JP2016220466A - Control device for rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize output torque of a rotary electric machine by suppressing a rectangular wave voltage from being output although PWM control is performed.SOLUTION: The present invention relates to a control device 40 which controls a rotary electric machine 10 by adjusting an output voltage output from an inverter 20 to the rotary electric machine 10. The control device comprises a PWM control part 41 which sets a fundamental wave of a sine wave as a command value of an output voltage based upon a torque command value, and performs PWM control based upon a comparison between the fundamental wave and a carrier; a rectangular wave control part 42 which performs rectangular wave control for adjusting the phase of the output voltage of the rectangular wave based upon the torque command value; and a switching control part 43 which performs switching from the PWM control to the rectangular wave control on condition that a modulation rate as a ratio of an amplitude of the fundamental wave and an input voltage to an inverter 20 exceeds a modulation rate threshold when the PWM control is being performed, the switching control part 43 setting the modulation rate threshold based upon the number of pulses of the carrier included in one cycle of the fundamental wave.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for a rotating electrical machine that controls the rotating electrical machine by adjusting an output voltage output from the inverter device to the rotating electrical machine.

  In control for adjusting the output voltage output from the inverter device to the rotating electrical machine, pulse width modulation control (PWM control) and rectangular wave control are used.

  PWM control is based on a torque command value for commanding the output torque of the rotating electrical machine and an output current output from the inverter device to the rotating electrical machine. A carrier wave having a higher frequency than the fundamental wave is compared. And based on the comparison with a fundamental wave and a carrier wave, the output voltage output with respect to a rotary electric machine from an inverter apparatus is adjusted. Further, in the rectangular wave control, a rectangular wave voltage is output from the inverter device to the rotating electrical machine. Further, an estimated torque value that is an estimated value of the output torque is calculated based on the output current, and the phase of the rectangular wave voltage is adjusted based on the estimated torque value and the torque command value.

  In the PWM control, torque fluctuation can be suppressed in the low rotation region, but there is a problem that the voltage utilization rate is limited. In addition, in the rectangular wave control, the voltage utilization rate can be maximized, while torque fluctuation increases in a low rotation region. Therefore, a configuration that uses PWM control and rectangular wave control properly is used (for example, Patent Document 1).

Japanese Patent No. 4404790

  In the configuration described in Patent Document 1, switching from PWM control to rectangular wave control is performed based on a modulation rate that is a ratio of the amplitude of the fundamental wave to the input voltage in PWM control.

  Here, when the number of carrier pulses included in one period of the fundamental wave decreases, the inventor of the present application outputs a rectangular wave voltage in a region where the modulation rate is high even though PWM control is performed. It was discovered that a situation occurs. As a result, the output torque of the rotating electrical machine becomes unstable.

  The present invention has been made in view of the above problems, and suppresses the output of a rectangular wave voltage in spite of performing PWM control, and stabilizes the output torque of the rotating electrical machine. Main purpose.

  The first configuration is a rotating electrical machine control device (40) that controls the rotating electrical machine by adjusting an output voltage output from the inverter device (20) to the rotating electrical machine (10), Based on a torque command value for commanding the output torque of the rotating electrical machine and an output current output from the inverter device to the rotating electrical machine, a sinusoidal fundamental wave is set as a command value for the output voltage, and the fundamental wave and the carrier wave The first control unit (41) that performs pulse width modulation control that is control for adjusting the output voltage based on the comparison with the output current, and the torque estimated value that is the estimated value of the output torque based on the output current A second control unit (42) for performing rectangular wave control, which is control for adjusting the phase of the rectangular wave-like output voltage based on the estimated torque value and the torque command value, and the first control In the case where the pulse width modulation control is performed by the first control, the first control is performed on the condition that a modulation rate that is a ratio of the amplitude of the fundamental wave and the input voltage of the inverter device exceeds a predetermined modulation rate threshold A switching control unit (43) for switching control from pulse width modulation control by the second control unit to rectangular wave control by the second control unit, wherein the switching control unit includes pulses of the carrier wave included in one period of the fundamental wave The modulation factor threshold is set based on the number.

  The modulation factor threshold used for switching from PWM control to rectangular wave control is set based on the number of carrier pulses included in one period of the fundamental wave. Thereby, it is possible to suppress the output of the rectangular wave voltage despite the PWM control, and to stabilize the output torque of the rotating electrical machine.

  The second configuration is a rotating electrical machine control device (40) that controls the rotating electrical machine by adjusting an output voltage output from the inverter device (20) to the rotating electrical machine (10). A sinusoidal fundamental wave is set as the output voltage command value based on a torque command value that commands the output torque of the rotating electrical machine, and the output voltage is adjusted based on a comparison between the fundamental wave and a carrier wave. A first control unit (41) that performs pulse width modulation control as control, and second control that performs rectangular wave control as control for adjusting the phase of the rectangular-wave output voltage based on the torque command value. A predetermined modulation rate threshold is set based on the number of pulses of the carrier wave included in one period of the fundamental wave and the first wave from the rectangular wave control by the second controller To width modulation control After switching, the pulse width by the first control unit is changed from the rectangular wave control by the second control unit so that the initial value of the modulation rate of the pulse width modulation control by the first control unit becomes the modulation factor threshold value. And a switching control unit (43) that performs switching to modulation control.

  After switching from rectangular wave control to PWM control, if the number of pulses of the carrier wave included in one period of the fundamental wave is small, the inverter device to the rotating electrical machine, despite performing PWM control, There is concern about the output of a rectangular wave voltage. Therefore, the modulation factor threshold is set based on the number of pulses of the carrier wave included in one period of the fundamental wave, and the rectangular wave control is performed so that the initial value of the modulation factor of the PWM control by the first control unit becomes the modulation factor threshold. Switch from PWM control to PWM control. By performing such control, when the number of pulses is small after switching from the rectangular wave control to the PWM control, the inverter device performs a rectangular operation on the rotating electrical machine even though the PWM control is performed. Output of wave voltage can be suppressed.

The electrical block diagram showing the rotary electric machine and inverter apparatus of this embodiment. The functional block diagram showing the control apparatus of this embodiment. The figure showing the control mode which can implement | achieve a desired torque and a desired rotational speed. The figure showing overmodulation PWM control. The figure showing switching of PWM control and rectangular wave control. The figure showing the state in which a rectangular wave voltage is output in spite of having implemented PWM control when a high modulation rate and the number of pulses are small. The figure showing the state in which the normal overmodulation PWM voltage is output when PWM control is implemented when the high modulation rate and the number of pulses are small. The figure showing the principle of destabilization of output torque accompanying the decrease in the number of pulses. The figure showing the correspondence between the number of pulses in one period of the fundamental wave and the modulation factor threshold. The flowchart showing a modulation factor threshold value setting process. The flowchart showing the switching process from PWM control to rectangular wave control. The figure showing the difference between this application and a prior art in switching from PWM control to rectangular wave control. The figure showing the difference between this application and a prior art in switching from rectangular wave control to PWM control. The flowchart showing the switching process from rectangular wave control to PWM control.

  Hereinafter, a first embodiment in which a control device according to the present invention is applied to a vehicle including an engine as an in-vehicle main machine will be described with reference to the drawings.

  As shown in FIG. 1, the rotating electrical machine 10 is a permanent magnet type synchronous motor having multiphase windings, and more specifically, a permanent magnet type synchronous motor having three phase windings. An armature winding 14 is wound around a stator 13 (stator) of the rotating electrical machine 10. The armature winding 14 is composed of a three-phase winding having different neutral points. The rotating electrical machine 10 may be a wound field type synchronous motor.

  An inverter 20 is connected to the armature winding 14 of the rotating electrical machine 10. A DC power source 22 is connected to the inverter 20. The inverter 20 includes three sets of serially connected bodies of U, V, W phase high potential side switches SUp, SVp, SWp and U, V, W phase low potential side switches SUn, SVn, SWn. The connection point of the series connection body in the U, V, and W phases is connected to the U, V, and W phase terminals of the armature winding 14.

  In the present embodiment, IGBTs are used as the switches SUp to SWn. Further, free-wheeling diodes DUp to DWn are connected in parallel to the switches SUp to SWn, respectively. Further, the switches SUp to SWn are not limited to IGBTs, and may be N-channel MOSFETs, for example.

  The positive terminal of the DC power supply 22 is connected to the high potential side terminal of the inverter 20 (the collector side terminal of each high potential side switch). The negative terminal of the DC power source 22 is connected to the low potential side terminal (the emitter side terminal of each low potential side switch). The inverter 20 includes a smoothing capacitor 21 between a high potential side terminal and a low potential side terminal. Note that the DC power source 22 is, for example, a secondary battery or a step-up / step-down circuit that steps up / down the power supplied from the secondary battery.

  The control device 40 also detects the torque command value T * of the rotating electrical machine 10, the detected values of the phase currents IU, IV, IW output from the inverter 20 to the rotating electrical machine 10, and the output voltage VB ( The detected value of the input voltage of the inverter 20 and the detected value of the rotation angle θ of the rotor 11 are acquired. The control device 40 acquires the torque command value T * from a control device higher than the control device 40. In addition, control device 40 obtains detected values of phase currents IU, IV, and IW from current sensor 31. In addition, the control device 40 acquires a detection value of the voltage VB from the voltage sensor 32. In addition, the control device 40 acquires the detected value of the rotation angle θ from the rotation angle sensor 33 provided in the rotating electrical machine 10. Then, control device 40 performs off-on control (open / close control) of switches SUp to SWn based on torque command value T *, phase currents IU, IV, IW, voltage VB, and rotation angle θ.

  FIG. 2 shows a functional block diagram of the control device 40. The control device 40 switches between a PWM control unit 41 (first control unit), a rectangular wave control unit 42 (second control unit), PWM control (current feedback control), and rectangular wave control (torque feedback control). And a switching control unit 43 that performs Here, the rectangular wave control is also referred to as one-pulse control, and the voltages of the phase voltages VU, VV, and VW are changed from VB / 2 to the predetermined energization period (for example, 180 degrees) in one cycle of the electrical angle θe. Control that changes in the order of 0 → −VB / 2. Hereinafter, description will be made in the order of PWM control, rectangular wave control, and switching control.

(PWM control)
The three-phase to two-phase converter 45 converts the detected values of the phase currents IU, IV, and IW from the UVW coordinate system (three phases) to the dq coordinate system (two phases) based on the rotation angle θ, and the d-axis current Id and q-axis current Iq are calculated. The current command value generation unit 46 calculates the d-axis current command value Id * and the q-axis current command value Iq * based on the torque command value T *.

  The deviation calculation units 47d and 47q calculate a deviation ΔId between the d-axis current command value Id * and the d-axis current Id and a deviation ΔIq between the q-axis current command value Iq * and the q-axis current Iq, respectively. The PID calculation units 48d and 48q perform PID calculation (proportional / integral / differential calculation) based on the deviations ΔId and ΔIq, respectively. The output value of the PID calculation unit 48d is a d-axis voltage reference value Vdb * that is the reference value of the d-axis voltage command value Vd * 1, and the output value of the PID calculation unit 48q is the q-axis voltage command value Vq * 1. This is the q-axis voltage reference value Vqb * that is the reference value.

  Here, the dq axis component of the voltage applied to the armature winding 14 is not only a term proportional to the same axis component of the current flowing through the armature winding 14, but also a term proportional to a different axis component or vice versa. It includes a so-called interference term such as electromotive force.

  Therefore, the non-interference control unit 49 calculates the d-axis interference voltage Vd0 and the q-axis interference voltage Vq0 based on the d-axis current Id and the q-axis current Iq. Then, the correction unit 50d performs correction by subtracting the d-axis interference voltage Vd0 from the d-axis voltage reference value Vdb *, and calculates a d-axis voltage command value Vd * 1. The correction unit 50q corrects the q-axis voltage reference value Vqb * by subtracting the q-axis interference voltage Vq0, and calculates a q-axis voltage command value Vq * 1.

  The two-phase / three-phase conversion unit 51 converts the d-axis voltage command value Vd * 1 and the q-axis voltage command value Vq * 1 from the dq coordinate system to the UVW coordinate system based on the rotation angle θ, and the U-phase voltage command A value VU * 1, a V-phase voltage command value VV * 1, and a W-phase voltage command value VW * 1 are calculated. Voltage command values VU * 1, VV * 1, and VW * 1 are sine waves, respectively, and their median values are zero. Here, when the voltage command values VU * 1, VV * 1, and VW * 1 are large with respect to the voltage VB, that is, when the modulation factor Amp is large, the final harmonic wave is superimposed on a sine wave. Output as voltage command values VU * 1, VV * 1, VW * 1.

  The carrier wave generation unit 52 generates a triangular wave as the carrier wave CA. The carrier wave generation unit 52 of the present embodiment outputs a carrier wave CA having a predetermined frequency that does not depend on the frequency of the fundamental wave. That is, the PWM control of this embodiment is frequency asynchronous PWM control.

  The comparator 53U receives the U-phase voltage command value VU * 1 and the carrier wave CA, compares the U-phase voltage command value VU * 1 with the carrier CA, and outputs a signal gU1. The comparator 53V receives the V-phase voltage command value VV * 1 and the carrier wave CA, compares the V-phase voltage command value VV * 1 with the carrier CA, and outputs a signal gV1. Comparator 53W receives W-phase voltage command value VW * 1 and carrier wave CA, compares W-phase voltage command value VW * 1 with carrier wave CA, and outputs signal gW1. The output signals gU1, gV1, and gW1 of the comparators 53U, 53V, and 53W are obtained by performing pulse width modulation on the voltage command values VU * 1, VV * 1, and VW * 1, which are fundamental waves, respectively.

  The output signals gU1, gV1, and gW1 are input to the switching unit 44. When PWM control is selected by the switching control unit 43, the output signals gU1, gV1, and gW1 are input to the dead time generation unit 55 via the switching unit 44. Further, the output signals gU1, gV1, and gW1 are inverted by the NOT circuits 54U, 54V, and 54W and input to the dead time generation unit 55.

  In the dead time generation unit 55, the combination of the upper arm switches SUp, SVp, SWp and the lower arm switches SUn, SVn, SWn are simultaneously turned on so that the DC power supply 22 is short-circuited. It suppresses that. Specifically, the output signal gU1 and its inverted signal are both prevented from going high, the output signal gV1 and its inverted signal are both restrained from going high, and the output signal gW1 , Both the inverted signals are suppressed from being in a high state.

  The output signals gU1, gV1, and gW1 shaped by the dead time generation unit 55 and the inverted signals of the output signals gU1, gV1, and gW1 are input to the gate driving circuit 56. The gate drive circuit 56 outputs gU1, gV1, and gW1 as drive signals gUp, gVp, and gWp to the respective gates of the switches SUp, SVp, and SWp. The gate drive circuit 56 outputs inverted signals of gU1, gV1, and gW1 as drive signals gUn, gVn, and gWn to the gates of the switches SUn, SVn, and SWn.

  The d-axis current Id and the q-axis current Iq obtained by converting the detected values of the phase currents IU, IV, and IW into dq coordinates are calculated based on the torque command value T * by the operation of the PWM control unit 41 described above. Control is performed so that the shaft current command value Id * and the q-axis current command value Iq * are obtained.

(Rectangular wave control)
The torque estimating unit 57 calculates a torque estimated value Te that is an estimated value of the output torque of the rotating electrical machine 10 based on the d-axis current Id and the q-axis current Iq. The estimated torque value Te can be calculated by the following equation using, for example, the number of pole pairs p, the induced voltage constant φ, the d-axis inductance Ld, and the q-axis inductance Lq of the rotating electrical machine 10.

Te = p {φ · Iq + (Ld−Lq) · Id · Iq}
The deviation calculation unit 58 calculates a deviation ΔT between the torque command value T * and the torque estimation value Te. The voltage phase calculation unit 59 calculates the voltage phase manipulated variable α * based on the deviation ΔT and the rotation speed FR. The output signal generator 60 generates signals gU2, gV2, and gW2 to manipulate the phase of the rectangular wave based on the voltage phase manipulated variable α *.

  The output signals gU2, gV2, and gW2 are input to the switching unit 44. When the rectangular wave control is selected by the switching control unit 43, the output signals gU 2, gV 2, and gW 2 are input to the dead time generation unit 55 via the switching unit 44. The output signals gU2, gV2, and gW2 are inverted by the NOT circuits 54U, 54V, and 54W and input to the dead time generation unit 55. Since the operations of the dead time generation unit 55 and the gate drive circuit 56 are equivalent to the PWM control, the description thereof is omitted.

(Switching control)
FIG. 3 shows a region where PWM control is performed and a region where rectangular wave control is performed. As shown in the figure, the PWM control is performed from the low rotation speed region to the medium rotation speed region, and the high rotation speed region is the region where the rectangular wave control is performed. The boundary between the area where PWM control is performed and the area where rectangular wave control is performed is on the lower rotational speed side as the torque command value T * is larger. The reason why the PWM control is switched to the rectangular wave control in the high rotation speed region is as follows.

  The maximum voltage that can be applied to each phase of the armature winding 14 is the voltage VB of the DC power supply 22. For this reason, the maximum value of the voltage command values VU * 1, VV * 1, and VW * 1 is “½” or more of the voltage VB, that is, the modulation factor Amp is 100% or more (the third harmonic is superimposed). In this case, the voltage actually applied to each phase of the armature winding 14 is a voltage command value VU * 1, VV * 1, VW. * 1 cannot be set.

  FIG. 4A shows the transition of the voltage (for example, VU) applied to each phase of the armature winding 14 when the modulation factor Amp is 100%, and FIG. 4B shows the modulation factor Amp. The transition of the voltage (for example, VU) applied to each phase of the armature winding 14 when it is larger than 100% is shown. As shown in the figure, when the modulation factor Amp is larger than 100%, the amplitude of the voltage VU applied to each phase of the armature winding 14 is limited to ½ of the voltage VB of the DC power supply 22. Therefore, it does not become a sinusoidal voltage. However, even in this case, as compared with the voltage shown in FIG. 4A, the utilization of the voltage is improved only in the region indicated by the oblique line in FIG.

  Thereby, the effective value of the voltage applied to each phase of the armature winding 14 can be made larger than that shown in FIG. 4A, and is determined by the current command values Id * and Iq *. A three-phase current command value can be passed through the armature winding 14. Therefore, when the maximum value of the voltage command values VU * 1, VV * 1, VW * 1 becomes “½” or more of the voltage VB, the PWM control is continued, so that the armature winding 14, the current It is possible to flow a three-phase current determined by the command values Id * and Iq *. As shown in FIG. 3, a region where the modulation factor Amp is 100% or more is called an overmodulation PWM control region.

  As the amplitudes of the voltage command values VU * 1, VV * 1, and VW * 1 increase, the voltage applied to each phase of the armature winding 14 eventually becomes the voltage command value VU * 1, It becomes a rectangular wave shape that alternately changes to “VB / 2” and “−VB / 2” in the same cycle as VV * 1 and VW * 1. Here, it is theoretically known that when the modulation rate Amp exceeds 4 / π, controllability by PWM control is extremely reduced. Therefore, in general, the amplitude of the voltage command values VU * 1, VV * 1, and VW * 1 is 127% (<4 / π) of the voltage VB of the DC power supply 22, so that a rectangular wave is generated from the PWM control. Switching to control is performed.

  FIG. 5 shows currents Id and Iq in the dq coordinate system that can be obtained by PWM control and rectangular wave control. A current command value line CL indicated by a solid line is a curve drawn by the current command values Id * and Iq * generated by the current command value generation unit 46 (FIG. 2). The current command value line CL is appropriately set according to a request for control of the rotating electrical machine 10, and in this embodiment, currents Id and Iq that can realize the torque command value T * with a minimum current. It is set to be. CT represents an isotorque line.

  On the other hand, what is indicated by a two-dot chain line is a limit line LL that defines a boundary of current that can actually flow through the rotating electrical machine 10 on the dq coordinate system. The limit line LL is determined according to the voltage VB of the DC power supply 22 and the rotational speed FR of the rotating electrical machine 10. For this reason, during PWM control, the d-axis current Id and the q-axis current Iq cannot exceed the upper limit PM, which is the intersection of the current command value line CL and the limit line LL. Therefore, when the current command values Iq * and Id * reach the upper limit PM, switching to the rectangular wave control is performed.

  When the rectangular wave control is performed, the currents Id and Iq do not match the currents Id and Iq defined by the current command value line CL. That is, in the rectangular wave control and the PWM control, for example, the torque command value T * is the same so that the currents Id and Iq are different even though the vector I1 and the vector I2 in FIG. However, the currents Id and Iq are different. However, if the length of the current vector (Id, Iq) when the torque T generated by the rectangular wave control is realized by the PWM control is equal to or less than the upper limit PM, the torque T generated by the rectangular wave control is PWM controlled. Can be generated.

  The switching control unit 43 (FIG. 2) performs switching between PWM control and rectangular wave control based on the modulation rate Amp, the d-axis current Id, and the q-axis current Iq in PWM control. The modulation factor Amp in the PWM control is calculated based on the input voltage VB of the inverter 20, the d-axis voltage command value Vd * 1, and the q-axis voltage command value Vq * 1.

  As described above, in PWM control, sinusoidal phase voltages VU, VV, and VW are output based on a comparison between voltage command values VU * 1, VV * 1, and VW * 1 and carrier wave CA. Here, in the high modulation region where the modulation factor Amp is 126% to 127%, the number of pulses Pn of the carrier CA in one cycle of the voltage command values VU * 1, VV * 1, and VW * 1 (fundamental wave) is small. In addition, there arises a problem that the torque T becomes unstable. Here, the number of pulses of the carrier wave CA in one period of the fundamental wave is specifically the case where the number of pulses in one period of the fundamental wave is less than 12. The cause of the decrease in the number of pulses Pn of the carrier wave CA in one period of the fundamental wave is mainly caused by a decrease in one period of the fundamental wave as a result of an increase in the rotational speed FR of the rotating electrical machine 10.

  The reason why the torque T is destabilized when the number of pulses Pn of the carrier wave CA in one period of the fundamental wave is decreasing is described with reference to FIGS. In the states shown in FIGS. 6 and 7, the modulation factor is 126%, and overmodulation PWM control is performed. In the overmodulation PWM control, the third harmonic is superimposed on the fundamental waves VU * 1, VV * 1, and VW * 1. In FIG. 6A, the phase difference between the fundamental waves VV * 1, VW * 1, VW * 1 and the carrier wave CA is 15 degrees, and FIG. 6B, the fundamental waves VV * 1, VW * 1. , VW * 1 and the carrier wave CA have a phase difference of 20 degrees.

  In FIG. 6, at time T10, the fundamental wave VU * 1 indicated by a solid line starts to increase from −VB / 2. At time T11, the fundamental wave VU * 1 becomes larger than the carrier wave CA, the output signal gU1 is set to the high state, the switch SUp is turned on, and the switch SUn is turned off. At time T12, the fundamental wave VU * 1 becomes VB / 2. That is, when the fundamental wave VU * 1 rises, the fundamental wave VU * 1 intersects the carrier wave CA only once.

  At time T13, the fundamental wave VU * 1 starts to decrease from VB / 2. Thereafter, at time T14, the fundamental wave VU * 1 becomes smaller than the carrier wave CA, the output signal gU1 is set to the low state, the switch SUp is turned off, and the switch SUn is turned on. At time T15, the fundamental wave VU * 1 becomes −VB / 2. That is, when the fundamental wave VU * 1 falls, the fundamental wave VU * 1 intersects the carrier wave CA only once.

  As described above, in the state shown in FIG. 6, the fundamental wave VU * 1 intersects the carrier wave CA only once at the rise of the fundamental wave VU * 1, and the fundamental wave VU * at the fall of the fundamental wave VU * 1. * 1 intersects carrier CA only once. Thereby, a rectangular wave phase voltage VU, that is, a phase voltage VU having the same waveform as that when rectangular wave control (one pulse control) is performed is output. Similarly, the phase voltages VV and VW also have a rectangular wave shape. Although the PWM control is performed, the torque T of the rotating electrical machine 10 is excessively output by outputting the rectangular wave phase voltages VU, VV, and VW.

  In FIG. 7, at time T20, the fundamental wave VU * 1 starts to increase from −VB / 2. At time T21, the fundamental wave VU * 1 becomes larger than the carrier wave CA, the output signal gU1 is set to the high state, the switch SUp is turned on, and the switch SUn is turned off. Thereafter, at time T22, the fundamental wave VU * 1 becomes smaller than the carrier wave CA, the output signal gU1 is set to the low state, the switch SUp is turned off, and the switch SUn is turned on. At time T23, the fundamental wave VU * 1 becomes larger than the carrier wave CA, the output signal gU1 is set to the high state, the switch SUp is turned on, and the switch SUn is turned off. At time T24, the fundamental wave VU * 1 becomes VB / 2.

  At time T25, the fundamental wave VU * 1 starts to decrease from VB / 2. At time T26, the fundamental wave VU * 1 becomes smaller than the carrier wave CA, the output signal gU1 is set to the low state, the switch SUp is turned off, and the switch SUn is turned on. Thereafter, at time T27, the fundamental wave VU * 1 becomes larger than the carrier wave CA, the output signal gU1 is set to the high state, the switch SUp is turned on, and the switch SUn is turned off. At time T28, the fundamental wave VU * 1 becomes smaller than the carrier wave CA, the output signal gU1 is set to the low state, the switch SUp is turned off, and the switch SUn is turned on. At time T29, the fundamental wave VU * 1 becomes −VB / 2.

  Thus, in the state shown in FIG. 7, normal overmodulation PWM control is performed, and a phenomenon in which the torque T of the rotating electrical machine 10 is output excessively does not occur.

  In the state shown in FIG. 6, when the number of pulses Pn of the carrier wave CA in one period of the fundamental wave decreases, the PWM control is performed by the phase difference between the fundamental waves VU * 1, VV * 1, VW * 1 and the carrier wave CA. It can be said that the maximum value of the modulation factor Amp that can be output decreases and a rectangular wave voltage is output.

  As shown in FIG. 8, when the number of pulses Pn of the carrier wave CA in one period of the fundamental wave decreases, output is possible due to the phase difference between the fundamental waves VU * 1, VV * 1, VW * 1 and the carrier wave CA. The limit line LL corresponding to the maximum value of the modulation factor Amp changes in the direction in which the output torque decreases, that is, in the d-axis direction. As a result, the current vector (Id, Iq) varies in the three states Ia, Ib, and Ic. Here, the current vector Ia is a vector between the limit line LL and the limit line LLa and indicating a point on the current command value line CL. The current vector Ib is a vector indicating the intersection of the current command value line CL and the limit line LLa. The current vector Ic is a vector indicating the intersection of the equal torque line CT and the limit line LLa. When the current vector (Id, Iq) varies in three states Ia, Ib, and Ic, the torque T varies and becomes unstable.

  Therefore, the switching control unit 43 of the present embodiment uses the modulation factor threshold Ath, which is a threshold of the modulation factor Amp used for determination of switching from PWM control to rectangular wave control, to the number of pulses of the carrier CA included in one period of the fundamental wave. Set according to Pn.

  FIG. 9 shows the setting of the modulation factor threshold Ath based on the number of pulses Pn of the carrier wave CA included in one period of the fundamental wave. This modulation factor threshold Ath is a modulation factor Amp at which a rectangular wave voltage is output from the inverter 20 to the rotating electrical machine 10 regardless of the phase difference between the fundamental wave and the carrier wave CA in a state where PWM control is being performed. It is set to be less. Specifically, when the pulse number Pn is less than 12, the modulation factor threshold Ath is set to less than 127. When the pulse number Pn is less than 12, the modulation factor threshold Ath is set smaller as the pulse number Pn is smaller. The switching control unit 43 calculates the number of pulses Pn based on the rotational speed FR of the rotating electrical machine 10 and the carrier frequency FC. Further, the rotation speed FR of the rotating electrical machine 10 is calculated as a differential value of the rotation angle θ.

  FIG. 10 shows a process for setting the modulation factor threshold Ath. This process is performed by the switching control unit 43 at predetermined intervals.

  In step S01, the rotation angle θ and the carrier frequency FC are acquired. In step S02, the rotation speed FR is calculated based on the rotation angle θ. In step S03, it is determined whether or not the rotational speed FR exceeds a predetermined value. If the rotational speed FR is equal to or lower than the predetermined value (S03: NO), the modulation factor threshold Ath is set to 127% in step S04, and the process is terminated. If the rotational speed FR exceeds a predetermined value (S03: YES), in step S05, the number of pulses Pn is calculated based on the rotational speed FR and the carrier frequency FC.

  In step S06, it is determined whether the number of pulses Pn is less than 12. When the pulse number Pn is 12 or more (S06: NO), in step S04, the modulation factor threshold Ath is set to 127%, and the process ends. When the pulse number Pn is less than 12 (S06: YES), in step S07, the modulation factor threshold Ath (n) is calculated based on the pulse number Pn using the map shown in FIG. In step S08, the modulation factor threshold Ath (n) calculated in step S07 is set as a new modulation factor threshold Ath, and the process ends.

  FIG. 11 shows a process for switching from PWM control to rectangular wave control. This process is performed by the switching control unit 43 at predetermined intervals.

  In step S11, voltage command values Vd * 1 and Vq * 1 are acquired. In step S12, the modulation factor Amp is calculated based on the voltage command values Vd * 1 and Vq * 1. Specifically, the modulation factor Amp is calculated as Amp = √ (Vd * 1 ^ 2 + Vq * 1 ^ 2) / (VB · √ (3/8)). In step S13, the modulation factor Amp is compared with the modulation factor threshold Ath. If the modulation factor Amp is greater than the modulation factor threshold Ath (S13: YES), switching from PWM control to rectangular wave control is performed in step S14, and the process is terminated. When the modulation factor Amp is equal to or less than the modulation factor threshold Ath (S13: NO), the process is terminated as it is.

  The difference between this embodiment and a prior art is shown using FIG. In the conventional technique (broken line), the modulation rate Amp increases with time, and the PWM rate is controlled in a region where the modulation rate Amp increases from about 126 to 127 (time TA to time TB). A rectangular wave voltage is output from the inverter 20 to the rotating electrical machine 10. After that, at time TB, the modulation factor Amp reaches 127, which is the modulation factor threshold Ath, and therefore switching from PWM control to rectangular wave control is performed.

  In the present embodiment (solid line), since the modulation factor threshold Ath is set based on the number of pulses Pn, switching from PWM control to rectangular wave control is performed at time TA. For this reason, it can suppress that a rectangular wave voltage is output with respect to the rotary electric machine 10 from the inverter 20, although PWM control is implemented, As a result, it suppresses that the torque T becomes unstable. be able to.

  In this embodiment, when switching from the rectangular wave control to the PWM control, the switching control is performed so that the modulation factor Amp immediately after the switching is equal to or less than the modulation factor threshold Ath based on the pulse number Pn.

  The difference between this embodiment and the prior art is shown using FIG. In the prior art (broken line), switching from rectangular wave control to PWM control is performed at time TC. Thereafter, in the region (time TC to time TD) in which the modulation rate Amp decreases with time and the modulation rate Amp decreases from 127 to about 126, the rotation is started from the inverter 20 even though the PWM control is performed. A rectangular wave voltage is output to the electric machine 10. Thereafter, at time TD, due to the decrease in the modulation factor Amp, the state in which the rectangular wave voltage is output from the inverter 20 to the rotating electrical machine 10 is eliminated despite the PWM control being performed.

  In the present embodiment (solid line), the modulation factor threshold Ath is set based on the number of pulses Pn. Then, in switching from the rectangular wave control to the PWM control, the initial value of the modulation factor Amp of the PWM control is set to the modulation factor threshold Ath. As a result, it is possible to suppress the output of the rectangular wave voltage from the inverter 20 to the rotating electrical machine 10 and the destabilization of the torque T in spite of the PWM control.

  FIG. 14 shows a switching process from rectangular wave control to PWM control. This process is performed by the switching control unit 43 at predetermined intervals.

  In step S21, a d-axis current Id and a q-axis current Iq are acquired. In step S22, the current phase α is calculated based on the d-axis current Id and the q-axis current Iq. In step S23, it is determined whether or not the current phase α is less than a predetermined threshold value αth. When the current phase α is equal to or greater than the threshold value αth (S23: NO), the switching process is not performed and the process ends.

  When the current phase α is less than the threshold value αth (S23: YES), in step S24, voltage command values Vd * 1, Vq * 1 are calculated based on the modulation factor threshold value Ath and the input voltage VB. In step S25, switching from rectangular wave control to PWM control is performed, and the process ends.

  The effects of this embodiment will be described below.

  The modulation factor threshold Ath used for switching from PWM control to rectangular wave control is set based on the number of pulses Pn of the carrier wave CA included in one cycle of the fundamental waves VU * 1, VV * 1, and VW * 1. . Thereby, it is possible to suppress the output of the rectangular wave voltage despite the PWM control, and to stabilize the output torque T of the rotating electrical machine 10.

  One period of the fundamental waves VU * 1, VV * 1, and VW * 1 is inversely proportional to the rotational speed FR of the rotating electrical machine 10. For this reason, the number of pulses Pn decreases as the rotational speed FR of the rotating electrical machine 10 increases. Therefore, the number of pulses Pn is calculated based on the rotational speed FR.

  The modulation factor threshold Ath is set to a modulation factor Amp at which no rectangular wave voltage is output from the inverter 20 to the rotating electrical machine 10 regardless of the phase difference between the fundamental wave and the carrier wave CA. By adopting such a configuration, it is possible to more reliably suppress a situation in which a rectangular wave voltage is output in spite of performing PWM control.

  One period of the fundamental waves VU * 1, VV * 1, and VW * 1 is inversely proportional to the rotational speed FR of the rotating electrical machine 10. For this reason, when the rotational speed FR is high, the number of pulses Pn of the carrier wave CA included in one cycle of the fundamental waves VU * 1, VV * 1, and VW * 1 is decreased, and the PWM control is performed. Therefore, a situation occurs in which a rectangular wave voltage is output. That is, when the rotational speed FR is smaller than the predetermined value, a situation in which a rectangular wave voltage is output does not occur even though the PWM control is performed. Therefore, the modulation rate threshold Ath is set based on the number of pulses Pn on condition that the rotational speed FR exceeds a predetermined value. By setting it as such a structure, the processing load of the control apparatus 40 can be reduced.

  When the modulation factor threshold is set to 127 when the number of pulses Pn of the carrier wave CA included in one period of the fundamental waves VU * 1, VV * 1, and VW * 1 is less than 12, the inventor of the present application sets the PWM control. It was discovered that a square wave voltage is output despite the fact that Therefore, the threshold is set to be less than 127 on condition that the number of pulses Pn is less than 12. Thereby, it is possible to suppress the output of the rectangular wave voltage although the PWM control is performed.

  After switching from rectangular wave control to PWM control, PWM control is performed when the number of pulses Pn of the carrier wave CA included in one cycle of the fundamental waves VU * 1, VV * 1, VW * 1 is small. Nevertheless, there is a concern that a rectangular wave voltage is output from the inverter 20 to the rotating electrical machine 10. Therefore, at the time of switching from the rectangular wave control to the PWM control, switching from the rectangular wave control to the PWM control is performed so that the initial value of the modulation factor Amp of the PWM control becomes the threshold value Ath. Thereby, it is possible to suppress the output of the rectangular wave voltage from the inverter 20 to the rotating electrical machine 10 even though the PWM control is performed after switching from the rectangular wave control to the PWM control. .

(Other embodiments)
In the above embodiment, the modulation factor threshold Ath is set to be smaller as the number of pulses Pn is smaller. By changing this, when the number of pulses Pn is less than 12, the modulation factor threshold Ath may be a predetermined value less than 127%, for example, 126%.

  The carrier wave CA may be a sawtooth wave instead of a triangular wave.

  The switching control unit 43 changes from the rectangular wave control to the PWM control based on the estimated torque Te or the rotational speed FR that is the estimated value of the output torque of the rotating electrical machine 10 instead of the d-axis current Id and the q-axis current Iq. May be switched.

  The control for setting the initial value of the modulation factor Amp of the PWM control to the modulation factor threshold Ath at the time of switching from the rectangular wave control to the PWM control may be omitted.

  When switching from rectangular wave control to PWM control, only the above control for setting the initial value of the modulation factor Amp of PWM control to the modulation factor threshold Ath is performed, and at the time of switching from PWM control to rectangular wave control, the fundamental wave The control for setting the modulation factor threshold Ath based on the pulse number Pn of the carrier wave CA included in one cycle of VU * 1, VV * 1, and VW * 1 may be omitted.

  The carrier wave generation unit 52 may perform synchronous PWM control in which the frequency of the carrier wave CA is a natural number multiple of the frequency of the fundamental waves VU * 1, VV * 1, and VW * 1. Furthermore, phase-synchronized PWM control may be performed in which the phase of the carrier wave CA is synchronized with the phases of the fundamental waves VU * 1, VV * 1, and VW * 1.

  Here, even when the synchronous PWM control is performed, when the rotational speed FR exceeds a predetermined value, the fundamental waves VU * 1, VV * 1 depend on the switching characteristics of the switches SUp to SWn and the processing load of the control device 40. , VW * 1 reduces the number Pn of carrier waves. For this reason, even in synchronous PWM control, a situation occurs in which a rectangular wave voltage is output even though PWM control is performed. Therefore, in the synchronous PWM control, by applying a configuration in which the modulation factor threshold Ath is set based on the number of pulses Pn of the carrier wave CA, a rectangular wave voltage is output despite the PWM control. This can be suppressed and the output torque of the rotating electrical machine 10 can be stabilized. In short, when the fundamental frequency increases relative to the frequency of the carrier CA, the modulation factor threshold Ath may be set based on the number of pulses Pn of the carrier CA. In other words, when the period of the fundamental wave is shortened relative to the period of the carrier wave CA, the modulation factor threshold Ath may be set based on the number of pulses Pn of the carrier wave CA.

  In a state in which PWM control is being performed, the fundamental wave so that the modulation factor Amp does not output a rectangular wave voltage from the inverter 20 to the rotating electrical machine 10 regardless of the phase difference between the fundamental wave and the carrier wave CA. The modulation factor threshold Ath may be set based on the number of pulses Pn of the carrier wave CA included in one period.

  The embodiment of the present invention has been described with reference to the examples. However, the present invention is not limited to these examples, and various forms are possible without departing from the spirit of the present invention. Can be implemented.

  DESCRIPTION OF SYMBOLS 10 ... Rotary electric machine, 20 ... Inverter, 40 ... Control apparatus, 41 ... PWM control part, 42 ... Rectangular wave control part, 43 ... Switching control part.

Claims (7)

A control device (40) for a rotating electrical machine that controls the rotating electrical machine by adjusting an output voltage output from the inverter device (20) to the rotating electrical machine (10),
Based on a torque command value for commanding the output torque of the rotating electrical machine and an output current output from the inverter device to the rotating electrical machine, a sinusoidal fundamental wave is set as a command value for the output voltage, and the fundamental wave and the carrier wave A first control unit (41) that performs pulse width modulation control, which is control for adjusting the output voltage, based on the comparison with
A rectangle that is a control that calculates a torque estimated value that is an estimated value of the output torque based on the output current, and adjusts the phase of the rectangular wave-shaped output voltage based on the torque estimated value and the torque command value. A second control unit (42) for performing wave control;
When the pulse width modulation control is performed by the first control unit, on the condition that the modulation rate, which is the ratio between the amplitude of the fundamental wave and the input voltage of the inverter device, exceeds a predetermined modulation rate threshold A switching control unit (43) for switching control from pulse width modulation control by the first control unit to rectangular wave control by the second control unit;
With
The control device, wherein the switching control unit sets the modulation factor threshold based on the number of pulses of the carrier wave included in one period of the fundamental wave.   The control device according to claim 1, wherein the switching control unit calculates the number of pulses of the carrier wave based on a rotation speed of the rotating electrical machine.   The switching control unit performs a rectangular wave from the inverter device to the rotating electrical machine regardless of a phase difference between the fundamental wave and the carrier wave in a state where the pulse width modulation control is performed by the first control unit. 3. The modulation factor threshold value is set based on the number of pulses of the carrier wave included in one period of the fundamental wave so that the voltage is less than the modulation factor to be output. Control device.   The switching control unit sets the modulation factor threshold based on the number of pulses of the carrier wave included in one period of the fundamental wave on condition that the rotation speed of the rotating electrical machine exceeds a predetermined value. The control device according to any one of claims 1 to 3.   The switching control unit sets the modulation factor threshold to less than 127% on the condition that the number of pulses of the carrier wave included in one period of the fundamental wave is less than 12. 5. The control device according to any one of 4.   After the switching from the rectangular wave control by the second control unit to the pulse width modulation control by the first control unit, the switching control unit has an initial value of the modulation rate of the pulse width modulation control by the first control unit. The switching from the rectangular wave control by the second control unit to the pulse width modulation control by the first control unit is performed so as to be the modulation factor threshold. The control device described in 1. A control device (40) for a rotating electrical machine that controls the rotating electrical machine by adjusting an output voltage output from the inverter device (20) to the rotating electrical machine (10),
A sinusoidal fundamental wave is set as the output voltage command value based on a torque command value that commands the output torque of the rotating electrical machine, and the output voltage is adjusted based on a comparison between the fundamental wave and a carrier wave. A first control unit (41) for performing pulse width modulation control as control,
A second control unit (42) for performing rectangular wave control, which is control for adjusting the phase of the rectangular wave-shaped output voltage, based on the torque command value;
A predetermined modulation rate threshold is set based on the number of pulses of the carrier wave included in one period of the fundamental wave, and switching from rectangular wave control by the second control unit to pulse width modulation control by the first control unit is performed. Later, from the rectangular wave control by the second control unit to the pulse width modulation control by the first control unit so that the initial value of the modulation rate of the pulse width modulation control by the first control unit becomes the modulation factor threshold value. A switching control unit (43) for switching to
A control device comprising:

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