Ac motor control device and vehicle

Abstract

Provided is an AC motor control device capable of maintaining torque response and torque accuracy by a simple method without increasing fitting time in control that allows freely changing a maximum modulation factor. An AC motor control device 300 controls an inverter 2 that converts a DC voltage Vdc into an AC voltage and outputs the AC voltage to an AC motor 1. The AC motor control device 300 comprises: a DC voltage correction value generation unit 43 that generates a DC voltage correction value Vdc2 on the basis of the value of the DC voltage Vdc and a modulation factor target value Ma* that is the target value of the modulation factor of the output voltage to the AC motor 1; an id command value FF generation unit 55 that generates a d-axis current command value Id* on the basis of a torque command value T* and the DC voltage correction value Vdc2; and a weakening magnetic flux control unit 57 that corrects the d-axis current command value Id* so that the modulation factor coincides with the modulation factor target value Ma*.

Description

AC Motor Control Device and Vehicle

[0001] The present invention relates to a control device for driving an AC motor and a vehicle.

[0002] In order to improve the voltage utilization rate, pulse-saving control such as rectangular wave drive (one-pulse control) is used. In Patent Document 1, means for switching between a rectangular wave control mode, an overmodulation control mode, and a PWM current control mode based on the required voltage amplitude calculated from the speed / torque command, the current command value, and the voltage phase is proposed. In Patent Documents 2 and Non-Patent Document 1, means for switching between a rectangular wave control mode, an overmodulation control mode, and a PWM current control mode based on information other than the required voltage amplitude such as phase sensor error information, speed, torque, efficiency, and noise value from the viewpoint of noise reduction is proposed. In Patent Document 3, a method of adjusting the d-axis current command value by voltage feedback so that the output voltage of the inverter does not exceed the maximum output voltage is shown. In Patent Document 4, a method of calculating the magnetic flux amount limit value from the DC voltage and the speed and calculating the dq-axis current command value based on the torque command value and the magnetic flux amount limit value is shown.

[0003] Patent No. 4939127, Patent No. 7015287, Patent No. 7419281, JP-A-2022-34471, "Development of a Low-Loss Motor for a Small Hybrid System", Proceedings of the Academic Lecture Meeting of the Japan Society of Automotive Engineers, Autumn 2020, Lecture No. 063

[0004] When switching between a rectangular wave control mode, an overmodulation control mode, and a PWM current control mode based on information other than the required voltage amplitude as in Patent Documents 2 and Non-Patent Document 1, the ratio of the maximum output voltage to the DC voltage (hereinafter referred to as the maximum modulation ratio) changes depending on the mode. If the current command value is generated in consideration of the change in the maximum modulation ratio using the voltage feedback shown in Patent Document 3, control can be performed without exceeding the voltage, but in the method of Patent Document 3, the torque response and torque accuracy decrease due to the control delay caused by the voltage feedback.

[0005] On the other hand, the current command value generation means shown in Patent Document 4 creates a reference table assuming that the maximum modulation rate is constant. If the maximum modulation rate changes, the torque response and torque accuracy will decrease unless a reference table is created for each maximum modulation rate. On the other hand, increasing the number of reference tables leads to problems such as increased adaptation time, increased program size, and increased processing load. Furthermore, if the maximum modulation rate changes, the outputtable torque also changes, so it is necessary to apply a torque limit that takes the maximum modulation rate into consideration. In view of these problems, the object of the present invention is to provide an AC motor control device and a vehicle that can maintain torque response and torque accuracy in a simple manner without increasing the adaptation time in a control where the maximum modulation rate can be freely changed.

[0006] To achieve the above objective, the present invention is configured as follows.

[0007] An AC motor control device for controlling an inverter that converts a DC voltage to an AC voltage and outputs it to an AC motor includes: a DC voltage correction value generation unit that generates a DC voltage correction value based on a modulation rate target value which is a target value of the modulation rate of the output voltage of the AC motor and the value of the DC voltage; an id command value FF generation unit that generates a d-axis current command value based on a torque command value and the DC voltage correction value; and a flux weakening control unit that corrects the d-axis current command value so that the modulation rate matches the modulation rate target value.

[0008] The vehicle also includes an inverter controlled by the AC motor control device that converts the DC voltage into the AC voltage and outputs it to the AC motor, and wheels driven by the AC motor.

[0009] The present invention provides an AC motor control device and a vehicle that can maintain torque response and torque accuracy in a simple manner without increasing the adaptation time, in a control system in which the maximum modulation rate can be freely changed.

[0010] Without significantly increasing calibration time, program size, or processing load, the maximum modulation rate can be freely changed while maintaining torque application and torque accuracy, enabling control that takes into account aspects such as noise and efficiency.

[0011] This allows the vehicle to achieve both noise reduction and improved energy efficiency.

[0012] This is a block diagram showing the overall configuration of the AC motor control device in Example 1. This is an example of a block diagram of the torque / command value calculation unit in Example 1. This is an example of a block diagram of the voltage phase control unit in Example 1. This is an example of a block diagram of the rectangular wave generation unit in Example 1. This is an example of a block diagram of the current control unit in Example 1. This is an example of a block diagram of the PWM mode determination unit in Example 1. This is an example of a block diagram of the current command value generation unit in Example 1. This is an example of a block diagram of the torque limit value / weakening current limit value generation unit 51 in Example 1. This is an example of a block diagram of the current command value generation unit 17 in Modification 1 of Example 1. This is a block diagram showing the overall configuration of the AC motor control device in Example 2. This is an example of a block diagram of the current command value generation unit 17B in Example 2. This is a configuration diagram of the electric vehicle in Example 3.

[0013] The present invention will be described with reference to the accompanying drawings. In the following description, we focus on permanent magnet synchronous motors (PMSMs), but the effects of the present invention are not limited to permanent magnet synchronous motors. Similar effects can be obtained with synchronous machines such as synchronous loluctance motors, permanent magnet synchronous generators, and wound-wound synchronous machines. Furthermore, while the semiconductor switching element of the inverter device is described as an IGBT, the effects of the present invention are not limited to this. MOSFETs or other power semiconductor elements may also be used.

[0014] (Example 1) The components of Example 1 will be described below.

[0015] Figure 1 is a block diagram showing the configuration of the AC motor control device 300 in Embodiment 1 of the present invention.

[0016] The overall configuration of the AC motor control device of Example 1 will be explained with reference to Figure 1.

[0017] In Figure 1, the power converter (inverter) 2 converts DC power from a DC voltage source 9 (e.g., a battery) into AC power according to a gate signal described later, and drives the PMSM (AC motor) 1. The phase current detector 3 consists of a Hall CT (Current Transformer) or the like, and detects the three phase current waveforms Iuc, Ivc, and Iwc of the U, V, and W phases flowing from the power converter 2 to the PMSM 1. The magnetic pole position detector 4 consists of a resolver or the like, and detects the magnetic pole position of the PMSM 1 and outputs magnetic pole position information θ*. The frequency calculation unit 5 outputs velocity information ω1* from the magnetic pole position information θ* detected by the magnetic pole position detector 4, for example, by differential calculation. The coordinate transformation unit 7 transforms the current waveforms Iuc, Ivc, and Iwc detected by the phase current detector 3 using the magnetic pole position information θ* detected by the magnetic pole position detector 4 and outputs the d-axis current detection value Idc and the q-axis current detection value Iqc.

[0018] The current command value generation unit 17 generates the d-axis current command value Id* and the q-axis current command value Iq* based on the torque command value T*, speed information ω1*, and the DC voltage Vdc detected by the DC voltage detection unit 6. The current command value generation unit 17 is a key component of the present invention, and its details will be described later.

[0019] The torque command value calculation unit 12 calculates the torque command value T** and torque T based on the d-axis current command value Id*, the q-axis current command value Iq*, the d-axis current detection value Idc, and the q-axis current detection value Iqc, for example, in a configuration as shown in Figure 2. In Figure 2, the dq-axis magnetic flux command calculation unit 21 calculates the d-axis magnetic flux command φd* and the q-axis magnetic flux command φq* from the d-axis current command value Id* and the q-axis current command value Iq*, for example using a lookup table, and calculates the torque command value T** based on the following equation (1).

[0020] T** = (3 / 2)P(φd*Iq* - φq*Id*) ... (1) Similarly, the dq-axis magnetic flux calculation unit 22 calculates the d-axis magnetic flux φd and the q-axis magnetic flux φq from the d-axis current detection value Idc and the q-axis current detection value Iqc, similar to the dq-axis magnetic flux command calculation unit 21, and calculates the torque T based on the following equation (2).

[0021] T = (3 / 2)P(φdIq - φqId) ... (2) The voltage phase control unit 13 outputs a voltage phase angle θv so that the torque T matches the torque command value T**. For example, as shown in Figure 3, the difference between the torque T and the torque command value T** is calculated by the subtractor 71, passed through the PI controller 72 (or I controller), and then limited by the limiter 74 before outputting the voltage phase angle θv.

[0022] The rectangular wave generation unit 15 generates a voltage phase signal by adding the voltage phase angle θv and π / 2 to the magnetic pole position information θ* in the adder 81, as shown in Figure 4, calculates the remainder when divided by 2π using the remainder calculation unit 87, subtracts π using the subtractor 93, and calculates the pulse signal Su using the sign determination unit 96 according to the sign.

[0023] Similarly, the voltage phase signal generated by adder 81 is added by adder 83 by 4π / 3, and the pulse signal Sv is calculated via the remainder calculation unit 89, subtractor 94, and sign determiner 97. In addition, the voltage phase signal generated by adder 81 is added by adder 85 by 2π / 3, and the pulse signal Sw is calculated via the remainder calculation unit 91, subtractor 95, and sign determiner 98.

[0024] As described above, a gate signal is generated from the square wave generation unit 15, taking into account the dead time from the pulse signals Su, Sv, and Sw, and output to the PWM mode switching unit 16.

[0025] The current control unit 16 is composed of the blocks shown in Figure 5, for example. In Figure 5, the subtractor 121 calculates the difference ΔIdc between the d-axis current command value Id* and the d-axis current detection value Idc, and outputs it to the stop selection unit 122. The stop selection unit 122 sets ΔIdc to 0 when the PWM mode MPWM is in square wave mode, and outputs ΔIdc as is to the gain multiplier 127 when it is in asynchronous PWM mode. The gain multiplier 127 multiplies the result by the d-axis proportional gain Kpd, the gain multiplier 125 multiplies the result by the d-axis integral gain Kid, the result is integrated by the integrator 123, and the d-axis voltage FF value VdFF* (described later) is added or subtracted by the adder / subtractor 129 to output the d-axis voltage command value Vd*.

[0026] Similarly, the subtractor 141 calculates the difference ΔIqc between the q-axis current command value Iq* and the q-axis current detection value Iqc, and outputs it to the stop selection unit 142. The stop selection unit 142 sets ΔIqc to 0 when the PWM mode MPWM is in square wave mode, and outputs ΔIqc as is when it is in asynchronous PWM mode. The gain multiplier 147 multiplies the result by the q-axis proportional gain Kpq, the gain multiplier 145 multiplies the result by the q-axis integral gain Kiq, the integrator 143 integrates the result, and the q-axis voltage FF value VqFF* (described later) is added by the adder 149 to output the d-axis voltage command value Vq*.

[0027] The low-pass filter 131 applies a first-order low-pass filter corresponding to the time constant of the reciprocal of ωc, which is the response of the current control system, to the d-axis current command value Id* and outputs it to the gain multiplier 133. The gain multiplier 133 multiplies by the d-axis inductance Ld, adds the magnetic flux coefficient Ke in the adder 135, and multiplies by the speed ω1* in the multiplier 136 to output the q-axis voltage FF value VqFF*. The low-pass filter 137 applies a first-order low-pass filter corresponding to the time constant of the reciprocal of ωc, which is the response of the current control system, to the q-axis current command value Iq* and outputs it to the gain multiplier 139. The gain multiplier 139 multiplies by the q-axis inductance Lq, and multiplier 138 multiplies by the speed ω1* to output the d-axis voltage FF value VdFF*.

[0028] As a result, in asynchronous PWM mode, dq-axis voltage command values ​​Vd* and Vq* are output so that the current matches dq, respectively, and in square wave mode, dq-axis voltage command values ​​calculated from the motor model are output. However, resistance is ignored.

[0029] In Figure 1, the coordinate transformation unit 8 transforms the dq-axis voltage command values ​​Vd* and Vq* into three-phase voltage command values ​​Vu*, Vv* and Vw* based on the magnetic pole position θ*, and outputs them to the M controller 10. The PWM controller 10 generates pulses by comparing them, for example, with a triangular wave. When the modulation rate calculation unit 14 applies a sinusoidal modulation method (a modulation method in which the ratio of the output voltage amplitude to the DC voltage Vdc is a maximum of 0.866 (≒√3 / 2) in line voltage), it is derived by the following equation (3).

[0030] Ma=2√{(Vd*) ２ + (Vq*) ２} / Vdc ... (3) The PWM mode switching unit 18 switches the gate signal according to the PWM mode MPWM. When in square wave mode, the PWM mode switching unit 18 outputs the gate signal output from the square wave generator 15 to the power converter 2. Also, when in asynchronous PWM mode, the PWM mode switching unit 18 outputs the gate signal output from the PWM controller 10 to the power converter 2.

[0031] The PWM mode determination unit 19 is composed of the blocks shown in Figure 6, for example. In Figure 6, the selectable PWM mode determination unit 101 determines the selectable PWM mode MPWM0 based on the torque command value T* and speed ω1*, for example using a lookup table. The modulation rate PWM mode determination unit 103 determines the modulation rate PWM mode Mmod based on the modulation rate Ma. For example, if the modulation rate Ma is greater than or equal to a set threshold, the square wave mode is output. If the modulation rate Ma calculated from the motor model in the square wave mode is less than or equal to a set threshold, the asynchronous PWM mode is output.

[0032] The PWM mode selection unit 105 outputs the asynchronous PWM mode when the selectable PWM mode MPWM0 is the asynchronous PWM mode. When the selectable PWM mode MPWM0 is the square wave mode, it outputs the modulation rate PWM mode determination Mmod as is. This makes it possible to forcibly set the PWM mode to asynchronous PWM mode even if the modulation rate can realize the square wave mode. On the other hand, since the modulation rate PWM mode refers to the modulation rate, it will not become the square wave mode at modulation rates where the square wave mode cannot be realized.

[0033] The details of the current command value generation unit 17, which is a key point of the present invention, will be described below with reference to Figure 7.

[0034] In Figure 7, the modulation rate target value generation unit 41 sets the modulation rate target value Ma* based on the PWM mode MPWM. For example, in the square wave mode, it is set to 1.103 (≈ 2 × √3 ÷ π). On the other hand, in the asynchronous PWM mode, for example, it is set to 1 so that distortion does not occur when a tertiary voltage is superimposed. If it is set to 1, although the maximum output torque will be small, the harmonic voltages included in the voltage harmonics will be small and noise will be reduced. The DC voltage correction unit 43 corrects the DC voltage using, for example, the following equation (4).

[0035] Vdc² = (Ma* / Man*) * Vdc ... (4) Here, Man* is the modulation rate target value assumed when fitting the lookup table used in the current command value generation unit 17. For example, when fitting the lookup table in square wave mode, 1.103 (≒ 2 × √3 ÷ π) is set. The magnetic flux limit value generation unit 45 calculates the magnetic flux limit value λlim by, for example, the following equation (5).

[0036] λlim = (Vdc2 / ω1*)・(2 / π) ... (5) The drag torque compensation unit 47 calculates the drag torque Tdrag* using the corrected DC voltage (DC voltage correction value) Vdc2 and the magnetic flux limit value λlim, for example, using a lookup table. When fitting the lookup table as described later, the fitting is performed with the modulation rate target value set to Man*, or the calculation is performed from the electromagnetic field analysis results. The adder 49 adds the drag torque Tdrag* to the torque command T* set from the higher level and outputs the second torque command T2*. The torque limit value / weakening current limit value generation unit 51 is configured as shown in Figure 8, for example.

[0037] In Figure 8, the torque limit initial value calculation unit 161 calculates the torque limit initial value Tlim0 using the corrected DC voltage Vdc2 and motor angular velocity ω1*, for example, using a lookup table. Similarly, the flux weakening current limit calculation unit 162 calculates the flux weakening current limit value idlim* using the corrected DC voltage Vdc2 and motor angular velocity ω1*, for example, using a lookup table. The gain multiplier 163 multiplies the flux weakening current excess Δid* by the gain Ktl (a predetermined gain (a gain determined for each individual device)) and outputs it. The adder 165 adds the output of the gain multiplier 163 (the result of the multiplication) to the torque limit initial value Tlim0 to calculate and output the torque limit value Tlim. Here again, when fitting the lookup table, the fitting is performed with the modulation rate target value set to Man*, or the calculation is performed from the electromagnetic field analysis results.

[0038] In Figure 7, the torque limiter 53 limits the second torque command T2* by the torque limit Tlim and outputs the limited torque command value Tlim* to the id command value FF generation unit 55. The id command value FF generation unit 55 calculates the d-axis current feedforward command value idFF* using, for example, a lookup table based on the limited torque command value Tlim* and the magnetic flux limit λlim, and outputs it to the adder 65. Here again, when fitting the lookup table, the fitting is performed with the modulation rate target value set to Man*, or the calculation is performed from the electromagnetic field analysis results. The adder 65 adds the weakened magnetic flux current command value idfw* output by the weakened magnetic flux control unit 57 (described later) and the d-axis current feedforward command value idFF* and outputs the d-axis current command value id* to the iq command value generation unit (q-axis current command value generation unit) 67. The iq command value generation unit 67 takes the limited torque command value Tlim* and the d-axis current command value id* as inputs and outputs the q-axis current command value iq* using, for example, a lookup table or a mathematical formula.

[0039] The subtractor 59 calculates the difference between the modulation rate target value Ma* and the modulation rate Ma, multiplies it by the flux weakening control gain for asynchronous PWM mode using the gain multiplier 61, and outputs it to the flux weakening control input switching unit 75. The subtractor 71 calculates the difference between the d-axis current command value id* and the d-axis current detection value idc, and outputs it to the gain multiplier 73. The gain multiplier 73 multiplies it by the flux weakening control gain for square wave mode and outputs it to the flux weakening control input switching unit 75.

[0040] The flux weakening control input switching unit 75 switches between the flux weakening control input for asynchronous PWM mode and the flux weakening control input for square wave mode according to the PWM mode MPWM. The subtractor 77 calculates the difference between the flux weakening current limit value idlim* and the d-axis current feedforward command value idFF* and outputs the integrator limit Δidlim* to the limit integrator 63. The limit integrator 63 integrates the flux weakening input output from the flux weakening control input switching unit 75 and outputs the flux weakening current idfw* to the adder 65. However, if the limit integrator 63 exceeds the integrator limit Δidlim*, it limits it by the integrator limit Δidlim* and outputs the excess as the flux weakening current excess Δid*.

[0041] The above components together are referred to as the flux weakening control unit 57. In other words, the flux weakening control unit 57 comprises subtractors 59, 71, and 77, gain multipliers 61 and 73, a limiting integrator 63, and a flux weakening control input switching unit 75.

[0042] Here, the torque command value correction unit 50 is composed of a drag torque compensation unit 47, an adder 49, a torque limiter 53, and a torque limit value / weakening current limit value generation unit 51.

[0043] The effects of Example 1 will be described below. The current command value generation unit 17 includes a drag torque compensation unit 47, a torque limit value / field-weakening current limit value generation unit 51 (two (shown in FIG. 8)), and an id command value FF generation unit 55 as look-up tables related to the DC voltage, for a total of four two-dimensional look-up tables. Since these are look-up tables linked to the modulation factor target value, in order to operate correctly, the modulation factor target value also needs to be input as a three-dimensional look-up table. In that case, there are concerns about an increase in program size, processing time, and adaptation time.

[0044] On the other hand, in the present Example 1, by correcting the DC voltage with the modulation factor target value before inputting the look-up table, the deviation between the modulation factor target value at the time of adaptation and the modulation factor target value during operation is corrected, and the two-dimensional look-up table can be used as it is. Although the resistance component is ignored as an assumption when performing the correction, the torque error due to the resistance component can be adjusted to an appropriate d-axis current command value id* by the action of the field-weakening flux control unit 57.

[0045] Also, the drag torque changes as a loss component depending on the modulation factor target value, but by correcting the DC voltage, the error in the drag torque can also be prevented and the torque accuracy can be maintained. Furthermore, although the torque limit value and the field-weakening current limit value also change depending on the modulation factor target value, appropriate values can also be output by correcting the DC voltage here, and it is possible to prevent the control from breaking down.

[0046] As described above, according to Example 1, there is an effect that torque accuracy and torque response can be maintained by a simple method when the modulation factor target value changes.

[0047] In Example 1, an example of 1-pulse control is shown as the rectangular wave mode. However, for example, even if 3-pulse control is selected, the same effect can be obtained. Also, in Example 1, there were two types, the rectangular wave mode and the asynchronous PWM mode, but it may be three types including the 3-pulse control mode.

[0048] Furthermore, in this embodiment 1, the modulation rate target value generation unit 41 instantaneously switched values, but the modulation rate target value may be generated gradually, for example by incorporating a change amount limit or a filter. There is a risk of a step in the modulation rate occurring between the asynchronous PWM mode and the square wave mode. By gradually changing the modulation rate target value, abrupt torque shocks can be prevented.

[0049] (Modification 1 of Example 1) As a modification 1 of Example 1, as shown in Figure 9, the modulation rate target value generation unit 41B may be used instead of the modulation rate target value generation unit 41, and the torque command T* and motor angular velocity ω1* may be used as inputs to the modulation rate target value generation unit 41B.

[0050] In this modified example 1, the target value of the modulation index can be changed even within the asynchronous PWM mode. Since loss and noise change depending on the modulation index in asynchronous PWM mode, this modified example 1 allows for finer adjustment than in Example 1.

[0051] (Example 2) The components of Example 2 will be described below.

[0052] Figure 10 is a block diagram showing the overall configuration of the AC motor control device 300 in Embodiment 2 of the present invention.

[0053] The differences in configuration between Example 1 and Example 2 will be explained.

[0054] In Example 2, the modulation rate target value is changed in asynchronous PWM mode. As explained in Modification 1 of Example 1, in asynchronous PWM mode, loss and noise change depending on the modulation rate, so even without a square wave mode, loss and noise can be reduced by changing the modulation rate target value.

[0055] The current command value calculation unit 17B is as shown in Figure 11, and similar to the modified example 1, it calculates the modulation rate target value from the torque command value T* and the motor angular velocity ω1*.

[0056] In Example 2, as in Example 1, the lookup table related to DC voltage includes a drag torque compensation unit 47, a torque limit value / weakening current limit value generation unit 51 (torque limit initial value calculation unit 161 and weakening magnetic flux current limit calculation unit 162), and an id command value FF generation unit 55. All of these are fitted with a predetermined modulation rate target value Man*, and based on this, the DC voltage is corrected by the DC voltage correction unit. As in Example 1, no additional fitting is required, and the current command values ​​related to torque response and torque accuracy can be output as expected.

[0057] In Example 2, the same effects as in Example 1 can be obtained.

[0058] (Example 3) The components of Example 3 will be described below.

[0059] Figure 12 shows the configuration of a vehicle (electric vehicle) in Embodiment 3 of the present invention. As shown in Embodiments 1 and 2, the AC motor control device 300 controls the power supplied from the power converter (inverter) 2 to the PMSM 1. The DC voltage source (e.g., battery) 9 supplies power to the power converter 2. The PMSM 1 is connected to the transmission 301. The transmission 301 is connected to the drive shaft 305 via the differential gear 303 and supplies power to the wheels 307. This configuration can also be applied to configurations where there is no transmission 301 and the PMSM 1 is directly connected to the differential gear 303, or to configurations where the PMSM 1 and inverter 2 are arranged for the front wheels and rear wheels, respectively.

[0060] In automobiles (vehicles) to which the AC motor control device 300 of the present invention is applied, the ability to freely switch the modulation rate target value offers advantages from the perspective of noise and energy efficiency. Similarly, railways also have a high demand for noise reduction and energy saving, making them an application where the effects of the present invention are easily apparent. By applying the present invention, both automobiles and railways can expect to achieve both noise reduction and improved energy efficiency.

[0061] 1: PMSM, 2: Power converter, 3: Current detector, 4: Magnetic pole position detector, 5: Frequency calculation unit, 6: DC voltage detection unit, 7: Coordinate transformation unit, 8: Coordinate transformation unit, 9: Battery, 10: PWM controller, 12: Torque / command value calculation unit, 13: Voltage phase control unit, 14: Modulation rate calculation unit, 15: Square wave generation unit, 16: Current control unit, 17: Current command value generation unit, 17B: Current command value generation unit (Example 2), 18: PWM mode switching unit, 19: PWM mode determination, 21: dq axis magnetic flux command calculation unit Calculation unit, 22: dq axis magnetic flux calculation unit, 23, 24, 25, 26, 136, 138: Multiplier, 27, 28, 59, 71, 77, 93, 94, 95, 121, 141: Subtractor, 29, 30, 61, 71, 73, 125, 127, 133, 139, 145, 147, 163: Gain multiplier, 41: Modulation rate target value generation unit, 41B: Modulation rate target value generation unit (modification 1), 43: DC voltage correction unit, 45: Magnetic flux limit value generation unit, 47: Drag torque compensation unit, 49, 65, 81, 83, 8 5, 135, 149, 165: Adder; 50: Torque command value correction unit; 51: Torque limit value / weakening current limit value generation unit; 53: Torque limiter; 55: id command value FF generation unit; 57: Weakening magnetic flux control unit; 57B: Weakening magnetic flux control unit (Example 2); 63: Limited integrator; 67: iq command value generation unit (q-axis current command value generation unit); 72: PI controller; 74: Limiter; 75: Weakening magnetic flux control input switching unit; 87, 89, 91: Remainder calculation unit; 96, 97, 98: Code determination unit 101: Selectable PWM mode determination unit, 103: Modulation rate PWM mode determination unit, 105: PWM mode selection unit, 122: Stop selection unit, 123, 143: Integrator, 129: Adder / subtractor, 131: Low-pass filter, 137: Low-pass filter, 142: Stop selection unit, 161: Torque limit initial value calculation unit, 300: AC motor control device, 301: Transmission, 303: Differential gear, 305: Drive shaft, 307: Wheel, Tlim: Torque limit value

Claims

1. An AC motor control device for controlling an inverter that converts a DC voltage to an AC voltage and outputs it to an AC motor, comprising: a DC voltage correction value generation unit that generates a DC voltage correction value based on a modulation rate target value which is a target value of the modulation rate of the output voltage of the AC motor and the value of the DC voltage; an id command value FF generation unit that generates a d-axis current command value based on a torque command value and the DC voltage correction value; and a flux weakening control unit that corrects the d-axis current command value so that the modulation rate matches the modulation rate target value.

2. An AC motor control device according to claim 1, comprising: a torque command value correction unit that corrects the torque command value based on the DC voltage correction value; 3. An AC motor control device according to claim 2, wherein the torque command value correction unit comprises a drag torque compensation unit that calculates the drag torque based on the DC voltage correction value, and an adder that adds the torque command value and the drag torque, and corrects the torque command value.

4. An AC motor control device according to claim 2, wherein the torque command value correction unit comprises a torque limit value / weakening current limit value generation unit that calculates a torque limit value based on the DC voltage correction value, and the torque command value is corrected so that the torque command value does not exceed the torque limit value.

5. An AC motor control device according to claim 4, wherein the torque limit value / weakening current limit value generation unit comprises: a torque limit value calculation unit that calculates and outputs an initial torque limit value from the DC voltage correction value and the angular velocity of the AC motor; a multiplier that multiplies the excess weakening current by a predetermined gain and outputs the multiplication result; and an adder that adds the initial torque limit value and the multiplication result to calculate the torque limit value.

6. An AC motor control device according to claim 1, characterized in that it comprises a q-axis current command value generation unit that generates a q-axis current command value based on the d-axis current command value and the torque command value.

7. A vehicle comprising: an AC motor control device according to any one of claims 1 to 6; an inverter controlled by the AC motor control device which converts the DC voltage into the AC voltage and outputs it to the AC motor; and wheels driven by the AC motor.

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