher than the frequency of the three-phase drive voltage command (fundamental wave).

< setting of frequency >

In the present embodiment, the frequency fh of the cycle Th of the estimation voltage command is set to 18000Hz or higher. The frequency fh is the inverse of the cycle Th of the estimation voltage command (fh is 1/Th). Thus, the frequency fh of the estimation voltage command can be set to be equal to or higher than the human audible range (18000Hz), and noise generated by superimposing the estimation voltage command on the voltage command can be reduced.

< phase difference between phases >

In the present embodiment, as shown in fig. 4, the estimation command generating unit 35 generates 3 estimation voltage commands Vuh, Vvh, Vwh corresponding to the three phases, respectively. The three-phase estimation voltage commands Vuh, Vvh, and Vwh are provided with a phase difference of 1/3 cycles of the estimation voltage command cycle between phases. That is, when the 1 cycle Th of the estimation voltage command is 360 °, the estimation voltage command Vvh of the V phase has a phase delay of 120 ° with respect to the estimation voltage command Vuh of the U phase, the estimation voltage command Vwh of the W phase has a phase delay of 120 ° with respect to the estimation voltage command Vvh of the V phase, and the estimation voltage command Vuh of the U phase has a phase delay of 120 ° with respect to the estimation voltage command Vwh of the W phase. The three-phase estimation voltage commands Vuh, Vvh, Vwh have the same waveform with a phase difference therebetween.

< 1 cycle 3 partitioning >

The voltage command for estimation may be a cosine wave (or a sine wave), but the processing load increases in order to generate a cosine wave of a higher frequency. Therefore, it is preferable to generate an estimation voltage command having a component with a predetermined frequency fh with a phase difference of 120 ° between phases while reducing the processing load.

In the present embodiment, in order to provide a phase difference of 120 °, the 1 cycle Th is divided equally into 3, which is the minimum number of divisions required. In the 3 divided periods, the voltage command for estimation of each phase is set so that values of at least 2 divided periods are different from each other. In the present embodiment, the values set for 2 divided periods among the 3 divided periods are different from each other. Thus, the value of 1 divided period is set to be different from the value of the remaining 2 divided periods. Each divided period is a period of 120 °, and the voltage command for estimation of each phase is shifted by 1 divided period between phases.

Thus, the voltage command for estimation of each phase has 2 different values in the 1 cycle Th, and has a component of the frequency fh of the cycle Th. This allows the frequency fh component of the voltage command for estimation to be generated in the current flowing through the winding, and the rotation angle to be estimated based on the detected value of the current. The 2 values that differ in the 1 cycle are the minimum voltage commands for estimating the rotation angle, and the processing load for producing the voltage commands for estimation can be minimized. As described in embodiment 2 below, the voltage command for estimation for each phase may have 3 or more different values in the 1 cycle Th.

As shown in the following equation, the total value of the three-phase estimation voltage commands Vuh, Vvh, Vwh is set to 0 at each time point, and three-phase balance is achieved. The integrated value of the estimation voltage command for each phase in 1 cycle is set to 0.

Vuh+Vvh+Vwh＝0···(1)

The estimation voltage commands for the respective phases may be shifted, and the total value of the estimation voltage commands Vuh, Vvh, Vwh for the three phases may be shifted from 0.

< relationship between voltage command for estimation and frequency component of current >

Here, when it is assumed that the component of the frequency fh of the estimation voltage command included in the estimation voltage command is a cosine wave of the amplitude B, the estimation voltage command vh (t), the component Ih of the frequency fh of the estimation voltage command included in the alternating current flowing through the winding, and the amplitude a of the frequency component Ih of the current have the following relationship.

Ih(t)＝A×sin(ωh×t)

Vh(t)＝B×cos(ωh×t)

＝L×dIh(t)/dt···(2)

A＝B/(L×ωh)

Here, ω h is the angular frequency of the voltage command for estimation, t is time, and L is the inductance of the rotating electric machine. The angular frequency ω h of the estimation voltage command is a value obtained by dividing 2 π by the cycle Th of the estimation voltage command.

Since the inductance L has a convex polarity, the inductance L changes according to the magnetic pole position θ, and a predetermined relationship exists between the inductance L and the magnetic pole position θ. From this, it is understood that the magnetic pole position θ can be estimated based on the amplitude a of the frequency component Ih of the estimation voltage command included in the current according to expression 3 of expression (2).

< noise resistance of current detection value >

Further, the larger the amplitude a of the frequency component Ih of the estimation voltage command included in the current, the higher the resistance against noise superimposed on the detected value of the current. According to expression 3 of expression (2), in order to increase the amplitude a of the frequency component Ih, the inductance L may be decreased, or the angular frequency ω h of the estimation voltage command may be decreased, so that the amplitude B of the estimation voltage command may be increased. The inductance L is related to the design of the rotating electric machine and is therefore not easily adjustable. It is not preferable that the angular frequency ω h of the estimation voltage command is small because the noise is large. On the other hand, if the amplitude B of the estimation voltage command is made too large, the voltage command on which the estimation voltage command is superimposed exceeds the limit (+ VDC/2 to-VDC/2) of the power supply voltage VDC, and therefore, the increase amount of the amplitude B of the estimation voltage command has an upper limit.

It is preferable to set the three-phase estimation voltage commands Vuh, Vvh, Vwh based on the above-described contents and to improve the noise resistance of the amplitude a of the frequency component Ih of the estimation voltage command included in the current. For example, in an operating region of the rotating electrical machine in which the angle estimation is to be performed using the estimation voltage command, the maximum value of the amplitude of the estimation voltage command that falls within the limited range of the power supply voltage VDC may be set as the amplitude of the estimation voltage command under the operating condition that the amplitude of the three-phase drive voltage command is maximum. Alternatively, a value that is smaller than the maximum value of the amplitude of the estimation voltage command that converges within the limit range of the power supply voltage VDC but that can ensure noise resistance may be set as the amplitude of the estimation voltage command.

1-3-4 voltage command value calculating part

The voltage command calculation unit 36 calculates a voltage command by adding the estimation voltage command to the driving voltage command. In the present embodiment, the voltage command calculation unit 36 calculates the voltage commands Vu, Vv, Vw for the three phases by adding the estimation voltage commands Vuh, Vvh, Vwh for the three phases to the drive voltage commands Vu _ ref, Vv _ ref, Vw _ ref for the three phases, as shown in the following expression.

Vu＊＝Vu＿ref+Vuh

Vv＊＝Vv＿ref+Vvh···(3)

Vw＊＝Vw＿ref+Vwh

1-3-5 carrier generation part

The carrier generation unit 37 generates a carrier having a cycle Th identical to the cycle Th of the estimation voltage command. The carrier wave oscillates with an amplitude of the power supply voltage VDC/2 centered at 0.

< phase difference between phases >

In the present embodiment, as shown in fig. 5, the carrier generation unit 37 generates 3 carriers Cau, Cav, and Caw corresponding to each of the three phases. The three-phase carriers Cau, Cav, and Caw have a phase difference of 1/3 cycles of the carrier cycle Th between the phases. That is, if the 1 Th period of the carrier is 360, the carrier Cav of the V phase has a phase delay of 120 ° with respect to the carrier Cau of the U phase, the carrier Caw of the W phase has a phase delay of 120 ° with respect to the carrier Cav of the V phase, and the carrier Cau of the U phase has a phase delay of 120 ° with respect to the carrier Caw of the W phase. The three-phase carriers Cau, Cav, and Caw have the same waveform with a phase difference therebetween.

The voltage command to which the estimation voltage command is added is compared with a carrier, and a PWM control signal for turning on and off the switching element is generated. Therefore, by providing the same phase difference between phases as the estimation voltage command to the carrier wave, the phase difference between phases can be provided to the PWM control signal as a result of the comparison, and much information can be left on the phase difference of the estimation voltage command in the PWM control signal. This enables the frequency component Ih of the voltage command for estimation required for angle estimation to be effectively superimposed on the winding current of each phase.

< waveform of carrier wave >

As shown in fig. 5, the carrier wave generator 37 generates a 1.5-cycle triangular wave starting from the peak of the peak and ending at the peak of the valley as a 1-cycle Th carrier wave. The carrier wave generator 37 may generate a 1.5-cycle triangular wave starting from the peak of the valley and ending at the peak of the peak as a 1-cycle Th carrier wave.

As described above, the current detection unit 31 detects the currents Iu, Iv, and Iw of the respective phases at the peaks of the carrier wave of the respective phases, but the peaks of the carrier wave exist 2 times in the 1-cycle Th of the estimation voltage command. Therefore, the current detection unit 31 can detect the current 2 times in the 1 cycle Th of the estimation voltage command. This makes it easy to detect the amplitude a of the frequency component Ih of the estimation voltage command included in the current.

1-3-6 voltage applying part

The voltage applying unit 38 applies a voltage to the winding based on the result of comparison of the voltage command and the carrier wave. The voltage applying unit 38 applies a voltage to the winding by turning on and off a plurality of switching elements included in the inverter 2.

The voltage application unit 38 compares the three-phase voltage commands Vu, Vv, Vw with the three-phase carriers Cau, Cav, Caw in the corresponding phases, and generates three-phase PWM control signals SWu, SWv, SWw. As shown in fig. 6, for each phase, when the voltage command exceeds the carrier wave, the voltage application unit 38 turns on the PWM control signal, and when the voltage command falls below the carrier wave, the voltage application unit 38 turns off the PWM control signal. The voltage application unit 38 outputs three-phase PWM control signals SWu, SWv, and SWw to the inverter 2. For each phase, when the PWM control signal is on, the positive-side switching element 22a is on and the negative-side switching element 22b is off, and when the PWM control signal is off, the positive-side switching element 22a is off and the negative-side switching element 22b is on.

Fig. 6 shows an example of generation of the three-phase PWM control signals SWu, SWv, SWw. Here, the three-phase drive voltage commands Vu _ ref, Vv _ ref, and Vw _ ref are set to zero, and the three-phase voltage commands Vu, Vv, and Vw are equal to the three-phase estimation voltage commands Vuh, Vvh, and Vwh. As indicated by the o mark where the switching elements perform switching, 4 times of switching are performed in 1 cycle Th of the estimation voltage command for each phase. In the technique of patent document 2, switching is performed 6 times in 1 cycle of the position estimating voltage, but in the present embodiment, the switching loss and the electromagnetic noise generated by switching can be reduced to 2/3.

Since the three-phase carrier wave is also provided with the same phase difference as the three-phase estimation voltage command, the waveforms of the three-phase PWM control signals have the same phase difference. Thus, even with a small number of switching times, information on the phase difference of the voltage commands for estimating the three phases can be left in the three-phase PWM control signals in a large amount.

< relationship between voltage command for estimation and carrier wave >

Here, the relationship between the voltage commands Vuh, Vvh, Vwh for estimating three phases and the carriers Cau, Cav, Caw for three phases will be described. As described above, the position estimation voltage used in patent document 2 has a period 3 times the period of the carrier wave (fig. 6 of patent document 2). Therefore, switching was performed 6 times in every 1 cycle of the position estimation voltage. As described above, when the frequency of the estimation voltage command is increased, the number of switching times in 1 cycle Th of the estimation voltage command is preferably small from the viewpoint of switching loss and the like. Therefore, the three-phase estimation voltage commands Vuh, Vvh, Vwh are set so that the number of switching times per 1 cycle Th of the estimation voltage command is reduced as shown in fig. 4.

On the other hand, if the number of switching times is reduced in only 1 Th cycle of the estimation voltage command, the waveform of the carrier wave can be maintained as the existing triangular wave, and only the estimation voltage command can be set to the waveform of fig. 4. However, if the current is detected 2 times in the 1 cycle Th of the estimation voltage command, the cycle of the triangular wave needs to be 2 times the cycle Th of the estimation voltage command, the cycle of the PWM control signal needs to be 2 times the cycle Th of the estimation voltage command, and a frequency component 1/2 times the frequency fh of the estimation voltage command is superimposed on the current. Therefore, even if the frequency fh of the estimation voltage command is set to be equal to or higher than the human audible range, frequencies below the frequency fh are generated, and noise cannot be sufficiently reduced.

On the other hand, in the present embodiment, as shown in fig. 6, since the period of the carrier wave is set to be the same as the period Th of the estimation voltage command, the period of the PWM control signal can be set to be the same as the period Th of the estimation voltage command, and it is possible to suppress the frequency components in the audible range or less from being superimposed on the current and reduce the noise generated by superimposing the estimation voltage command.

1-3-7. angle estimation part

The angle estimation unit 32 estimates a rotation angle θ (magnetic pole position θ) at the electrical angle of the rotor based on the detected value of the current. Angle estimating unit 32 extracts frequency component Ih of cycle Th of the voltage command for estimation from the detected value of the current, and estimates rotation angle θ (magnetic pole position θ) based on frequency component Ih.

As described by equation 3 using equation (2), the magnetic pole position θ is estimated using the fact that the amplitude a of the frequency component Ih of the estimation voltage command included in the current changes according to the inductance L, which changes according to the magnetic pole position θ. Further, since the rotor has a salient polarity, the inductance L in the stationary coordinate system changes depending on the magnetic pole position θ, and a predetermined relationship exists between the inductance L and the magnetic pole position θ.

< timing of Current detection >

The current detection according to the present embodiment will be described with reference to fig. 7. In the example of fig. 7, the carriers Cau, Cav, and Caw of the three phases are offset from the voltage commands Vuh, Vvh, and Vwh for estimation of the three phases by 1/3 cycles, as compared with the example of fig. 6.

As described above, the current sensor 4 is provided on the negative electrode side of the negative-electrode-side switching element 22b, and current detection is performed at the peak of the carrier wave on which the negative-electrode-side switching element 22b is turned on. In 1 cycle Th of the estimation voltage command, the peak of the carrier wave exists 2 times. In addition, if the PWM control signal is off and the switching element 22b on the negative side is on, the current can be detected even at a timing other than the peak of the carrier wave, and the number of current detections can be increased.

Alternatively, the current detection of the remaining 1 phase may be calculated based on the current detection values of the 2 phases, using a case where the total value of the currents Iu, Iv, and Iw of the three phases is zero (Iu + Iv + Iw is 0). For example, even when the U-phase carrier Cau is at the peak of the valley and the U-phase current Iu cannot be detected, the V-phase carrier Cav and the W-phase carrier Caw are at the peak, and the V-phase current Iv and the W-phase current Iw can be detected. Then, a value obtained by multiplying the sum of the V-phase current detection value Iv and the W-phase current detection value Iw by-1 is calculated as the U-phase current detection value Iu. This increases the number of current detections in the 1-cycle Th to 3.

< detailed Structure of Angle estimating part >

In the present embodiment, the angle estimation unit 32 calculates the amplitude a of the frequency component Ih of the estimation voltage command included in the current based on the current detection values detected at least 2 times (2 times in the present example) within the 1 cycle Th of the estimation voltage command, and estimates the rotation angle θ (magnetic pole position θ) based on the amplitude a.

As shown in fig. 8, the angle estimation unit 32 includes amplitude calculation units 32au, 32av, and 32aw for the three phases, and an angle calculation unit 32 b.

The U-phase amplitude calculation unit 32Au extracts the frequency component Ihu of the estimation voltage command from the current detection value Iu of the U-phase, and calculates the amplitude Au of the frequency component of the estimation voltage command included in the U-phase current based on the frequency component Ihu. The V-phase amplitude calculation unit 32Av extracts the frequency component Ihv of the voltage command for estimation from the current detection value Iv of the V-phase, and calculates the amplitude Av of the frequency component of the voltage command for estimation included in the V-phase current based on the frequency component Ihv. The W-phase amplitude calculation unit 32Aw extracts the frequency component Ihw of the voltage command for estimation from the current detection value Iw of the W-phase, and calculates the amplitude Aw of the frequency component of the voltage command for estimation included in the W-phase current based on the frequency component Ihw.

In the frequency component extraction process, a band-pass filter process may be used in which a component of the frequency fh of the estimation voltage command is passed through and components other than the frequency fh of the estimation voltage command are attenuated. In the amplitude calculation process, the self-interphase integration may be used, or the difference between the maximum value and the minimum value may be simply calculated as the amplitude. Alternatively, in the frequency component extraction process and the amplitude calculation process, a fourier transform that extracts only the frequency fh of the estimation voltage command may be used.

Alternatively, as shown in the U-phase current detection value Iu in fig. 7, the amplitude Au of the frequency component Ihu of the estimation voltage command is proportional to the difference between the 2 current detection values detected in 1 cycle Th of the estimation voltage command. Therefore, the amplitude calculation units 32au, 32av, and 32aw for the three phases can calculate the difference between 2 current detection values detected in 1 cycle Th of the estimation voltage command for each phase, and calculate the difference between the current detection values as the amplitude of the frequency component of the estimation voltage command included in the current.

For example, as shown in fig. 9 showing an example of the U-phase current detection value Iu, the U-phase amplitude calculation unit 32Au subtracts the U-phase current detection value Iu2 detected at the current detection timing of the 2 nd time from the U-phase current detection value Iu1 detected at the current detection timing of the 1 st time, at the current detection timing of the 2 nd time within the 1 cycle Th of the estimation voltage command, and calculates the absolute value of the value obtained thereby as the amplitude Au of the frequency component of the estimation voltage command included in the U-phase current (Au | Iu1-Iu2 |).

Then, the angle calculating unit 32b estimates the magnetic pole position θ based on the amplitudes Au, Av, and Aw of the frequency components of the estimation voltage command included in the currents of the three phases. For example, the angle calculating unit 32b may convert the three-phase amplitudes Au, Av, and Aw from three phases to two phases, and then perform an arctangent calculation to calculate the magnetic pole position θ, may perform an arccosine calculation on any one of the three-phase amplitudes Au, Av, and Aw to calculate the magnetic pole position θ, or may perform an arccosine calculation on each of the three-phase amplitudes Au, Av, and Aw to calculate 3 magnetic pole positions θ, and set the average value as the final magnetic pole position θ.

2. Embodiment mode 2

Next, the control device 10 for a rotating electric machine according to embodiment 2 will be described. The same components as those in embodiment 1 will not be described. The basic configuration of the control device 10 according to the present embodiment is the same as that of embodiment 1, but the configuration of the estimation command generating unit 35 is different from that of embodiment 1.

As shown in fig. 10, as in embodiment 1, the 1 cycle Th of the estimation voltage command is equally divided into 3, which is the minimum number of divisions required. However, unlike embodiment 1, in the present embodiment, the values of the voltage command for estimation for each phase are set to be different from each other for 3 divided periods among 3 divided periods. Each divided period is a period of 120 °, and the voltage command for estimation of each phase is shifted by 1 divided period between phases.

At each time, the total value of the three-phase estimation voltage commands Vuh, Vvh, Vwh is set to 0, as in embodiment 1. The integral value of the voltage command for estimation of each phase in 1 cycle is set to 0.

In the example of fig. 10, the estimation voltage command in the 2 nd divided period within 1 cycle Th of the estimation voltage command is set to zero, the estimation voltage command in the 1 st divided period is set to a negative value, and the estimation voltage command in the 3 rd divided period is set to a negative/positive inversion value (positive value) of the negative value in the 1 st divided period. In addition, if the total value of the three phases is zero and the integrated value of 1 cycle of each phase is zero, the value of each divided period may be replaced.

As in embodiment 1, the carrier wave generator 37 generates a 1.5-cycle triangular wave starting from the peak of the peak and ending at the peak of the valley as a 1-cycle Th carrier wave. Fig. 11, 12, and 13 show examples of the control operation of the U phase. In fig. 11 to 13, the phases of the voltage commands for estimation are different from each other by 120 ° with respect to the carrier wave.

As shown in fig. 11 to 13, if the phase of the estimation voltage command differs from the carrier, the waveform of the PWM control signal SWu of the U phase differs, and the waveform of the frequency component of the estimation voltage command superimposed on the U phase current also differs. Therefore, the magnitude of the difference between the 2 current detection values detected in 1 cycle Th of the estimation voltage command is different. Since the noise resistance becomes higher as the difference between the 2 current detection values becomes larger, the setting of the phase difference in fig. 11 or 13 is more preferable than the setting of the phase difference in fig. 12. Thus, by setting the waveform and relative phase of the carrier wave and the estimation voltage command in accordance with the electrical characteristics of the rotating electric machine, the difference between the 2 current detection values can be increased, and noise resistance can be improved.

3. Embodiment 3

Next, the control device 10 for a rotating electric machine according to embodiment 3 will be described. The same components as those in embodiment 1 will not be described. The basic configuration of the control device 10 according to the present embodiment is the same as that of embodiment 1, but the configuration of the carrier generation unit 37 is different from that of embodiment 1.

In the present embodiment, as shown in fig. 14, the carrier wave generator 37 generates an asymmetric triangular wave with 1 cycle as a carrier wave with 1 cycle Th. The asymmetric triangular wave is a triangular wave whose slope at the time of increase is different from that at the time of decrease. In embodiments 1 and 2, a symmetrical triangular wave is used, and the slope at the time of increase is the same as the slope at the time of decrease. The three-phase carriers Cau, Cav, and Caw have phase differences of 1/3 cycles of the cycle Th of the carrier wave provided between the phases.

While embodiment 1 has 4 switching times per 1 cycle Th of the estimation voltage command, the present embodiment has 2 switching times per 1 cycle Th of the estimation voltage command. By further reducing the number of switching times, switching loss and electromagnetic noise generated by switching can be further reduced.

As shown in fig. 15, in the current detection operation, in the present embodiment, the current detection unit 31 detects the currents Iu, Iv, and Iw of the respective phases based on the output signals of the current sensors 4 of the respective phases at both the peaks and the valleys of the carrier wave of the respective phases.

In the present embodiment, the current sensor 4 is provided on the electric wire connecting the series circuit of the switching element and each phase of the winding, and can detect the current at an arbitrary timing regardless of the period during which the switching element is on. In addition, the current sensor 4 is provided on the positive side of the positive-side switching element 22a in addition to the negative side of the negative-side switching element 22 a.

Since the number of current detections in 1 cycle Th of the estimation voltage command can be maintained at 2 even if the number of switching times is reduced, the rotation angle θ can be estimated by extracting the frequency component of the cycle Th of the estimation voltage command from the detected current values (in this example, the difference between 2 detected current values is calculated in 1 cycle Th of the estimation voltage command) as in embodiment 1.

Alternatively, even in the case where the current sensor 4 is provided only on the negative side of the negative-side switching element 22a, if the current is detected 2 times while the PWM control signal is off and the negative-side switching element 22b is off, as in the operation of the circuit detection of the U-phase shown in fig. 16, the current can be detected 2 times in the 1 cycle Th of the estimation voltage command. This enables the frequency component of the cycle Th of the estimation voltage command to be extracted, and the rotation angle θ to be estimated.

The control device 10 for the rotating electric machine according to each of the above embodiments can be applied to a control device for an electric power steering device that assists steering of an automobile. In this case, the output torque of the rotating electrical machine can be controlled by estimating the rotation angle of the rotor without using an angle sensor. Further, even if the voltage command for estimation is superimposed, it is possible to suppress an increase in noise and an increase in the number of switching times. Thus, the electric power steering apparatus can be obtained at low cost and comfortably.

The control device 10 for a rotating electrical machine according to each of the embodiments described above may be applied to a control device for a driving rotating electrical machine or a generating rotating electrical machine of an electric vehicle or a hybrid vehicle. In this case, similarly, a high-efficiency rotating electrical machine in which an increase in switching loss is suppressed can be obtained. Alternatively, the control device 10 for a rotating electrical machine may be configured to control a rotating electrical machine for various purposes.

While various exemplary embodiments and examples are described herein, the various features, aspects, and functions described in one or more embodiments are not limited in their application to a particular embodiment, but may be applied to embodiments alone or in various combinations. Therefore, it is considered that numerous modifications not illustrated are also included in the technical scope disclosed in the present specification. For example, the present invention includes a case where at least one of the components is modified, added, or omitted, and a case where at least one of the components is extracted and combined with the components of the other embodiments.

Description of the reference symbols

1 rotating electrical machine

2 inverter

4 current sensor

10 control device for rotating electric machine

22a switching element on the positive side

22b negative side switching element

25 D.C. power supply

31 current detecting part

32-degree estimation unit

33 voltage detecting part

34 current control part

35 estimation instruction generating unit

36 voltage command calculation unit

37 carrier wave generating part

38 voltage applying part

Cau, Cav and Caw three-phase carrier wave

Voltage command for estimating three phases Vuh, Vvh and Vwh

Theta rotation angle (magnetic pole position)

frequency of voltage command for fh estimation

ω h is an angular frequency of the voltage command.