JP6536801B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device such as an inverter that controls a drive load device such as a large-capacity power supply device or a motor drive device.

  A power conversion device that performs power conversion and control includes a power conversion unit having a main circuit in which a large number of active elements such as transistors and diodes are combined, and power for generating a control signal for controlling the active elements on / off. A control unit is provided and can perform DC-AC conversion, AC-DC conversion, and the like.

For example, FIG. 6 shows a converter main circuit unit of a power conversion unit of a three-phase inverter which is well known as this kind of power conversion apparatus, and FIG. 7 shows the configuration of the power conversion unit and the power control unit.
As shown in FIG. 6, the converter main circuit 13 includes a diode rectifier 16 consisting of bridge circuit connected to the three-phase AC power source, a capacitor 17 connected between its output terminal, the transistor T ₁ through T ₆ And an inverter main circuit 18 consisting of

The base of the transistor T ₁ through T ₆ is supplied with on-off signals from the pulse restorer 12 in the power converter 10 in FIG. 7, the operation of the transistor T ₁ through T ₆ in accordance with the signal A three-phase voltage or current of a predetermined waveform is output to a drive load device 90 such as a power supply device or a motor drive device.
In addition, various semiconductor switching elements, such as a power transistor, IGBT, FET, etc., are used for the active element which comprises the inverter main circuit 18. FIG.

Such a power conversion device is used in, for example, drive control of a motor in a wide range of fields such as construction and civil engineering machines, food processing machines, transport machines, fan and pump machines.
When driving the motor in the drive load device 90 using the power conversion unit 10 shown in FIG. 7, if the power control unit 20 is installed near the power conversion unit 10, there is a possibility that malfunction may occur due to external noise. The power control unit 20 is generally installed at a location distant from the power conversion unit 10.
For this reason, the control signal transmitted from the power control unit 20 to the power conversion unit 10 is generally transmitted by the optical fiber 80 so as not to be affected by external noise.

Since the cost of an optical fiber and an optical link for converting an electrical signal (control signal) transmitted by the optical fiber into light is very high, the optical fiber and the optical link can be used to reduce the cost of the entire power conversion apparatus. It is desirable that the amount and number of used be small.
Therefore, Patent Document 1 discloses a power conversion device in which the usage amount and the number of optical fibers and optical links are reduced by transmitting a control signal by a serial communication method.

FIG. 7 mentioned above is a block diagram which shows the whole structure of the power converter device described in patent document 1. As shown in FIG.
In power control unit 20 in FIG. 7, control calculation unit 21 performs calculations for controlling power conversion unit 10. The switching pulse generation unit 22 performs pulse modulation represented by a PWM (Pulse Width Modulation) method according to the calculation result, and a parallel for controlling the transistors T _{1 to} T ₆ of the converter main circuit unit 13 described above. A switching pulse signal as data is generated.
The switching pulse signal is converted into a serial signal by the serial signal converter 23. The serial signal is transmitted from the transmitter 28 to the optical fiber 80 through the serial signal synthesizer 27.

Further, since the power control unit 20 transmits the pulse signal for failure monitoring generated from the pulse signal generation unit 24 during the period when the switching pulse signal is not transmitted, the serial signal synthesis unit 27 The pulse signal is synthesized and sent to the transmission unit 28.
Further, the driving condition determining unit 25 of FIG. 7 has a function of outputting a driving stop command signal to the transmitting unit 28 when stopping the operation of the power conversion device, and the failure detecting unit 26 includes the power converting unit 13 and the like. When the failure of the is detected, the transmission operation by the transmission unit 28 is stopped.

In the power conversion unit 10 connected to the power control unit 20 of the above configuration via the optical fiber 80, the signal sent from the transmission unit 28 is received by the reception unit 11, and the pulse restoration unit 12 performs the original switching pulse signal Is restored. The transistors T _{1 to} T ₆ of the converter main circuit unit 13 are on / off controlled by this switching pulse signal.
In order to synchronize the transmission unit 28 and the reception unit 11, the transmission interval of the serial signal or pulse signal transmitted from the transmission unit 28 is set to a certain interval, and the reception interval determination unit 14 may be a serial signal or When the pulse signal is not received at a constant interval, a stop command signal is sent to the pulse recovery unit 12.

Next, an operation of stopping the operation of the power conversion device when a failure occurs in this prior art will be described.
For example, in the failure detection unit 26 provided in the power control unit 20, when the failure is detected because the level of the current flowing through the converter main circuit unit 13 exceeds a predetermined detection level, the failure detection unit 26 And controls the transmission unit 28 to stop the transmission operation.

The reception interval determination unit 14 in the power conversion unit 10 determines that there is no change in the output signal of the reception unit 11 as the transmission signal is stopped, and restores the switching pulse signal to the pulse recovery unit 12. The operation is stopped, and the operation of the inverter main circuit 18 in the converter main circuit unit 13 is stopped.
By the above-described series of operations, the power converter can be protected, for example, from failure or destruction due to overcurrent.

Patent No. 4200856 (paragraphs [0021] to [0025], FIG. 1, FIG. 2 etc.)

In the prior art described in Patent Document 1, the serial signal synthesis unit 27 converts the serial signal converted from the switching pulse signal of parallel data by the serial signal conversion unit 23 and the pulse signal generated by the pulse signal generation unit 24. The combined signal is sent from the transmitting unit 28 to the receiving unit 11 via the optical fiber 80.
For this reason, in the reception unit 11, a dedicated circuit is required to distinguish between the serial signal and the pulse signal. In order to construct a dedicated circuit having this type of function, usually, a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC) is used, which tends to be expensive.
Further, when the failure detection unit 26 notifies the transmission unit 28 of the failure detection, the transmission unit 28 stops the transmission operation to the power conversion unit 10, and thereafter, between the power control unit 20 and the power conversion unit 10. There is a problem that communication becomes impossible.

  Therefore, the problem to be solved by the present invention is that an expensive dedicated circuit for identifying a signal in the power conversion unit is not necessary, and communication between the power control unit and the power conversion unit can be continued even after notification of failure detection. To provide a power converter.

In order to solve the above-mentioned problems, the invention according to claim 1 is a power conversion unit that performs power conversion by turning on / off a plurality of active elements, and a control signal for turning on / off the active elements, a transmission path And a power control unit that transmits the power to the power conversion unit via
The power control unit detects a fault by a fault detection unit that detects a fault of the power conversion device, a dummy data generation unit that generates a dummy data signal during a period when the control signal is not generated, and the fault detection unit when not, and transmits the dummy data signal generated by said control signal and said dummy data generating means to said transmission line, wherein when a fault is detected by the failure detection means, said control signal or in the dummy data and transmitting means for transmitting the control signal or the dummy data signal including the period to generate a period frameless in the signal, a,
The power conversion unit generates a failure stop signal for stopping the operation of the active element when the period without frames included in the received signal received via the transmission line reaches a predetermined monitoring time set value. it characterized by comprising stop control means to output.

  According to a second aspect of the present invention, in the power conversion device according to the first aspect, the transmission means continuously transmits the control signal and the dummy data signal by serial communication in the asynchronous mode.

The invention according to claim 3 is the power conversion device according to claim 1 or 2,
The stop control means measures a period without the frame , and includes a timer which is reset each time the control signal or the dummy data signal changes, and the measurement time by the timer is set to the monitoring time you and outputting the fault stop signal when it reaches a value.

According to the present invention, it is not necessary to use a dedicated circuit for identification of a received signal in the power conversion unit, and a failure occurs between the power control unit and the power conversion unit using a widely used asynchronous communication system. Detection can be notified. For this reason, cost reduction is possible compared to the prior art.
Further, according to the present invention, a failure detection notification function can be achieved by setting no change in the control signal or the dummy data signal to, for example, a non-communication state in the start-stop synchronization method. The communication state with the power conversion unit can be continued.

It is a block diagram showing composition of a power converter concerning an embodiment of the present invention. It is a figure which shows the transmission data of the normal time in embodiment of this invention. It is a figure which shows the frame format of the control signal in embodiment of this invention, and a dummy data signal. It is operation | movement explanatory drawing at the time of the failure detection in embodiment of this invention. It is the figure which divided and showed the frame format at the time of failure detection in the embodiment of the present invention. It is a block diagram of the power conversion part of a three phase inverter. It is a block diagram which shows the whole structure of the power converter device described in patent document 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the power conversion device according to this embodiment. However, in FIG. 1, parts corresponding to the respective parts of the prior art shown in FIG. 7 are given the same reference numerals, and in the following, parts different from FIG. 7 will be mainly described.

The power conversion device shown in FIG. 1 includes a power control unit 40 and a power conversion unit 30 connected to the power control unit 40 via an optical fiber 80, and the output of the power conversion unit 30 outputs The drive load device 90 is configured to operate.
In this embodiment, the power control unit 40 is added to the control calculation unit 21, the switching pulse generation unit 22, the serial signal conversion unit 23, the failure detection unit 26, the serial signal synthesis unit 27, and the transmission unit 28 described above. In addition to the reception unit 11, the pulse recovery unit 12, and the converter main circuit unit 13, the power conversion unit 30 includes a frame monitoring unit. It has 31. The frame monitoring unit 31 and the pulse restoration unit 12 constitute stop control means described in the claims.

Next, the function of the characterizing portion in this embodiment will be described.
When the dummy frame generation unit 41 in the power control unit 40 recognizes that the generation period of the switching pulse signal has ended based on the operation of the control calculation unit 21, the dummy frame formed of the dummy data signal is sent to the serial signal synthesis unit 27. When it is recognized that the generation period of the switching pulse signal has started based on the operation of the control calculation unit 21, the output of the above-mentioned dummy frame is stopped.

The serial signal synthesis unit 27 is formed of, for example, a logical sum circuit, and transmits a switching pulse signal as a serial signal output from the serial signal conversion unit 23 or a dummy data signal output from the dummy frame generation unit 41 Output to the unit 28.
As shown in FIG. 2, the transmission data 50 output from the transmission unit 28 is as control signals 51-1 and 51-2 for switching pulse signals and as dummy data signals 52-1 and 52-2 for dummy frames. , Optical fiber 80 continuously.

The control signal and the dummy data signal in the transmission data 50 of FIG. 2 are each configured by a frame. This frame will be described with reference to FIG.
The control signal and the dummy data signal have 1 byte (8 bits) of data, and the 1 byte unit is referred to as a frame here. The format of one frame consists of start bit ST, data D0 to D7 (8 bits), parity bit P, and stop bit SP in total of 11 bits according to the serial transmission format of the asynchronous system, for both control signal and dummy data signal. It is done. In FIG. 3, t _b represents a time corresponding to one bit.
Here, the dummy data signal is set to be used by setting specific data (fixed value) as dummy data, and is distinguished from the control signal.

  On the other hand, the frame monitoring unit 31 provided in the power conversion unit 30 of FIG. 1 does not change the received signal of the receiving unit 11 by the timer (not shown) (no frame) “1” (High) level Measure the time of Then, when the measured time exceeds a predetermined set time (monitored time set value), a stop command signal for stopping the operation of the converter main circuit unit 13 is sent to the pulse restoration unit 12.

In more detail, as shown in FIG. 4, the time t ₁ ~t ₂ and between time t ₄ ~t ₅ between the the reception signal in the state of "with frame" is changed, the timer of the frame monitor 31 By being sequentially reset with the level change of the received signal as a trigger, it becomes a sawtooth timekeeping operation.
Now, assuming that the failure detection unit 26 in FIG. 1 detects a failure at time t _F in FIG. 4 and notifies the transmission unit 28 of the failure detection, the transmission unit 28 does not have data “No frame after time t ₂ State, that is, transition to a non-communication state (idle state) in the asynchronous mode. In this case, since there is no frame during the time t _{2 to} t _{4 and} there is no change in the received signal by the receiving unit 11, the measurement time by the timer of the frame monitoring unit 31 is added. It is "No frame" detection signal when the measured time reaches the monitoring time set value at time t _3, i.e. causing oN the stop command signal. In FIG. 4, reference numerals 61-1 to 61-4 indicate “with frame” and 71-1 indicates “without frame”.

When the pulse recovery unit 12 of FIG. 1 does not receive the stop command signal from the frame monitoring unit 31, the pulse recovery unit 12 restores the serial signal received by the receiving unit 11 into a switching pulse signal which is the original parallel data. The signal is distributed to the transistors T _{1 to} T ₆ of the converter main circuit 13.
On the other hand, when receiving the stop command signal from the frame monitoring unit 31, the pulse recovery unit 12 outputs a failure stop signal to stop the operation of the converter main circuit unit 13 and to stop the power supply to the drive load device 90.

  Next, the frame format at the time of failure detection in this embodiment will be described separately for the case where the failure detection is within the dummy data signal transmission period and the case where it is within the control signal transmission period.

First, FIG. 5A shows the case where a failure is detected at the time of transmitting a dummy data signal. In FIG. 5A, when the failure detection unit 26 of the power control unit 40 detects a failure during transmission of the dummy data signal 52-1a, the transmission unit 28 is notified of the failure detection, and the transmission unit 28 does not have a frame. State 52-1b is generated.
In the power conversion unit 30, the frame monitoring unit 31 monitoring the output of the receiving unit 11 detects “no frame” by the operation of the timer, and outputs a stop command signal to the pulse recovery unit 12. The pulse recovery unit 12 outputs a failure stop signal to the converter main circuit unit 13 to stop the operation.

Here, FIG. 4 mentioned above is equivalent to what represented the dummy data signal 52-1 of FIG. 5 (a) by the logic signal of "1" and "0" which are receiving signals.
That is, the dummy data signal 52-1a of FIG. 5 (a) corresponds to the signals of the states 61-1 and 61-2 of the "with frame" of FIG. 4, and the state 52 of "no frame" of FIG. 5 (a). -1b corresponds to the "no frame" state 71-1 of FIG. 4, and the dummy data signal 52-1c of FIG. 5A is the signal of the "frame present" state 61-3 and 61-4 of FIG. It corresponds to

Further, FIG. 5 (b) is a case where a failure is detected at the time of control signal transmission.
In this case, a failure is detected in the transmission period of the control signal 51-2a, and thereafter, the transmission unit 28 generates the "no frame" state 51-2b. Thereby, the timer of the frame monitoring unit 31 determines the lapse of the monitoring time setting value to detect "no frame", and outputs the failure stop signal through the pulse recovery unit 12 so that the converter main circuit unit 13 Stop the operation of

As described above, in the present embodiment, the dummy frame generation unit 41 in the power control unit 40 generates a dummy data signal in a period other than the control signal generation period, and transmits this dummy data signal from the transmission unit 28 to the optical fiber 80. It transmits to the power conversion part 30 via. When a failure occurs, the failure detection unit 26 notifies the transmission unit 28 of the failure detection, whereby the transmission unit 28 generates a “no frame” state and continuously communicates with the power conversion unit 30.
Further, in the power conversion unit 30, based on the output of the receiving unit 11, the frame monitoring unit 31 detects that the level of the received signal has not changed due to the state of "no frame", and the measurement time by the timer is monitored. When the set value is exceeded, a stop command signal is sent to the pulse recovery unit 12, and the pulse recovery unit 12 outputs a failure stop signal to stop the converter main circuit unit 13.

That is, in the present embodiment, the failure detection notification from the power control unit 40 to the power conversion unit 30 is realized by the presence or absence of a change in the serial signal (the presence or absence of a frame). The UART (Universal Asynchronous Receiver Transmitter) used can be used for the receiver. This makes it possible to use a general-purpose microcomputer or the like in which the UART is built in, as compared to the prior art in which a dedicated circuit such as an FPGA or ASIC is required to identify received signals in the power conversion unit, thereby reducing manufacturing costs. Can.
Further, in the prior art, since communication between the power control unit and the power conversion unit is stopped to perform failure notification, communication can not be performed after notification of the failure. However, in the present embodiment, “no frame” By transmitting and receiving the state of (1), the failure detection notification is performed, and the communication state between the power control unit and the power conversion unit can be continued even after the failure detection.

The present invention is not limited to the case where the transmission line between the power control unit and the power conversion unit is an optical fiber, but in the case of a power conversion device provided with appropriate noise suppression means, the above transmission line is a metal cable If it is also available.
Further, the function of the power conversion unit (converter main circuit unit) can also be applied to various power conversion devices without being particularly limited, such as between DC and AC, between DC and AC, and so forth. .

10, 30: power conversion unit 11: reception unit 12: pulse restoration unit 13: converter main circuit unit 14: reception interval determination unit 16: diode rectifier 17: capacitor 18: inverter main circuit 20, 40: power control unit 21: Control operation unit 22: switching pulse generation unit 23: serial signal conversion unit 24: pulse signal generation unit 25: operation condition determination unit 26: failure detection unit 27: serial signal synthesis unit 28: transmission unit 41: dummy frame generation unit 50: Transmission data 51-1, 51-2: Control signal 52-1, 52-2: Dummy data signal 61-1, 61-2, 61-3, 61-4: "With frame" state 71-1: " state frameless "80: optical fiber 90: driven load device _D 1 to D _6: diode _T 1 through T _6: transistor

Claims (3)

A power conversion unit that performs power conversion by turning on / off a plurality of active elements; and a power control unit that transmits a control signal for turning on / off the active elements to the power conversion unit via a transmission path. Power converter provided with
The power control unit detects a fault by a fault detection unit that detects a fault of the power conversion device, a dummy data generation unit that generates a dummy data signal during a period when the control signal is not generated, and the fault detection unit when not, and transmits the dummy data signal generated by said control signal and said dummy data generating means to said transmission line, wherein when a fault is detected by the failure detection means, said control signal or in the dummy data and transmitting means for transmitting the control signal or the dummy data signal including the period to generate a period frameless in the signal, a,
The power conversion unit generates a failure stop signal for stopping the operation of the active element when the period without frames included in the received signal received via the transmission line reaches a predetermined monitoring time set value. power conversion apparatus characterized by comprising a stop control means to output. In the power conversion device according to claim 1,
The power conversion device, wherein the transmitting means continuously transmits the control signal and the dummy data signal by serial communication in an asynchronous mode. The power converter according to claim 1 or 2
The stop control means measures a period without the frame , and includes a timer which is reset each time the control signal or the dummy data signal changes, and the measurement time by the timer is set to the monitoring time The power conversion device characterized in that the fault stop signal is output when the value is reached.

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