Rotary electric machine drive control device

文档序号：1892884 发布日期：2021-11-26 浏览：15次中文

阅读说明：本技术 旋转电机驱动控制装置 (Rotary electric machine drive control device ) 是由田中贤太松浦大树佐藤大介金原义彦于 2021-05-14 设计创作，主要内容包括：本发明提供一种旋转电机驱动控制装置,其特征在于,包括：载波载体波生成部,将电压指令、感应电压、电动机电流作为输入来生成载波载体波；和脉冲宽度调制电压生成部,将直流电压、所述电压指令、所述载波载体波作为输入,在对于所述载波载体波而言电压指令较大时输出直流电压,在对于载波载体波而言电压指令较小时输出零电压,所述载波载体波生成部决定所述载波载体波的载体波周期以使得与载体波周期的下限值一致,所述载体波周期的下限值根据电动机电流的最大值以及电阻分量的电流和电流变化率来进行计算。(The present invention provides a rotary electric machine drive control device, comprising: a carrier wave generation unit that generates a carrier wave by inputting a voltage command, an induced voltage, and a motor current; and a pulse width modulation voltage generation unit that receives the direct-current voltage, the voltage command, and the carrier wave, outputs the direct-current voltage when the voltage command is large for the carrier wave, and outputs a zero voltage when the voltage command is small for the carrier wave, wherein the carrier wave generation unit determines a carrier wave period of the carrier wave so as to coincide with a lower limit value of the carrier wave period, the lower limit value of the carrier wave period being calculated from a maximum value of the motor current and a current change rate of the resistance component.)

1. A rotary electric machine drive control device characterized by comprising:

a carrier wave generation unit that generates a carrier wave by inputting a voltage command, an induced voltage, and a motor current; and

a pulse width modulation voltage generating unit that receives the direct-current voltage, the voltage command, and the carrier wave, outputs the direct-current voltage when the voltage command for the carrier wave is large, and outputs a zero voltage when the voltage command for the carrier wave is small,

the carrier wave generation unit determines a carrier wave period of the carrier wave so as to coincide with a lower limit value of the carrier wave period,

the lower limit value of the carrier wave period is calculated from the maximum value of the motor current, the current of the resistance component, and the current change rate.

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

the voltage command is externally input to the pulse width modulation voltage generation unit and the carrier wave generation unit as a voltage command value having a voltage dimension.

3. The rotating electric machine drive control device according to claim 1,

the voltage command is externally input to the pulse width modulation voltage generation unit and the carrier wave generation unit as a voltage utilization rate,

the carrier wave generation unit calculates a voltage command value based on the input voltage utilization rate.

4. The rotating electric machine drive control device according to claim 1,

the voltage command is inputted as a duty ratio from the outside to the pulse width modulation voltage generation unit and the carrier wave generation unit,

the carrier wave generation unit calculates a voltage command value based on the input duty ratio.

5. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit calculates a current change rate from a voltage command value, an induced voltage, a motor current, an inductance value, and a winding resistance value.

6. The rotating electric machine drive control device according to claim 5,

the carrier wave generation unit multiplies the rotation speed by an induced voltage coefficient to obtain an induced voltage.

7. The rotating electric machine drive control device according to claim 5,

the carrier wave generation unit compares the calculated current change rate with a threshold value,

if the calculated current change rate is determined to be less than the threshold value, increasing the carrier wave period of the next time compared with the carrier wave period of the current time,

if the calculated current change rate is determined to be greater than the threshold value, the next carrier wave period is reduced from the carrier wave period at the present time point.

8. The rotating electric machine drive control device according to claim 5,

the carrier wave generation unit has a map showing a relationship between a current change rate and a carrier wave period,

the carrier wave generation unit calculates a next carrier wave cycle based on the calculated current change rate and the map.

9. The rotating electric machine drive control device according to claim 5,

the carrier wave generation unit calculates a current of the inductance component from the calculated current change rate and a carrier wave cycle at the present time point,

if the determined current of the inductance component is determined to be smaller than the threshold value, the next carrier wave period is increased from the carrier wave period at the present time point,

if it is determined that the obtained current of the inductance component is larger than the threshold, the next carrier wave cycle is reduced from the carrier wave cycle at the present time.

10. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit, when detecting the current of the inductance component, divides the current of the inductance component by the carrier wave period at the current time point to obtain a current change rate,

if the obtained current change rate is determined to be smaller than the threshold value, the next carrier wave period is increased from the carrier wave period at the present time point,

if it is determined that the obtained current change rate is greater than the threshold value, the carrier wave cycle at the next time is reduced from the carrier wave cycle at the present time.

11. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation section has a map indicating a relationship between a voltage command value and a current change rate, and calculates the current change rate from the map when the voltage command value is acquired,

if the calculated current change rate is determined to be smaller than the threshold value, the carrier wave cycle of the next time is increased from the carrier wave cycle of the current time point,

if it is determined that the calculated current change rate is greater than the threshold value, the carrier wave cycle at the next time is reduced from the carrier wave cycle at the present time.

12. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit has a map showing a relationship between a maximum value of the motor current and a current change rate, and calculates the current change rate from the map when the maximum value of the motor current is acquired,

if the calculated current change rate is determined to be smaller than the threshold value, the carrier wave cycle of the next time is increased from the carrier wave cycle of the current time point,

if it is determined that the calculated current change rate is greater than the threshold value, the carrier wave cycle at the next time is reduced from the carrier wave cycle at the present time.

13. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit has a map showing a relationship between a current of the resistance component and a carrier wave period,

if the average value of the motor current is obtained, the current of the resistance component is obtained,

the next carrier wave period is calculated from the acquired current and map of the resistance component.

14. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit has a map showing a relationship between a current of the resistance component and a carrier wave period,

if the voltage command value is obtained, the current of the resistance component is obtained,

the next carrier wave period is calculated from the acquired current and map of the resistance component.

15. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit has a map showing a relationship between phases of the d-axis current and the q-axis current and a current constraint,

calculating the phases of the d-axis current and the q-axis current, calculating a current constraint from the calculated phases of the d-axis current and the q-axis current and a map,

if the calculated current constraint is determined to be less than the threshold value, the next carrier wave period is increased from the carrier wave period at the present time point,

if the calculated current constraint is determined to be greater than the threshold, the next carrier wave cycle is reduced from the carrier wave cycle at the present time.

16. The rotating electric machine drive control device according to any one of claims 2 to 4,

the carrier wave generation unit performs dq-axis coordinate transformation on the motor current and the inductance value to calculate a d-axis inductance and a q-axis inductance,

calculating a current change rate from the calculated d-axis inductance and q-axis inductance,

if the calculated current change rate is determined to be smaller than the threshold value, the carrier wave cycle of the next time is increased from the carrier wave cycle of the current time point,

if it is determined that the calculated current change rate is greater than the threshold value, the carrier wave cycle at the next time is reduced from the carrier wave cycle at the present time.

Technical Field

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

Background

Conventionally, inverters using Pulse Width Modulation (PWM) have been widely used as rotating electric machine drive control devices. An inverter is a device that converts direct current power into alternating current power by appropriately controlling switching elements. In this inverter, pulse width modulation control is often used as a current control method for controlling a current flowing through the rotating electric machine. The pulse width modulation control is a method of generating a control signal for a switching element using a magnitude relationship between a triangular carrier wave signal as a modulation wave and a voltage command as a modulated wave. The present invention relates to a method for calculating a carrier wave period in pulse width modulation control of a rotating electrical machine drive control device.

The carrier wave period (period of the triangular carrier wave signal) has a high degree of freedom in setting. Since the switching loss is reduced if the carrier wave period as the modulation wave is reduced, the efficiency of the rotating electric machine drive control device can be increased. On the other hand, the lower the carrier wave cycle, the larger the peak current due to switching, and therefore the maximum value of the current flowing through the rotating electrical machine increases. An increase in the maximum value of the current flowing through the rotating electrical machine may cause damage to the rotating electrical machine such as an increase in the loss generated in the coil, irreversible demagnetization of the magnet in the permanent magnet synchronous machine, and the like.

As a method for avoiding the above-described problem in the rotating electric machine drive control device, a motor control device disclosed in patent document 1 is known. The motor control device described in patent document 1 selects the number of pulses in one electrical angle period so that the distortion rate of the current becomes minimum. In the method of patent document 1, although the loss of the rotating electric machine due to the harmonics can be reduced by reducing the distortion ratio of the current (the proportion of the harmonics), the loss due to the magnitude of the motor current cannot necessarily be reduced. Further, since the maximum value of the motor current cannot be suppressed to the threshold value or less, damage to the rotating electric machine such as irreversible demagnetization of the magnet cannot be prevented.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5845115

Disclosure of Invention

Technical problem to be solved by the invention

The present application has been made to solve the above-described problems in the rotary electric machine drive control device. That is, in the rotating electrical machine drive control device that generates the motor current flowing through the rotating electrical machine, the loss due to the magnitude of the motor current is reduced by suppressing the maximum value of the motor current flowing through the rotating electrical machine to a predetermined value or less.

Means for solving the problems

The rotating electric machine drive control device according to the present application is characterized by comprising:

a carrier wave generation unit that generates a carrier wave by inputting a voltage command, an induced voltage, and a motor current; and

a pulse width modulation voltage generating unit that receives the direct-current voltage, the voltage command, and the carrier wave, and outputs the direct-current voltage when the voltage command for the carrier wave is large, and outputs a zero voltage when the voltage command for the carrier wave is small;

the carrier wave generation unit determines a carrier wave period of the carrier wave so as to coincide with a lower limit value of the carrier wave period,

the lower limit value of the carrier wave period is calculated from the maximum value of the motor current, the current of the resistance component, and the current change rate.

Effects of the invention

The rotating electrical machine drive control device according to the present invention is configured as described above, and can suppress the maximum value of the motor current flowing through the rotating electrical machine to a predetermined value or less, and therefore, can obtain an effect that has not been achieved in the past, such as reduction of loss due to the magnitude of the motor current.

Drawings

Fig. 1 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 1 of the present application.

Fig. 2 is a diagram showing a relationship between a pulse width modulation voltage and a motor current in the embodiment of the present application.

Fig. 3 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 1 of the present invention.

Fig. 4 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 2 of the present application.

Fig. 5 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 2 of the present invention.

Fig. 6 is a block configuration diagram showing the configuration of a rotating electric machine drive control device according to embodiment 3 of the present application.

Fig. 7 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 3 of the present invention.

Fig. 8 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 4 of the present application.

Fig. 9 is a diagram showing a map of the relationship between the current change rate and the carrier wave period in embodiment 4 of the present application.

Fig. 10 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 4 of the present invention.

Fig. 11 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 5 of the present application.

Fig. 12 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 5 of the present invention.

Fig. 13 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 6 of the present application.

Fig. 14 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 6 of the present invention.

Fig. 15 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 7 of the present application.

Fig. 16 is a diagram showing a map of the relationship between the voltage command value and the current change rate in embodiment 7 of the present application.

Fig. 17 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 7 of the present invention.

Fig. 18 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 8 of the present application.

Fig. 19 is a map showing a relationship between the maximum value of the motor current and the current change rate in embodiment 8 of the present application.

Fig. 20 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 8 of the present invention.

Fig. 21 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 9 of the present application.

Fig. 22 is a diagram showing a map of the relationship between the current of the resistance component and the carrier wave period in embodiment 9 of the present application.

Fig. 23 is a first flowchart showing steps for determining a carrier wave period in embodiment 9 of the present invention.

Fig. 24 is a second flowchart showing the steps for determining the carrier wave period in embodiment 9 of the present invention.

Fig. 25 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 10 of the present application.

Fig. 26 is a diagram showing the definition of the phases of the d-axis current and the q-axis current in embodiment 10 of the present application.

Fig. 27 is a diagram showing a map of the relationship between the phases of the d-axis current and the q-axis current and the current constraint in embodiment 10 of the present application.

Fig. 28 is a flowchart showing a procedure for determining the carrier wave period in embodiment 10 of the present invention.

Fig. 29 is a block configuration diagram showing a configuration of a rotating electric machine drive control device according to embodiment 11 of the present application.

Fig. 30 is a diagram showing a map of the relationship between the d-axis current and the d-axis inductance in embodiment 11 of the present application.

Fig. 31 is a diagram showing a map of the relationship between the q-axis current and the q-axis inductance in embodiment 11 of the present application.

Fig. 32 is a flowchart showing a procedure for determining a carrier wave cycle in embodiment 11 of the present invention.

Fig. 33 is a schematic diagram showing an internal configuration of a rotating electric machine drive control device according to an embodiment of the present application.

Detailed Description

A rotary electric machine drive control device according to an embodiment of the present application will be described below with reference to the drawings. In the drawings, the same or similar components are denoted by the same reference numerals, and the dimensions and scales of the corresponding components are independent of each other. For example, when the same constituent part is not changed in the drawings, the size and scale of the same constituent part may be different between cross-sectional views in which a part of the structure is changed. In addition, although the rotating electric machine drive control device actually includes a plurality of members, only the portions necessary for the description are described for the sake of simplifying the description, and the other portions are omitted.

Embodiment 1.

First, the configuration of a rotating electric machine drive control device 1 according to embodiment 1 of the present application will be described with reference to the drawings. Fig. 1 is a configuration diagram of a rotating electric machine drive control apparatus 1 including a rotating electric machine 4 to be controlled. The rotating electric machine drive control device 1 according to the present embodiment is configured by a pulse width modulation voltage generation unit 2 and a carrier wave generation unit 3. The carrier wave generator 3 generates a carrier wave and outputs the carrier wave to the pwm voltage generator 2. The pulse width modulation voltage generation unit 2 generates a pulse width modulation voltage (PWM voltage) to be applied to the rotating electrical machine 4 based on the dc voltage, the voltage command, and the carrier wave.

Hereinafter, the structure, function, and operation of each part of the rotating electric machine drive control device 1 will be described in order. First, the pulse width modulation voltage generation unit 2 will be described. The Pulse Width Modulation voltage generation unit 2 converts the direct current voltage (V) into a Pulse Width Modulation voltage (PWM voltage) by Pulse Width Modulation (PWM) based on the voltage commands [ Vu, Vv, Vw ] inputted from the outside. In addition, in the voltage command [ Vu, Vv, Vw ], a value having a dimension of voltage (voltage command value) or a value having no dimension (for example, duty ratio, voltage utilization rate) is externally input. Pulse width modulation is a method in which voltage command values (Vu, Vv, Vw) are compared with a carrier wave, and when the voltage command is large for the carrier wave, a pulse width modulation voltage equal to a direct current voltage (V) is output, and when the voltage command is small for the carrier wave, a pulse width modulation voltage equal to zero volts (zero voltage) is output.

Next, the operation of the carrier wave generator 3 will be described. The carrier wave generation unit 3 determines a carrier wave period (Pc) from the voltage command values (Vu, Vv, Vw), the induced voltages (Eu, Ev, Ew), and the motor currents (Iu, Iv, Iw), and transmits the generated carrier wave to the pulse width modulation voltage generation unit 2. The pulse width modulation voltage is generated using pulse width modulation such that the average voltage coincides with the voltage command. The carrier wave period (Pc) is determined by carrier wave period calculation described below in the carrier wave generation unit 3.

Fig. 2 shows a waveform of a current (motor current) flowing through the rotating electrical machine 4 when the pulse width modulation voltage is applied to the rotating electrical machine. When the pulse width modulation voltage is applied to the rotating electrical machine 4, a current (motor current) obtained by combining a current (IR) of a resistance component linear with respect to the voltage and a current (IL) of an inductance component nonlinear with respect to the voltage flows through the rotating electrical machine 4. Therefore, the maximum value (Imax) of the motor current (I) in the pulse width modulation is in the relationship shown in expression (1). Further, by using the current change rate (dI/dt) of the motor current and the carrier wave period (Pc) of the carrier wave, the current (IL) of the inductance component flowing through the rotating electrical machine 4 is expressed by equation (2).

Imax＝IR+IL (1)

IL＝(dI/dt)×Pc (2)

As is clear from expressions (1) and (2), when the current change rate (dI/dt) is constant, the maximum current flowing through the rotating electrical machine 4 increases in proportion to the carrier wave period. From the viewpoint of preventing burnout of the stator winding of the rotating electrical machine 4 and irreversible demagnetization of the magnet, there is a restriction on the magnitude of the maximum current that can flow through the rotating electrical machine 4. In order to suppress the maximum current flowing through the rotating electrical machine 4, it is effective to reduce the carrier wave period. On the other hand, the cycle of the output switching of the pulse width modulation voltage decreases due to the decrease in the carrier wave cycle. In the pulse width modulation voltage generation unit 2, a loss occurs every time the output of the pulse width modulation voltage is switched, and therefore the reduction of the carrier wave period causes a reduction in the efficiency of the rotating electric machine drive control device 1.

Therefore, the carrier wave period is selected in the carrier wave generation unit 3 so that the loss generated in the pulse width modulation voltage generation unit 2 can be minimized while satisfying the current restriction of the rotating electrical machine 4. In addition, unlike other industrial equipment, a rotating electric machine applied to an electric vehicle or a hybrid vehicle is often disposed adjacent to an engine. The heat generated in the engine causes the coils and magnets of the rotating electric machine to be in a high-temperature state. Under such high temperature conditions, it is desirable to reduce the maximum value of the motor current for supplying power to the rotating electric machine and to suppress heat generation due to loss caused by the magnitude of the motor current.

In electric vehicles and hybrid vehicles, the rotating electric machine operates at a high frequency with low rotation. Under such operating conditions, the loss due to the magnitude of the motor current accounts for a large proportion of the total loss. Therefore, suppressing the maximum value of the motor current and reducing the loss due to the magnitude of the motor current leads to miniaturization and weight reduction of the cooling device of the rotating electrical machine, and is thus particularly effective for electric vehicles and hybrid vehicles.

Next, selection and calculation of the carrier wave period (Pc) of the carrier wave will be described. In equations (1) and (2), when the maximum value (Imax) of the motor current is set as the current constraint (Icon) of the rotating electrical machine 4, the lower limit value of the carrier wave period satisfying the current constraint of the rotating electrical machine 4 is calculated by equation (3a) or (3 b). Here, the current (IR) of the resistance component linear with respect to the voltage may be an average value of the motor current flowing through the rotating electrical machine 4, or may be a value obtained by dividing the voltage command value by the winding resistance value (R) of the rotating electrical machine 4.

Lower limit of carrier wave period ═ (Icon-IR)/(dI/dt) (3a)

Lower limit of carrier wave period ═ (Imax-IR)/(dI/dt) (3b)

In order to select the carrier wave period (Pc) of the carrier wave, it is also effective to keep a carrier wave period satisfying the current restriction (Icon) of the rotating electrical machine 4 as a map for the current change rate (dI/dt) or the current (IR) of the resistance component. According to this method, the carrier wave period corresponding to the current change rate or the current of the resistance component is calculated from a map generated in advance. The carrier wave generation unit 3 sets the carrier wave period calculated by the above method to a lower limit value of the carrier wave period in the carrier wave.

Next, a method of calculating the current change rate (dI/dt) will be described. Using the winding resistance values (Ru, Rv, Rw), the differential operator (p), and the mutual inductances (Muv, Mvw, and Mwu) of the rotating electrical machine 4, the voltage equations of the rotating electrical machine 4 are represented by equations (4a) to (4 c).

Vu＝(Ru+pLu)×Iu+pMuv×Iv+pMwu×Iw+Eu (4a)

Vv＝(Rv+pLv)×Iv+pMvw×Iw+pMuv×Iu+Ev (4b)

Vw＝(Rw+pLw)×Iw+pMwu×Iu+pMvw×Iv+Ew (4c)

Here, the U-phase voltage command value (Vu), the V-phase voltage command value (Vv), and the W-phase voltage command value (Vw) have voltage dimensions, and correspond to the U-phase voltage command [ Vu ], the V-phase voltage command [ Vv ], and the W-phase voltage command [ Vw ], respectively. The U-phase induced voltage (Eu), the V-phase induced voltage (Ev), and the W-phase induced voltage (Ew) represent terminal voltages of the rotating electric machine (voltages of lines connecting the PWM voltage generation unit 2 and the rotating electric machine 4). The U-phase motor current (Iu), the V-phase motor current (Iv), and the W-phase motor current (Iw) represent a U-phase PWM current, a V-phase PWM current, and a W-phase PWM current, respectively. The PWM current indicates a current flowing through a line connecting the PWM voltage generator 2 and the rotating electrical machine 4. The U-phase inductance, the V-phase inductance, and the W-phase inductance are Lu, Lv, and Lw, respectively.

For simplification, assuming that the mutual inductances (Muv, Mvw, and Mwu) are negligible, expressions (4a) to (4c) may be transformed into expressions (5a) to (5c), respectively. The current change rates (dI/dt) of the U-phase, V-phase and W-phase are represented as dIu/dt, dIv/dt and dIw/dt, respectively. The current supplied to the rotating electrical machine 4 is the same as the current flowing through the rotating electrical machine 4. Hereinafter, dIu/dt, dIv/dt and dIw/dt are sometimes collectively referred to as a current change rate (dI/dt).

dIu/dt＝(Vu-Eu)/Lu-Ru/Lu×Iu (5a)

dIv/dt＝(Vv-Ev)/Lv-Rv/Lv×Iv (5b)

dIw/dt＝(Vw-Ew)/Lw-Rw/Lw×Iw (5c)

As can be seen from equation (5a), the U-phase current change rate (dIu/dt) can be calculated from the U-phase voltage command value (Vu), the U-phase induced voltage (Eu), the U-phase motor current (Iu), the U-phase inductance value (Lu), and the U-phase winding resistance value (Ru) of the rotating electrical machine 4. As is clear from equation (5b), the V-phase current change rate (dIv/dt) can be calculated from the V-phase voltage command value (Vv), the V-phase induced voltage (Ev), the V-phase motor current (Iv), the V-phase inductance value (Lv), and the V-phase winding resistance value (Rv) of the rotating electrical machine 4. As can be seen from equation (5c), the W-phase current change rate (dIw/dt) can be calculated from the W-phase voltage command value (Vw), the W-phase induced voltage (Ew), the W-phase motor current (Iw), the W-phase inductance value (Lw), and the W-phase winding resistance value (Rw) of the rotating electrical machine 4.

In the rotating electrical machine drive control device according to the present embodiment, the carrier wave generation unit 3 calculates the current change rate based on equations (5a) to (5c), and then determines the lower limit value of the carrier wave period. The flow of determining the carrier wave period by the carrier wave generator 3 will be described with reference to fig. 3. Hereinafter, formulae (5a) to (5c) may be collectively referred to as formula (5). When the flow of calculating the carrier wave period starts in step ST100, the carrier wave generator 3 calculates the current change rate based on equation (5) (step ST 101).

In equation (5), the U-phase current change rate (dIu/dt), the V-phase current change rate (dIv/dt), and the W-phase current change rate (dIw/dt) are calculated from the voltage command values (Vu, Vv, Vw), the induced voltages (Eu, Ev, Ew), the motor currents (Iu, Iv, Iw), the inductance values (Lu, Lv, Lw), and the winding resistance values (Ru, Rv, Rw) of the rotating electrical machine 4. In step ST102, the current change rate (dI/dt) is set as a determination parameter, and in step ST103, it is determined whether or not the determination parameter is equal to or less than a threshold value.

If it is determined that the determination parameter is equal to or less than the threshold value, the carrier wave generator 3 proceeds to step ST104, and increases the carrier wave cycle at the next time by, for example, one unit with respect to the carrier wave cycle at the current time. If it is determined that the determination parameter is larger than the threshold value, the carrier wave generation unit 3 proceeds to step ST105 to decrease the carrier wave cycle at the next time by, for example, one unit from the carrier wave cycle at the current time. When step ST104 or step ST105 ends, the present calculation of the carrier wave cycle ends (step ST 106).

Next, a method of setting the threshold value of the current change rate will be described. The threshold value of the current change rate is determined so that the maximum value (Imax) of the motor current becomes equal to or less than the current limit (Icon) of the rotating electric machine. In order to make the maximum value of the motor current less than the current limit of the rotating electric machine 4, it is necessary to satisfy the formula (6a) using the current (IL) of the inductance component and the current (IR) of the resistance component. Here, the current (IR) of the resistance component may be an average value of the motor current flowing through the rotating electrical machine 4, or may be a value obtained by dividing the voltage command value by the winding resistance value (R) of the rotating electrical machine 4. When the formula (6a) is modified, the formula (6b) is obtained.

Icon≤IR+IL (6a)

Icon-IR≤IL (6b)

Here, since IL (the current of the inductance component) is obtained from the product of the current change rate (dI/dt) and the carrier wave period (Pc), the current constraint (Icon) of the rotating electric machine for setting the maximum current to be equal to or less than the current constraint of the rotating electric machine is expressed by equation (7). From this equation, the threshold value of the current change rate (the threshold value of the determination parameter) is set to equation (8). As described above, by setting the threshold value of the current change rate as the threshold value of the determination parameter, the carrier wave cycle can be determined so that the maximum value (Imax) of the motor current becomes equal to or less than the current limit of the rotating electric machine.

(Icon-IR)/Carrier wave period at current time ≤ dI/dt (7)

(Icon-IR)/carrier wave period at present time ═ threshold value of current change rate (8)

In the case of adopting a method of switching to the number of pulses capable of reducing the current distortion rate on the premise of synchronous pulse width modulation, it is necessary to perform a complicated switching process in which the switching of the number of pulses does not affect the control. On the other hand, as described in the above-described embodiments, the rotating electrical machine drive control device of the present application may change the carrier wave period of the carrier wave to reduce the peak current. Since the carrier wave period of the carrier wave can be changed regardless of the driving state of the rotating electric machine, no special switching process is required. Further, since the carrier wave period of the carrier wave that is the basis of the pulse width modulation is changed, the present invention has a feature that it can be applied to either of the synchronous pulse width modulation and the asynchronous pulse width modulation. The induced voltage may be obtained by multiplying the rotation speed by an induced voltage coefficient.

Therefore, the rotating electric machine drive control device according to the present application is characterized by comprising:

a carrier wave generation unit that generates a carrier wave by inputting a voltage command, an induced voltage, and a motor current; and

the carrier wave generation unit determines a carrier wave period of the carrier wave so as to coincide with a lower limit value of the carrier wave period,

the lower limit value of the carrier wave period is calculated from the maximum value of the motor current, the current of the resistance component, and the current change rate.

In addition, in the rotary electric machine drive control device according to the present application,