JP4493431B2 - Inverter control device - Google Patents

Description

  The present invention relates to an inverter control device that performs two-phase PWM (pulse width modulation) control of an inverter.

  A conventional general inverter control device is configured as shown in FIG. The control target of this inverter control device is the inverter 1. The inverter 1 converts a DC power obtained from a commercial AC power supply through a converter or a DC power 2 from a battery DC power 2 into AC power, and the converted AC power is converted into a three-phase AC motor 3 (for example, a permanent magnet synchronous motor). Supply and drive. The inverter 1 is composed of a high-power switching element such as an IGBT having a logarithm corresponding to the number of phases of the load that is the three-phase AC motor 3, and is switching-controlled by the inverter control device 10.

The inverter control device 10 includes a speed detector 11 that detects the rotational speed of the electric motor 3, and a current expressed in a dq2-phase coordinate system based on the deviation between the speed detected by the speed detector 11 and the speed command. A current command generator 13 for generating commands Id ^* and Iq ^* , and a U-phase current detector 14u and a W-phase current detector 14w provided on the U-phase output and W-phase output side of the output phases of the inverter 1 And a UVW / dq converter 15 for taking out the measured currents Id and Iq converted into the d-q2 phase coordinate system.

Further, the inverter control device 10 takes out the deviations between the current commands Id ^* and Iq ^* from the current command generator 13 and the measured currents Id and Iq from the UVW / dq converter 15, respectively. Current controller 16d, 16q for converting to dq-axis voltage commands Vd ^* , Vq ^* , and these dq-axis voltage commands Vd ^* , Vq ^* as inputs, U-phase voltage command Vu, V-phase voltage command Vv and W-phase voltage command A dq / UVW converter 17 for converting to Vw and outputting, and a PWM converter 18 are provided.

  As shown in FIG. 4, the PWM converter 18 compares the U-phase voltage command Vu with a carrier wave es having a predetermined waveform such as a triangular wave, and U-phase PWM signals Su (+), Su (- ) Is taken out and the switching element which is a pair corresponding to the U phase of the inverter 1 is driven and controlled. The V-phase voltage command Vv and the W-phase voltage command Vw are also not shown in the figure, but V-phase PWM signals Sv (+), Sv (−) and W-phase PWM signals Sw ( +) And Sw (-). Therefore, if the voltage command for each phase is varied, the pulse width of the PWM signal can be varied.

  By the way, in such PWM control, from the viewpoint of reducing electromagnetic wave noise and switching loss and improving the efficiency of power conversion, the ± 30 ° (electrical angle) section at the peak time of each phase voltage command is maximized as shown in FIG. Two-phase PWM control that fixes at the voltage command level, and fixes the phase of ± 30 ° at the peak time of the voltage command at the maximum voltage command level in the same way, and stops the switching of the corresponding phase of the inverter 1 for each phase. There is also a method. The means for fixing the ± 30 ° section of each phase at the maximum voltage command level is realized by applying an offset voltage to each phase voltage command. Therefore, switching of each phase to the switching pause phase is performed every 60 ° of the voltage phase.

  However, in the two-phase PWM control as described above, the highest voltage command level is set in the switching pause phase, and the offset voltage that sets the highest voltage command level in a predetermined section is also set in the switching pause phase of the other phases. Therefore, the following problem arises when there is a phase difference between the current phase of the current command and the voltage phase of the voltage command applied to the PWM converter 18. That is, when the switching pause interval of a certain phase is switched, the voltage command of the other phase becomes a value exceeding the power supply voltage of the inverter 1 based on the discontinuity of the voltage commands Vu, Vv, Vw of each phase. The current waveform is distorted and controllability deteriorates.

  Therefore, conventionally, in order to prevent the voltage command of the other phase from exceeding the power supply voltage of the inverter 1 when switching to the switching pause phase of one phase, the phase difference between the current command and the voltage command is detected and The voltage commands Vu, Vv, Vw of each phase are changed according to the phase difference.

Specifically, as shown in FIG. 6, a phase difference detection unit 21 that detects a voltage phase (hereinafter referred to as a voltage phase) that is a phase difference from the current phase Qi and the biaxial voltage commands Vd ^* and Vq ^*. , Provided between the dq / UVW conversion unit 17 and the PWM conversion unit 18, not only to set the predetermined interval of the switching pause phase to the highest voltage command level, but also to the voltage for intervals other than the switching pause interval of other phases There is provided a two-phase PWM converter 22 for setting a desired offset voltage to the voltage commands Vu, Vv, Vw of each phase according to the phase and outputting so-called corrected voltage commands Vu ^* , Vv ^* , Vw ^*. ing.

The phase difference detection unit 21 includes a current phase detector 21a such as a resolver that detects the current phase Qi, and a d-axis voltage command Vd ^* and a q-axis voltage command Vq ^* based on V _Q = tan ⁻¹ (Vd ^* / Vq ^*) the calculation formula is taken out and biaxial voltage phase calculation section 21b for obtaining a biaxially voltage phase V _Q, these current phase Qi and biaxial voltage phase V _Q from the voltage phase Qv (= current phase Qi-V _Q) A phase calculation unit 21c is provided.

In the two-phase PWM converter 22, for example, when the switching pause phase is switched every 60 ° voltage phase of the U-phase voltage command Vu with respect to the input voltage commands Vu, Vv, and Vw, By applying correction voltages Av and Aw by offset voltage to phase voltage commands Vv and Vw, voltage commands Vv ^* and Vw ^* corrected as indicated by solid lines shown in FIG. 7 are taken out and output to inverter 1. The power supply voltage of 1 is not exceeded. When switching between the V-phase and W-phase switching pause phases, the voltage commands Vw ^* , Vu ^* , which are corrected by the correction voltages Aw, Au, Au, Av based on the offset voltage from the two-phase PWM converter 22 as described above. Vu ^* and Vv ^* are output.

(Patent Document 1)
JP-A-8-340691

By the way, in the two-phase PWM control as described above, as shown in FIG. 7 (d), switching pauses are performed every 60 ° of the voltage phase with respect to the voltage commands Vu, Vv, Vw having a deviation of 120 ° in each phase. The phase is switched, the switching pause interval is set to the maximum voltage command level, and the voltage commands Vu, Vv, Vw of the other phases are corrected with the offset voltage when switching the switching pause phase, and the desired voltage commands Vu ^* , Vv ^{* And Vw} * are taken out.

However, when the voltage phase Qv changes at a low speed, the current control units 16d and 16q take out the biaxial voltage commands Vd ^* and Vq ^* by feedback control, but the current phase of the current phase detector 21a such as a resolver. When noise is included, each phase is shifted by 120 °. Therefore, when the voltage phase Qv = 120 °, when switching from the U phase to the V phase, oscillation is performed by feedback control of the current control units 16d and 16q. A phenomenon occurs, and fluctuations occur in the biaxial voltage commands 2Vd ^* and Vq ^* that are the outputs of the current control units 16d and 16q.

  Therefore, as shown in FIG. 8 which shows the 120 ° portion of FIG. 7D in an enlarged manner, it returns from the V phase to the U phase again despite the transition from the U phase to the V phase based on the voltage phase Qv. The phase return (I) will occur. As a result, an appropriate switching pause control in the switching pause phase cannot be performed.

  The present invention has been made in view of the circumstances as described above, and at the time of switching to the switching pause phase of each phase, the voltage phase after switching the switching pause phase is maintained regardless of the phase change, An object of the present invention is to provide an inverter control device that reliably performs phase switching suspension control.

In order to solve the above problems, the present invention relates to a dq / UVW conversion means for converting a biaxial voltage command into a three-phase voltage command, and a voltage command for each phase output from the dq / UVW conversion means. (Pulse width modulation) and a PWM conversion means for outputting each phase PWM signal, and an inverter control device for driving and controlling the motor via each phase PWM signal,
Phase difference detection means for detecting the voltage phase using the two-axis voltage phase obtained from the two-axis voltage command and the current phase extracted from the motor side, and 60 ° of the voltage phase detected by the phase difference detection means Each phase is sequentially switched to the switching pause phase, a predetermined offset voltage is set near the positive or negative peak of the voltage command corresponding to the switching pause phase, and the voltage is switched to the switching pause phase. When the phase changes and returns to the voltage phase of the phase after the switching again, if the returned voltage phase is within a predetermined hysteresis region, hold the voltage phase when switching to the switching pause phase, Based on the held voltage phase, the predetermined offset voltage is set to a voltage command corresponding to the switching pause phase, and predetermined switching is performed. It is a structure in which a capital and a two-phase PWM converter means for generating a stop period.

  According to the present invention, when the switching pause phase of each phase is switched, even if there is a phase change such that the voltage phase returns to the voltage phase of the phase that has been switched again, the voltage phase of the switching pause phase at the time of switching is changed. Since it is held, each phase switching pause control of the inverter can be reliably executed.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a block diagram showing an embodiment of a main part of an inverter control device according to the present invention.

  First, since the whole structure of the inverter control apparatus including the inverter 1 is the same as that shown in FIGS. 3 and 6, the same components will be described using the same reference numerals.

  As the two-phase PWM conversion unit (two-phase PWM conversion means) 22 which is a main part of the present invention in this inverter control device, a hysteresis region setting for setting a hysteresis region that becomes a predetermined phase voltage range corresponding to each phase switching is performed. A portion 22a is provided. This hysteresis region setting unit 22a is, for example, a hysteresis region that has a phase voltage range of 45 ° to 60 ° when switching from the W phase to the U phase, and a phase voltage range of 105 ° to 20 ° when switching from the U phase to the V phase. And a hysteresis region for setting a phase voltage range of 165 ° to 180 ° when switching from the V phase to the W phase is set.

  Further, the two-phase PWM conversion unit 22 is provided with a phase difference hold unit 22b, the offset voltage setting unit 22c and the two-phase PWM correction unit 22d described above.

  The phase difference hold unit 22b changes from the voltage phase Qv detected by the phase difference detection unit 21 to 120 ° as shown in FIG. 7D, that is, from the U phase (+) to the V phase that is a switching pause phase. Switching is performed and the maximum voltage command level is set on the V phase (−) side of the voltage command Vv to execute the switching pause control.

  However, when switching from the U phase to the V phase that is the switching pause phase based on the voltage phase Qv, the current phase Qi detected by the current phase detector 21a such as a resolver when the phase changes at a low speed. If noise is included, a phase return occurs in the voltage phase of the switching source.

  Therefore, when the voltage phase Qv returned to the switching source changes within the hysteresis region at the time of V-phase switching from the U-phase set by the hysteresis region setting unit 22a, the V-phase phase voltage Qv shifted from the U-phase is obtained. Has a hold function. Further, when the voltage phase Qv returns to the W phase again due to the phase return when switching from the W phase to the U phase that is the switching pause phase, the range (45 ° to 60 °) similarly set by the hysteresis region setting unit 22a. If it is within the hysteresis region (°), the voltage phase Qv transferred to the switching pause phase (U phase) that is the switching destination is held, and the U phase (+) switching pause can be executed.

  For example, when switching from the U phase (+) to the V phase, the offset voltage setting unit 22c determines that the V phase (−) side is a switching pause interval, and the V phase voltage command Vv is a level corresponding to the V phase maximum voltage command. And the other phase V-phase voltage commands Vu and Vw have a function of outputting a desired offset voltage. That is, the offset voltage setting unit 22c is preset with an offset voltage set for each phase, and the offset voltage set based on the voltage phase Qv output from the phase difference hold unit 22b is input to the two-phase PWM correction unit 22d. Set.

The two-phase PWM correction unit 22d corrects the input phase voltage commands Vu, Vv, Vw using the offset voltage output from the offset voltage setting unit 22c, and the corrected phase voltage commands Vu ^*. , Vv ^* , Vw ^* are output and sent to the PWM converter 18. Next, the operation of the above apparatus will be described with reference to FIG.

Now, in the phase range of 60 ° to 120 ° of the voltage phase Qv in FIG. 7 (d), 60 °, which becomes ± 30 with the peak of the U phase (+) as the boundary, is the U phase (+) as the switching pause interval, The switching pause control of the inverter 1 is performed. Thereafter, when the voltage phase Qv reaches 120 °, the phase is switched from the U phase to the V phase and the V phase (−) is set as the switching pause period, and the switching pause control of the inverter 1 is performed. If noise is included in the current phase detector 21a in a changing state, an oscillation phenomenon occurs due to feedback control of the current control units 16a and 16b, and a biaxial voltage command 2Vd that is an output of the current control units 16d and 16q. ^* , Vq ^* swings. Therefore, the voltage phase Qv also changes greatly, and the phase voltage Qv reverts back to the original U phase even when the U phase is switched to the V phase as shown in FIG.

  Therefore, in the device of the present invention, when switching from the U phase to the V phase, the hysteresis region when switching from the U phase to the V phase is set to 105 ° to 120 ° in the hysteresis region setting unit 22a. As long as the voltage phase Qv changes to the U phase after switching to the V phase, the phase difference hold unit 22b holds the voltage phase Qv that becomes the V phase switching pause interval to offset voltage. Since the data is continuously sent to the setting unit 22c, the V-phase (−) switching pause state can be continued.

  The phase difference hold unit 22b then returns to the voltage phase Qv corresponding to the V phase, but since it is the voltage phase Qv that originally becomes the V phase switching pause interval, the voltage phase Qv is used as it is as the offset voltage setting unit 22c. To send. As a result, when the current phase Qi of the current phase detector 21a contains noise when the voltage phase Qv is changing at a low speed, when switching from one phase to another based on the voltage phase Qv Even in an unstable state, the voltage phase Qv in which the switching destination phase of the switching destination phase is in a suspension state can be stably output.

  Based on the voltage phase Qv sent from the phase difference hold unit 22b, the offset voltage setting unit 22c outputs the offset voltage of the highest voltage command level that should be given to the switching pause period of each phase sequentially every 60 ° phase, Also in other phases that are not in the switching pause period, a predetermined offset voltage is output and supplied to the two-phase PWM correction unit 22d.

The two-phase PWM correction unit 22d takes in the offset voltage of each phase from the offset voltage setting unit 22c, and gives it to the voltage commands Vu, Vv, Vw of each phase input from the dq / UVW conversion unit 17, thereby providing a desired value. The voltage commands Vu ^* , Vv ^* , and Vw ^* for each phase are taken out and sent to the PWM converter 18.

  Therefore, according to the embodiment as described above, each 60 ° voltage phase is based on the voltage phase which is the phase difference between the biaxial voltage phase obtained from the biaxial voltage command and the current phase extracted from the electric motor 3. The phases are sequentially switched, and an offset voltage for forming a predetermined switching pause interval is output in the vicinity of the positive and negative peaks of the corresponding phase, but after each phase is switched, the voltage phase of the switching source phase is reversed. When there is a change, the phase difference hold unit 21b holds and outputs the voltage phase of the switching phase that is the switching destination as long as the voltage phase changes within a preset hysteresis region. Pause control can be executed reliably.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, various deformation | transformation can be implemented. Moreover, each embodiment can be implemented in combination, and in that case, the effect of the combination can be obtained.

The block diagram which shows one Embodiment of the principal part of the inverter control apparatus which concerns on this invention. The figure explaining the relationship between the change of the voltage phase at the time of each phase switching, and a hysteresis region. The block diagram of the conventional general inverter control apparatus. The wave form diagram explaining the principle of PWM conversion. The figure set to the level of the highest voltage command in order to provide the switching pause section of ± 30 degrees at the peak time of the voltage command of each phase. Configuration of another conventional inverter control device that provides a two-phase PWM conversion unit between the two-phase / three-phase conversion unit and the PWM conversion unit, and solves a problem when the switching pause interval is set to the maximum voltage command level Figure. The wave form diagram of each phase voltage command by the two-phase PWM converter shown in FIG. The figure explaining the change of the voltage phase at the time of each phase switching.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inverter, 3 ... Electric motor, 10 ... Inverter control apparatus, 11 ... Speed detector, 12 ... Speed control part, 13 ... Current command generation part, 14u, 14w ... Current detector, 15 ... UVW / dq conversion part, 16d , 16q ... current control unit, 17 ... dq / UVW conversion unit, 18 ... PWM conversion unit, 21 ... phase difference detection unit, 22 ... two-phase PWM conversion unit, 22a ... hysteresis region setting unit, 22b ... phase difference hold unit, 22c: Offset voltage setting unit, 22d: Two-phase PWM correction unit.

Claims (2)

PWM (pulse width modulation) for each phase voltage command output from the dq / UVW conversion means for converting the biaxial voltage command into a three-phase voltage command, and the dq / UVW conversion means, An inverter control device for driving and controlling the motor via each inverter with each phase PWM signal.
Phase difference detection means for detecting a voltage phase difference using a biaxial voltage phase obtained from the biaxial voltage command and a current phase extracted from the motor side;
Provided between the dq / UVW conversion means and the PWM conversion means, and sequentially switches to the switching pause phase every 60 ° phase of the voltage phase detected by the phase difference detection means, and corresponds to the switching pause phase. A predetermined offset voltage is set in the vicinity of the positive or negative peak of the voltage command, and the voltage phase changes at the time of switching to the switching pause phase, and then returns to the voltage phase of the phase that has finished the switching again. If the returned voltage phase is within a predetermined hysteresis region, the voltage phase at the time of switching to the switching pause phase is held, and the predetermined offset voltage is applied to the switching pause phase based on the held voltage phase. Two-phase PWM conversion means for setting a voltage command corresponding to a phase and generating a predetermined switching pause interval The inverter control device. The inverter control device according to claim 1,
The two-phase PWM conversion means includes a hysteresis area setting means for setting a hysteresis area having a predetermined voltage phase width below the voltage phase for each 60 ° phase of the voltage phase detected by the voltage phase detection means, When the voltage phase is changed to the switching pause phase every 60 ° phase of the voltage phase detected by the voltage phase detection means and the voltage phase is changed again to return to the voltage phase of the phase that has been switched again, this return If the voltage phase is within the hysteresis region, the phase difference hold means for holding the voltage phase when switching to the switching pause phase, and every 60 ° of the voltage phase output via the phase difference hold means Offset voltage setting means for outputting a predetermined offset voltage on the positive side or negative side of a predetermined phase, and the voltage command corresponding to the switching pause phase in the voltage command Set the offset voltage, an inverter control device being characterized in that a two-phase PWM correction means for generating a predetermined switching pause interval.

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