JP2009038891A - Power conversion apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion apparatus maintaining a stable rectangular wave state and suppressing fluctuation of output voltage at the time of outputting power from a plurality of power supplies, and also to provide a driving method of the power conversion apparatus. <P>SOLUTION: The power conversion apparatus is connected to a plurality of power supplies 12a and 12b, and generates a driving voltage for a driving a motor M from output voltage of the plurality of power supplies 12a and 12b. The apparatus is provided with a rectangular pulse generating part 40 dividing one period of an electrical angle of the motor M into the number of partitions, which is 2N times (N is natural number) as much as the number of motor phases, in accordance with the electrical angle with respect to each of the plurality of power supplies 12a and 12b, outputting a plurality of rectangular wave voltage pulses in a divided section and distributing power of the plurality of power supplies 12a and 12b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power conversion device and a method for driving the power conversion device, and more particularly, to a power conversion device that supplies driving power for driving an electric motor based on power output from a plurality of power supplies and a control method for the power conversion device.

2. Description of the Related Art Conventionally, a power conversion device that supplies driving power for driving an electric motor based on power output from a plurality of power sources is known.
FIG. 1 is a block diagram showing a schematic configuration of a motor drive system including a conventional power converter. FIG. 2 is an explanatory diagram showing the occurrence of current and torque pulsations in a conventional power converter.
As shown in FIG. 1, the conventional motor drive system 1 has two power supplies 2a and 2b, a power converter (power converter) 3, and a power control unit 4. It includes a torque control unit 4a, a current control unit 4b, a power control / modulation operation unit 4c, a pulse width modulation (PWM) pulse generation unit 4d, and a three-phase / dq conversion unit 4e.

When the torque command value Te ^* is input to the torque control unit 4a of the power control unit 4, the PWM pulse generated by the PWM pulse generation unit 4d is output to the power converter 3, and the PWM pulse is input, The power converter 3 generates a voltage to be applied to the motor M based on the electric power Pa and Pb input from the two power supplies 2a and 2b, and supplies electric power Pm necessary for driving the motor M.

As such a conventional power conversion device, for example, there is a “motor drive system control device” (see Patent Document 1) that can control the power supplied from each power source of a plurality of power sources to an arbitrary value. In the control method of the power conversion device that outputs power from a plurality of power sources in this “motor drive system control device”, in order to control the power from the plurality of power sources, the voltage applied to the motor is divided in time and divided. The electric power of a plurality of power supplies is controlled by changing the pulse width of the generated pulses by PWM control.
JP 2006-129644 A

However, in the conventional “motor drive system control device”, in the rectangular wave control mode in which a rectangular wave voltage is output once in one cycle of the electrical angle of the motor, even if the pulse is divided and the pulse width is changed, the UVW Since the voltage vectors of the respective phases are not uniform, it is inevitable that the output voltage fluctuates as shown in FIG.
An object of the present invention is to provide a power converter that can maintain a stable rectangular wave state and suppress fluctuations in output voltage when outputting power from a plurality of power supplies, and a method for driving the power converter. That is.

In order to achieve the above object, a power conversion device according to the present invention is a power conversion device that is connected to a plurality of power supplies and generates a drive voltage for driving an AC motor from each output voltage of the plurality of power supplies. Then, from each of the plurality of power sources, one cycle of the electrical angle of the AC motor is divided into 2N (N is a natural number) times the number of sections of the motor phase according to the electrical angle, and a plurality of rectangles are divided in this divided section. A pulse generation unit that outputs a wave voltage pulse and distributes the power of the plurality of power supplies is provided.
Moreover, in this invention, it is preferable that the number of the said division | segmentation area is twice the said motor phase number.
In the present invention, it is preferable that the sizes of the divided sections are equal to each other.

In the present invention, it is preferable that the width of each of the plurality of power supply pulses output in the divided section is variable.
In the present invention, it is preferable that the phase of each of the plurality of power supply pulses output in the divided section is varied.
In the present invention, the pulse generation unit generates a base pulse generator that generates a base pulse according to a voltage command value applied to the AC motor, and generates a distribution pulse according to the power output from the plurality of power supplies. It is preferable that a distribution pulse generator for generating a pulse is generated, and a pulse is generated by logical synthesis of the base pulse and the distribution pulse.

Moreover, in this invention, it is preferable to have a rectangular wave electric power control part which produces | generates the said voltage command value.
Further, in the present invention, the distribution pulse generator includes a synchronization carrier generator that generates a section synchronization carrier synchronized with the divided section, and a power comparison value for controlling power output from a plurality of power sources according to a command value. It is preferable that the distribution pulse is generated by comparing the section synchronization carrier and the power comparison value.
In the present invention, the power comparison value generator includes:
The power comparison value is preferably generated based on a map made up of the motor output voltage command value, the power command value, and the motor rotation speed.

In the present invention, it is preferable that the interval synchronous carrier is a triangular wave.
In the present invention, it is preferable that the section synchronization carrier which is a triangular wave is asymmetrical.
In the present invention, it is preferable that the section synchronization carrier is a sawtooth wave.
Moreover, in this invention, it is preferable to change the vertex of the said interval synchronous carrier with respect to an electrical angle based on the said electric power command value.
Also, in the present invention, the rectangular wave power control unit includes a detection unit that detects a current value of the AC motor, and a current value of the AC motor detected by the detection unit and a desired torque for the AC motor. It is preferable to obtain a voltage command value from a motor current command value for outputting.

In the present invention, the rectangular wave power control unit includes detection means for detecting the torque of the AC motor, and outputs the torque of the AC motor detected by the detection means and a desired torque to the AC motor. It is preferable to obtain the voltage command value from the motor torque command value for the control.
According to the present invention, the rectangular wave power control unit is configured to detect a motor torque from a detection unit that detects a rotation position of the AC motor, a current value of the AC motor, and a rotation position of the AC motor detected by the detection unit. It is preferable that a voltage command value is obtained from the motor torque command value and the motor torque calculation value.

  Further, in the present invention, means for obtaining a motor current value for outputting a desired torque to the AC motor, and means for generating a control mode switching signal according to the rotational speed and torque command value of the AC motor. A PWM control mode for varying a voltage pulse width output from the power converter according to a switching signal; a rectangular wave control mode for varying a voltage phase output from the power converter; It is preferable to switch between overmodulation modes in which part of the output is PWM.

  A method for controlling a power converter according to the present invention is a method for controlling a power converter that is connected to a plurality of power supplies and generates a drive voltage for driving an AC motor from each output voltage of the plurality of power supplies. A process of dividing one cycle of the electrical angle of the AC motor from each of the plurality of power sources into a number of sections 2N (N is a natural number) times the number of motor phases according to the electrical angle, and a plurality of sections in the divided section. And a process of distributing the power of the plurality of power sources.

  According to the present invention, the pulse generator included in the power converter that is connected to the plurality of power sources and generates the drive voltage for driving the AC motor from the output voltages of the plurality of power sources can be used. From each of them, a plurality of rectangular wave voltage pulses are output in this divided section in which one cycle of the electrical angle of the AC motor is divided into 2N (N is a natural number) times the number of motor phases according to the electrical angle. Since the power of the plurality of power sources is distributed, when outputting power from the plurality of power sources, a stable rectangular wave state can be maintained and fluctuations in the output voltage can be suppressed.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 3 is a block diagram showing the configuration of the power conversion apparatus according to the first embodiment of the present invention. FIG. 4 is a circuit diagram of the power converter of FIG.
As illustrated in FIG. 3, the power conversion device 10 includes a power converter 11, a plurality (two in this example) of power supplies (DC power supplies) 12 a and 12 b, and a control unit 13. From the above, a necessary voltage is supplied to the motor (multiphase AC motor) M. Here, the motor M is a three-phase AC motor.

  As shown in FIG. 4, the power converter 11 has a plurality of sets of switch means (semiconductor switches) for each phase (U phase, V phase, W phase) of the motor M. The power source 12a (power source a) and the power source 12b (power source b) are both connected to the common negative electrode bus 14 on the negative electrode side, and the common negative electrode bus 14 and each phase terminal of the motor M are connected under a general inverter. Similarly to the arm, the semiconductor switches 15a, 16a, and 17a are connected to each other through respective sets of diodes 15b, 16b, and 17b. The positive electrode bus 18 of the power supply 12a and each phase terminal of the motor M are connected via a set of two semiconductor switches 19a / 19b, 20a / 20b, 21a / 21b capable of controlling bidirectional conduction. Yes. Similarly, the positive electrode bus 22 of the power supply 12b and each phase terminal of the motor M are connected via a set of two semiconductor switches 23a / 23b, 24a / 24b, and 25a / 25b capable of controlling bidirectional conduction. Has been.

A smoothing capacitor 26 is connected between the positive electrode bus 18 and the common negative electrode bus 14 of the power source 12a, and a smoothing capacitor 27 is connected between the positive electrode bus 22 and the common negative electrode bus 14 of the power source 12b.
The power converter 11 generates a voltage to be applied to the motor M based on the three potentials of the common negative electrode bus 14, the positive electrode bus 18 of the power source 12a, and the positive electrode bus 22 of the power source 12b. (AC) Power converter. A semiconductor switch provided in each phase of the motor M is a switch means for generating a voltage to be output to each phase of the motor M, and alternatively, one of these potentials is connected, and the proportion of the connection time is determined. By changing the voltage, a necessary voltage is supplied to the motor M.

Next, the configuration of the control unit 13 will be described.
As shown in FIG. 3, the control unit 13 includes a torque control unit 28, a PWM control unit 29, a rectangular wave control unit 30, and a three-phase / dq conversion unit 31.
The torque control unit 28 calculates the command value id ^* of the d-axis current of the motor M and the command value iq ^* of the q-axis current from the torque command value Te ^* and the motor rotation speed ω given from the outside. The torque control unit 28 is also a switching unit that switches between three drive modes shown in FIG. 5, that is, PWM drive, overmodulation drive, and rectangular wave drive, depending on the state of the motor rotation speed ω and the torque command value Te ^* . FIG. 5 is an explanatory diagram showing, in a graph, each drive mode region for PWM drive, overmodulation drive, and rectangular wave drive.

  The PWM drive is a control method for controlling the output voltage by changing the width of the voltage pulse output from the power converter 11. Overmodulation driving is a mode in which a part of the PWM pulse is always on (ON). The rectangular wave driving is a control mode in which the motor is controlled by changing the voltage phase output from the power converter 11 with respect to the electrical angle of the motor without changing the pulse width.

6 is a block diagram showing a configuration of the torque control unit shown in FIG. As shown in FIG. 6, the torque control unit 28 includes a control mode determination unit 32, a rectangular wave current command generation unit 33, and a PWM current command generation unit 34. In the torque control unit 28, the control mode determination unit 32 outputs a control mode signal to the rectangular wave current command generation unit 33 and the PWM current command generation unit 34 in accordance with the motor rotation speed ω and the torque command value Te ^* . The control mode determination unit 32 generates a drive mode signal with reference to the map shown in FIG. 5 with the motor rotation speed ω and the torque command value Te ^* as axes.

FIG. 7 is an explanatory diagram of a map for generating a current command in the PWM drive control mode and the overmodulation drive control mode. As shown in FIG. 7, when the PWM drive control mode is selected, the q-axis current command value iq ^* is obtained by referring to a map that is created with the motor rotation speed ω and the torque command value Te ^* as axes. A d-axis current command value id ^* is generated. In the overmodulation drive control mode, the current command value is obtained with reference to a map in the same format as in the PWM drive control mode.

FIG. 8 is an explanatory diagram of a torque map that graphically shows the torque with respect to the q-axis current. When the rectangular wave drive control mode is selected, a q-axis current command value iq ^* is generated based on a torque map for each motor rotational speed ω created in advance shown in FIG. Since the q-axis current iq and the torque are uniquely determined for a certain torque, the torque can be controlled by controlling the q-axis current iq.
That is, the power conversion device 10 includes means for obtaining a motor current value for outputting a desired torque to the motor M, and means for generating a control mode switching signal in accordance with the rotational speed of the motor M and the torque command value. A PWM control mode in which the voltage pulse width output from the power converter 11 is varied according to the switching signal; a rectangular wave control mode in which the voltage phase output from the power converter 11 is varied; Switches between overmodulation modes, some of which are PWM outputs.

By configuring in this way, either the PWM drive control mode with a small torque ripple according to the rotational speed and torque of the motor, the high output rectangular wave drive control mode, or the overmodulation drive control mode having an intermediate characteristic between the two. Since the optimum control mode can be selected according to the driving state, both high output and low torque ripple can be achieved.
The PWM control unit 29 includes a PWM current control unit 35, a power control / PWM modulation rate calculation unit 36, and a PWM pulse generation unit 37. The PWM current control unit 35 receives the d-axis current command value id ^* , the q-axis current command value iq ^* from the torque control unit 28, and the d-axis current value id and the q-axis current value iq from the three-phase / dq conversion unit 31, respectively. By inputting, current control for matching these is performed. By this control, voltage command values vu ^* , vv ^* , vw ^* for each phase of the three-phase alternating current are output.

The power control / PWM modulation factor calculation unit 36 receives the voltage command values vu ^* , vv ^* , vw ^{* of} the three-phase AC from the PWM current control unit 35, the voltage Vdc_a of the power supply 12a, the voltage Vdc_b of the power supply 12b, and the power supply 12a. There the output electric power command value Pa ^*, but by inputting respectively, for power control and PWM modulating arithmetic operation. By this control and calculation, final modulation factor command values mu_a_c ^* , mu_b_c ^* , mv_a_c ^* , mv_b_c ^* , mw_a_c ^* , mw_b_c ^* are output.
The PWM pulse generation unit 37 receives the PWM pulse when the final modulation rate command values mu_a_c ^* , mu_b_c ^* , mv_a_c ^* , mv_b_c ^* , mw_a_c ^* , mw_b_c ^* are input from the power control / PWM modulation rate calculation unit 36. The generated PWM pulse is output to the power converter 11.

The rectangular wave control unit 30 includes a rectangular wave current control unit 38, a rectangular wave power control unit 39, and a rectangular pulse generation unit 40.
The rectangular wave current control unit 38 obtains a voltage phase command value δ ^* to be applied to the motor M by performing current control for matching these from the q-axis current command value iq ^* and the q-axis current value iq. The rectangular wave current control unit 38 performs feedback control by P (proportional) I (integral) control so that the q-axis current value iq follows the q-axis current command value iq ^* , thereby generating a rectangular wave voltage phase command. The value δ ^* is output. The voltage phase command value δ ^* for obtaining a desired q-axis current value iq can determine the voltage phase δ from the relationship of the q-axis current value iq to the voltage phase δ [deg] shown in FIG. FIG. 9 is an explanatory diagram illustrating the q-axis current iq with respect to the voltage phase δ.

When a torque detector that detects motor torque is used, the voltage phase command value δ ^* may be obtained by performing feedback control from the motor torque and the torque command value. In this case, as shown in FIG. 10, an appropriate voltage phase δ is obtained from the relationship of the motor torque [Nm] with respect to the voltage phase δ [deg]. FIG. 10 is an explanatory diagram showing the motor torque with respect to the voltage phase in a graph.
Alternatively, the motor torque may be calculated from the current value of the motor M, and the voltage phase δ ^* may be obtained from the calculated torque value and the torque command value.

  That is, the rectangular wave power control unit 38 includes a detection unit that detects a current value of the motor M, and a motor current command for causing the motor M to output a desired torque and a current value detected by the detection unit. The voltage command value is obtained from the value. Further, the rectangular wave power control unit 38 includes detection means for detecting the torque of the motor M, and the torque of the motor M detected by the detection means and a motor torque command value for causing the motor M to output a desired torque. From this, the voltage command value is obtained. The rectangular wave power control unit 38 includes detection means for detecting the rotation position of the motor M, and calculation means for calculating motor torque from the current value of the motor M and the rotation position of the motor M detected by the detection means. The voltage command value is obtained from the motor torque command value and the motor torque calculation value.

With this configuration, the motor current is detected and the voltage command value is generated, so that a desired torque can be accurately output.
Further, when the voltage command value is obtained based on the torque detection value and the motor torque command value, no means for detecting the motor current or means for converting the motor current to the d and q axes is required. Can be configured simply and inexpensively.
Further, when the motor torque is calculated from the detected current value, a torque detector is not required and a current controller is not required, so that the controller can be configured simply and inexpensively.

Next, the rectangular wave power control unit 39 will be described. The rectangular wave power control unit 39 inputs the power command value Pa ^* output from the power source 12a, the motor voltage phase command value δ ^*, and the voltages of the power source 12a and the power source 12b, and the output power of the power source 12a is the power command value Pa. ^* to generate a power comparison value Rto_a ^* to conform to, and generates a U-phase voltage phase command value .delta.u ^* indicating timing for U-phase arm is switched. The motor voltage phase command value δ ^* and the U-phase voltage phase command value δu ^* have an equivalent relationship. However, for convenience of explanation, δu ^* , which determines the U-phase switching timing, is a voltage applied to the motor M. The overall phase is defined as δ ^* .
Next, the rectangular wave power control method will be described in detail.

FIG. 11 is an explanatory diagram showing the pulse generation logic in a graph. Here, the horizontal axis indicates time, and the motor M rotates at a constant speed. As shown in FIG. 11, the motor electrical angle θ [deg] periodically changes over time in the range of 0 to 360 degrees according to the rotation of the motor M. With respect to the motor electrical angle θ, the voltage of the power source 12a or the power source 12b is applied to the U phase of the motor M at the timing of the U phase voltage phase command value δu ^* .

For V phase and W phase,
V phase: -120 degree timing from U phase W phase: Each voltage is applied at a timing of +120 degree from U phase. This timing is indicated by the U-phase, V-phase, and W-phase base pulses. By configuring in this way and varying the U-phase voltage phase command value δu ^* , the motor voltage phase command value δ ^* changes, and the torque can be controlled as shown in FIG.
Next, power control of each power source will be described.

As shown in FIG. 11, to generate a phase synchronization carrier that varies with a period of 6 times the electrical angle, to produce a distribution pulses from the comparison of the phase carrier synchronization and power comparison value rto_a ^*. A U-phase power source a pulse is generated by the logical product of the distribution pulse and the U-phase base pulse. Further, a U-phase power supply b pulse is generated by the logical product of the negation of the distribution pulse and the U-phase base pulse. The V phase and the W phase are similarly configured.
This logic can be generated by a circuit as shown in FIG.

12A and 12B show a pulse generation unit that generates a pulse. FIG. 12A is a configuration explanatory diagram of a pulse generator and a logic circuit, and FIG. 12B is a configuration block diagram of the distributed pulse generator of FIG. As shown in FIG. 12, the base pulse generator 41 receives the motor electrical angle θ and the voltage phase command value δ ^* , and generates a base pulse by comparing the two. On the other hand, the distribution pulse generator 42 inputs the motor electrical angle θ, the voltage phase command value δ ^*, and the power comparison value rto_a ^* , generates a carrier corresponding to the motor electrical angle θ and the voltage phase command value δ ^* , generating a distribution pulse by the carrier and the comparison of the power comparison value rto_a ^* ((a) refer).

Outputs from both pulse generators 41 and 42 are input to an AND (logical product) circuit 43 and logically synthesized to output a U-phase power supply a pulse. In addition, the output from the NOT (negative logic) circuit 44 to which the output from the base pulse generator 41 and the output from the distribution pulse generator 42 are input is input to the AND circuit 45 and logically synthesized to be a U-phase power supply b pulse. Is output. That is, the outputs from both pulse generators 41 and 42 are logically synthesized to generate the final pulses from the respective power supplies 12a and 12b. The V phase and the W phase are configured similarly.
Next, the effect | action by the power converter which has the said structure is demonstrated using a spatial voltage vector.

FIG. 13 is an explanatory diagram of a voltage vector and a current vector output from the power converter according to the first embodiment. As shown in FIG. 13, the output voltage in the rectangular wave drive mode of a normal three-phase inverter is 6 patterns. However, since the power converter 11 of this configuration has two power supplies, the output voltage is 12 It is a pattern.
In the symbols in the figure, for example, “Va1 (1, 0, 0)”, Va1 corresponds to the power source a, and (1, 0, 0) corresponds to the U phase, V phase, and W phase in order from the left side. is doing. That is, in the case of “Va1 (1, 0, 0)”, the power source a outputs the vector 1, the U-phase upper arm of the power source a is on (ON), and the V phase and W phase are off (OFF). Indicates. The vector 1 is a U-phase direction vector, which is numbered 2 and 3 in the clockwise direction. Further, in the figure, a bold line is a current vector flowing through the motor. In the case of a synchronous motor, the direction of the vector changes as indicated by an arrow in the figure in synchronization with the rotation angle of the motor.

When pulse generation as shown in FIG. 11 is performed, voltage vectors are regularly output from the power supply 12a and the power supply 12b in synchronization with changes in the current vector, as shown in the lower part of FIG.
As described above, the power conversion device 10 connected to the plurality of power supplies 12a and 12b changes the electrical angle cycle of the motor M according to the electrical angle (for example, 0 degrees to 60 degrees, 60 degrees to 120 degrees, etc.). The pulse generation unit (rectangular pulse) that divides the number of sections into 2N (N is a natural number) times the number of motor phases, outputs a plurality of rectangular wave voltage pulses in this divided section, and distributes the power of the plurality of power supplies 12a and 12b. Generator 40). That is, power distribution is performed in the divided sections, and drive voltages for driving the motor M are generated from the output voltages of the plurality of power supplies 12a and 12b.

The number of divided sections is twice the number of motor phases, and the sizes of the divided sections are equal to each other. Further, the width of each of the plurality of power supply pulses output in the divided section is varied.
The pulse generation unit generates a base pulse according to the voltage command value applied to the motor M, and a distribution pulse that generates a distribution pulse according to the power output from the plurality of power supplies 12a and 12b. A generator 42 is provided, and a pulse for finally driving the switch means is generated by logical synthesis of the base pulse and the distribution pulse. The voltage command value is generated by the rectangular wave power control unit 39.

The distribution pulse generator 42 generates a synchronization carrier generator 42a that generates a section synchronization carrier synchronized with the divided section, and a power comparison value for controlling the power output from the plurality of power supplies 12a and 12b according to the command value. The power comparison value generator 42b is provided (see FIG. 12B), and the distribution pulse is generated by comparing the section synchronization carrier and the power comparison value. This interval synchronous carrier is a sawtooth wave.
The rectangular wave power control unit 39 includes detection means for detecting the current value of the motor M, the current value of the motor M detected by the detection means, and the motor current command value for causing the motor M to output a desired torque. From these, the voltage command value is obtained. The rectangular wave power control unit 39 includes detection means for detecting the torque of the motor M. The torque of the motor M detected by the detection means and a motor torque command value for causing the motor M to output a desired torque. From these, the voltage command value is obtained.

The rectangular wave power control unit 39 includes detection means for detecting the rotation position of the motor M, and calculation means for calculating the motor torque from the current value of the motor M and the rotation position of the motor M detected by the detection means. The voltage command value is obtained from the motor torque command value and the motor torque calculation value.
With this configuration, one cycle of the phase current is divided, and a plurality of pulses are output in the divided section, so that a plurality of pulses can be generated corresponding to the output voltage vector of the power converter in the rectangular wave state. Can be output. For this reason, pulsation of electric power and torque can be suppressed to a small extent, which is effective in suppressing motor vibration and improving efficiency.

That is, in general, rectangular wave control is known because SW loss is small, but known rectangular wave control is a control method in the case of driving one motor with one power source. Thus, in a power conversion device (D-EPC) that supplies driving power for driving an electric motor based on electric power output from a plurality of power sources, there is room for examination when a single motor is driven by a plurality of power sources. is there.
In D-EPC, in order to control the power from a plurality of power supplies, the voltage applied to the motor is time-divided, and the pulse width of the divided pulses is changed by PWM modulation. I have control. Even if the rectangular wave control is simply applied to such D-EPC, in the rectangular wave control that outputs a rectangular wave voltage once per electrical angle of the motor, the pulse is divided and the pulse width is changed. However, since the voltage vectors of the UVW phases are not uniform, it is inevitable that the output voltage fluctuates.

Next, effects obtained by the power converter according to the first embodiment will be described.
FIG. 14 is an explanatory diagram illustrating, in a graph, the occurrence of current and torque pulsations in the power conversion device according to the first embodiment. FIG. 14 shows q-axis current iq, d-axis current id, U-phase current iu, V-phase current iv of motor M, U-phase base pulse and pulses of power supply 12a and power supply 12b corresponding thereto, power supply 12a, power supply 12b direct current bus current output. The smoothed DC bus current is the power output from the power supply 12a and the power supply 12b. Here, the power distribution operation is performed at time 50 m [sec].

As can be seen from FIG. 14, each power of the power source 12 a and the power source 12 b can be distributed without a large fluctuation in the current of the motor M. Accordingly, the pulsation of electric power and the pulsation of torque can be suppressed to a small extent, and effects can be obtained in suppressing motor vibration and improving efficiency.
In addition, since the distribution pulse can be output with a simple configuration, the control device can be configured at low cost.
Further, the width of the plurality of voltage pulses output in the divided section can be varied. When a plurality of power supply voltages are different, the average voltage output in the divided section can be varied by varying the width of the voltage pulse, so that the degree of freedom can be increased by one. Therefore, since the voltage output to the motor M can be controlled more finely, the controllability is good and the efficiency is good.

The power comparison value is obtained from a power command value Pa ^* , voltage phase command value δ ^* , and motor rotation speed map on the power supply 12a side. That is, the power comparison value generator 42b generates a power comparison value based on a map made up of the motor output voltage command value, the power command value, and the motor rotation speed.
FIG. 15 is a map for generating a power comparison value. When the motor output voltage command value changes according to the map showing the relationship between the power command value Pa ^* on the power source a side and the voltage phase command value δ ^* corresponding to the motor rotation speed (for example, 300 rpm) shown in FIG. When the motor rotation speed changes, even if the power output from the motor M changes, an appropriate distribution pulse corresponding to the power command value can be generated, so that power control of a plurality of power supplies can be performed stably. Can do.
Next, the rectangular pulse generator 40 will be described.

FIG. 16 is a circuit diagram for the U phase of FIG. In the switch configuration of the main power converter shown in FIG. 16, signals A to E for driving the U-phase switch means are set as follows.
A: A signal for driving switch means conducting from the power supply 12a to the output terminal B: A signal for driving switch means conducting from the output terminal to the negative electrode C: A switch means conducting from the output terminal to the power supply 12a Signal D for driving: Signal for driving switch means conducting in the direction from the power supply 12b to the output terminal E: Signal for driving the switch means conducting in the direction from the output terminal to the power supply 12b

First, a pulse generation method when a voltage pulse is output from the power supply 12a will be described. When the PWM pulse is output from the power supply 12a, the drive signal A needs to be turned on. When there is a potential difference between the positive electrode of the power supply 12a and the positive electrode of the power supply 12b and the power supply voltage Vdc_a of the power supply 12a is greater than the power supply voltage Vdc_b of the power supply 12b (Vdc_a> Vdc_b), both the drive signal A and the drive signal E are turned on. Then, a current for short-circuiting between both positive electrodes flows.
For example, when the drive signal A is simultaneously switched from the on state to the off state (OFF) and the drive signal E is switched from the off state to the on state, it takes time until the drive signal A is completely turned off. Overlap with the ON state of E, a time for both to be ON occurs, a short-circuit current flows, and the amount of heat generated by the semiconductor switch installed in this path increases.

In order to prevent such an increase in heat generation, the drive signal A and the drive signal E are switched from the off state to the on state after a time when both the drive signal A and the drive signal E are off. In this way, pulse generation is performed by adding a short-circuit prevention time (dead time) to the drive signal.
Similarly to adding a dead time to the drive signal A and the drive signal E, a dead time is added to the drive signal E and the drive signal C, and in order to prevent a short circuit between the positive electrode and the negative electrode, A dead time is added to the drive signal B, the drive signal E, and the drive signal B.
Next, the correspondence between the pulse generation logic of FIG. 11 and the switch means will be described.
U-phase power supply a pulse: drive signal A
U-phase power supply b pulse: drive signal D

The correspondence of the pulses is as described above, and the remaining drive signal B, drive signal C, and drive signal E are generated by the following logic in consideration of the above-described dead time.
E = A
C = D
B = E ・ C
Based on the switch signal generated in this way, each switch of the power converter 11 is turned on / off to generate an output voltage pulse.
(Second Embodiment)

FIG. 17 is an explanatory diagram showing, in a graph, pulse generation logic in the rectangular wave power control method according to the second embodiment of the present invention.
The rectangular wave power control method according to the second embodiment is different from the first embodiment in the method of generating the distribution pulse, and the distribution pulse is obtained by using a modified triangular carrier (see FIG. 17) as the phase synchronization carrier. , And the position of the apex of the deformed triangular carrier is changed to the left and right based on the power supply command value. Other configurations and operations are the same as those in the first embodiment.
That is, the plurality of power supply pulses output in the divided sections vary the phase for each divided section. The interval synchronization carrier is a triangular wave, in particular, an asymmetric triangle wave, and the apex of the interval synchronization carrier is varied with respect to the electrical angle based on the power command value.

  By configuring in this way, it is possible to vary the phases of the plurality of voltage pulses output in the divided section. In the rectangular wave control mode, the voltage output to the motor M is six for a three-phase motor, and a constant voltage is output when one of the six voltage patterns is output. The On the other hand, since the current of the motor M changes continuously, the power of the power converter changes in the divided section. On the other hand, by varying the phase without changing the width of one voltage pulse among the plurality of voltage pulses, the power from the plurality of power sources is distributed while maintaining the average voltage in the divided section. be able to.

  Therefore, it is possible to control the power of both without using a DC-DC converter in a fuel cell that requires output control of a plurality of power sources, a fuel cell vehicle with a battery, a vehicle with a plurality of power sources with a capacitor, a battery, etc. -It is effective in terms of cost and efficiency for a DC converter. In addition, since the triangular carrier can be generated with a simple configuration using up / down and down counters, the control device can be configured at low cost.

It is a block diagram which shows schematic structure of the motor drive system provided with the conventional power converter device. It is explanatory drawing which shows generation | occurrence | production of the pulsation of the electric current and torque in the conventional power converter device with a graph. It is a block diagram which shows the structure of the power converter device which concerns on 1st Embodiment of this invention. FIG. 4 is a circuit diagram of the power converter of FIG. 3. It is explanatory drawing which shows each drive mode area | region of PWM drive, overmodulation drive, and a rectangular wave drive with a graph. It is a block diagram which shows the structure of the torque control part shown in FIG. It is explanatory drawing of the map for producing | generating the current command in PWM drive control mode and overmodulation drive control mode. It is explanatory drawing of the torque map which showed the torque with respect to q-axis current with the graph. It is explanatory drawing which shows the q-axis current iq with respect to voltage phase (delta) with a graph. It is explanatory drawing which shows the motor torque with respect to a voltage phase with a graph. It is explanatory drawing which shows a pulse generation logic with a graph. The pulse generation part which produces | generates a pulse is shown, (a) is a structure explanatory drawing of a pulse generator and a logic circuit, (b) is a block diagram of a structure of the distribution pulse generator of (a). It is explanatory drawing of the voltage vector and current vector which the power converter of 1st Embodiment outputs. It is explanatory drawing which shows the generation | occurrence | production of the pulsation of the electric current and torque in the power converter device of 1st Embodiment with a graph. It is a map for producing | generating an electric power comparison value. It is a circuit diagram about the U phase of FIG. It is explanatory drawing which shows the pulse generation logic in the rectangular wave power control method which concerns on 2nd Embodiment of this invention with a graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Power converter 11 Power converter 12a, 12b Power supply 13 Control part 14 Common negative electrode bus 15a, 16a, 17a, 19a, 19b, 20a, 20b, 21a, 21b, 23a, 23b, 24a, 24b, 25a, 25b Semiconductor switch 15b, 16b, 17b Diode 18, 22 Positive bus 26, 27 Smoothing capacitor 28 Torque control unit 29 PWM control unit 30 Rectangular wave control unit 31 Three-phase / dq conversion unit 32 Control mode determination unit 33 Rectangular wave current command generation unit 34 PWM Current command generation unit 35 PWM current control unit 36 Power control / PWM modulation factor calculation unit 37 PWM pulse generation unit 38 Rectangular wave current control unit 39 Rectangular wave power control unit 40 Rectangular pulse generation unit 41 Base pulse generator 42 Distribution pulse generator 42a Synchronous carrier generator 42b Power comparison value Forming units 43 and 45 the AND circuit 44 NOT circuit M motor

Claims (18)

A power converter that is connected to a plurality of power supplies and generates a drive voltage for driving an AC motor from output voltages of the plurality of power supplies,
From each of the plurality of power sources, one cycle of the electrical angle of the AC motor is divided into 2N (N is a natural number) times the number of motor phases according to the electrical angle, and a plurality of rectangular wave voltages in this divided section A power conversion device comprising a pulse generation unit that outputs a pulse and distributes power of the plurality of power supplies.   The number of the said division | segmentation area is twice the said motor phase number, The power converter device of Claim 1 characterized by the above-mentioned.   The power converter according to claim 1, wherein the divided sections have the same size.   The power converter according to any one of claims 1 to 3, wherein a width of each of the plurality of power supply pulses output in the divided section is variable.   4. The power conversion device according to claim 1, wherein the phase of each of the plurality of power supply pulses output in the divided section is varied. 5. The pulse generator is
A base pulse generator for generating a base pulse according to a voltage command value applied to the AC motor;
A distribution pulse generator for generating a distribution pulse according to the power output from the plurality of power supplies,
The power conversion device according to claim 1, wherein a pulse is generated by logical synthesis of the base pulse and the distribution pulse.   The power converter according to claim 6, further comprising a rectangular wave power control unit that generates the voltage command value. The distributed pulse generator is
A synchronization carrier generator for generating a section synchronization carrier synchronized with the divided section;
A power comparison value generator for generating a power comparison value for controlling the power output from the plurality of power sources according to the command value;
The power conversion device according to any one of claims 1 to 7, wherein the distribution pulse is generated by comparing the section synchronization carrier and the power comparison value. The power comparison value generator
The power conversion apparatus according to claim 8, wherein the power comparison value is generated based on a map including the motor output voltage command value, the power command value, and a motor rotation speed.   The power converter according to claim 8 or 9, wherein the section synchronization carrier is a triangular wave.   The power converter according to claim 10, wherein the section synchronous carrier which is a triangular wave is asymmetrical.   The power converter according to claim 8 or 9, wherein the section synchronization carrier is a sawtooth wave.   The power converter according to any one of claims 10 to 12, wherein an apex of the section synchronization carrier is varied with respect to an electrical angle based on the power command value. The rectangular wave power control unit
A detecting means for detecting a current value of the AC motor;
14. The voltage command value is obtained from the current value of the AC motor detected by the detection means and a motor current command value for causing the AC motor to output a desired torque. The power converter device as described in any one. The rectangular wave power control unit
A detecting means for detecting the torque of the AC motor;
The voltage command value is obtained from the torque of the AC motor detected by the detection means and a motor torque command value for causing the AC motor to output a desired torque. The power conversion device according to claim 1. The rectangular wave power control unit
Detecting means for detecting the rotational position of the AC motor;
A calculation means for calculating a motor torque from the current value of the AC motor and the rotational position of the AC motor detected by the detection means;
The power conversion device according to claim 14, wherein a voltage command value is obtained from a motor torque command value and a motor torque calculation value. Means for obtaining a motor current value for outputting a desired torque to the AC motor;
Means for generating a control mode switching signal in accordance with the rotational speed of the AC motor and a torque command value;
PWM control mode for changing the voltage pulse width output from the power converter according to the switching signal, rectangular wave control mode for changing the voltage phase output from the power converter, partly rectangular wave output, partly The power conversion device according to claim 14, wherein the power conversion device is switched to an overmodulation mode in which becomes a PWM output. A control method for a power conversion device that is connected to a plurality of power supplies and generates a drive voltage for driving an AC motor from output voltages of the plurality of power supplies,
A process of dividing one cycle of the electrical angle of the AC motor from each of the plurality of power sources into 2N (N is a natural number) times the number of sections according to the electrical angle;
And a process of outputting a plurality of rectangular wave voltage pulses in the divided section and distributing the power of the plurality of power sources.

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