JP2008228399A - Vehicular ac motor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular AC motor device that can reduce torque ripples and various noises. <P>SOLUTION: When driving a motor 3 having stator coils consisting of first and second three-phase windings 31, 32 each wound by the distributed winding, a first three-phase inverter 1 applies a first three-phase voltage to a first three-phase winding 31, while a second three-phase inverter 2 applies a second three-phase voltage to a second three-phase winding 32. The phase windings of the three-phase windings 31, 32 are each wound apart by π/6 from each other. A control circuit 4 forms PWM drive signals for the PWM drive control of switching elements of the first and second three-phase inverters 1, 2, but the PWM drive signals are formed in such a manner that one state transition and the other inverse state transition overlap of the two PWM drive signals applied to the two phase windings wound apart by π/6. Thereby, noise can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle AC motor device, and more particularly to an improvement in a vehicle AC motor device that individually applies a total of six phase voltages output by a pair of three-phase inverters to a pair of three-phase windings of a vehicle motor.

  In an AC motor that forms a stator rotating magnetic field by applying phase voltages of different phases to the phase windings constituting the stator coil, smooth rotation of the stator rotating magnetic field is important for reducing torque ripple and the like. Concentrated winding and distributed winding are known as winding methods of the stator coil, but the spatial current distribution of the distributed winding is formed more smoothly than that of concentrated winding, so that the stator rotating magnetic field rotates smoothly. Can do. Taking three phases as an example, in distributed winding, the spatial current distribution of Iu, -Iw, Iv, -Iu, Iw, -Iv with a phase angle difference between adjacent currents of 60 degrees and the corresponding stator rotating magnetic field However, in the case of concentrated winding, a stator rotating magnetic field obtained by synthesizing a 120-degree phase current magnetic field is formed.

The following Patent Document 1 discloses a first triangular wave voltage for forming a PWM signal when generating a 6-phase voltage with an interphase phase angle of 60 degrees in two sets of three-phase windings concentrated and wound apart from each other by an electrical angle π. (First carrier voltage) is used to generate a first three-phase voltage, and a second carrier voltage having a phase opposite to that of the first carrier voltage (hereinafter also referred to as phase-inverted carrier voltage) is used to generate a second three-phase voltage. Propose to generate voltage. Further, it is proposed that the first three-phase drive voltage is replaced with the upper arm and the lower arm to obtain the second three-phase drive voltage.
JP 2004-64893 A

  According to the driving method of Patent Document 1, PWM drive signals for forming two phase voltages separated from each other by an electrical angle π of two sets of three-phase voltages are turned on and off in opposite phases, thereby reducing various noise voltages. it can.

  However, in Patent Document 1 described above, it is necessary to wind two sets of three-phase windings around the stator core and to provide two three-phase inverters that operate independently from each other, and the circuit wiring and stator coil winding structure is complicated. There is a problem of becoming.

  Further, the double three-phase driving method of Patent Document 1 distributes a total of six-phase currents separated by 60 degrees between electrical angles 2π, as in the case of three-phase driving of a conventional distributed winding stator coil. Therefore, the torque ripple is equivalent to that of the conventional three-phase driving method of the distributed winding stator coil despite the complicated circuit and driving operation.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle AC motor device capable of greatly reducing torque ripple as compared with the conventional art.

  An AC motor device for a vehicle according to the present invention that solves the above-described problems includes a motor having a stator coil composed of first and second three-phase windings distributedly wound, and the first and second three-phase windings. The first and second three-phase inverters that individually apply the first and second three-phase voltages, and the first and second three-phase inverters by PWM driving control of the first and second three-phase inverters. In a vehicle AC motor device comprising a control circuit for generating a second three-phase voltage, one phase winding of the first three-phase winding and one phase winding of the second three-phase winding Are spatially wound at a distance of π / 6, applied to one phase winding of the first three-phase winding, and to the phase winding to which the phase voltage U is applied. The phase voltage X applied to one phase winding of the second three-phase winding separated by π / 6 is a phase between 0 and π / 6. It is characterized by having a difference. In this way, since the rotating magnetic field can be formed by the rotating vector current constituted by the spatial current distribution of 12 phases in total, the torque ripple as compared with the double three-phase inverter configuration of Patent Document 1 described above. And magnetic noise can be reduced.

  The vehicle AC motor device of the present invention is suitable for a permanent magnet rotor type synchronous machine, a reluctance motor, and the like, but can also be applied to other AC motors.

  In a preferred embodiment, the control circuit overlaps the state transition of the PWM drive signal Upwm for forming the phase voltage U and the reverse state transition of the PWM drive signal Xpwm for forming the phase voltage X. Let

  In a preferred aspect, the control circuit forms one phase voltage of the second three-phase voltage with a phase angle of π / 6 apart from one phase voltage of the first three-phase voltage. The state transition of the PWM drive signal and the state transition of the PWM drive signal for forming one phase voltage of the first three-phase voltage are overlapped. As a result, various noise voltages, such as switching noise and common mode noise, generated by the switching of the switching element of the three-phase inverter due to the state transition of the PWM drive signal can be reduced satisfactorily.

  In a preferred aspect, the control circuit sets the pulse width of the PWM drive signal Xpwm to be equal to the pulse width of the immediately preceding PWM drive signal Upwm. In this way, two PWM drive signals whose phases are close to each other and state transitions overlap can be formed with a simple circuit configuration.

  In a preferred embodiment, the control circuit includes a first carrier signal generator that generates a first carrier signal composed of a sawtooth voltage that gradually decreases after the voltage suddenly increases, and a voltage that is proportional to the amplitude of the phase voltage of the U phase. And a first comparator for forming a U-phase PWM drive signal by comparing the first carrier signal with the first carrier signal, and a second carrier signal comprising a sawtooth voltage that suddenly decreases after the voltage gradually increases. A second carrier signal generator for generating two carrier signals, a voltage proportional to the amplitude of the phase voltage of the X phase that is about π / 6 away from the phase voltage of the U phase, and the second carrier And a second comparator that compares the signal and forms an X-phase PWM drive signal. In this way, with a simple circuit configuration, the pulse width of the X-phase PWM drive signal can be generated following the pulse width of the U-phase PWM drive signal separated by π / 6 from each other. As a result, a 12-phase spatial current distribution can be formed and various noises can be reduced.

  A preferred embodiment of a vehicle AC motor device of the present invention will be specifically described with reference to the drawings.

(Circuit configuration)
The circuit configuration of the vehicle AC motor device of this embodiment is shown in FIG. Reference numeral 1 denotes a first three-phase inverter circuit, 2 denotes a second three-phase inverter circuit, 3 denotes a field winding type three-phase synchronous generator motor (hereinafter simply referred to as a motor) that forms a vehicle running motor, and 4 denotes a controller (Control unit).

  The three-phase inverter circuits 1 and 2 are ordinary three-phase inverter circuits using a pair of IGBT and a freewheeling diode or a power MOS transistor as a switching element, and have a well-known configuration, and thus detailed description thereof is omitted. The three-phase inverter circuits 1 and 2 are fed with DC power from a battery or a DCDC converter (not shown).

  The motor 3 has a first three-phase winding 31 and a second three-phase winding 32. The three-phase winding 31 is driven by the three-phase inverter circuit 1, and the three-phase winding 32 is It is driven by a three-phase inverter circuit 2. The three-phase winding 31 is configured by star connection of phase windings 311, 312, and 313, and the three-phase winding 32 is configured by star connection of phase windings 321, 322, and 323.

  FIG. 2 schematically shows the arrangement of the three-phase windings 31 and 32. As shown in FIG. 2, the three-phase winding 31 and the three-phase winding 32 are wound around the slot of the armature core by a distributed wave winding method (other winding methods may be used as long as they are distributed winding). However, in FIG. 2, each phase winding 311 to 323 shows only one turn per electrical angle 2π. Phase windings 311 to 313 are arranged π / 3 apart from each other. The phase windings 321 to 323 are also arranged away from each other by π / 3. Phase winding 311 is arranged at a position advanced by electrical angle π / 6 with respect to phase winding 321. Phase winding 312 is arranged at a position advanced by electrical angle π / 6 with respect to phase winding 322. The phase winding 313 is arranged at a position advanced by an electrical angle π / 6 with respect to the phase winding 323. Eventually, the in-slot conductor portions of the stator coil are spaced apart by an interphase phase angle of electrical angle π / 6.

  The phase voltage U applied to the phase winding 311 is advanced by an electrical angle π / 6 from the phase voltage X applied to the phase winding 321. The phase voltage V applied to the phase winding 312 is ahead of the phase voltage Y applied to the phase winding 322 by an electrical angle π / 6. The phase voltage W applied to the phase winding 313 is advanced by an electrical angle π / 6 from the phase voltage Z applied to the phase winding 323. Eventually, the phase voltages flowing through a total of twelve slot conductors arranged between the electrical angles 2π are sequentially separated by an electrical angle π / 6 as shown in FIG.

(effect)
As described above, in this embodiment, since the phase difference between the two three-phase voltages applied to the two three-phase windings 31 and 32 is shifted by π / 6, a total 12-phase spatial current distribution is created. Torque ripple can be reduced well.

(PWM drive signal Upwm and PWM drive signal Xpwm)
The phase relationship between the PWM drive signal Upwm and the PWM drive signal Xpwm that characterize this embodiment will be described with reference to FIGS. The PWM drive signal Upwm is a signal for opening and closing the upper arm side switching element of the U-phase half inverter, and the PWM drive signal Xpwm is for opening and closing the upper arm side switching element of the X phase half inverter. Signal. Similarly, the PWM drive signal Vpwm and the PWM drive signal Ypwm are formed to open and close the upper arm side switching element of the V-phase half inverter and the upper arm side switching element of the Y phase half inverter, and the PWM drive signal Wpwm and PWM The drive signal Zpwm is formed to open and close the upper arm side switching element of the W phase half inverter and the upper arm side switching element of the Z phase half inverter, but they are only 2π / 3 apart in phase angle. Since it is basically the same as the PWM drive signal Upwm and the PWM drive signal Xpwm, description thereof is omitted. It is assumed that the lower arm side switching element of each half inverter of the three-phase inverters 1 and 2 operates in reverse with respect to the upper arm side switching element with a dead time. 4 and 5, overmodulation is not performed, but overmodulation may be performed.

  FIG. 4 shows a case where the phase voltage U is a positive predetermined value and the duty ratio (Tp / T) of the PWM drive signal Upwm is larger than 50%, and FIG. 5 is a case where the phase voltage U is a negative predetermined value. The case where the duty ratio (Tp / T) of the drive signal Upwm is smaller than 50% is shown.

  4 and 5, in order to simplify the circuit configuration of the controller 4, the phase voltage U and the phase voltage X have the same duty ratio, the phase voltage V and the phase voltage Y have the same duty ratio, and the phase voltage W and It is assumed that the phase voltage Z has an equal duty ratio. That is, the phase angle difference between the phase voltage U and the phase voltage X, the phase angle difference between the phase voltage V and the phase voltage Y, and the phase angle difference between the phase voltage W and the phase voltage Z are almost zero.

  Of course, using a high-speed arithmetic circuit, the phase voltage U and the phase voltage X are provided with a duty ratio difference equal to the phase difference of π / 6, and the phase voltage V and the phase voltage Y are equal to the phase difference of π / 6. A difference in duty ratio may be provided, and the phase voltage W and the phase voltage Z may be provided with a duty ratio difference equal to a phase difference of π / 6.

  The feature of this embodiment is that the state transition is performed so that the PWM drive signal Xpwm changes from the low level state L to the high level H by overlapping with the timing when the PWM drive signal Upwm changes from the high level state H to the low level L. It is in the point where it overlapped. By doing so, various noise voltages that are generated when the PWM drive signal Upwm changes state from H to L and various noise voltages that are generated when the PWM drive signal Xpwm changes state from L to H are obtained. Since it cancels out, it is effective in the noise reduction of the AC motor device for vehicles. The various noise voltages include, for example, switching surge voltage and common mode voltage. Of course, similar to the overlap of the state transition between the PWM drive signal Upwm and the PWM drive signal Xpwm described above, the PWM drive signal Vpwm and the PWM drive signal Ypwm and the PWM drive signal Wpwm and the PWM drive signal Zpwm have the same overlap. It wraps and can produce the same effect.

(Controller 4)
The controller 4 is a circuit that forms PWM drive voltages S1 to S6 and S1 ′ to S6 ′ to be applied to the switching elements of the three-phase inverters 1 and 2. The controller 4 determines the current value determined based on the torque command input from the outside and the maximum duty ratio of the PWM drive voltages S1 to S6 and S1 ′ to S6 ′ of each phase corresponding to the current value. Since this type of circuit is the same as a conventional motor control circuit and is not the gist of the present invention, the description thereof is omitted.

  FIG. 6 shows a circuit for forming PWM drive signals Upwm and Xpwm for forming PWM drive voltages S1 and S1 'among PWM drive voltages S1 to S6 and S1' to S6 '. The PWM drive signal Upwm is power amplified by a buffer circuit (not shown) and the reference potential level is changed to become the PWM drive voltage S1, and the PWM drive signal Xpwm is power amplified by the buffer circuit (not shown) and the reference potential level is changed and PWM driven. The voltage is S1 ′. In addition, the upper arm side switching element and the lower arm side switching element of each half bridge of the three-phase inverters 1 and 2 are conducted in opposite phases with a short dead time.

  The operation of forming the PWM drive signal Upwm and the PWM drive signal Xpwm by the circuit of FIG. 6 will be described below.

  A carrier voltage Vc, which is a triangular wave voltage with a predetermined carrier frequency, is output from the carrier signal generator 10 to the comparator 100, and the comparator 100 compares the analog voltage Vduty proportional to the duty with the carrier voltage Vc and outputs a PWM drive signal Upwm. To do.

  The output voltage of the comparator 100 is converted into a one-pulse voltage by a mono multivibrator (or Schmitt trigger) 101 and input to the reset terminal R of the first counter 102. The first counter 102 is reset at the time point to and starts counting. . The output voltage of the comparator 100 is input to the first counter 102 through the AND gate 103 together with the high frequency clock signal CLK. The first counter 102 starts counting from the timing to when the output voltage of the comparator 100, that is, the PWM drive signal Upwm changes from L to H. At the timing t1 when the output voltage of the comparator 100 transitions from H to L, the AND gate 103 is closed and the count is completed, and the first counter 102 holds a count value proportional to the pulse width TP of the PWM drive signal Upwm.

  The output voltage of the comparator 100 is inverted by the inverter circuit 104 and then input to the mono multivibrator (or Schmitt trigger) 105. The one-pulse voltage output from the mono multivibrator (or Schmitt trigger) 105 is input to the reset terminal R of the second counter 106, and the second counter 106 is reset at time t1 and starts counting. A high frequency clock signal CLK is input to the second counter 106. Therefore, the second counter 106 starts counting from the timing t1 when the output voltage of the comparator 100, that is, the PWM drive signal Upwm changes from H to L.

  The one-pulse voltage output from the mono multivibrator (or Schmitt trigger) 105 is input to the set terminal S of the latch 107. The latch 107 starts from the timing t1 when the output voltage of the comparator 100, that is, the PWM drive signal Upwm changes from H to L. The high level of the PWM drive signal Xpwm is output.

  When the count value of the second counter 106 that counts the clock signal CLK from time t1 matches the count value held by the first counter 102, the match circuit 108 outputs a high level to the reset terminal R of the latch 107. As a result, the latch 107 is reset and the PWM drive signal Xpwm output from the latch 107 is shifted to a low level.

  With the circuit configuration shown in FIG. 6, the PWM drive signal Xpwm whose high level continues for a time equal to the PWM drive signal Upwm and its high level duration time Tp is formed. 6 are added, the PWM drive signal Vpwm, the PWM drive signal Ypwm, the PWM drive signal Wpwm, and the PWM drive signal Zpwm are formed.

  In this embodiment, the three-phase inverter circuits 1 and 2 output a three-phase voltage having substantially the same phase although the pulse timing is shifted. Therefore, in this embodiment, the only U-phase winding of the three-phase winding exists at the circumferential intermediate position between the phase winding 311 of the three-phase winding 31 and the phase winding 321 of the three-phase winding 32. There is a unique V-phase winding of the three-phase winding at the intermediate position in the circumferential direction between the phase winding 312 of the three-phase winding 31 and the phase winding 322 of the three-phase winding 32. It is preferable to correct the rotor angular position on the assumption that the only w-phase winding of the three-phase winding exists at the circumferential intermediate position between the winding 313 and the phase winding 323 of the three-phase winding 32. In this case, each phase voltage of the first three-phase voltage and each phase voltage of the second three-phase voltage are deviated back and forth by 15 degrees from the optimum position. Therefore, the phase shift between the phase voltage and the rotor position can be almost ignored. This kind of correction of the rotor angular position is simple. Of course, a more complicated circuit may be formed so as to accurately determine the high-bell time of the PWM drive signals Xpwm, Ypwm, and Zpwm for forming the second three-phase voltage.

(Other embodiments)
Other embodiments will be described with reference to FIGS.

  In this embodiment, a carrier signal generator (second carrier signal generator referred to in the present invention) 200, comparators 201 and 202, and an analog inverting circuit 204 are used. Instead of the analog inverting circuit 204, another carrier signal generator (first carrier signal generator) that outputs a voltage having a waveform opposite to that of the carrier signal generator 200 is provided, and the output voltage is input to the comparator 201. Also good.

  In FIG. 7, the carrier signal generator 200 inputs a second carrier signal composed of a sawtooth voltage that rapidly decreases after the output voltage gradually increases to the negative input terminal of the comparator 202, and further receives the second carrier signal. Is input to the negative input terminal of the comparator 201 through the analog inverting circuit 20. Therefore, the first carrier signal composed of the sawtooth voltage that gradually decreases after the voltage suddenly increases is input to the negative input terminal of the comparator 201. The analog voltage Vduty−U for forming the U-phase phase voltage S1 is input to the + input terminal of the comparator 201, and the analog voltage for forming the X-phase phase voltage S1 ′ is input to the + input terminal of the comparator 202. Vduty-X is input.

  In this way, as shown in FIG. 8, the state transition period in which the PWM drive signal Upwm changes from the high level to the low level and the state transition period in which the PWM drive signal Xpwm changes from the low level to the high level are overlapped. In addition, since the duty ratio of the PWM drive signal of each phase can be accurately formed, a symmetrical 12-phase current space distribution can be accurately formed in distributed winding, and torque ripple and switching noise Both can be reduced well.

It is a circuit diagram showing an AC motor device for vehicles of the present invention. It is a voltage vector diagram which shows the phase of each phase voltage applied to each phase winding of the motor of FIG. FIG. 2 is a wiring diagram showing a state of two three-phase windings wound on the motor of FIG. 1 by distributed wave winding. It is a wave form diagram which shows the state which forms the PWM drive signal for carrying out intermittent control of the switching element of the upper arm side of the half bridge of two three-phase inverters shown in FIG. It is a wave form diagram which shows the state which forms the PWM drive signal for carrying out intermittent control of the switching element of the upper arm side of the half bridge of two three-phase inverters shown in FIG. It is a circuit diagram which shows the circuit for forming two PWM drive signals which are temporally continuous. It is a circuit diagram which shows the circuit for forming two PWM drive signals which are temporally continuous of other embodiment. It is a timing chart which shows each part waveform of the circuit of FIG.

Explanation of symbols

1 3-phase inverter 2 3-phase inverter 3 Motor 4 Controller (control circuit)
DESCRIPTION OF SYMBOLS 10 Carrier signal generator 31 Three-phase winding 32 Three-phase winding 100 Comparator 102 Counter 103 And gate 104 Inverter circuit 106 Counter 107 Latch 108 Match circuit 311 to 313 Phase winding 321 to 323 Phase winding

Claims (4)

First and second three-phase voltages are individually applied to a motor having a stator coil composed of first and second three-phase windings that are each distributedly wound, and the first and second three-phase windings. A vehicle comprising: first and second three-phase inverters; and a control circuit that generates the first and second three-phase voltages by performing PWM drive control of the switching elements of the first and second three-phase inverters. AC motor device for
One phase winding of the first three-phase winding and one phase winding of the second three-phase winding are wound spatially π / 6 apart,
A phase voltage U applied to one phase winding of the first three-phase winding, and the second three-phase winding separated by π / 6 from the phase winding to which the phase voltage U is applied An AC motor device for a vehicle having a phase angle difference between 0 and π / 6 with a phase voltage X applied to one of the phase windings. The vehicle AC motor device according to claim 1,
The control circuit includes:
An AC motor device for a vehicle that overlaps a state transition of the PWM drive signal Upwm for forming the phase voltage U and a reverse state transition of the PWM drive signal Xpwm for forming the phase voltage X. In the vehicle AC motor device according to claim 2,
The control circuit includes:
The vehicle AC motor device in which the pulse width of the PWM drive signal Xpwm is set equal to the pulse width of the immediately preceding PWM drive signal Upwm. In the vehicle AC motor device according to claim 2,
The control circuit includes:
A first carrier signal generator for generating a first carrier signal comprising a sawtooth voltage that gradually decreases after the voltage suddenly rises;
A first comparator that compares a voltage proportional to the amplitude of the phase voltage of the U phase with the first carrier signal to form a U phase PWM drive signal;
A second carrier signal generator for generating a second carrier signal for generating a second carrier signal comprising a sawtooth voltage that rapidly decreases after the voltage gradually increases;
A voltage proportional to the amplitude of the X-phase phase voltage that is about π / 6 apart from the U-phase phase voltage is compared with the second carrier signal to form an X-phase PWM drive signal. Two comparators,
An AC motor device for a vehicle having the vehicle.

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