JP2019213316A - Controller for rotary electric machine - Google Patents

Abstract

To provide a controller for a rotary electric machine capable of enhancing the whole efficiency of a rotary electric machine system.SOLUTION: A controller is provided with a voltage calculation section, a switching control section, and a limit section. The voltage calculation section calculates a voltage command value of an AC voltage supplied to MG from a target torque. The switching control section controls switching of each switching element included in an inverter so that the calculated voltage command value is supplied to the MG. The limit section limits an ON period, during which each switching element can be turned to an ON state in an electric angle half cycle of the voltage command value when a voltage utilization rate is less than a utilization rate threshold value in an inverter control, to a period shorter than a period obtained by subtracting a dead time from the electric angle half cycle of the voltage command value. When the ON period is limited, the switching control section controls switching of each switching element in the limited ON period, and carries out rectangular wave control or overmodulation control.SELECTED DRAWING: Figure 4

Description

  The present disclosure relates to a technique for controlling driving of a rotating electrical machine.

  In recent years, in order to extend the cruising range of an electric vehicle, it is desired to reduce the loss in each component. As one of techniques for reducing loss in each component, a technique for reducing loss in a rotating electrical machine system has been proposed. The control device of the electric drive device described in Patent Document 1 expands the rectangular wave control region by increasing the voltage supplied to the rotating electrical machine by the strong field control and increasing the voltage utilization factor. By enlarging the rectangular wave control region, the switching frequency of the inverter is reduced, and the switching loss is reduced. Further, since the current ripple of the carrier harmonic component is reduced, the MG iron loss is also reduced.

JP 2010-279113 A

  In the control of the rotating electrical machine by the control device, in the low torque range, the increase in the MG loss due to the strong field control and the conduction loss of the inverter is larger than the decrease in the loss due to the decrease in the number of switching operations. Therefore, the control of the rotating electrical machine by the control device cannot be applied to the low torque range. However, since the torque range normally used by the vehicle and the operating point during WLTP mode running are in the low torque range, it is desired to improve the efficiency of the entire rotating electrical machine system in the low torque range.

  The present disclosure provides a control device for a rotating electrical machine capable of improving the efficiency of the entire rotating electrical machine system even in a low torque range.

  One aspect of the present disclosure is a rotating electrical machine control device (20) that controls driving of a rotating electrical machine (15) in the rotating electrical machine system (100) mounted on a vehicle. A DC power source (11), an inverter (13), and a torque command unit (40). The inverter includes a plurality of switching elements (S1 to S6), converts the DC power of the DC power supply into AC power, and supplies the AC power to the rotating electrical machine. The torque command unit commands a target torque of the rotating electrical machine. The control device for a rotating electrical machine includes a voltage calculation unit (23, 25), a switching control unit (27), and a limiting unit (27). The voltage calculation unit calculates a voltage command value of the AC voltage supplied to the rotating electrical machine from the target torque commanded by the torque command unit. The switching control unit controls switching of each switching element included in the inverter so that the voltage command value calculated by the voltage calculation unit is supplied to the rotating electrical machine. In the control of the inverter, the limiting unit can turn on each switching element in the electrical angle half cycle of the voltage command value when the voltage utilization factor of the DC voltage is smaller than a preset utilization factor threshold value. The ON period is limited to a period shorter than the period obtained by subtracting the dead time of the switching element from the electrical angle half cycle of the voltage command value. The switching control unit performs the rectangular wave control or the overmodulation control by controlling the switching of each switching element in the limited on period when the on period is limited by the limiting unit.

  According to one aspect of the present disclosure, when the voltage usage rate is smaller than the usage rate threshold value, that is, when the number of times of switching is relatively large, the on period is limited, and the control of the inverter is rectangular wave control or overmodulation control. It is moved to. Thereby, the frequency | count of switching is reduced and a switching loss can be reduced. In addition, by limiting the ON period without changing the DC voltage input to the inverter, the control of the inverter is shifted to rectangular wave control or overmodulation control. Exceed the rise of. Therefore, the efficiency of the entire rotating electrical machine system can be improved even in a low torque range.

  Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with the specific means described in the embodiment described later as one aspect, and the technical scope of the present disclosure It is not limited.

It is a figure which shows the structure of MG system. It is a block diagram which shows the function of the control apparatus of MG system. It is a figure which shows the switching waveform in PWM control. It is a figure which shows the switching waveform in the case of restrict | limiting the ON period of the switching waveform shown in FIG. 3, and making control of an inverter transfer to overmodulation control. It is a figure which shows the switching waveform in the case of restrict | limiting the ON period of the switching waveform shown in FIG. 3, and making control of an inverter transfer to rectangular wave control. It is a flowchart which shows the procedure of the production | generation process of the control signal with respect to a switching element. It is a figure which shows the operation area | region of each control prescribed | regulated by a rotational speed and a torque. It is a figure which shows the method of producing | generating a switching waveform in the case of restrict | limiting an ON period. It is a figure explaining the setting method of an ON period. It is a figure which shows the comparison of the loss of the comparative example which does not restrict | limit an ON period, and this embodiment which restrict | limits an ON period.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.
<1. Configuration>
First, the configuration of the MG system 100 according to the present embodiment will be described with reference to FIG.

  The MG system 100 is mounted on an electric vehicle or a hybrid vehicle. The MG system 100 includes an MG 15, a DC power supply 11, a smoothing capacitor 12, an inverter 13, a current sensor 14, a rotation sensor 16, a torque command unit 40, and a control device 20.

  The MG 15 is a three-phase AC motor generator and a traveling drive source. The MG 15 has a function of a motor that generates torque for driving the driving wheels of the vehicle, and a function of a generator that generates power by being driven by the kinetic energy of the vehicle.

  The DC power supply 11 is connected to the MG 15 via the inverter 13. DC power supply 11 exchanges power with MG 15 via inverter 13. The DC power supply 11 is a chargeable / dischargeable power storage device such as a secondary battery such as lithium ion or a capacitor.

  Inverter 13 is a three-phase power converter connected between DC power supply 11 and MG 15. The inverter 13 converts the DC power of the DC power supply 11 into AC power and supplies the AC power to the MG 15. Further, the inverter 13 converts AC power generated by the MG 15 into DC power and supplies the DC power to the DC power source 11.

  The inverter 13 includes switching elements S1 to S6 and diodes D1 to D6. In the present embodiment, Insulated Gate Bipolar Transistors (IGBTs) are employed as the switching elements S1 to S6, but Metal Oxide Semiconductor (MOS) transistors, bipolar transistors, and the like may be employed. The diodes D1 to D6 each function as a freewheel diode and are connected in parallel to the switching elements S1 to S6.

  Switching element S1 and switching element S2, switching element S3 and switching element S4, switching element S5 and switching element S6 are connected in series, respectively. The series body of the switching element S1 and the switching element S2 is connected between the positive terminal and the negative terminal of the DC power supply 11, and the connection point of the two switching elements is connected to the U-phase winding of the MG15. ing. The series body of the switching element S3 and the switching element S4 is connected between the positive terminal and the negative terminal of the DC power supply 11, and the connection point of these two switching elements is the V-phase winding of the MG15. It is connected. Further, the series body of the switching element S5 and the switching element S6 is connected between the positive terminal and the negative terminal of the DC power source 11, and the connection point of these two switching elements is the W-phase winding of the MG15. It is connected. The switching elements of the upper arm and the lower arm of each phase operate in a complementary manner.

  The smoothing capacitor 12 is connected in parallel with the inverter 13 between the positive terminal and the negative terminal of the DC power supply 11. Smoothing capacitor 12 smoothes the power transferred between inverter 13 and DC power supply 11.

  The current sensor 14 detects the current value of the actual current flowing through the three-phase winding of the MG 15 and outputs the detected actual current values Iur, Ivr, and Iwr to the control device 20. The current sensor 14 may only detect the value of the current flowing through the two-phase winding of the MG 15. In this case, the current value of the remaining one phase is calculated using Kirchhoff's law.

  The rotation sensor 16 is provided in the vicinity of the rotor of the MG 16, detects the rotation angle θ of the rotor, and outputs the detected rotation angle θ to the control device 20. The rotation angle θ is an electrical angle. The rotational speed N of the MG 15 is calculated from the rotational angle θ. As the rotation sensor 16, a sensor such as a resolver or an encoder can be employed.

  The torque command unit 40 calculates the target torque Tr of the MG 15 and commands the target torque Tr to the control device 20. The torque command unit 40 acquires an accelerator signal from an accelerator sensor (not shown), a brake signal from a brake switch, a shift signal from a shift switch, and the like, and calculates a target torque Tr according to the driving state.

  The control device 20 is mainly composed of a microcomputer having a CPU and a semiconductor memory such as a ROM, a RAM, and a flash memory. Various functions of the control device 20 are realized when the CPU loads and executes a program stored in a non-transitional tangible recording medium (for example, the above-described semiconductor memory). The control device may include one microcomputer or a plurality of microcomputers.

  The control device 20 controls the driving of the MG 15 so that the output torque of the MG 15 becomes the target torque Tr commanded from the torque command unit 40. That is, the control device 20 controls switching of the switching elements S1 to S6 based on the target torque Tr.

  Specifically, as shown in FIG. 2, the control device 20 includes a current command value calculation unit 21, a three-phase / two-phase conversion unit 22, a voltage command value calculation unit 23, a voltage utilization rate calculation unit 24, and a two-phase A three-phase converter 25, a rotation speed calculator 26, and a control signal generator 27 are provided. The method by which the control device 20 realizes these functions is not limited to software, and some or all of the functions may be realized by using hardware that combines a logic circuit, an analog circuit, and the like.

  The current command value calculation unit 21 calculates a d-axis current command value Id and a q-axis current command value Iq based on the target torque Tr. Specifically, the current command value calculation unit 21 calculates the d-axis current command value Id and the q-axis current command value Iq in the rotating coordinate system using a map or the like so as to realize the minimum current / maximum torque control. Then, the current command value calculation unit 21 outputs the calculated d-axis current command value Id and q-axis current command value Iq to the voltage command value calculation unit 23.

  The three-phase / two-phase converter 22 uses the rotational position θ of the rotor to convert the three-phase actual current values Iur, Ivr, and Iwr detected by the current sensor 14 into the two-phase d in the rotating coordinate system. It converts into the shaft actual current value Idr and the q axis actual current value Iqr. Then, the three-phase / two-phase conversion unit 22 outputs the d-axis actual current value Idr and the q-axis actual current value Iqr to the voltage command value calculation unit 23.

  The voltage command value calculation unit 23 calculates the d-axis voltage command value Vd so that the difference between the d-axis current command value Id and the d-axis actual current value Idr converges to zero. Moreover, the voltage command value calculation unit 23 calculates the q-axis voltage command value Vq so that the difference between the q-axis current command value Iq and the q-axis actual current value Iqr converges to zero. Then, the voltage command value calculation unit 23 outputs the calculated d-axis voltage command value Vd and q-axis voltage command value Vq to the voltage utilization rate calculation unit 24 and the two-phase / three-phase conversion unit 25.

  The voltage usage rate calculation unit 24 calculates the voltage usage rate m from the following equation (1). Vdc is a DC voltage value supplied to the inverter 13. In the present embodiment, Vdc is a voltage value of the DC power supply 11. Then, the voltage usage rate calculation unit 24 outputs the calculated voltage usage rate m to the control signal generation unit 27.

  The two-phase three-phase conversion unit 25 converts the d-axis voltage command value Vd and the q-axis voltage command value Vq into three-phase voltage command values VU, VV, VW using the rotational position θ. Then, the two-phase / three-phase converter 25 outputs the three-phase voltage command values VU, VV, and VW to the control signal generator 27.

  The rotation speed calculation unit 26 differentiates the rotation position θ detected by the rotation sensor 16 to calculate the rotation speed N of the MG 15. Then, the rotation speed calculation unit 26 outputs the calculated rotation speed N to the control signal generation unit 27.

  The control signal generator 27 generates control signals g1 to g6 for controlling switching of the switching elements S1 to S6 of the inverter 13 based on the comparison between the voltage command values VU, VV, and VW and the carrier wave. The control signals g1 to g6 are gate signals input to the gates of the switching elements S1 to S6. The switching elements S1 to s6 are turned on or off according to the control signals g1 to g6.

  Specifically, in this embodiment, as shown in FIG. 7, the control signal generation unit 27 performs Pulse Width Modulation (hereinafter referred to as PWM) control, first overmodulation control, and first rectangular wave as control of the inverter 13. Control signals g1 to g6 for executing one of the control, the second overmodulation control, and the second rectangular wave control are generated.

  The PWM control is control in which the amplitude value of the modulation wave is limited to less than the DC voltage value Vd, and is control in a low rotation speed region. In the PWM control, the control signal generator 27 becomes a sine wave in a certain period based on a comparison between the modulated wave having the sinusoidal voltage command values VU, VV, and VW and the carrier wave as shown in FIG. Switching waveforms are generated as control signals g1 to g6. The amplitude value of the carrier wave coincides with the DC voltage value Vd. This switching waveform is based on a set of pulses including a high level period in which the upper arm switching elements S1, S3, S5 are in the on state and a low level period in which the lower arm switching elements S2, S4, S6 are in the on state. It is configured. In PWM control, the voltage utilization factor m can be changed within a range of less than 0.613. The voltage utilization factor m is 0.613 when the amplitude value of the modulated wave matches the DC voltage value Vd.

  The first overmodulation control is control in which the amplitude value of the modulated wave is equal to or greater than the DC voltage value Vd, and is control in the middle rotation speed range. In the first overmodulation control, the control signal generation unit 27 generates a switching waveform that continuously becomes a high level or a low level in a portion where the amplitude value of the modulation wave is equal to or greater than the DC voltage value Vd. Generate as This switching waveform is composed of pulses similar to the switching waveform in PWM control in the portion where the amplitude value of the modulation wave is less than the DC voltage value Vd. In the first overmodulation control, the modulation factor m can be changed in a range of 0.613 or more and less than 0.78.

  The first rectangular wave control is a control in which the amplitude value of the modulated wave becomes a value corresponding to the upper limit voltage utilization factor m (that is, m = 0.78) in overmodulation control, and is controlled in a high rotation speed range. It is. In the first rectangular wave control, the control signal generator 27 alternately displays the high level period and the low level period once in one period of the modulated wave, and the ratio of the high level period to the low level period is 1. 1 is generated as a switching waveform of rectangular waves, which are 1: control signals g1 to g6. In the first rectangular wave control, the modulation factor m is fixed at 0.78.

  The second overmodulation control and the second rectangular wave control are controls that are executed when the voltage utilization factor m is less than the utilization factor threshold value 0.78 and when a predetermined condition is satisfied. That is, the second overmodulation control and the second rectangular wave control are executed when a predetermined condition is satisfied when the operation region of the inverter 13 is the PWM control region and the first overmodulation control region. Control. In the second overmodulation control and the second rectangular wave control, the control signal generation unit 27 generates the control signals g1 to g6 by limiting the ON period θc in the electrical angle half cycle of the modulation wave. The on period θc is a period during which the switching element can be turned on. The control signal generator 27 limits the ON period θc to a period (for example, 120 ° or 90 °) shorter than a period obtained by subtracting the dead time of the switching elements S1 to S6 from the electrical angle half cycle. The switching elements S1 to S6 are maintained in the off state during a period other than the on period θc in the electrical angle half cycle.

  FIG. 3 shows a switching waveform when the on period θc is not limited. FIG. 4 shows a switching waveform when the ON period θc is limited to θ1. FIG. 5 shows a switching waveform when the ON period θc is limited to θ2 (θ1> θ2).

  In the case illustrated in FIG. 4, the control signal generation unit 27 uses the d-axis voltage command value Vd and the q-axis voltage command in which the AC voltage of the MG 15 within the on period θ1 is calculated by the voltage command value calculation unit 23 for each switching element. The control signals g1 to g6 are generated by determining the high level period in the on period θ1 so as to be the value Vq.

  Similarly, in the case illustrated in FIG. 5, the control signal generation unit 27 has the d-axis voltage obtained by calculating the AC voltage of the MG 15 within the ON period θ <b> 2 by the voltage command value calculation unit 23 for each switching element. The control signals g1 to g6 are generated by determining the high level period in the ON period θ2 so as to be the command value Vd and the q-axis voltage command value Vq. Control signals g1-g6 are generated.

  Therefore, the lower the ON period θc, the smaller the low level period in the ON period θc. As a result, as shown in FIG. 4, the high level period continues and the switching waveform changes from the PWM waveform to the overmodulation waveform. The switching waveform generated in this manner is output to the inverter 13 as the control signals g1 to g6, so that the second overmodulation control of the inverter 13 is executed in the same manner as the first overmodulation control.

  Further, when the ON period θc is narrowed, as shown in FIG. 5, the switching waveform changes from the overmodulation waveform to the rectangular waveform. The switching waveform generated in this manner is output to the inverter 13 as the control signals g1 to g6, so that the second rectangular wave control of the inverter 13 is executed in the same manner as the first rectangular wave control.

  That is, the control signal generation unit 27 performs PWM control or first overmodulation control when a predetermined condition is satisfied when the operation region of the inverter 13 is the region of PWM control or first overmodulation control. The control signals g1 to g6 for executing the second overmodulation control or the second rectangular wave control in which the number of times of switching is further reduced are generated. The predetermined condition is a condition related to the target torque Tr and the rotation speed N. Details of the predetermined condition will be described later.

  In the present embodiment, the MG system 100 corresponds to a rotating electrical machine system, and the MG 15 corresponds to a rotating electrical machine. The voltage command value calculation unit 23 and the two-phase / three-phase conversion unit 25 correspond to a voltage calculation unit, and the control signal generation unit 27 corresponds to a switching control unit and a limiting unit. Further, the rotation speed detection unit 26 corresponds to a speed detection unit.

<2. Control signal generation processing>
Next, the generation process of the control signals g1 to g6 executed by the control device 20 will be described with reference to the flowchart of FIG. The control device 20 repeatedly executes this processing procedure at predetermined intervals.

First, in S <b> 10, the control device 20 acquires the target torque Tr calculated by the torque command unit 40.
Subsequently, in S20, the control device 20 acquires the rotational position θ detected by the rotation sensor 16, and calculates the rotational speed N from the rotational position θ.

Subsequently, in S30, the control device 20 calculates the d-axis voltage command value Vd and the q-axis voltage command value Vq, and calculates the voltage utilization rate m using Equation (1).
Subsequently, in S40, the control device 20 determines whether or not the voltage usage rate m calculated in S30 is less than the usage rate threshold value 0.78. That is, the control device 20 determines whether or not it is necessary to limit the ON period θc and reduce the number of switching times.

  When the voltage utilization factor m is 0.78 or more, that is, when the operation region of the inverter 13 is a rectangular wave control region, the control device 20 proceeds to the process of S80. In S80, the control device 20 calculates the voltage command values VU, VV, VW, and executes the first rectangular wave control based on the comparison between the voltage command values VU, VV, VW and the carrier wave. Control signals g1-g6 are generated.

  On the other hand, when the voltage utilization factor m is less than 0.78, the control device 20 proceeds to the process of S50. In S50, the control device 20 determines whether or not a predetermined condition is satisfied. Here, the predetermined conditions determined by the control device 20 are the following conditions (i) and (ii). (I) The effective current value at the target torque Tr is smaller than the current threshold. (Ii) The target torque Tr is larger than a preset minimum threshold Tmin.

  In condition (i), the control device 20 sets the current value of the smallest maximum rating among the maximum ratings of a plurality of devices included in the MG system 100 such as the MG 15 and the inverter 13 as the current threshold. The effective current value at the target torque Tr is calculated from the d-axis current command value Id and the q-axis current command value Iq.

  When the ON period θc is limited, the current amount that has flowed in the electrical angle half cycle flows in the ON period θc that is shorter than the electrical angle half cycle, so that the current effective value increases. When the current effective value increases, the maximum rating of the device included in the MG system 100 may be exceeded. Therefore, the control device 20 does not limit the ON period θc when the current effective value at the target torque Tr is equal to or greater than the current threshold. Specifically, the control device 20 determines whether or not the condition (i) is satisfied by comparing the target torque Tr and the maximum threshold value Tmax. The maximum threshold value Tmax is a value determined by the current threshold value.

  In the condition (ii), the minimum threshold Tmin is a value determined by torque ripple. By making the switching waveform an overmodulation waveform or a rectangular waveform, the switching loss is reduced but the torque ripple becomes larger than when the switching waveform is a PWM waveform. Therefore, for example, when the target torque Tr during power running is relatively small, if a large torque ripple is applied by limiting the ON period θc, the minimum torque may become a negative torque. When the minimum torque becomes negative, gear rattling occurs, and abnormal noise is generated or the gear deteriorates.

  Therefore, the control device 20 sets the minimum value of the target torque Tr at which the minimum torque does not become negative even if a relatively large torque ripple is added during overmodulation control or rectangular wave control, as the minimum threshold Tmin. And the control apparatus 20 does not restrict | limit ON period (theta) c, when the target torque Tr is below the minimum threshold value Tmin.

Therefore, in S50, the control device 20 determines whether or not the target torque Tr is larger than the minimum threshold value Tmin and the target torque Tr is smaller than the maximum threshold value Tmax.
When the target torque Tr is not more than the minimum threshold value Tmin or the target torque Tr is not less than the maximum threshold value Tmax, the control device 20 proceeds to the process of S80. In S80, control device 20 calculates voltage command values VU, VV, and VW. Further, as shown in FIG. 7, in this operation region, the control device 20 performs the PWM control or the first overmodulation control based on the comparison between the voltage command values VU, VV, VW and the carrier wave. Control signals g1-g6 are generated.

  On the other hand, when the target torque Tr is larger than the minimum threshold value Tmin and the target torque Tr is smaller than the maximum threshold value Tmax, the control device 20 proceeds to the process of S60. In S60, the control device 20 determines whether or not the remaining one of the predetermined conditions is satisfied. Here, the predetermined condition determined by the control device 20 is the following condition (iii). (Iii) The inertial force of the vehicle axle determined from the rotational speed N is greater than a preset inertial force threshold.

  If the torque ripple is relatively large when the inertial force of the axle is relatively small, drivability and noise viblation (hereinafter referred to as NV) deteriorate. For this reason, when the inertial force of the axle is relatively small and the large torque ripple is generated by limiting the on period θc, the drivability and NV may exceed the allowable values. The allowable values of drivability and NV are determined by vehicle specifications.

  Accordingly, the control device 20 sets the inertial force threshold of the axle so that the drivability and NV do not exceed the allowable values even if a relatively large torque ripple occurs during overmodulation control or rectangular wave control.

  Specifically, the control device 20 determines whether or not the condition (iii) is satisfied by comparing the rotational speed N with the speed threshold Nmin. The speed threshold Nmin is a value determined by the inertial force threshold.

  When the rotational speed N is equal to or less than the speed threshold Nmin, the control device 20 proceeds to the process of S80. In S80, control device 20 calculates voltage command values VU, VV, and VW. Further, as shown in FIG. 7, in this operation region, control device 20 generates control signals g1 to g6 for executing PWM control based on comparison of voltage command values VU, VV, VW and a carrier wave. To do.

  On the other hand, when the rotational speed N is greater than the speed threshold Nmin, the control device 20 proceeds to the process of S70. In S70, the control device 20 limits the ON period θc. Specifically, the limited on period θc is set using a map prepared in advance. The map shows a correspondence relationship between the target torque Tr, the rotation speed N, and the ON period θc. For example, as shown in FIG. 7, the map divides the operation area where m <0.78 and the conditions (i) to (iii) are satisfied into three areas, and associates the ON period θcθ1 or θ2 with each area. ing. For example, θ1 is an electrical angle of 120 °, and θ2 is an electrical angle of 90 °, for example.

  Subsequently, in S80, the control device 20 calculates the voltage command values VU, VV, and VW, and generates control signals g1 to g6 for executing the second overmodulation control or the second rectangular wave control. Specifically, as illustrated in FIG. 8, the control device 20 calculates the logical sum of the comparison between the modulated wave and the carrier wave and the comparison between the modulated wave and the on-period setting wave, and the control signals g1 to g6. Is generated. As shown in FIG. 9, the ON period setting wave is a waveform having a constant voltage value. In the positive range of the modulated wave, the on period θc can be narrowed as the value of the on period setting wave is increased. In the negative range of the modulated wave, the on period θc can be narrowed as the value of the on period setting wave is decreased. This process is complete | finished above.

<3. Experimental results>
FIG. 10 shows the breakdown of losses of the MG system 100 according to the present embodiment and the MG system according to the comparative example at the operating point (rotational speed 6000 rpm, torque 20 N · m) in the Worldwide-harmonized Light vehicles Test Cycle (WLTC) mode. Show. In the present embodiment, the on period θc is limited when the voltage utilization factor m <0.78 and the predetermined conditions (i) to (iii) are satisfied. On the other hand, in the comparative example, the ON period θc is not limited when the voltage utilization factor m <0.78 and the predetermined conditions (i) to (iii) are satisfied. In FIG. 10, the loss of the comparative example is shown as 1.

  As shown in FIG. 10, the MG iron loss, the MG copper loss, and the conduction loss of the present embodiment are the MG iron loss, MG of the comparative example due to the increase in the effective current value due to the limitation of the ON period θc. It is larger than copper loss and conduction loss. On the other hand, the switching loss of the present embodiment is smaller than the switching loss of the comparative example because the number of times of switching has decreased with the limitation of the ON period θc. Since the reduction amount of the switching loss of this embodiment is sufficiently larger than the sum of the increase of MG iron loss, MG copper loss, and conduction loss of this embodiment, the loss of this embodiment as a whole is that of the comparative example. 14% less than the loss. That is, the MG system 100 according to the present embodiment can improve the overall efficiency even in a low torque range where the operation point of the WLTC mode is present.

<4. Effect>
According to the first embodiment described above, the following effects can be obtained.
(1) When the voltage utilization factor m is smaller than the utilization factor threshold, that is, when the number of times of switching is relatively large, the on period is limited. Thereby, the frequency | count of switching is reduced and a switching loss can be reduced. In addition, by limiting the ON period without changing the DC voltage input to the inverter 13, the control of the inverter 13 is changed from PWM control or first overmodulation control to second overmodulation control or second rectangular wave. In order to shift to control, the decrease in switching loss exceeds the increase in other losses even in the low torque range. Therefore, the overall efficiency of the MG system 100 can be improved even in the low torque range.

  (2) When the ON period θc is not limited, when the control of the inverter 13 is the voltage use rate m that is the PWM control or the first overmodulation control, the ON period θc is limited to control the inverter 13 2 overmodulation control or second rectangular wave control. As a result, the frequency | count of switching can be reduced.

  (3) The on period θc is limited on condition that the current effective value at the target torque Tr is smaller than the current threshold. Therefore, even if the current effective value rises by limiting the ON period θc, the current effective value can be limited to the maximum rating of the devices such as the MG 15 and the inverter 13. As a result, damage to the devices included in the MG100 system can be prevented.

  (4) The on period θc is limited on condition that the target torque Tr is larger than the minimum threshold value Tmin. Therefore, by limiting the ON period θc, it is possible to prevent the minimum torque from becoming negative even if the torque ripple increases. As a result, the generation of abnormal noise and the deterioration of gears can be prevented.

  (5) The on period θc is limited on condition that the inertial force of the axle is larger than the inertial force threshold. Therefore, even if the torque ripple increases by limiting the ON period θc, it is possible to prevent the deterioration of the drivability and the NV.

(Other embodiments)
As mentioned above, although the form for implementing this indication was demonstrated, this indication is not limited to the above-mentioned embodiment, and can carry out various modifications.

  (A) In the above-described embodiment, the MG 15 is a three-phase AC motor generator, but may be a single-phase, two-phase, or a multi-phase AC motor generator other than three phases. Moreover, although MG15 was provided with the function as an electric motor and the function as a generator, it does not need to be provided with the function as a generator.

  (B) In the above embodiment, the utilization rate threshold is set to 0.78, but the utilization rate threshold is not limited to 0.78. For example, when the utilization threshold value is set to the upper limit value 0.613 of the voltage utilization factor m of the PMW control and the operation region of the inverter 13 is the first overmodulation control region, the on period θc is not limited. You may do it. The utilization threshold value may be set to a value of 0.613 or more and 0.78 or less.

  (C) In the above embodiment, the on-period θc is limited when the voltage utilization factor m is less than the utilization factor threshold and all the predetermined conditions (i) to (iii) are satisfied. It is not limited to. In the present disclosure, it is desirable that all of the predetermined conditions (i) to (iii) are satisfied. However, the voltage utilization rate m is less than the utilization threshold value, and less than the predetermined conditions (i) to (iii). Alternatively, the ON period θc may be limited when one is satisfied. Further, in the present disclosure, when the voltage utilization rate m is less than the utilization threshold, the on period θ may be limited regardless of whether or not the predetermined conditions (i) to (iii) are satisfied.

  (D) A plurality of functions of one constituent element in the above embodiment may be realized by a plurality of constituent elements, or a single function of one constituent element may be realized by a plurality of constituent elements. . Further, a plurality of functions possessed by a plurality of constituent elements may be realized by one constituent element, or one function realized by a plurality of constituent elements may be realized by one constituent element. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claims are embodiments of the present disclosure.

  (E) In addition to the above-described rotating electrical machine drive control device, a system including the rotating electrical machine drive control device as a component, a program for causing a computer to function as the rotating electrical machine drive control device, and a semiconductor recording the program The present disclosure can also be realized in various forms such as a non-transitional actual recording medium such as a memory and a drive control method for a rotating electrical machine.

  DESCRIPTION OF SYMBOLS 11 ... DC power supply, 13 ... Inverter, 20 ... Control apparatus, 23 ... Voltage command value calculation part, 25 ... Two-phase three-phase conversion part, 27 ... Control signal generation part, 40 ... Torque command part, 100 ... MG system, S1 ~ S6 ... switching element.

Claims (6)

A rotating electrical machine control device (20) for controlling driving of a rotating electrical machine (15) in a rotating electrical machine system (100) mounted on a vehicle,
The rotating electrical machine system includes:
Rotating electrical machinery,
DC power supply (11),
An inverter (13) that includes a plurality of switching elements (S1 to S6), converts DC power of the DC power source to AC power, and supplies the AC power to the rotating electrical machine;
A torque command unit (40) for commanding a target torque of the rotating electrical machine,
The control device for the rotating electrical machine includes:
A voltage calculation unit (23, 25) for calculating a voltage command value of an AC voltage supplied to the rotating electrical machine from the target torque commanded by the torque command unit;
A switching control unit (27) for controlling switching of each switching element included in the inverter so that the voltage command value calculated by the voltage calculation unit is supplied to the rotating electrical machine;
In the control of the inverter, when the voltage utilization factor of the DC power supply is smaller than a preset utilization factor threshold value, each switching element can be turned on in an electrical angle half cycle of the voltage command value. A limiting unit (27) for limiting the on period to a period shorter than a period obtained by subtracting the dead time of the switching element from the electrical angle half cycle of the voltage command value,
When the on period is limited by the limiting unit, the switching control unit controls switching of each switching element in the limited on period, and performs rectangular wave control or overmodulation control.
Control device for rotating electrical machines. The voltage utilization rate is
M is a voltage utilization factor, Vdc is a DC voltage value supplied to the inverter, Vd is a d-axis component of the voltage command value, and Vq is a q-axis component of the voltage command value.
The control device for a rotating electrical machine according to claim 1. The utilization threshold is 0.78.
The control device for a rotating electrical machine according to claim 1 or 2. The limiting unit limits the ON period θc when the current effective value at the target torque commanded by the torque command unit is smaller than a preset current threshold value.
The control apparatus of the rotary electric machine of any one of Claims 1-3. The limiting unit limits the on period when the target torque commanded by the torque command unit is larger than a preset torque threshold value.
The control apparatus of the rotary electric machine of any one of Claims 1-4. A speed detector for detecting the rotational speed of the rotating electrical machine;
The limiting unit limits the ON period when an inertial force of the axle of the vehicle obtained from the rotational speed detected by the speed detection unit is greater than a preset inertial force threshold;
The control apparatus of the rotary electric machine of any one of Claims 1-5.