阅读说明：本技术 马达驱动系统 (Motor drive system ) 是由 高冈碧 矶部纯希 明円恒平 安岛俊幸 户张和明 岩路善尚 于 2018-11-28 设计创作，主要内容包括：在本发明的马达驱动装置(120)中,相位补偿量运算部(110)在控制选择部(90)中的控制模式的切换时运算用于补偿电压相位(θv*)的相位补偿量(Δθ)。控制选择部(90)根据调制系数(Kh*)、电压相位(θv*)及相位补偿量(Δθ)来输出与多种控制模式中的某一种控制模式相应的三相电压指令(Vuvw*)。PWM控制部(100)根据三相电压指令(Vuvw*)及转子位置(θd)来输出栅极信号(Gun、Gup、Gvn、Gvp、Gwn、Gwv)。逆变器(20)具有多个开关元件,根据栅极信号(Gun、Gup、Gvn、Gvp、Gwn、Gwv)来控制多个开关元件而驱动交流马达(10)。(In a motor drive device (120), a phase compensation amount calculation unit (110) calculates a phase compensation amount (Delta theta) for compensating a voltage phase (theta v) when a control mode is switched in a control selection unit (90). A control selection unit (90) outputs a three-phase voltage command (Vuvw) corresponding to one of a plurality of control modes on the basis of a modulation factor (Kh), a voltage phase (θ v), and a phase compensation amount (Δ θ). A PWM control unit (100) outputs gate signals (Gun, Gup, Gvn, Gvp, Gwn, Gwv) in accordance with a three-phase voltage command (Vuvw) and a rotor position (θ d). The inverter (20) has a plurality of switching elements, and drives the AC motor (10) by controlling the plurality of switching elements in accordance with gate signals (Gun, Gup, Gvn, Gvp, Gwn, Gwv).)

1. A motor drive system is characterized by comprising:

an AC motor;

a rotor position detection unit that detects a rotor position of the ac motor;

a current sensor that detects a three-phase alternating current flowing to the alternating current motor;

a coordinate conversion unit that calculates a d-axis current and a q-axis current of the ac motor based on the rotor position and the three-phase ac current;

a current control unit that outputs a d-axis voltage command and a q-axis voltage command based on a d-axis current command value and a q-axis current command value that are input, and the d-axis current and the q-axis current;

a modulation factor and voltage phase calculation unit that calculates a modulation factor and a voltage phase from the d-axis voltage command and the q-axis voltage command;

a phase compensation amount calculation unit that calculates a phase compensation amount for compensating the voltage phase;

a control selection unit that outputs a three-phase voltage command corresponding to one of a plurality of control modes based on the modulation factor, the voltage phase, and the phase compensation amount;

a PWM control unit that outputs a gate signal based on the three-phase voltage command and the rotor position; and

an inverter having a plurality of switching elements, the plurality of switching elements being controlled in accordance with the gate signal to drive the AC motor,

the phase compensation amount calculation unit calculates the phase compensation amount and outputs the calculated amount to the control selection unit when the control mode is switched in the control selection unit.

2. The motor drive system of claim 1,

the control selection unit includes:

a modulation region selection unit that selects one of a linear region, an overmodulation region and a rectangular wave region according to the modulation factor, and determines the control mode according to the selected modulation region;

a final voltage phase calculation unit that calculates a final voltage phase from the voltage phase and the phase compensation amount; and

and a voltage command calculation unit that calculates the three-phase voltage commands based on the control pattern determined by the modulation region selection unit and the final voltage phase calculated by the final voltage phase calculation unit.

3. The motor drive system of claim 2,

the modulation region selection unit sets the threshold value of the modulation factor for selection of the modulation region at the time of increase of the modulation factor and the threshold value of the modulation factor for selection of the modulation region at the time of decrease of the modulation factor to different values.

4. The motor drive system according to any one of claims 1 to 3,

the phase compensation amount calculation unit sets the phase compensation amount to 0 and outputs the phase compensation amount to the control selection unit except when the control mode is switched.

5. The motor drive system according to any one of claims 1 to 4,

the phase compensation amount calculation unit calculates the phase compensation amount based on at least one of the rotor position, the modulation factor, and the voltage phase.

6. The motor drive system of claim 5,

the phase compensation amount calculation unit estimates a torque variation of the ac motor at the time of switching of the control mode, based on at least one of the rotor position, the modulation factor, and the voltage phase, and calculates the phase compensation amount based on the estimated torque variation and the rotor position.

7. The motor drive system of claim 5,

the phase compensation amount calculation unit estimates a change amount of the voltage phase at the time of switching of the control mode based on the modulation factor, and calculates the phase compensation amount based on the estimated change amount of the voltage phase.

8. The motor drive system according to any one of claims 1 to 7,

the ac motor generates a torque for assisting an operation force of the electric power steering apparatus by being driven by the inverter.

9. The motor drive system according to any one of claims 1 to 7,

the ac motor generates torque for running an electric vehicle by being driven by the inverter.

10. The motor drive system according to any one of claims 1 to 7,

the ac motor generates torque for running a rail vehicle by being driven by the inverter.

Technical Field

The present invention relates to a motor drive system.

Background

Conventionally, in a motor drive system that drives a motor by PWM (Pulse Width Modulation) control using an inverter, in order to expand the operating range of the motor, it is desired to increase the output voltage of the inverter. In order to achieve high output of the inverter output voltage, it is effective to make full use of voltage waveform regions called an overmodulation region and a rectangular wave region, and in these regions, a large torque can be output from the motor in a medium/high speed region as compared with a normal sine wave region. On the other hand, the inverter output voltage is saturated in the overmodulation region and the rectangular wave region, and therefore the PWM pulse disappears. As a result, when the control region is switched between the sine wave region and the overmodulation region or the rectangular wave region, the voltage vector of the motor increases discontinuously, and the modulation factor changes steeply. This phenomenon is called a switching surge. Such switching shock causes torque fluctuation, and thus the motor control becomes unstable. Therefore, in order to stably output torque from the sine wave region to the rectangular wave region, a technique for suppressing switching shock at the time of switching of the control region is required. In particular, in the asynchronous PWM control in which the PWM control is performed with the carrier frequency fixed, the positive-side voltage integral and the negative-side voltage integral that change at 1/2 cycles of the ac output are unbalanced, and therefore, the occurrence of switching shock is more noticeable than in the synchronous PWM control. Therefore, it becomes important to appropriately suppress the switching shock.

As for reducing the switching shock, the technique of patent document 1 is known. Patent document 1 describes the following technique: the modulation wave is linearly approximated within a predetermined angle interval around a zero-crossing point of the inverter output voltage, and either one of the center intervals of the on pulses and the center intervals of the off pulses of the plurality of PWM pulses is changed in the angle interval in accordance with the motor output request. This prevents the PWM pulse near the zero crossing (near 0 degrees or 180 degrees) where the slope of the voltage command is relatively steep from being extinguished, and thus suppresses the switching shock.

Disclosure of Invention

Problems to be solved by the invention

The technique described in patent document 1 prevents the disappearance of the PWM pulse near the zero crossing, and therefore, it is not possible to sufficiently prevent the disappearance of the PWM pulse near the peak of the inverter output voltage (near 90 degrees or 270 degrees). Thus, reduction of switching shock is in room for improvement.

Means for solving the problems

A motor drive system of the present invention includes: an AC motor; a rotor position detection unit that detects a rotor position of the ac motor; a current sensor that detects a three-phase alternating current flowing to the alternating current motor; a coordinate conversion unit that calculates a d-axis current and a q-axis current of the ac motor based on the rotor position and the three-phase ac current; a current control unit that outputs a d-axis voltage command and a q-axis voltage command based on a d-axis current command value and a q-axis current command value that are input, and the d-axis current and the q-axis current; a modulation factor and voltage phase calculation unit that calculates a modulation factor and a voltage phase from the d-axis voltage command and the q-axis voltage command; a phase compensation amount calculation unit that calculates a phase compensation amount for compensating the voltage phase; a control selection unit that outputs a three-phase voltage command corresponding to one of a plurality of control modes based on the modulation factor, the voltage phase, and the phase compensation amount; a PWM control unit that outputs a gate signal based on the three-phase voltage command and the rotor position; and an inverter having a plurality of switching elements, the inverter driving the ac motor by controlling the plurality of switching elements according to the gate signal, wherein the phase compensation amount calculation unit calculates the phase compensation amount and outputs the phase compensation amount to the control selection unit when the control mode is switched in the control selection unit.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, switching shock can be reduced.

Drawings

Fig. 1 is a configuration diagram of a motor drive system according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing details of the control selecting unit.

Fig. 3 is a diagram showing a relationship between a voltage command waveform and a PWM pulse.

Fig. 4 is a diagram showing a relationship between a modulation region, a voltage command waveform, and a motor operation region.

Fig. 5 is an explanatory diagram of a switching shock due to the disappearance of the pulse.

Fig. 6 is an explanatory diagram of a method of reducing switching shock due to disappearance of pulses.

Fig. 7 is a diagram illustrating a case where the phase compensation amount calculation unit calculates the phase compensation amount Δ θ.

Fig. 8 is a flowchart of the processing of the phase compensation amount calculation unit.

Fig. 9 is a diagram illustrating an operation of the motor drive system according to embodiment 1 of the present invention.

Fig. 10 is a configuration diagram of an electric power steering apparatus having a motor drive system according to embodiment 2 of the present invention.

Fig. 11 is a configuration diagram of an electric vehicle equipped with a motor drive system according to embodiment 3 of the present invention.

Fig. 12 is a configuration diagram of a railway vehicle equipped with a motor drive system according to embodiment 4 of the present invention.

Detailed Description

(embodiment 1)

Next, embodiment 1 of the present invention will be described with reference to fig. 1 to 9.

Fig. 1 is a configuration diagram of a motor drive system according to embodiment 1 of the present invention. The motor drive system shown in fig. 1 includes an ac motor 10 and a motor drive device 120. The motor drive device 120 is connected to the ac motor 10 to control the driving of the ac motor 10, and includes an inverter 20, a current sensor 30, a current command calculation unit 40, a current control unit 50, a coordinate conversion unit 60, a rotor position detection unit 70, a modulation factor and voltage phase calculation unit 80, a control selection unit 90, a PWM control unit 100, and a phase compensation amount calculation unit 110. The current command calculation unit 40, the current control unit 50, the coordinate conversion unit 60, the rotor position detection unit 70, the modulation factor and voltage phase calculation unit 80, the control selection unit 90, the PWM control unit 100, and the phase compensation amount calculation unit 110 are realized as functions of a CPU by executing a predetermined program in the CPU provided in the motor drive device 120, for example.

The ac motor 10 is mounted with a rotational position sensor 11. Here, the rotational position sensor 11 is preferably a resolver formed of a core and a winding. However, other sensors capable of detecting the rotational position of the ac motor 10, such as a GMR sensor using a giant magnetoresistance effect, a sensor using a hall element, and the like, may be used as the rotational position sensor 11.

The rotor position detection unit 70 detects the rotor position θ d of the ac motor 10 based on the signal from the rotational position sensor 11. The rotor position θ d detected by the rotor position detecting unit 70 is output from the rotor position detecting unit 70 to the coordinate converting unit 60, the PWM control unit 100, and the phase compensation amount calculating unit 110.

The current sensor 30 detects three-phase ac currents Iu, Iv, and Iw flowing from the inverter 20 to the ac motor 10, and outputs the three-phase ac currents Iu, Iv, and Iw to the coordinate conversion unit 60.

The coordinate conversion unit 60 calculates a d-axis current Id and a q-axis current Iq of the ac motor 10 based on the rotor position θ d from the rotor position detection unit 70 and the three-phase ac currents Iu, Iv, and Iw from the current sensor 30, and outputs the calculated currents to the current control unit 50.

The current command calculation unit 40 calculates a d-axis current command value Id and a q-axis current command value Iq, and outputs the calculated values to the current control unit 50. For example, when the motor drive device 120 controls the rotation speed ω r of the ac motor 10, the current command calculation unit 40 calculates the rotation speed ω r from the temporal change in the rotor position θ d, and calculates the d-axis current command value Id and the q-axis current command value Iq so that the rotation speed ω r matches a speed command ω r input from a host controller, not shown. When the motor drive device 120 controls the output torque τ m of the ac motor 10, the current command calculation unit 40 calculates the d-axis current command value Id and the q-axis current command value Iq using a predetermined calculation formula, a map (マップ), or the like so that the output torque τ m matches the torque command value τ inputted from the upper controller. In addition, the d-axis current command value Id and the q-axis current command value Iq may be calculated by any method. Alternatively, the d-axis current command value Id and the q-axis current command value Iq may be directly input from the outside without providing the current command calculation unit 40 in the motor drive device 120.

The current control unit 50 calculates and outputs a d-axis voltage command Vd and a q-axis voltage command Vq so that the d-axis current command value Id and the q-axis current command value Iq input from the current command calculation unit 40 and the d-axis current Id and the q-axis current Iq from the coordinate conversion unit 60 match each other.

The modulation factor and voltage phase calculation unit 80 calculates and outputs a modulation factor Kh and a voltage phase θ v from a d-axis voltage command Vd and a q-axis voltage command Vq input from the current control unit 50. Here, the modulation factor Kh and the voltage phase θ v are calculated according to the following (formula 1) and (formula 2), respectively.

[ numerical formula 1]

In the formula (1), tranF represents a coordinate conversion coefficient, and Vdc represents a dc voltage input to the inverter 20.

[ numerical formula 2]

The modulation factor Kh and the voltage phase θ v output from the modulation factor and voltage phase calculation unit 80 and the rotor position θ d output from the rotor position detection unit 70 are input to the phase compensation amount calculation unit 110. When the control pattern M output from the control selection unit 90 changes, the phase compensation amount calculation unit 110 calculates a phase compensation amount Δ θ for compensating the voltage phase θ v from at least one of these contents. The phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ in detail as will be described later.

The control selection unit 90 outputs the control pattern M and the three-phase voltage command Vuvw based on the modulation factor Kh and the voltage phase θ v from the modulation factor and voltage phase calculation unit 80 and the phase compensation amount Δ θ from the phase compensation amount calculation unit 110. The three-phase voltage command Vuvw is composed of a U-phase voltage command Vu, a V-phase voltage command Vv, and a W-phase voltage command Vw. Further, details of the control selecting portion 90 will be described later with reference to fig. 2.

The PWM control unit 100 performs pulse width modulation using a triangular wave or a sawtooth wave, which is periodically converted at a predetermined frequency, as a carrier wave on the basis of the three-phase voltage command Vuvw from the control selection unit 90 and the rotor position θ d from the rotor position detection unit 70, and generates gate signals Gun, Gup, Gvn, Gvp, Gwn, and Gwv for each of the upper and lower arms of each phase. Then, the generated gate signals are output to the inverter 20.

The inverter 20 has a plurality of switching elements corresponding to the upper and lower arms of each phase. Each switching element is formed using a semiconductor element such as an IGBT or a MOSFET, for example. The inverter 20 controls on/off of each switching element based on the gate signals Gun, Gvn, Gvp, Gwn, and Gwv, generates pulse voltages Vu, Vv, and Vw for each phase using the dc voltage Vdc, and outputs the generated pulse voltages Vu, Vv, and Vw to the ac motor 10. Thereby, the ac motor 10 is driven by converting the dc voltage Vdc into an ac voltage and adjusting the frequency and the voltage effective value of the ac voltage.

Fig. 2 is a diagram showing details of the control selecting unit 90. As shown in fig. 2, the control selecting unit 90 includes functional blocks of a modulation region selecting unit 91, a final voltage phase calculating unit 92, and a voltage command calculating unit 93.

Modulation region selection unit 91 selects one of a linear region, an overmodulation region and a rectangular wave region based on modulation coefficient Kh input from modulation coefficient and voltage phase calculation unit 80. The linear region is a modulation region in which the output voltage of the inverter 20 is not saturated, and the overmodulation region is a modulation region in which the output voltage of the inverter 20 is saturated. The rectangular wave region is a modulation region in which the output voltage of the inverter 20 is maximized, that is, a modulation region in which the dc voltage Vdc is alternately output to each phase in accordance with the rotation of the ac motor 10. When a certain modulation region is selected, the modulation region selection unit 91 determines the control pattern corresponding to the selected modulation region as the control pattern M to be operated as the voltage command, and outputs the determined control pattern M to the phase compensation amount operation unit 110.

The final voltage phase calculation unit 92 calculates a final voltage phase θ v, which is a final voltage phase used for calculation of the voltage command, based on the voltage phase θ v input from the modulation factor and voltage phase calculation unit 80 and the phase compensation amount Δ θ input from the phase compensation amount calculation unit 110, and outputs the final voltage phase θ v to the voltage command calculation unit 93.

The voltage command calculation unit 93 calculates a three-phase voltage command Vuvw from the control pattern M determined by the modulation region selection unit 91 and the final voltage phase θ v calculated by the final voltage phase calculation unit 92, and outputs the three-phase voltage command Vuvw to the PWM control unit 100.

Next, a method of selecting a modulation region in the modulation region selection unit 91 in the control selection unit 90 and a method of calculating the three-phase voltage command Vuvw in the voltage command calculation unit 93 will be described with reference to fig. 3 and 4. Fig. 3 is a diagram showing a relationship between a voltage command waveform and a PWM pulse. In fig. 3, (a) shows an example of a voltage command waveform and a PWM pulse in a sine wave region of a modulation factor of 1, and (b) shows an example of a voltage command waveform and a PWM pulse in an overmodulation region of a modulation factor of 1.16. Fig. 4 is a diagram showing a relationship between a modulation region, a voltage command waveform, and a motor operation region. In fig. 4, (a) shows a relation between the modulation region and the voltage command waveform, and (b) shows a relation between the modulation region and the motor operation region.

As shown in fig. 3 (a) and 3 (b), the PWM control unit 100 compares the three-phase voltage command Vuvw with the amplitude of the carrier wave, and generates PWM pulses for each phase according to the comparison result. Then, the gate signals Gun, Gvn, Gvp, Gwn, and Gwv are generated by determining the timing of setting the gate signals Gun, Gvn, Gvp, Gwn, and Gwv high or low, respectively, based on the generated PWM pulses of the respective phases. Note that, in fig. 3 (a) and 3 (b), only the U-phase voltage command Vu among the three-phase voltage commands Vuvw is shown as a representative example, and the V-phase voltage command Vv and the W-phase voltage command Vw are also the same. In fig. 3 (a) and 3 (b), a triangular wave is used as a carrier wave, but a sawtooth wave may be used as a carrier wave. Here, the PWM control unit 100 may perform asynchronous PWM control in which the frequency of the carrier is fixed, or may perform synchronous PWM control in which the frequency of the carrier is changed in accordance with the rotation speed ω r of the ac motor 10. In the present embodiment, the PWM control unit 100 performs asynchronous PWM control.

The inverter 20 switches and drives the switching elements in accordance with the gate signals Gun, Gup, Gvn, Gvp, Gwn, and Gwv input from the PWM control unit 100, thereby generating the pulse voltages Vu, Vv, and Vw for each phase as shown in fig. 3 (a) and 3 (b), respectively. In fig. 3 (a) and 3 (b), only the U-phase pulse voltage Vu of the three-phase pulse voltages Vu, Vv, and Vw is shown as a representative example, and the V-phase pulse voltage Vv and the W-phase pulse voltage Vw are the same.

It is known that, in the PWM control performed by the PWM control unit 100, the relationship between the modulation coefficient Kh and the effective value of the inverter output voltage (hereinafter referred to as the actual modulation coefficient Kh) is generally linear in a region where the pulse voltages Vu, Vv, Vw, which are the output voltages of the inverter 20, are not saturated and the modulation coefficient Kh ≦ 1. Here, when the modulation coefficient Kh is 1, the actual modulation coefficient Kh is set to 1.

Here, in general, in the PWM control, not only a sine wave which is a fundamental wave but also a waveform obtained by superimposing 3 th harmonic wave on the fundamental wave may be used as the voltage command waveform of each phase. As shown in fig. 4(a), when a sinusoidal wave is used as the voltage command waveform, the peak reaches the maximum value when the modulation factor Kh is 1, and the value of the modulation factor Kh becomes the overmodulation region when the modulation factor Kh is not less than this, whereas when a superimposed wave of 3 harmonics is used as the voltage command waveform, the peak reaches the maximum value when the modulation factor Kh is 1.15, and the value of the modulation factor Kh becomes the overmodulation region when the modulation factor Kh is not less than this. Therefore, the linear region can be expanded to the range of the modulation factor Kh ≦ 1.15.

Based on the above, in the motor drive device 120 of the present embodiment, when the modulation factor Kh is 1.15 or less, the modulation region selection unit 91 selects the linear region in the control selection unit 90. At this time, a superimposed wave of 3 rd harmonic waves as shown in fig. 4(a) is generated in the voltage command calculation unit 93, and is output to the PWM control unit 100 as the three-phase voltage command Vuvw. When the modulation factor Kh is 1 or less, a sine wave may be output to the PWM control unit 100 as the three-phase voltage command Vuvw.

In the overmodulation region where the modulation factor Kh exceeds 1.15, the output voltage of the inverter 20 is saturated. Therefore, as shown in fig. 3 (b), the number of PWM pulses per 1 cycle of the voltage command is reduced as compared with the case of the linear region shown in fig. 3 (a). Hereinafter, such a decrease in the PWM pulse in the overmodulation region is referred to as "pulse blanking". The pulse vanishes such that the relationship of the modulation factor Kh in the overmodulation region to the actual modulation factor Kh becomes non-linear.

If the overmodulation region is sufficiently used, the actual modulation factor Kh can be increased as compared with the linear region. Therefore, as shown in fig. 4 (b), the motor operating region can be expanded compared to the linear region, and the ac motor 10 can be driven to a higher rotation speed. Therefore, in the motor drive device 120 of the present embodiment, when the modulation factor Kh is in the range of 1.15 to the predetermined maximum value, the control selection unit 90 selects the overmodulation region by the modulation region selection unit 91. At this time, a waveform of a predetermined shape corresponding to the value of the modulation factor Kh, for example, a waveform obtained by deforming a 3 rd harmonic superimposed wave, a trapezoidal wave, or the like is generated in the voltage command calculation unit 93, and is output to the PWM control unit 100 as the three-phase voltage command Vuvw.

Further, when the modulation factor Kh is increased to increase the actual modulation factor Kh to the maximum value of 1.27, the rectangular wave region is entered. In this rectangular wave region, as shown in fig. 4 (b), the motor operation region can be further expanded than the overmodulation region, and the ac motor 10 can be driven to a higher rotation speed. Therefore, in the motor drive device 120 of the present embodiment, when the modulation factor Kh is a predetermined maximum value corresponding to Kh 1.27, the rectangular wave region is selected by the modulation region selection unit 91 in the control selection unit 90. At this time, a rectangular wave as shown in fig. 4(a) is generated in the voltage command calculation unit 93, and is output to the PWM control unit 100 as the three-phase voltage command Vuvw.

As described above, in the motor drive device 120 of the present embodiment, the control selection unit 90 determines the control pattern M based on the modulation factor Kh, and outputs the three-phase voltage command Vuvw in a waveform corresponding to the control pattern M. That is, the modulation region selection unit 91 selects one of the linear region, the overmodulation region and the rectangular wave region based on the modulation coefficient Kh, and determines the control pattern M according to the selection result. Then, the voltage command calculation unit 93 changes the waveform of the three-phase voltage command Vuvw according to the control pattern M and outputs the same to the PWM control unit 100. The PWM control unit 100 generates a PWM pulse from the waveform of the three-phase voltage command Vuvw, generates gate signals Gun, Gup, Gvn, Gvp, Gwn, and Gwv, and outputs the gate signals to the inverter 20, thereby performing PWM control. This makes full use of the linear region to the rectangular wave region, and allows the inverter 20 to achieve a high output, thereby allowing the motor operating region to be enlarged.

Next, with reference to fig. 5, a description will be given of a problem in utilizing the overmodulation region and the rectangular wave region. Fig. 5 is an explanatory diagram of a switching shock due to the disappearance of the pulse.

In the overmodulation region and the rectangular wave region, the output voltage of the inverter 20 is saturated, so that the pulse disappears as described above, and the relationship between the modulation factor Kh and the actual modulation factor Kh becomes nonlinear. When the pulse extinction occurs, the off time of the pulse voltages Vu, Vv, Vw decreases and the on time increases. Therefore, as shown in part a of fig. 5 (a), when the modulation factor Kh becomes 1.15 or more, the actual modulation factor Kh may increase steeply. At this time, the magnitude of the voltage vector V of the d-axis voltage command Vd and the q-axis voltage command Vq increases discontinuously from V1 to V2 as shown in fig. 5 (b). As a result, the magnitude of the q-axis voltage command Vq changes discontinuously. This phenomenon is called a switching surge. Furthermore, the voltage vector V can beAnd (4) showing.

When a switching shock occurs, the ac motor 10 varies in torque due to a change in the q-axis voltage command Vq. In particular, in the asynchronous PWM control, since pulse loss is more noticeable than in the synchronous PWM control, switching shock increases, and accordingly, torque variation of the ac motor 10 also increases. Therefore, when the linear region to the rectangular wave region are sufficiently utilized, it is important to suppress the switching shock due to the pulse disappearance and reduce the torque variation caused by this factor, thereby stably driving the ac motor 10.

In the motor driving device 120 of the present embodiment, in order to suppress the switching shock due to the above-described pulse disappearance, phase compensation using the phase compensation amount calculation unit 110 is performed. That is, when the control pattern M changes, the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ. At this time, in the control selecting unit 90, the final voltage phase calculating unit 92 calculates a final voltage phase θ v from the phase compensation amount Δ θ calculated by the phase compensation amount calculating unit 110, and the voltage command calculating unit 93 calculates the three-phase voltage command Vuvw using the final voltage phase θ v. This prevents the magnitude of the voltage vector V from changing abruptly, thereby reducing torque variation.

Next, the phase compensation performed by the phase compensation amount calculation unit 110 will be described with reference to fig. 6. Fig. 6 is an explanatory diagram of a method of reducing switching shock due to disappearance of pulses.

As a method of reducing torque variation by suppressing switching shock due to pulse extinction, there are a method called voltage compensation in which the magnitude of the voltage vector V is changed and a method called phase compensation in which the phase of the voltage vector V is changed. In the voltage compensation, as shown in fig. 6 (a), a voltage compensation amount Δ V is calculated, and the magnitude of the voltage vector V is adjusted by the voltage compensation amount Δ V when the pulse disappears, thereby suppressing the discontinuous increase of the voltage vector V from V1 to V2. In the phase compensation, as shown in fig. 6 (b), a phase compensation amount Δ θ is calculated, and the phase of the voltage vector V is adjusted by the phase compensation amount Δ θ when the pulse disappears, whereby the distribution of the d-axis voltage command Vd and the q-axis voltage command Vq is changed without changing the magnitude of the voltage vector V, thereby suppressing the switching shock and reducing the torque variation.

In the motor drive device 120 of the present embodiment, the latter type, i.e., phase compensation, is employed in consideration of the calculation load of the voltage compensation amount Δ V and the like. That is, when the pulse disappears, the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ. In the control selection unit 90, the final voltage phase calculation unit 92 calculates the final voltage phase θ v using the phase compensation amount Δ θ, and the voltage command calculation unit 93 calculates and outputs the three-phase voltage command Vuvw. This suppresses switching shock due to the pulse disappearance and reduces torque variation.

Next, a method of calculating the phase compensation amount Δ θ will be described.

The d-axis voltage Vd and the q-axis voltage Vq of the ac motor 10 are represented as shown in the following (expression 3) by using the d-axis current Id and the q-axis current Iq described above calculated by the coordinate conversion unit 60.

[ numerical formula 3]

In the formula (3), L d and L q represent the d-axis inductance and the q-axis inductance of the ac motor 10, respectively, R represents the resistance of the ac motor 10, and Ke represents the induced voltage constant of the ac motor 10.

Here, in the middle-high speed range in which the overmodulation region and the rectangular wave region are fully utilized, the rotational speed ω r of the ac motor 10 increases, and therefore, the d-axis voltage Vd and the q-axis voltage Vq dominate respectively after the 2 nd term in (expression 3). Therefore, (equation 3) can be modified such that the d-axis voltage Vd and the q-axis voltage Vq are approximated as in (equation 4) below.

[ numerical formula 4]

On the other hand, the torque τ of the ac motor 10 is expressed as in the following (equation 5) using the d-axis current Id and the q-axis current Iq.

[ numerical formula 5]

τ＝tranF·P_r{K_eI_q+(L_d-L_q)I_dI_q… (formula 5)

In the formula 5, Pr represents the pole pair number of the ac motor 10.

From (equation 5), the torque variation Δ τ of the ac motor 10 due to the switching shock is expressed by the following (equation 6) using the variation Δ Id of the d-axis current Id and the variation Δ Iq of the q-axis current Iq.

[ numerical formula 6]

Δτ＝tranF·P_r{K_eΔI_q+(L_d-L_q)ΔI_dΔI_q… (formula 6)

Here, according to the above-described (equation 4), the amount of change Δ Vd in the d-axis voltage Vd and the amount of change Δ Vq in the q-axis voltage Vq can be approximated as in the following (equation 7) using the amount of change Δ Id in the d-axis current Id and the amount of change Δ Iq in the q-axis current Iq.

[ number formula 7]

As shown in (equation 7), the amount of fluctuation Δ Id of the d-axis current Id is represented by a value corresponding to the amount of fluctuation Δ Vq of the q-axis voltage Vq. Similarly, the amount Δ Iq of fluctuation of the q-axis current Iq corresponds to the amount Δ Vd of fluctuation of the d-axis voltage Vd. Therefore, from this fact and (equation 6), it is found that torque fluctuation Δ τ can be suppressed by changing the distribution of the fluctuation amount Δ Vd of the d-axis voltage Vd and the fluctuation amount Δ Vq of the q-axis voltage Vq, that is, the distribution of the fluctuation amount Δ Id of the d-axis current Id and the fluctuation amount Δ Iq of the q-axis current Iq.

Therefore, in the motor drive device 120 of the present embodiment, when the control mode M in which the pulse disappears is switched, the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ by the following (equation 8). Then, the final voltage phase calculation unit 92 of the control selection unit 90 adds the phase compensation amount Δ θ to the voltage phase θ v, that is, advances the phase, or subtracts the phase compensation amount Δ θ, that is, retards the phase, to obtain the final voltage phase θ v. Thereby, the torque variation Δ τ is suppressed, so that the ac motor 10 can output a smooth torque τ from the linear region to the rectangular wave region.

[ number formula 8]

Next, the specific processing contents of the phase compensation amount calculation unit 110 will be described with reference to fig. 7 and 8. Fig. 7 is a diagram illustrating a case where the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ. In fig. 7, (a) shows a case where the pulse disappears due to the change in the shape of the modulation wave, and (b) shows a case where the switching shock. Fig. 8 is a flowchart of the processing of the phase compensation amount calculation unit 110.

When the control mode M is switched in the control selection unit 90, the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ according to any one of the following (1) to (3), for example. On the other hand, the phase compensation amount calculation unit 110 outputs the phase compensation amount Δ θ as 0 except when the control mode M is switched.

(1) Changing the waveform of the modulated wave

In the example shown in fig. 7 (a), the waveform of the modulation wave output from the control selection unit 90 to the PWM control unit 100, that is, the three-phase voltage command Vuvw, is a 3-order harmonic superimposed wave in which 3-order harmonics are superimposed on the fundamental wave in the linear region where the modulation factor Kh is less than 1.15. On the other hand, in the overmodulation region where the modulation factor Kh is 1.15 or more, the waveform of the three-phase voltage command Vuvw, which is the modulation wave, is a trapezoidal wave. As described above, when the waveform of the modulation wave in the linear region and the overmodulation region is different, the pulse disappearance becomes obvious as shown in part a of fig. 7 (a). As a result, the torque variation Δ τ due to the switching shock increases.

Therefore, in the motor drive device 120 of the present embodiment, when the waveform of the modulation wave is changed as described above due to a change in the control pattern M, information such as an arithmetic expression or a map indicating the relationship between the modulation coefficient Kh and the torque variation Δ τ is stored in advance in the phase compensation amount calculation unit 110. Thus, the torque variation Δ τ corresponding to the change in the shape of the modulated wave can be calculated from the modulation coefficient Kh. When the control mode M is switched, the phase compensation amount calculation unit 110 estimates the torque variation Δ τ from the modulation factor Kh after the switching by using the information. Then, the phase compensation amount Δ θ for suppressing the estimated torque variation Δ τ is calculated using the above-described (equations 6) to (8), and is output to the control selection unit 90. Further, the rotation speed ω r in (equation 7) may be calculated from the temporal change in the rotor position θ d.

(2) When the voltage phase changes greatly at the time of occurrence of switching shock

In the example shown in fig. 7 (b), when the modulation region is switched, the value of the voltage phase θ v greatly changes from θ v1 to θ v2, and thus a switching shock occurs. Therefore, in the motor drive device 120 of the present embodiment, when the value of the voltage phase θ v significantly changes due to a change in the control pattern M, information such as a calculation formula or a map indicating the relationship between the modulation factor Kh and the change amount Δ θ v of the voltage phase θ v is stored in the phase compensation amount calculation unit 110 in advance. Thus, the voltage phase change amount Δ θ v corresponding to the change of the modulation region is calculated from the modulation coefficient Kh. When the control pattern M is switched, the phase compensation amount calculation unit 110 estimates the voltage phase change amount Δ θ v from the modulation factor Kh after the switching by using the information. Then, when the estimated voltage phase change amount Δ θ v exceeds a predetermined threshold, the voltage phase change amount Δ θ v is output to the control selector 90 as a phase compensation amount Δ θ so as to cancel the voltage phase change amount Δ θ v.

(3) Other cases

In the case where the above (1) or (2) is not satisfied, in the motor drive device 120 of the present embodiment, information such as an arithmetic expression or a map indicating a relationship between at least one of the modulation factor Kh, the voltage phase θ v, and the rotor position θ d and the torque variation Δ τ is stored in advance in the phase compensation amount calculation unit 110. Thus, the torque variation Δ τ corresponding to the change in the modulation region can be calculated from the variables such as the modulation coefficient Kh, the voltage phase θ v, and the rotor position θ d. When the control mode M is switched, the phase compensation amount calculation unit 110 estimates the torque variation Δ τ from the modulation factor Kh, the voltage phase θ v, or the rotor position θ d after the switching, by using the information. In this case, the torque variation Δ τ may be estimated using a plurality of variables among the modulation factor Kh, the voltage phase θ v, and the rotor position θ d. Then, the phase compensation amount Δ θ for suppressing the estimated torque variation Δ τ is calculated using the above-described (equations 6) to (8), and is output to the control selection unit 90. As in the case of (1) above, the rotation speed ω r in (equation 7) may be calculated from the temporal change in the rotor position θ d.

When the phase compensation amount Δ θ is calculated as described above, the phase compensation amount calculation unit 110 executes processing according to the processing flow of fig. 8, for example. The phase compensation amount calculation unit 110 executes a predetermined program in the CPU, for example, to perform the processing shown in the processing flow of fig. 8 at predetermined intervals.

In step S10, the phase compensation amount calculation unit 110 determines whether or not the control mode M has been switched by the control selection unit 90. As a result, when the control mode M is switched, the process proceeds to step S20. On the other hand, if the control mode M is not switched, the process flow of fig. 8 is ended. In this case, the phase compensation amount calculation unit 110 sets the phase compensation amount Δ θ to 0 and outputs the same to the control selection unit 90.

In step S20, the phase compensation amount calculation unit 110 determines whether or not the shape of the modulated wave in the linear region and the overmodulation region has changed as described in (1) above. As a result, when the shape of the modulated wave has changed, the process proceeds to step S30, and when the shape of the modulated wave has not changed, the process proceeds to step S40.

In step S30, the phase compensation amount calculation unit 110 calculates the torque variation Δ τ corresponding to the modulation factor Kh after the control mode is switched, using the relationship between the modulation factor Kh and the torque variation Δ τ stored in advance by a map or the like. When the torque variation Δ τ is calculated by executing step S30, the phase compensation amount calculation unit 110 advances the process to step S80.

In step S40, the phase compensation amount calculation unit 110 calculates the voltage phase change amount Δ θ v corresponding to the modulation coefficient Kh after the control mode switching, using the relationship between the modulation coefficient Kh and the voltage phase change amount Δ θ v stored in advance by means of a map or the like.

In step S50, the phase compensation amount calculation unit 110 determines whether or not the voltage phase change amount Δ θ v calculated in step S40 exceeds a predetermined threshold. As a result, when the voltage phase change amount Δ θ v exceeds the threshold value, the process proceeds to step S60, and when not exceeding, the process proceeds to step S70.

In step S60, the phase compensation amount calculation unit 110 outputs the voltage phase change amount Δ θ v calculated in step S40 to the control selection unit 90 as the phase compensation amount Δ θ as described in (2) above. Thus, the phase compensation amount Δ θ is calculated from the voltage phase change amount Δ θ v, and the voltage phase change amount Δ θ is output while being canceled. When the phase compensation amount Δ θ is output in step S60, the phase compensation amount calculation unit 110 ends the processing flow of fig. 8.

In step S70, the phase compensation amount calculation unit 110 calculates the torque variation Δ τ corresponding to the variable values after the control mode switching, using the modulation factor Kh and/or the voltage phase θ v and/or the relationship between the rotor position θ d and the torque variation Δ τ stored in advance by means of a map or the like, as described in (3) above. When the torque variation Δ τ is calculated by executing step S70, the phase compensation amount calculation unit 110 advances the process to step S80.

In step S80, the phase compensation amount calculation unit 110 obtains the rotation speed ω r of the ac motor 10 by measuring the time change of the rotor position θ d.

In step S90, the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ from the torque variation Δ τ calculated in step S30 or S70 and the rotation speed ω r acquired based on the rotor position θ d in step S80 using the above-described (expression 6) to (expression 8). Then, the calculated phase compensation amount Δ θ is output to the control selection unit 90. Thus, the phase compensation amount Δ θ for canceling the torque variation Δ τ is calculated from the torque variation Δ τ and the rotor position θ d and output. When the phase compensation amount Δ θ is output in step S90, the phase compensation amount calculation unit 110 ends the processing flow of fig. 8.

Fig. 9 is a diagram illustrating an operation of the motor drive system according to embodiment 1 of the present invention. Fig. 9 shows an example of the relationship among the rotational speed, the torque τ, and the actual modulation factor Kh of the ac motor 10 in the case where the phase compensation is not performed, and (b) shows an example of the relationship among the rotational speed, the torque τ, and the actual modulation factor Kh of the ac motor 10 in the case where the phase compensation is performed.

When the phase compensation is not performed in the motor drive device 120, as shown in part a of fig. 9 (a), when the modulation region is switched from the linear region to the overmodulation region, the actual modulation factor Kh increases steeply, and the torque τ fluctuates greatly. In contrast, when the phase compensation is performed in the motor drive device 120, as shown in a' portion of fig. 9 (b), even when the modulation region is switched from the linear region to the overmodulation region, the change in the actual modulation factor Kh is smooth because the switching shock is suppressed, so that the variation in the torque τ is reduced. Therefore, it is found that the motor drive system of the present embodiment can stably drive the ac motor 10 over a wide operating range by performing phase compensation.

According to embodiment 1 of the present invention described above, the following operational effects are obtained.

(1) The motor drive system includes an ac motor 10 and a motor drive device 120, and the motor drive device 120 includes a rotor position detection unit 70, a current sensor 30, a coordinate conversion unit 60, a current control unit 50, a modulation factor and voltage phase calculation unit 80, a phase compensation amount calculation unit 110, a control selection unit 90, a PWM control unit 100, and an inverter 20. In the motor drive device 120, the rotor position detection unit 70 detects the rotor position θ d of the ac motor 10. The current sensor 30 detects three-phase ac currents Iu, Iv, Iw flowing to the ac motor 10. The coordinate conversion unit 60 calculates a d-axis current Id and a q-axis current Iq of the ac motor 10 from the rotor position θ d and the three-phase ac currents Iu, Iv, Iw. The current control unit 50 outputs a d-axis voltage command Vd and a q-axis voltage command Vq based on the input d-axis current command value Id and q-axis current command value Iq and the input d-axis current command value and q-axis current command value Id and q-axis current Iq. The modulation factor and voltage phase calculation unit 80 calculates a modulation factor Kh and a voltage phase θ v from the d-axis voltage command Vd and the q-axis voltage command Vq. The phase compensation amount calculation unit 110 calculates a phase compensation amount Δ θ for compensating the voltage phase θ v. The control selector 90 outputs a three-phase voltage command Vuvw corresponding to one of the plurality of control modes, based on the modulation factor Kh, the voltage phase θ v, and the phase compensation amount Δ θ. The PWM control unit 100 outputs gate signals Gun, Gvn, Gvp, Gwn, and Gwv based on the three-phase voltage command Vuvw and the rotor position θ d. The inverter 20 has a plurality of switching elements, and drives the ac motor 10 by controlling the plurality of switching elements based on the gate signals Gun, Gup, Gvn, Gvp, Gwn, and Gwv. In this motor drive system, the phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ and outputs the phase compensation amount Δ θ to the control selection unit 90 when the control mode of the control selection unit 90 is switched. Therefore, the phase compensation can suppress the torque fluctuation of the ac motor 10 at the time of switching the control mode, thereby reducing the switching shock.

(2) The control selection unit 90 includes a modulation region selection unit 91, a final voltage phase calculation unit 92, and a voltage command calculation unit 93. The modulation region selection unit 91 selects one of a linear region, an overmodulation region and a rectangular wave region based on the modulation coefficient Kh, and determines the control pattern M based on the selected modulation region. The final voltage phase calculation unit 92 calculates a final voltage phase θ v from the voltage phase θ v and the phase compensation amount Δ θ. The voltage command calculation unit 93 calculates the three-phase voltage command Vuvw based on the control pattern M determined by the modulation region selection unit 91 and the final voltage phase θ v calculated by the final voltage phase calculation unit 92. Therefore, the control selector 90 can select an appropriate control pattern corresponding to the modulation factor Kh, and can output the three-phase voltage command Vuvw in which the switching shock is reduced at the time of switching the control pattern.

(3) Except for the switching of the control mode (no in step S10 in fig. 8), the phase compensation amount calculation unit 110 sets the phase compensation amount Δ θ to 0 and outputs the same to the control selection unit 90. Therefore, unnecessary phase compensation can be prevented from being performed at a time other than when the control mode is switched.

(4) The phase compensation amount calculation unit 110 calculates the phase compensation amount Δ θ from at least one of the rotor position θ d, the modulation coefficient Kh, and the voltage phase θ v. Specifically, the phase compensation amount calculation unit 110 may estimate the torque variation Δ τ of the ac motor 10 at the time of switching of the control mode M from at least one of the rotor position θ d, the modulation factor Kh, and the voltage phase θ v (fig. 8, steps S30 and S70), and may calculate the phase compensation amount Δ θ from the estimated torque variation Δ τ and the rotor position θ d (fig. 8, steps S80 and S90). The phase compensation amount calculation unit 110 may estimate a change amount Δ θ v of the voltage phase θ v at the time of switching of the control pattern M based on the modulation coefficient Kh (fig. 8, step S40), and calculate the phase compensation amount Δ θ based on the estimated change amount Δ θ v of the voltage phase θ v (fig. 8, step S60). Therefore, the phase compensation amount calculation unit 110 can calculate the phase compensation amount Δ θ that can reliably suppress the torque variation of the ac motor 10 and reduce the switching shock.

In embodiment 1, an example in which the PWM control unit 100 performs asynchronous PWM control is described, but similar effects can be obtained even when synchronous PWM control is performed. In embodiment 1, the threshold values of the modulation factor Kh for switching from the linear region to the overmodulation region (when the modulation factor Kh increases) and switching from the overmodulation region to the linear region (when the modulation factor Kh decreases) are each set to 1.15. Further, different thresholds may be set at the rise and fall of the modulation factor Kh. That is, in the control selector 90, the modulation region selector 91 may set the threshold value of the modulation coefficient Kh for selection of the modulation region when the modulation coefficient Kh increases, and the threshold value of the modulation coefficient Kh for selection of the modulation region when the modulation coefficient Kh decreases, to different values. In this way, the modulation region can be flexibly selected.

(embodiment 2)

Next, embodiment 2 of the present invention will be described with reference to fig. 10. Here, the description of the same contents as those of embodiment 1 will be omitted.

Fig. 10 is a configuration diagram of an electric power steering apparatus having a motor drive system according to embodiment 2 of the present invention. The electric power steering apparatus shown in fig. 10 is equipped with the ac motor 10 and the motor drive device 120 described in embodiment 1, and operates with the ac motor 10 as a drive source. That is, the ac motor 10 of the present embodiment is driven by the inverter 20 provided in the motor drive device 120, thereby generating a torque for assisting the operation force of the electric power steering device.

The electric power steering apparatus of the present embodiment includes a steering detector 201, a torque transmission mechanism 202, and an operation amount commander 203 in addition to the ac motor 10 and the motor drive device 120. The steering detector 201 detects a steering angle and a steering torque of the steering wheel (steering)200, and outputs the steering angle and the steering torque to the operation amount commander 203. The operation amount commander 203 generates a torque command τ to the ac motor 10 as a steering assist amount of the steering wheel 200 based on the steering angle detected by the steering detector 201, the steering torque, and the state amount such as the combined vehicle speed and the road surface state, and outputs the torque command τ to the motor drive device 120. The motor driving device 120 drives the ac motor 10 so that the output torque τ m of the ac motor 10 follows the torque command τ by the method described in embodiment 1, based on the torque command τ from the operation amount command device 203.

The ac motor 10 is driven by the motor drive device 120 to output the output torque τ m to the output shaft directly coupled to the rotor. The torque transmission mechanism 202 is configured using a speed reduction mechanism such as a worm, a worm wheel, a planetary gear, or a hydraulic mechanism, and transmits the output torque τ m from the ac motor 10 to the output shaft to the rack 204. The torque transmitted to the rack 204 reduces the steering force (operating force) of the steering wheel 200 by the driver, thereby performing steering assistance using electric power and controlling the steering angle of the steering wheels 205 and 206.

According to embodiment 2 of the present invention described above, the ac motor 10 is driven by the inverter 20 to generate the output torque τ m for assisting the operation force of the electric power steering apparatus. Therefore, vibration and noise generated when the electric power steering apparatus rotates at high speed can be reduced.

(embodiment 3)

Next, embodiment 3 of the present invention will be described with reference to fig. 11. Here, the description of the same contents as those of embodiment 1 will be omitted.

Fig. 11 is a configuration diagram of an electric vehicle equipped with a motor drive system according to embodiment 3 of the present invention. An electric vehicle 300 shown in fig. 11 is equipped with the ac motor 10 and the motor drive device 120 described in embodiment 1, and operates with the ac motor 10 as a drive source. That is, the ac motor 10 of the present embodiment is driven by the inverter 20 provided in the motor drive device 120, thereby generating torque for running the electric vehicle 300.

In the electric vehicle 300 of the present embodiment, a drive wheel axle 305 and a driven wheel axle 306 are pivotally supported. Drive wheels 307 and 308 are provided at both ends of the drive wheel axle 305, and driven wheels 309 and 310 are provided at both ends of the driven wheel axle 306. The drive wheels 307 and 308 and the driven wheels 309 and 310 may be either front wheels or rear wheels of the electric vehicle 300. In addition, both the front wheels and the rear wheels may be used as drive wheels.

The drive wheel axles 305 are provided with a differential 304 as a power distribution mechanism. The differential 304 transmits the rotational power transmitted from the engine 302 via the transmission 303 to the drive wheel axles 305. The engine 302 and the ac motor 10 are mechanically coupled to each other, the rotational power of the ac motor 10 is transmitted to the engine 302, and the rotational power of the engine 302 is transmitted to the ac motor 10.

The motor driving device 120 drives the ac motor 10 so that the output torque τ m of the ac motor 10 follows the torque command τ by the method described in embodiment 1, based on the torque command τ input from a host controller not shown. When driven by motor drive device 120, ac motor 10 outputs output torque τ m to drive wheel axle 305 via engine 302 and transmission 303, thereby causing electric vehicle 300 to travel. Further, the rotor is rotated by receiving the rotational power of the engine 302 to generate three-phase alternating current. That is, the ac motor 10 operates as a motor and also as a generator.

According to embodiment 3 of the present invention described above, ac motor 10 is driven by inverter 20 to generate output torque τ m for running electric vehicle 300. Therefore, the operation region of the electric vehicle 300 can be expanded, and a stable torque output can be obtained in all the operation regions.

In embodiment 3, the description has been given of the case where the electric vehicle 300 is a hybrid vehicle, but similar effects can be obtained also in the case of a plug-in hybrid vehicle, an electric vehicle, or the like. In embodiment 3, an example in which 1 ac motor 10 is mounted on the electric vehicle 300 is described, but 2 or more ac motors 10 may be mounted.

(embodiment 4)

Next, embodiment 4 of the present invention will be described with reference to fig. 12. Here, the description of the same contents as those of embodiment 1 will be omitted.

Fig. 12 is a configuration diagram of a railway vehicle equipped with a motor drive system according to embodiment 4 of the present invention. A rail vehicle 400 shown in fig. 12 is mounted with a plurality of ac motors 10 described in embodiment 1 and a motor drive device 120, and operates with each ac motor 10 as a drive source. That is, the ac motor 10 of the present embodiment is driven by the inverter 20 provided in the motor drive device 120, and thereby generates torque for running the rail vehicle 400.

The rail vehicle 400 of the present embodiment is mounted with carriages 401 and 402. Wheels 403 and 404 are provided on the carriage 401, and wheels 405 and 406 are provided on the carriage 402. The AC motors 10 are connected to wheels 403-406, respectively.

The motor driving device 120 drives each ac motor 10 so that the output torque τ m of each ac motor 10 follows the torque command τ by the method described in embodiment 1, based on the torque command τ input from a host controller not shown. Each ac motor 10 is driven by the motor drive device 120 to output an output torque τ m to each of the wheels 403 to 406, thereby causing the railway vehicle 400 to travel.

According to embodiment 4 of the present invention described above, the ac motor 10 is driven by the inverter 20 to generate the output torque τ m for running the track vehicle 400. Therefore, the operating region of the railway vehicle 400 can be enlarged, and a stable torque output can be obtained in all the operating regions.

The embodiments and the modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the present invention are not damaged. In the above, various embodiments and modifications have been described, but the present invention is not limited to these. Other embodiments contemplated within the scope of the technical idea of the present invention are also included in the scope of the present invention.

Description of the symbols

10 … alternating current motor, 11 … rotation position sensor, 20 … inverter, 30 … current sensor, 40 … current command operation part, 50 … current control part, 60 … coordinate transformation part, 70 … rotor position detection part, 80 … modulation factor and voltage phase operation part, 90 … control selection part, 91 … modulation region selection part, 92 … final voltage phase operation part, 93 … voltage command operation part, 100 … PWM control part, 110 … phase compensation amount operation part, 120 … motor drive device, 200 … steering wheel (steering), 201 … steering detector, 202 … torque transmission mechanism, 203 … operation amount instruction device, 204 …, 205, 206 … steering wheel, 300 … electric vehicle, 302 … engine, 303 … transmission, 304 … differential, 305 … drive wheel, axle 306 … driven wheel, 307, 308, …, 309, … driven wheel 400, … driven wheel, …, 401. 402 … trolley, 403, 404, 405, 406 … wheels.