JP2007006580A - Power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter which controls it so that the output voltage of a power converting circuit is zero, by detecting transmission abnormality, when abnormality occurs in a transmission path between a control circuit and the power conversion circuit. <P>SOLUTION: For AC power converter 1, a switching control circuit 10 and a power conversion circuit 20 are connected with each other by a transmission path 30. The switching control circuit 10 is constituted of a control operator part 11, a switching pulse generator 12, a pulse coder 13, and a transmitter 14, and the power conversion circuit 20 is constituted of a receiver 21, a pulse decoder 22, a power converter 23, and a received signal determining section 24. When a transmission abnormality has occurred in the transmission path 30 at the operation of the AC power converter 1, the converter can detect the transmission abnormality by the received signal determining section 24 and can immediately zero the output of the AC power converter 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power conversion device in which a control circuit and a power conversion circuit are connected by a transmission line, and more particularly to a power conversion device that enables continuous power conversion when a transmission abnormality occurs in the transmission line.

  In inverter devices that convert DC power into AC power with variable voltage and variable frequency, and converter devices that convert AC power into DC power, a gate turn-off thyristor (GTO) or bipolar MOSFET is used to drive loads such as induction motors. A power conversion circuit is configured using a power switching element such as (IGBT). In such an AC power conversion device, a control circuit in which a control calculation unit for power conversion for commanding a variable voltage or variable current is mounted, and a power conversion circuit in which a power conversion unit composed of a plurality of power switching elements is mounted. Some are divided so that a control signal is transmitted from a control circuit to a power conversion device via a signal transmission line.

  Patent Document 1 describes a pulse width modulation control device that can reduce the number of signal transmission lines for gate signal transmission in a pulse width modulation control device that performs pulse width modulation control of a plurality of switching elements constituting a power conversion device. Has been. In this case, it is necessary to stop the output and check whether or not the transmission data transmitted by the signal transmission line is broken on the way, thereby improving the reliability of the data.

FIG. 6 is a diagram illustrating a voltage waveform when the control signal transmitted from the power converter is normally received, and FIG. 7 is a diagram illustrating a voltage waveform when transmission abnormality is detected in the conventional device.
Here, in a power conversion circuit in which a power conversion unit capable of two-level output (E / 2, −E / 2) as a phase voltage is mounted, such as a three-phase voltage source inverter shown in FIG. If the control signal transmitted from the apparatus is normally received, the U-phase output voltage Vu and the V-phase output voltage Vv shown in FIGS. 6A and 6B are respectively shown in FIG. The voltage waveform of the inter-stage output voltage Vu−Vv is 0 → E → −E → 0 → E. In this case, it may be dealt with by stopping the output as in the case of Patent Document 1, but if a transmission abnormality is detected at the data transmission timing N2 as shown in FIG. ) Can also hold the output value that was successfully received.

As shown in FIG. 6C, at the data transmission timing N2, the value of the line output voltage Vu−Vv that should be output is (−E), and the output value (E of the previous data transmission timing N1) ) Is held, an output difference of a maximum of two levels (2E) occurs. In other words, in the event of a transmission error, if the output of the power converter differs greatly from the output value that should be output, an overvoltage or overcurrent is supplied from the power converter to the load. The operation of the device will be stopped.
JP 11-178349 A (particularly paragraph number [0035] and FIG. 6)

  In the conventional power conversion device, when communication abnormality occurs due to external noise during communication between the control circuit and the power conversion circuit, the power conversion circuit cannot receive the output command normally. The output that was successfully received last time was held or the output was stopped. Whichever method is used, when a transmission abnormality occurs in the transmission line between the power conversion circuit and the control circuit, there is a problem that a sudden output change in the power conversion device cannot be suppressed. It was.

  The present invention has been made in view of the above points. When an abnormality occurs in the transmission path between the control circuit and the power conversion circuit, the transmission abnormality is detected and the output voltage of the power conversion circuit becomes zero. An object of the present invention is to provide a controlled power converter.

  In the present invention, in order to solve the above problem, a control circuit and a power conversion circuit are connected by a transmission line, and a control signal is generated by a control arithmetic unit for power conversion mounted on the control circuit side, and the power conversion In the power conversion device that controls the output voltage from the power conversion unit of the circuit, the power conversion circuit receives the control signal from the reception unit connected to the transmission path and the transmission signal input through the reception unit. A pulse restoration unit for restoring, and determining whether or not there is a transmission abnormality of the transmission signal, and a reception signal determination unit that transmits to the pulse restoration unit, when the transmission signal is determined to be abnormal by the reception signal determination unit, A power converter is provided, wherein the power converter is controlled by the pulse restoration unit so that the output voltage becomes zero.

  According to the present invention, when a transmission abnormality occurs in the transmission path between the control circuit and the power conversion circuit during operation of the power conversion device, the transmission abnormality is detected by the reception signal determination unit provided on the power conversion circuit side, The output of the power conversion circuit can be made zero immediately. Therefore, it is possible to suppress the occurrence of trip due to overvoltage or overcurrent even when there is a transmission abnormality by preventing the power conversion device from having an abnormal output.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram showing an AC power converter according to Embodiment 1 of the present invention, and FIG. 2 is a circuit configuration diagram showing a power converter of the AC power converter.

  In the AC power converter 1, the switching control circuit 10 and the power conversion circuit 20 are connected by a transmission line 30, and the switching control circuit 10 includes a control calculation unit 11, a switching pulse generation unit 12, a pulse encoding unit 13, and a transmission. The power conversion circuit 20 includes a reception unit 21, a pulse restoration unit 22, a power conversion unit 23, and a reception signal determination unit 24.

  For example, as shown in FIG. 2, the power conversion unit 23 is configured as a three-phase voltage source inverter including six switching circuits. The three-phase switching circuit includes transistors T1 to T6 that are on / off controlled and feedback diodes D1 to D6 connected in antiparallel between the positive side (P) and the negative side (N) of the DC power supply. The U-phase output voltage Vu, the V-phase output voltage Vv, and the W-phase output voltage Vw are output from the connection point of each phase switching circuit to the load. Any of the transistors T1 to T6 can be configured by a power switching element such as GTO or IGBT.

  When the AC power converter 1 is operated, in the switching control circuit 10, the control calculation unit 11 receives the control signal and calculates a PWM (Pulse Width Modulation) signal. When the calculation result is input from the control calculation unit 11 to the switching pulse generation unit 12, the switching pulse generation unit 12 performs pulse modulation using the input PWM signal, and controls each of the transistors T1 to T6 in the power conversion circuit 20. A switching pulse signal is output. The switching pulse signal is input from the switching pulse generation unit 12 to the pulse encoding unit 13, and the pulse encoding unit 13 generates a transmission signal in which the switching pulse signal is encoded in a predetermined manner. Is output.

  Thus, the transmission signal of the transmission unit 14 is input to the reception unit 21 of the power conversion circuit 20 through the transmission path 30. When the reception signal transmitted to the reception unit 21 is input to the pulse restoration unit 22 and the reception signal determination unit 24, the reception signal determination unit 24 determines whether there is a transmission abnormality in the reception signal, and the pulse restoration unit 22 In response to this, a transmission abnormality determination result is output. The pulse restoration unit 22 restores the switching pulse signal from the received signal if the transmission abnormality judgment result is normal based on the received reception signal and the transmission abnormality judgment result, and outputs them to the power conversion unit 23. In the power converter 23, the transistors T1 to T6 are on / off controlled based on the input switching pulse signal.

Next, a case where a disturbance such as external noise occurs in the transmission line 30 and a transmission abnormality is detected in the reception signal determination unit 24 of the power conversion circuit 20 will be described.
FIG. 3 is a diagram illustrating a voltage waveform of the inverter when a transmission abnormality is detected.

  Now, it is assumed that the transmission abnormality determination result from the reception signal determination unit 24 is output as a transmission abnormality. When the transmission error is input to the pulse restoration unit 22, the transmission reception signal that is the output of the reception unit 21 is ignored. At the same time, a switching pulse signal for turning on the transistors T1, T3, and T5 and turning off T2, T4, and T6 is output to the power converter 23. Therefore, in the power conversion unit 23, the phase output voltages Vu, Vv, and Vw simultaneously become E / 2, and the line-to-line output voltage Vu−Vv can be made zero. Therefore, the line output voltage Vu−Vv that is an AC output with respect to the load of the power converter 1 is controlled so as not to change abruptly with respect to the state before the abnormality detection.

  As described above, the line-to-line output voltage Vu−Vv, which is the output value of the power conversion circuit 20, is compared with the voltage value (E) that should be output after the data transmission timing N2 shown in FIG. Even if it exists, it is suppressed to the voltage value (0), that is, the output difference of 1 level at the maximum. Therefore, compared with the transmission abnormality of the prior art shown in FIG. 7, the voltage value change can be compressed to ½.

  In the AC power converter 1, the phase output voltages Vu, Vv, and Vw are simultaneously changed to E / 2 by the switching pulse signal output from the pulse restoration unit 22 to the transistors T1 to T6 in FIG. However, by turning off the transistors T1, T3, and T5 and turning on the transistors T2, T4, and T6, the phase output voltages Vu, Vv, and Vw may be set to −E / 2 at the same time.

  Further, the switching pulse signal output to each of the transistors T1 to T6 may be serially transmitted to the transmission line 30 or may be parallelly transmitted. Further, the switching control circuit 10 encodes the output of the control arithmetic unit 11 and transmits it to the power conversion circuit 20 through the transmission line 30, and generates a switching pulse after restoring the signal received on the power conversion circuit 20 side. You may do it. In this way, the switching pulse generator 12 on the switching control circuit 10 side becomes unnecessary.

(Embodiment 2)
FIG. 4 is a block diagram showing an AC power converter according to Embodiment 2 of the present invention.
In this AC power conversion device 2, the switching control circuit 10 is connected to the power conversion device units 41 to 46 through the transmission lines 31 to 36, and controls the three sets of power conversion device units 41 to 46 connected in series and two multiplexes, respectively. The U, V, and W phase output voltages Vu, Vv, and Vw are generated for the output terminals 2a, 2b, and 2c. The switching control circuit 10 of FIG. 4 is basically configured the same as that of the first embodiment (FIG. 1), and the same portions are denoted by the same reference numerals and description thereof is omitted.

FIG. 5 is a block diagram showing a specific configuration of the power conversion device unit shown in FIG. 4. The power conversion device units 41 to 46 in FIG. 4 have the same configuration.
The power conversion device unit 4 includes a reception unit 21, a pulse restoration unit 22, a reception signal determination unit 24, and a power conversion unit 25. The power conversion unit 25 is configured as a single-phase inverter composed of four switching circuits, the connection point between the transistors T1 and T2 is connected to the output terminal 4a, and the connection point between the transistors T3 and T4 is connected to the output terminal 4b. ing.

  Here, it is assumed that a disturbance such as external noise occurs in the transmission lines 31 to 36 in a part of the six power conversion device units 41 to 46 and a transmission abnormality is detected by the reception signal determination unit 24. In that case, only the power conversion unit 25 of the power conversion device unit 4 that detected the transmission abnormality is a switching pulse signal for turning on the transistors T1 and T3 and turning off the transistors T2 and T4, or conversely, turning off the transistors T1 and T3. , T4 is output to output a switching pulse signal, so that the output of the power converter 25 can be made zero. Therefore, as in the case of the first embodiment, each phase output voltage Vu, Vv, Vw output from the output terminals 2a, 2b, 2c of the AC power converter 2 is controlled so as not to change suddenly.

  Although two embodiments have been described above, the present invention is not limited to these embodiments. For example, as the circuit configuration of the power conversion unit 23, the three-phase inverter has been described in the first embodiment and the single-phase inverter has been described in the second embodiment, but a multi-phase output configuration having three or more phases may be employed. In addition, although the inverter circuit of the power conversion unit 23 has a two-level configuration with one switching circuit provided above and below, a multi-level configuration may be used. Further, even in the case of the first embodiment, the switching control circuit 10 may be configured to control two or more power conversion circuits 20.

It is a block diagram which shows the alternating current power converter device which concerns on Embodiment 1 of this invention. It is a circuit block diagram which shows the power conversion part of an alternating current power converter device. It is a figure which shows the voltage waveform of the inverter at the time of transmission abnormality detection. It is a block diagram which shows the alternating current power converter device which concerns on Embodiment 2 of this invention. It is a block diagram which shows the specific structure of the power converter device part shown in FIG. It is a figure which shows a voltage waveform when the control signal transmitted from the power converter device is received normally. It is a figure which shows the voltage waveform at the time of transmission abnormality detection in the conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 AC power converter 10 Switching control circuit 11 Control calculating part 12 Switching pulse generation part 13 Pulse encoding part 14 Transmission part 20 Power conversion circuit 21 Receiving part 22 Pulse decompression | restoration part 23,25 Power conversion part 24 Reception signal determination part 30, 31-36 Transmission path 41-46 Power converter unit T1-T6 Transistor D1-D6 Feedback diode

Claims (1)

A control circuit and a power conversion circuit are connected by a transmission line, and a control signal is generated by a control calculation unit for power conversion mounted on the control circuit side, and an output voltage from the power conversion unit of the power conversion circuit is controlled. In the power converter,
The power conversion circuit is
A receiver connected to the transmission path;
A pulse restoration unit for restoring the control signal from a transmission signal input via the reception unit;
Determining the presence or absence of transmission abnormality of the transmission signal, and receiving the signal determination unit for transmitting to the pulse restoration unit;
And the power conversion unit controls the power conversion unit so that the output voltage becomes zero by the pulse restoration unit when the reception signal determination unit determines that the transmission is abnormal.

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