WO2024080294A1

WO2024080294A1 - Electric motor control device

Info

Publication number: WO2024080294A1
Application number: PCT/JP2023/036839
Authority: WO
Inventors: 翔輔兼子
Original assignee: 株式会社アドヴィックス
Priority date: 2022-10-11
Filing date: 2023-10-11
Publication date: 2024-04-18
Also published as: JP2024056305A

Abstract

This control device comprises: a target speed derivation unit that derives a target speed ωr of an electric motor, within an available output range of the electric motor, in accordance with a required value; a command value conversion unit 85 that executes a conversion process for converting a d-axis voltage command value Vdc and a q-axis voltage command value Vqc into a U-phase command voltage VU*, a V-phase command voltage VV*, and a W-phase command voltage VW*; and a rotational position correction unit 81 that corrects, on the basis of the target speed ωr, a deviation amount of a rotational position caused by a time difference between a timing at which the conversion process is executed and a timing at which an inverter operates on the basis of the command values VU*, VV*, VW* derived by the conversion process. The command value conversion unit 85 executes the conversion process using a rotational position θe(n+1) corrected by the rotational position correction unit 81.

Description

Electric Motor Control Unit

The present invention relates to an electric motor control device that controls an electric motor.

Patent Document 1 discloses a motor control device that drives a synchronous motor having coils of three phases (U-phase, V-phase, and W-phase). The control device converts the voltage command value of the d-axis and the voltage command value of the q-axis of the vector control rotation coordinate system into a voltage command value of the U-phase, a voltage command value of the V-phase, and a voltage command value of the W-phase based on the rotational position of the synchronous motor. The synchronous motor is then driven by an inverter operating based on the voltage command values of each phase.

JP 2009-254117 A

Known methods for obtaining the rotational position of a synchronous motor include detecting the rotational position based on the detection signal of a rotational angle sensor that detects the rotational position of the synchronous motor, and estimating the rotational position using the extended induced voltage method.

However, if the detection accuracy of the rotation angle sensor is low, the detected value of the rotation position may deviate from the actual value. Also, when the extended induced voltage method is used to estimate the rotation position, the estimation accuracy of the rotation position may deteriorate if the synchronous motor is driven at a low speed. If the detected value of the rotation position deviates from the actual value or the estimation accuracy of the rotation position deteriorates in this way, the low accuracy of the detected and estimated values of the rotation position will affect the voltage command values of each phase, and the control accuracy of the synchronous motor may deteriorate.

An electric motor control device for solving the above problem is a device that generates command values for the coils of multiple phases of the electric motor based on a required value for the output of the electric motor and a current supplied from an inverter to the coils of the multiple phases of the electric motor, and controls the electric motor by operating the inverter based on the command values. This electric motor control device includes a target speed derivation unit that derives a target speed that is a target for the rotational speed of the electric motor according to the required value within a range that the electric motor can output, a command value conversion unit that performs a conversion process to convert a first axis component voltage command value that is a command value for the voltage of a first axis component of a voltage vector of a rotating coordinate system of vector control, and a second axis component voltage command value that is a command value for the voltage of a second axis component orthogonal to the first axis, into command values for the coils of the multiple phases based on the rotational position of the electric motor, and a rotational position correction unit that performs correction of a deviation in the rotational position of the electric motor caused by a time difference between the execution timing of the conversion process and the timing at which the inverter operates based on the command value derived by the conversion process, based on the target speed. The command value conversion unit performs the conversion process using the rotational position corrected by the rotational position correction unit.

In the conversion process, the command value for the voltage of the first axis component and the command value for the voltage of the second axis component are converted into command values corresponding to the coils of the multiple phases of the electric motor based on the rotational position of the electric motor. The electric motor is driven by the inverter operating based on the command values derived by the conversion process. Therefore, a certain time difference occurs between the timing at which the conversion process is executed and the timing at which the inverter operates based on the command values derived by the conversion process. In the conversion process, it is preferable to convert the command values using the rotational position of the electric motor corrected to take into account this time difference.

The rotational position of the electric motor can be corrected according to the time difference using the rotational speed of the electric motor. Generally, the rotational speed is determined by time-differentiating the detection value of a sensor that detects the rotational position of the electric motor, or by using the extended induced voltage method to estimate the rotational speed. In this case, if the detection value or estimate is not accurate, there is a risk that the detection value or estimate of the rotational speed may deviate from the actual rotational speed of the electric motor. Therefore, even if the rotational position of the electric motor is corrected using such a rotational speed, it is difficult to say that the correction is highly accurate.

The electric motor control device uses the target speed when correcting the rotational position of the electric motor in accordance with the time difference. The target speed is derived in accordance with the required value for the output of the electric motor. Therefore, even if the accuracy of the detected or estimated value of the rotational position is poor, the target speed is not affected. As a result, the target speed is less likely to deviate from the actual value of the rotational speed of the electric motor. This makes it possible to perform the correction with high accuracy by correcting the rotational position of the electric motor using the target speed.

Therefore, the electric motor control device can improve the control accuracy of the electric motor.
The electric motor control device for solving the above problem generates command values for coils of multiple phases of the electric motor based on a required value for the output of the electric motor and currents supplied from an inverter to the coils of the multiple phases of the electric motor, and controls the electric motor by operating the inverter based on the command values. The electric motor control device includes a target speed derivation unit that derives a target speed, which is a target for the rotational speed of the electric motor, within a range that the electric motor can output, according to the required value, and a non-interference voltage derivation unit that derives, based on the target speed, a second-axis interference voltage compensation value for canceling an interference voltage on a second axis orthogonal to the first axis that is generated by a current of a first-axis component that is a current of a first-axis component of a current vector of a rotating coordinate system of vector control, and a first-axis interference voltage compensation value for canceling an interference voltage on the first axis that is generated by a current of a second-axis component that is a current of the second-axis component. The electric motor control device controls the electric motor based on the first-axis interference voltage compensation value and the second-axis interference voltage compensation value.

Generally, the first axis interference voltage compensation value and the second axis interference voltage compensation value are derived using the detected value of the rotation speed, which is the time-differentiated value of the detection value of a sensor that detects the rotation position of the electric motor, or an estimated value of the rotation speed derived using the extended induced voltage method. In this case, if the detected value or estimated value is poor in accuracy, the detected value or estimated value of the rotation speed may deviate from the actual value of the rotation speed of the electric motor. Therefore, if the first axis interference voltage compensation value and the second axis interference voltage compensation value are derived using the detected value or estimated value of the rotation speed, it is difficult to say that the accuracy of the derivation is high.

The electric motor control device uses the above target speed when deriving the first axis interference voltage compensation value and the second axis interference voltage compensation value. The target speed is derived according to the required value for the electric motor. Therefore, even if the accuracy of the detected value or estimated value of the rotational position is poor, the target speed is not affected. As a result, the target speed is less likely to deviate from the actual value of the rotational speed of the electric motor. This makes it possible to improve the accuracy of the derivation by deriving the first axis interference voltage compensation value and the second axis interference voltage compensation value using the target speed.

Therefore, the electric motor control device described above can improve the control accuracy of the electric motor.

FIG. 1 is a schematic diagram showing an electric motor control device according to an embodiment and an electric motor that is an object of control by the electric motor control device. FIG. 2 is a block diagram showing the functional configuration of a voltage command value derivation unit of the electric motor control device. FIG. 3 is a block diagram showing the functional configuration of a two-phase/three-phase conversion unit of the electric motor control device.

An embodiment of an electric motor control device will be described below with reference to FIGS.
FIG. 1 illustrates an electric motor controller 10 , an electric motor 100 , and a motor power supply 110 .

<Electric motor>
The electric motor 100 includes a rotor 101 provided with a permanent magnet. The electric motor 100 is an embedded magnet type synchronous motor in which the permanent magnet is embedded inside the rotor 101. The electric motor 100 includes a U-phase coil 105, a V-phase coil 106, and a W-phase coil 107 as three-phase coils. The electric motor 100 is used, for example, as a power source for an electric cylinder that discharges brake fluid in an on-vehicle brake device.

<Electric motor control device>
A description will now be given of the electric motor control device 10. In this specification, the electric motor control device 10 will be referred to simply as the "control device 10".

The control device 10 drives the electric motor 100 by drive control that controls the current of the d-axis component and the current of the q-axis component. The d-axis and q-axis are control axes of the rotating coordinates of the vector control. In other words, the d-axis and q-axis are control axes of the current vector and also the control axes of the voltage vector. The d-axis is a control axis that extends in the direction of the magnetic flux axis of the permanent magnet. The q-axis is a control axis that extends in the direction of the torque and is perpendicular to the d-axis. In this embodiment, the d-axis corresponds to the "first axis" and the q-axis corresponds to the "second axis". Furthermore, the d-axis component corresponds to the "first axis component" and the q-axis component corresponds to the "second axis component".

The control device 10 controls the electric motor 100 by inputting signals based on the command values of the d-axis component current and the q-axis component current to the three-phase coils 105 to 107 .
The control device 10 includes an inverter 11 and an electronic control device 20 .

The inverter 11 has a number of switching elements that operate with power supplied from the motor power supply 110. The inverter 11 generates a U-phase signal, a V-phase signal, and a W-phase signal by turning on/off the switching elements based on commands from the electronic control device 20 (U-phase command voltage VU*, V-phase command voltage VV*, and W-phase command voltage VW*, which will be described later). Specifically, the inverter 11 generates a U-phase signal based on the U-phase command voltage VU*, and inputs the U-phase signal to the U-phase coil 105 of the electric motor 100. The inverter 11 generates a V-phase signal based on the V-phase command voltage VV*, and inputs the V-phase signal to the V-phase coil 106 of the electric motor 100. The inverter 11 generates a W-phase signal based on the W-phase command voltage VW*, and inputs the W-phase signal to the W-phase coil 107 of the electric motor 100. This drives the electric motor 100.

The electronic control device 20 has an execution unit and a memory unit, not shown. For example, the execution unit is a CPU. The memory unit stores a control program that is executed by the execution unit.

The electronic control device 20 functions as a response model 21, a target speed derivation unit 22, a command torque derivation unit 23, a current command value derivation unit 24, a voltage command value derivation unit 25, a two-phase/three-phase conversion unit 26, a three-phase/two-phase conversion unit 27, a rotational speed estimation unit 28, and a rotational position estimation unit 29, as a result of the execution unit executing the control program. These are functional units for driving the electric motor 100.

<Functional department>
In the response model 21, the rotational position of the electric motor 100 corresponding to the required hydraulic pressure Prq, which is the required value of the hydraulic pressure to be generated in the electric cylinder, is derived as a target position θr. The rotational position of the electric motor 100 is the rotational angle of the rotor 101, and the target position θr is a target for the rotational position of the electric motor 100. In the control device 10, the required hydraulic pressure Prq corresponds to the "required value for the output of the electric motor."

The response model 21 is a model designed based on the characteristics of the electric motor 100. Therefore, the response model 21 derives the rotational position that can be achieved by driving the electric motor 100 as the target position θr. In other words, the response model 21 derives the target position θr within the range that the electric motor 100 can output at that time.

The target speed derivation unit 22 derives a target speed ωr, which is a target for the rotational speed of the rotor 101 of the electric motor 100, based on the target position θr. For example, the target speed derivation unit 22 derives the target speed ωr by time-differentiating the target position θr. As described above, the target position θr is a value that corresponds to the required hydraulic pressure Prq. The target speed derivation unit 22 then derives the target speed ωr based on this target position θr. Furthermore, the target position θr is a value that can be achieved by driving the electric motor 100. Therefore, the target speed derivation unit 22 derives the target speed ωr according to the required hydraulic pressure Prq within the range that the electric motor 100 can output.

The command torque derivation unit 23 derives a torque command value TR*, which is a command value for the torque of the electric motor 100, based on the target position θr and the estimated rotational position θe, which is an estimate of the rotational position of the rotor 101 derived by the rotational position estimation unit 29. For example, the command torque derivation unit 23 derives the torque command value TR* by feedback control using the deviation between the target position θr and the estimated rotational position θe as an input.

The current command value derivation unit 24 derives a d-axis current command value Idc, which is the command value for the current of the d-axis component, and a q-axis current command value Iqc, which is the command value for the current of the q-axis component, based on the torque command value TR*. In other words, the current command value derivation unit 24 obtains the d-axis current command value Idc, which is the current of the d-axis component according to the torque command value TR*, and the q-axis current command value Iqc, which is the current of the q-axis component.

The voltage command value derivation unit 25 derives a d-axis voltage command value Vdc, which is a command value for the voltage of the d-axis component, and a q-axis voltage command value Vqc, which is a command value for the voltage of the q-axis component. For example, the voltage command value derivation unit 25 derives the d-axis voltage command value Vdc and the q-axis voltage command value Vqc based on the d-axis current command value Idc and the q-axis current command value Iqc, the d-axis current Id and the q-axis current Iq, and the estimated rotational speed (estimated value of electrical angular velocity) ωe, which is an estimated value of the rotational speed of the electric motor 100. In this embodiment, the d-axis voltage command value Vdc corresponds to the "first axis voltage command value", and the q-axis voltage command value Vqc corresponds to the "second axis voltage command value". The detailed functional configuration of the voltage command value derivation unit 25 will be described later.

The two-phase/three-phase converter 26 converts the d-axis voltage command value Vdc and the q-axis voltage command value Vqc into a U-phase command voltage VU*, a V-phase command voltage VV*, and a W-phase command voltage VW* based on the estimated rotational position (estimated value of electrical angle) θe. The U-phase command voltage VU* is a command value for the voltage applied to the U-phase coil 105. The V-phase command voltage VV* is a command value for the voltage applied to the V-phase coil 106. The W-phase command voltage VW* is a command value for the voltage applied to the W-phase coil 107. The U-phase command voltage VU*, the V-phase command voltage VV*, and the W-phase command voltage VW* correspond to the command values for the three-

phase coils

105, 106, and 107 of the electric motor 100. The detailed functional configuration of the two-phase/three-phase converter 26 will be described later.

The three-phase/two-phase conversion unit 27 receives as input the U-phase current IU, which is the current flowing through the U-phase coil 105, the V-phase current IV, which is the current flowing through the V-phase coil 106, and the W-phase current IW, which is the current flowing through the W-phase coil 107. Based on the estimated rotation position (estimated electrical angle) θe, the three-phase/two-phase conversion unit 27 converts the U-phase current IU, V-phase current IV, and W-phase current IW into a d-axis current Id, which is the d-axis component of the current, and a q-axis current Iq, which is the q-axis component of the current.

The rotational speed estimation unit 28 derives the axis phase deviation dθ between the direction of the actual d-axis and the direction of the estimated d-axis. The d-axis current Id and q-axis current Iq derived by the three-phase/two-phase conversion unit 27 are input to the rotational speed estimation unit 28. Furthermore, the d-axis voltage command value Vdc and q-axis voltage command value Vqc derived by the voltage command value derivation unit 25 are input to the rotational speed estimation unit 28. The rotational speed estimation unit 28 derives the axis phase deviation dθ, for example, by the extended induced voltage method. In this case, the rotational speed estimation unit 28 derives the axis phase deviation dθ based on the d-axis current Id and q-axis current Iq, and the d-axis voltage command value Vdc and q-axis voltage command value Vqc.

The rotational speed estimation unit 28 derives an estimated rotational speed (estimated value of electrical angular velocity) ωe, which is an estimate of the rotational speed of the electric motor 100. The rotational speed estimation unit 28 derives the estimated rotational speed ωe, for example, by performing proportional-integral control so that the axial phase deviation dθ becomes the target value "0". In this embodiment, the rotational speed estimation unit 28 corresponds to an "acquisition unit" that acquires the rotational speed estimate of the electric motor 100.

The rotational position estimation unit 29 acquires an estimated rotational position (estimated electrical angle) θe, which is an estimate of the rotational position of the electric motor 100. The rotational position estimation unit 29 derives the estimated rotational position θe, for example, by integrating the estimated rotational speed ωe derived by the rotational speed estimation unit 28.

<Voltage command value derivation section>
The voltage command value derivation unit 25 will be described in detail with reference to FIG.
The voltage command value derivation unit 25 has a first d-axis calculator 51, a second d-axis calculator 52, a d-axis integrator 53, a d-axis resistance value integrator 54, a d-axis inductance integrator 55, a third d-axis calculator 56, and a fourth d-axis calculator 57.

The first d-axis calculator 51 derives the d-axis current deviation ΔId, which is the deviation between the d-axis current command value Idc and the d-axis current Id. Specifically, the first d-axis calculator 51 derives the value obtained by subtracting the d-axis current Id from the d-axis current command value Idc as the d-axis current deviation ΔId.

The second d-axis calculator 52 derives the product of the d-axis current deviation ΔId and the response frequency ωc of the electric motor 100 as a derived value ΔIdA.
The d-axis integrator 53 derives the d-axis integrated value Inpd by integrating the derived value ΔIdA of the second d-axis calculator 52. Specifically, the d-axis integrator 53 derives the sum of the previous value of the d-axis integrated value Inpd and the derived value ΔIdA as the latest value of the d-axis integrated value Inpd.

The d-axis resistance value integrator 54 derives the product of the resistance value R of the electric motor 100 and the d-axis integrated value Inpd as the d-axis reference voltage Vdb.
The d-axis inductance integrator 55 derives the product of the derived value ΔIdA of the second d-axis calculator 52 and the d-axis inductance Ld of the electric motor 100 as a calculated value Vde.

The third d-axis calculator 56 derives the sum of the d-axis reference voltage Vdb and the calculated value Vde as a virtual d-axis command voltage value VdA.
The fourth d-axis calculator 57 derives the d-axis voltage command value Vdc based on the d-axis command voltage virtual value VdA. Specifically, the fourth d-axis calculator 57 derives the sum of the d-axis interference voltage compensation value Vdi derived by a non-interference voltage derivation unit 70 (described later) and the d-axis command voltage virtual value VdA as the d-axis voltage command value Vdc. That is, the fourth d-axis calculator 57 constitutes an example of a "command value correction unit."

The voltage command value derivation unit 25 has a first q-axis calculator 61, a second q-axis calculator 62, a q-axis integrator 63, a q-axis resistance value integrator 64, a q-axis inductance integrator 65, a third q-axis calculator 66, and a fourth q-axis calculator 67.

The first q-axis calculator 61 derives the q-axis current deviation ΔIq, which is the deviation between the q-axis current command value Iqc and the q-axis current Iq. Specifically, the first q-axis calculator 61 derives the q-axis current deviation ΔIq by subtracting the q-axis current Iq from the q-axis current command value Iqc.

The second q-axis calculator 62 derives the product of the q-axis current deviation ΔIq and the response frequency ωc of the electric motor 100 as a derived value ΔIqA.
The q-axis integrator 63 derives the q-axis integrated value Inpq by integrating the derived value ΔIqA of the second q-axis calculator 62. Specifically, the q-axis integrator 63 derives the sum of the previous value of the q-axis integrated value Inpq and the derived value ΔIqA as the latest value of the q-axis integrated value Inpq.

The q-axis resistance value integrator 64 derives the product of the resistance value R of the electric motor 100 and the q-axis integrated value Inpq as the q-axis reference voltage Vqb.
The q-axis inductance integrator 65 derives the product of the derived value ΔIqA of the second q-axis calculator 62 and the q-axis inductance Lq of the electric motor 100 as a calculated value Vqe.

The third q-axis calculator 66 derives the sum of the q-axis reference voltage Vqb and the calculated value Vqe as a virtual q-axis command voltage value VqA.
The fourth q-axis calculator 67 derives a q-axis voltage command value Vqc based on the q-axis command voltage provisional value VqA. Specifically, the fourth q-axis calculator 67 derives the sum of a q-axis interference voltage compensation value Vqi derived by a non-interference voltage derivation unit 70 (described later) and the q-axis command voltage provisional value VqA as the q-axis voltage command value Vqc. That is, the fourth q-axis calculator 67 constitutes an example of a "command value correction unit."

The voltage command value derivation unit 25 has a non-interference voltage derivation unit 70. The non-interference voltage derivation unit 70 includes a first non-interference voltage derivation unit 71 and a second non-interference voltage derivation unit 72. The first non-interference voltage derivation unit 71 derives a d-axis interference voltage compensation value Vdi for canceling the interference voltage on the d-axis generated by the current of the q-axis component. The second non-interference voltage derivation unit 72 derives a q-axis interference voltage compensation value Vqi for canceling the interference voltage on the q-axis generated by the current of the d-axis component. In this embodiment, the d-axis interference voltage compensation value Vdi corresponds to the "first axis interference voltage compensation value" and the q-axis interference voltage compensation value Vqi corresponds to the "second axis interference voltage compensation value."

The first non-interference voltage derivation unit 71 derives the product of the q-axis current Iq, the q-axis inductance Lq of the electric motor 100, and the rotation speed of the electric motor 100 as the d-axis interference voltage compensation value Vdi. At this time, the first non-interference voltage derivation unit 71 uses the target speed ωr or the estimated rotation speed ωe as the rotation speed of the electric motor 100. For example, when the rate of change of the required hydraulic pressure Prq is less than a predetermined rate of change judgment value, the first non-interference voltage derivation unit 71 derives the d-axis interference voltage compensation value Vdi using the target speed ωr. On the other hand, when the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, the first non-interference voltage derivation unit 71 derives the d-axis interference voltage compensation value Vdi using the estimated rotation speed ωe. Specifically, when the rate of change of the required hydraulic pressure Prq is less than the rate of change judgment value, the first non-interference voltage derivation unit 71 derives the product of the q-axis current Iq, the q-axis inductance Lq, and the target speed ωr as the d-axis interference voltage compensation value Vdi. On the other hand, when the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, the first non-interference voltage derivation unit 71 derives the product of the q-axis current Iq, the q-axis inductance Lq, and the estimated rotation speed ωe as the d-axis interference voltage compensation value Vdi.

The second non-interference voltage derivation unit 72 derives the product of the d-axis current Id, the d-axis inductance Ld of the electric motor 100, and the rotation speed of the electric motor 100 as the q-axis interference voltage compensation value Vqi. At this time, the second non-interference voltage derivation unit 72 uses the target speed ωr or the estimated rotation speed ωe as the rotation speed of the electric motor 100. For example, when the rate of change of the required hydraulic pressure Prq is less than the above-mentioned rate of change judgment value, the second non-interference voltage derivation unit 72 derives the q-axis interference voltage compensation value Vqi using the target speed ωr. On the other hand, when the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, the second non-interference voltage derivation unit 72 derives the q-axis interference voltage compensation value Vqi using the estimated rotation speed ωe. Specifically, when the rate of change of the required hydraulic pressure Prq is less than the rate of change judgment value, the second non-interference voltage derivation unit 72 derives the product of the d-axis current Id, the d-axis inductance Ld, and the target speed ωr as the q-axis interference voltage compensation value Vqi. On the other hand, when the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, the second non-interference voltage derivation unit 72 derives the product of the d-axis current Id, the d-axis inductance Ld, and the estimated rotation speed ωe as the q-axis interference voltage compensation value Vqi.

Note that the greater the rate of change of the required hydraulic pressure Prq, the faster the electric motor 100 rotates. Therefore, a change rate judgment value is set as a criterion for judging whether or not high-speed rotation of the electric motor 100 is required. When the electric motor 100 is driven at high speed, the target speed ωr is less likely to deviate from the actual value of the rotation speed of the electric motor 100 than when the electric motor 100 is driven at low speed. Therefore, in this embodiment, when the rate of change of the required hydraulic pressure Prq is less than the change rate judgment value, it can be judged that high-speed rotation of the electric motor 100 is not required, and it can be estimated that there is no deviation between the target speed ωr and the actual value of the rotation speed of the electric motor 100. Therefore, the non-interference voltage derivation unit 70 derives the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi based on the target speed ωr. On the other hand, if the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, it can be determined that high speed rotation of the electric motor 100 is required, and it can be estimated that there is a deviation between the target speed ωr and the actual value of the rotation speed of the electric motor 100. Therefore, the non-interference voltage derivation unit 70 derives the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi based on the estimated rotation speed ωe.

<2-phase/3-phase conversion unit>
The two-phase/three-phase conversion unit 26 will now be described in detail with reference to FIG.
The two-phase/three-phase conversion unit 26 includes a rotational position correction unit 81 and a command value conversion unit 85 .

The rotational position correction unit 81 includes a correction amount derivation unit 82 and a calculator 83 .
The correction amount derivation unit 82 derives the product of the rotation speed of the electric motor 100 and the time difference TL as the rotation position correction amount Δθ. The time difference TL is the time difference between the execution timing of the conversion process by the command value conversion unit 85 and the timing at which the inverter 11 operates based on the U-phase command voltage VU*, the V-phase command voltage VV*, and the W-phase command voltage VW* derived by the conversion process. The conversion process by the command value conversion unit 85 is a process of converting the d-axis voltage command value Vdc and the q-axis voltage command value Vqc into the U-phase command voltage VU*, the V-phase command voltage VV*, and the W-phase command voltage VW*. The time difference TL is based on the response speed of the inverter 11, etc. Therefore, the time difference TL can be set by experiments, simulations, etc.

The correction amount deriver 82 uses the target speed ωr or the estimated rotational speed ωe as the rotational speed of the electric motor 100. For example, when the rate of change of the required hydraulic pressure Prq is less than the rate of change judgment value, the correction amount deriver 82 uses the target speed ωr to derive the rotational position correction amount Δθ. On the other hand, when the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, the correction amount deriver 82 uses the estimated rotational speed ωe to derive the rotational position correction amount Δθ. Specifically, when the rate of change of the required hydraulic pressure Prq is less than the rate of change judgment value, the correction amount deriver 82 derives the product of the target speed ωr and the time difference TL as the rotational position correction amount Δθ. On the other hand, when the rate of change of the required hydraulic pressure Prq is equal to or greater than the rate of change judgment value, the correction amount deriver 82 derives the product of the estimated rotational speed ωe and the time difference TL as the rotational position correction amount Δθ.

As described above, the change rate judgment value is set as a criterion for judging whether or not high-speed rotation of the electric motor 100 is required. Therefore, in this embodiment, if the change rate of the required hydraulic pressure Prq is less than the change rate judgment value, it can be judged that high-speed rotation of the electric motor 100 is not required, and it can be estimated that there is no deviation between the target speed ωr and the actual value of the rotation speed of the electric motor 100. Therefore, the correction amount derivation unit 82 derives the rotation position correction amount Δθ based on the target speed ωr. On the other hand, if the change rate of the required hydraulic pressure Prq is equal to or greater than the change rate judgment value, it can be judged that high-speed rotation of the electric motor 100 is required, and it can be estimated that there is a deviation between the target speed ωr and the actual value of the rotation speed of the electric motor 100. Therefore, the correction amount derivation unit 82 derives the rotation position correction amount Δθ based on the estimated rotation speed ωe.

The calculator 83 derives the sum of the current estimated rotational position θe(n) and the rotational position correction amount Δθ as the corrected estimated rotational position θe(n+1). The estimated rotational position θe(n+1) is the rotational position of the electric motor 100 taking into account the time difference between the execution timing of the conversion process and the timing at which the inverter 11 operates based on the command values VU*, VV*, VW* derived by the conversion process. In other words, the rotational position correction unit 81 can correct the deviation amount of the rotational position of the electric motor 100 caused by the time difference between the execution timing of the conversion process and the timing at which the inverter 11 operates based on the command values VU*, VV*, VW* derived by the conversion process, based on the target speed.

The command value converter 85 performs a conversion process to convert the d-axis voltage command value Vdc and the q-axis voltage command value Vqc into a U-phase command voltage VU*, a V-phase command voltage VV*, and a W-phase command voltage VW* based on the estimated rotational position θe(n+1).

<Actions and Effects of the Present Embodiment>
(1) In the conversion process, the d-axis voltage command value Vdc and the q-axis voltage command value Vqc are converted into a U-phase command voltage VU*, a V-phase command voltage VV*, and a W-phase command voltage VW* based on the rotational position of the electric motor 100. At this time, a predetermined time difference occurs between the execution timing of the conversion process and the timing at which the inverter 11 operates based on the command values VU*, VV*, and VW* derived by the conversion process. Therefore, in the conversion process, the command values are converted using the rotational position of the electric motor 100 corrected in consideration of the time difference.

The rotational position of the electric motor 100 can be corrected according to the time difference using the rotational speed of the electric motor 100. The rotational speed used is the time-differentiated value of the detection value of the sensor that detects the rotational position of the electric motor 100, or the time-differentiated value of the estimated rotational position θe, which is an estimate of the rotational position derived using the extended induced voltage method. In this case, if the accuracy of the detection value or estimate is poor, the detection value or estimate of the rotational speed may deviate from the actual value of the rotational speed of the electric motor 100.

Then, when the control device 10 corrects the rotational position of the electric motor 100 in accordance with the time difference, the above target speed ωr is used. The target speed ωr is derived in accordance with the required hydraulic pressure Prq, which is a required value for the electric motor 100. Therefore, even if the accuracy of the detected value or estimated value of the rotational position is poor, the target speed ωr is not affected. As a result, the target speed ωr is unlikely to deviate from the actual value of the rotational speed of the electric motor 100. This makes it possible to perform the correction with high accuracy by correcting the rotational position of the electric motor 100 using the target speed ωr.

(2) If the rate of change of the required value of the output of the electric motor 100 is greater than a predetermined rate of change judgment value, the deviation between the target speed ωr, which changes according to the required value, and the actual value of the rotation speed of the electric motor 100 is likely to become large.

Therefore, when the rate of change of the required value of the output for the electric motor 100 is greater than a predetermined rate of change judgment value, the control device 10 corrects the rotational position of the electric motor 100 using the estimated rotational speed ωe instead of the target speed ωr. By selectively using the target speed ωr and the estimated rotational speed ωe, the rotational position of the electric motor 100 can be corrected with high accuracy.

(3) Consider the case where the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi are derived using a rotation speed derived based on a detected value or an estimated value of the rotation position of the electric motor 100. In this case, if the accuracy of the detected value or the estimated value of the rotation position of the electric motor 100 is poor, it is difficult to say that the accuracy of the derivation of the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi is high.

The control device 10 therefore uses the target speed ωr when deriving the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi. As described above, even if the accuracy of the detected value or estimated value of the rotational position is poor, the target speed ωr is not affected. Therefore, by deriving the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi using the target speed ωr, the derivation accuracy can be increased. Therefore, the control device 10 can increase the control accuracy of the electric motor 100.

(4) If the rate of change of the required value of the output of the electric motor 100 is greater than a predetermined rate of change judgment value, the deviation between the target speed ωr, which changes according to the required value, and the actual value of the rotation speed of the electric motor 100 is likely to become large.

Then, when the rate of change of the required value of the output for the electric motor 100 is greater than a predetermined rate of change judgment value, the control device 10 uses the estimated rotation speed ωe instead of the target speed ωr to derive the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi. Therefore, by selectively using the target speed ωr and the estimated rotation speed ωe, the accuracy of deriving the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi can be improved.

<Example of change>
The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

- In the above embodiment, the target speed ωr and the estimated rotation speed ωe were used to derive the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi, but this is not limited to the above. For example, the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi may be derived using the target speed ωr regardless of the rate of change of the required hydraulic pressure Prq.

- If the command value conversion unit 85 performs the conversion process using the corrected estimated rotation speed ωe(n+1), it is not necessary to use the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi when deriving the d-axis voltage command value Vdc and the q-axis voltage command value Vqc.

In the above embodiment, when the estimated rotational speed ωe(n) is corrected to derive the estimated rotational speed ωe(n+1), the target speed ωr and the estimated rotational speed ωe are used interchangeably, but this is not limited to the above. For example, the estimated rotational speed ωe(n+1) may be derived using the target speed ωr regardless of the rate of change of the required hydraulic pressure Prq.

- If the d-axis voltage command value Vdc and the q-axis voltage command value Vqc are derived using the d-axis interference voltage compensation value Vdi and the q-axis interference voltage compensation value Vqi, the command value conversion unit 85 may perform the conversion process using the current estimated rotational position θe.

- The q-axis may be the first axis, the d-axis may be the second axis, and the voltage command values Vqc and Vdc may be derived, and the electric motor 100 may be driven by operating the inverter 11 based on the voltage command values Vqc and Vdc.

- As shown by the two-dot chain line in FIG. 1, the electric motor 100 may be provided with a rotation angle sensor 200 that detects the rotational position of the electric motor 100. In this case, the control device 10 has an acquisition unit that acquires the detected value of the rotational speed of the electric motor 100. Therefore, the control device 10 can use the detected value of the rotational position of the electric motor 100 based on the detected value of the rotation angle sensor instead of the estimated rotational position θe. The control device 10 can also use the value obtained by time-differentiating the detected value of the rotational position (i.e., the detected value of the rotational speed) instead of the estimated rotational speed ωe.

In the above embodiment, the target speed ωr and the estimated rotation speed ωe are differentiated using the rate of change of the required hydraulic pressure Prq, but this is not limited to the above. For example, the target speed ωr and the estimated rotation speed ωe may be differentiated by comparing the target speed ωr with a target speed determination value.

- In the above embodiment, the required hydraulic pressure Prq is input to the control device 10 as the required value for the output of the electric motor 100, but this is not limited to the above. For example, the required value for the rotational position of the electric motor 100 may be input to the control device as the required value for the electric motor 100, or the required value for torque may be input to the control device as the required value for the electric motor 100.

In the above embodiment, the control device 10 is provided with a response model 21 that derives a rotational position that can be realized by driving the electric motor 100 as the target position θr, but the control device may not be provided with the response model 21. For example, the control device may be provided with a conversion unit that converts the required hydraulic pressure Prq (required value for the electric motor 100) into a target position. The conversion unit derives the target position regardless of whether it is possible to realize it by driving the electric motor 100. In this case, the target speed derivation unit derives a provisional value of the target speed by time differentiating the target position. Then, the target speed derivation unit determines whether the provisional value of the target speed is a value within a range that the electric motor 100 can output. If the provisional value of the target speed is a value within a range that the electric motor 100 can output, the target speed derivation unit derives the provisional value as the target speed ωr. On the other hand, if the provisional value of the target speed is not a value within a range that the electric motor 100 can output, the target speed derivation unit derives the target speed ωr by correcting the provisional value so that it becomes a value within the range that the electric motor 100 can output. This allows for the same effects and benefits as the above embodiment to be achieved.

The electric motor may be a synchronous motor having coils of four or more phases as long as the electric motor is a synchronous motor having coils of multiple phases.
The control device may be configured as a circuit including one or more processors operating according to a computer program, one or more dedicated hardware circuits such as dedicated hardware for performing at least some of the various processes, or a combination of these. Dedicated hardware may include, for example, an ASIC, which is an application specific integrated circuit. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to perform the process. The memory, i.e., the storage medium, includes any available medium accessible by a general-purpose or dedicated computer.

The expression "at least one" used in this specification means "one or more" of the desired options. As an example, the expression "at least one" used in this specification means "only one option" or "both of two options" if the number of options is two. As another example, the expression "at least one" used in this specification means "only one option" or "any combination of two or more options" if the number of options is three or more.

Claims

1. An electric motor control device that generates command values for coils of multiple phases of an electric motor based on a required value for an output of the electric motor and currents supplied from an inverter to the coils of multiple phases of the electric motor, and controls the electric motor by operating the inverter based on the command values,
a target speed derivation unit that derives a target speed that is a target for a rotation speed of the electric motor in accordance with the required value within a range that the electric motor can output;
a command value conversion unit that converts a first-axis component voltage command value, which is a first-axis component voltage command value of a voltage vector of a rotating coordinate system of vector control, and a second-axis component voltage command value, which is a second-axis component voltage command value orthogonal to the first axis, into command values for the coils of the multiple phases, based on a rotational position of the electric motor;
a rotational position correction unit that corrects, based on the target speed, a deviation amount of a rotational position of the electric motor caused by a time difference between a timing at which the conversion process is executed and a timing at which the inverter operates based on the command value derived by the conversion process;
The electric motor control device, wherein the command value conversion unit performs the conversion process by using the rotational position corrected by the rotational position correction unit.
an acquisition unit that acquires a detected value or an estimated value of a rotation speed of the electric motor;
The rotational position correction unit
when the rate of change of the required value is less than a predetermined rate of change judgment value, a deviation amount of the rotational position of the electric motor caused by the time difference is corrected by using the target speed;
2. The electric motor control device according to claim 1, wherein, when the rate of change of the required value is equal to or greater than the rate of change judgment value, a deviation in the rotational position of the electric motor caused by the time difference is corrected using the detected value or the estimated value acquired by the acquisition unit.
a non-interference voltage derivation unit that derives a second-axis interference voltage compensation value for canceling an interference voltage on the second axis generated by a current of the first axis component and a first-axis interference voltage compensation value for canceling an interference voltage on the first axis generated by a current of the second axis component based on the target speed;
a command value correction unit that derives a first axis voltage command value by correcting a command value of a voltage of the first axis component based on the required value with the first axis interference voltage compensation value, and that derives a second axis voltage command value by correcting a command value of a voltage of the second axis component based on the required value with the second axis interference voltage compensation value,
2. The electric motor control device according to claim 1, wherein the command value conversion unit converts the first shaft voltage command value and the second shaft voltage command value derived by the command value correction unit into the command values for the coils of the multiple phases based on a rotational position of the electric motor in the conversion process.
1. An electric motor control device that generates command values for coils of multiple phases of an electric motor based on a required value for an output of the electric motor and currents supplied from an inverter to the coils of multiple phases of the electric motor, and controls the electric motor by operating the inverter based on the command values,
a target speed derivation unit that derives a target speed that is a target for a rotation speed of the electric motor in accordance with the required value within a range that the electric motor can output;
a non-interference voltage derivation unit that derives, based on the target speed, a second-axis interference voltage compensation value for canceling an interference voltage on a second axis orthogonal to the first axis that is generated by a current of a first-axis component that is a current of a first-axis component of a current vector of a rotating coordinate system of vector control, and a first-axis interference voltage compensation value for canceling an interference voltage on the first axis that is generated by a current of a second-axis component that is a current of the second-axis component,
an electric motor control device that controls the electric motor based on the first axis interference voltage compensation value and the second axis interference voltage compensation value.
an acquisition unit that acquires a detected value or an estimated value of a rotation speed of the electric motor;
The non-interfering voltage derivation unit includes:
When the change rate of the required value is less than a predetermined change rate judgment value, the first axis interference voltage compensation value and the second axis interference voltage compensation value are derived based on the target speed;
5. The electric motor control device according to claim 3, wherein when a rate of change of the required value is equal to or greater than the rate of change determination value, the first-axis interference voltage compensation value and the second-axis interference voltage compensation value are derived based on the detected value or the estimated value acquired by the acquisition unit.