JP4974227B2 - Power converter - Google Patents

Description

  The present invention relates to a power converter having DC voltage detecting means for a DC section.

  In general, in a power converter having a DC part, a DC voltage of the DC part is detected and fed back to a control circuit for control or protection.

For example, power conversion that receives AC input and supplies DC output to a load by a self-excited power converter consisting of bridge-connected self-extinguishing semiconductor elements and feedback diodes connected in reverse parallel to these elements. In the device, the DC voltage is detected by the DC voltage detector and fed back for control, and input to the control circuit for protection, overvoltage protection is provided by the overvoltage detector, and undervoltage protection is provided by the undervoltage detector. Has been done. In this case, the operation of the power converter is stopped by the detection signal of either the undervoltage detector or the overvoltage detector (see, for example, Patent Document 1).
JP-A-6-276670 (Overall)

  As a general circuit of the DC voltage detector used in the power conversion device disclosed in Patent Document 1, there is an insulation amplifier. In general, an insulation amplifier divides a DC voltage of a power converter by a voltage dividing resistor and inputs the divided voltage to an insulation amplifier main body. Therefore, the characteristic is 0 V when there is no DC voltage, and a positive output when there is a DC voltage.

  Here, if the DC voltage detector is damaged or the wiring on the output side of the DC voltage detector is disconnected, the DC voltage feedback signal disappears and the undervoltage detector operates to stop the power converter. . However, since there is no DC voltage before the power converter is activated, it is necessary to mask the abnormality detection of the undervoltage detector, and the power converter is activated and the mask of the undervoltage detector is released. Until then, there is a problem that the DC voltage detector cannot be broken or the wire breakage cannot be detected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a power conversion device that can detect breakage of a DC voltage detector and disconnection of wiring on the output side of the DC voltage detector even before startup. There is to do.

  In order to achieve the above object, a power conversion device according to a first aspect of the present invention has a DC voltage detection means for a DC section on the input or output side of a power converter, and the output of the DC voltage detection means is The power converter is configured to stop the operation of the power converter when an overvoltage set value or less, wherein the DC voltage detection means is an insulation amplifier that receives the voltage of the DC unit and an output thereof A reference power supply whose reference voltage is set to the full-scale output of the insulation amplifier, and a subtracting means for subtracting the output of the insulation amplifier from the reference voltage, and the output of the subtraction means is the output of the DC voltage detection means It is characterized by that.

  The power conversion device according to the second aspect of the present invention has a DC voltage detection means for a DC section on the input or output side of the power converter, and the output of the DC voltage detection means is equal to or less than an overvoltage set value. The power converter is configured to stop the operation of the power converter, wherein the DC voltage detection means receives an input of the voltage of the DC unit and outputs an opposite polarity to the input, and an output thereof. A reference power supply in which a certain reference voltage is set to a full-scale output of the insulation amplifier; and an adding means for adding the reference voltage and the output of the insulation amplifier; and the output of the adding means is the output of the DC voltage detecting means It is characterized by output.

  Furthermore, a power conversion device according to a third aspect of the present invention has DC voltage detection means for a DC section on the input or output side of the power converter, and the frequency output by the DC voltage detection means is equal to or lower than an overvoltage set value. In this case, the power converter is configured to stop the operation of the power converter, wherein the DC voltage detection means includes an amplifier that receives the voltage of the DC unit and a reference voltage that is an output of the amplifier. A reference power supply set to full scale output, a subtracting means for subtracting the output of the isolation amplifier from the reference voltage, an output frequency is zero when the output of the subtracting means is zero, and an output of the subtracting means is full scale And a VF converting means whose output frequency becomes full scale, and the output of the VF converting means is the output of the DC voltage detecting means.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the power converter device which can detect the failure | damage of a DC voltage detector, and the disconnection of the wiring by the side of the output of a DC voltage detector before starting.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, the power converter concerning Example 1 of the present invention is explained with reference to FIG.1 and FIG.2.

  FIG. 1 is a circuit configuration diagram of a power conversion apparatus according to Embodiment 1 of the present invention. The AC voltage supplied from the AC power source 1 is converted into self-excited power conversion through a filter circuit 3, for example, a bridge-connected self-extinguishing semiconductor element and a feedback diode connected in antiparallel to these elements. Is supplied to the vessel 3. The power converter 3 converts an AC voltage into a DC voltage, and its output is supplied to a load 5 via a DC smoothing capacitor 4 in the DC section.

  The DC voltage of the DC unit is detected as a feedback DC voltage by the DC voltage detector 6 and applied to the control circuit 8. The input current of the power converter 3 detected by the input current detector 7 is also given to the control circuit 8.

In the control circuit 8, voltage control is performed so that the difference between the feedback DC voltage and the DC voltage reference is zero, and current minor control is performed so that the difference between the obtained current reference and the input current is zero. And a gate signal is generated according to the manipulated variable to control the self-extinguishing semiconductor element of the power converter 3.

  In the above description, the power converter 1 may have a DC part on the input side or output side, and may be a chopper, for example. Further, the control circuit 8 may be any circuit as long as it controls the semiconductor elements constituting the power converter 1, and does not necessarily have the configuration shown in FIG.

  The feedback DC voltage detected by the DC voltage detector 6 is supplied to the overvoltage detector 9 and the undervoltage detector 10, respectively. The overvoltage detector 9 outputs a gate signal stop command to the control circuit 8 when the DC voltage of the DC section exceeds a predetermined overvoltage set value. Similarly, the undervoltage detector 10 outputs a gate signal stop command to the control circuit 8 when the direct current voltage of the direct current section becomes equal to or less than the undervoltage setting value.

  FIG. 2A is an internal circuit configuration diagram of the DC voltage detector 6, and FIG. 2B is an explanatory diagram of input / output characteristics of the DC voltage detector 6.

In FIG. 2A, the feedback DC voltage is divided by the voltage dividing resistor 61 and the voltage dividing resistor 62, and the voltage at both ends of the voltage dividing resistor 62 is input to the insulation amplifier 63. The output of the insulation amplifier 63 is subtracted by the subtractor 65 from the reference voltage that is the output of the reference power supply 64. Here, the reference voltage of the reference power supply 64 is set to full-scale output of the isolation amplifier 6 3, input to the subtractor 65 with a positive polarity, subtracts the output of the isolation amplifier 63 in the subtracter 65. In this way, as shown in FIG. 2B, when the DC voltage of the DC section is 0 V, the output of the DC voltage detector 6 outputs the full scale voltage c of the insulation amplifier 63. Further, the output of the DC voltage detector 6 is set to 0 V when the DC voltage of the DC section increases and becomes the full scale input B of the insulation amplifier 63.

  As described above, when the DC voltage exceeds A in FIG. 2B, the output of the DC voltage detector 6 becomes d or less, so that the power conversion device can stop overvoltage. Therefore, the overvoltage detector 9 detects an overvoltage when the output of the DC voltage detector 6 becomes d or less. When the output of the DC voltage detector 6 becomes 0 due to internal damage of the secondary side of the DC voltage detector 6 or when the wiring on the output side of the DC voltage detector 6 is disconnected, the DC voltage detection is performed. Since the output of the converter 6 becomes 0V and the DC voltage detector 6 can apparently detect the DC overvoltage, the DC voltage detector 6 is damaged before the power converter is started, and the output side wiring It is possible to detect disconnection.

  In the above description, the undervoltage detector 10 detects an undervoltage when the output of the DC voltage detector 6 exceeds a predetermined value. However, a configuration without the undervoltage detector 10 is also possible. Even in this case, if it is detected that the output of the DC voltage detector 6 becomes 0 V when the control power supply is turned on before starting, an abnormality in the DC voltage detector 6 or the wiring on the output side of the DC voltage detector 6 is detected. It becomes possible to do.

  FIG. 3 is an internal circuit configuration diagram of a DC voltage detector 6A used in the power conversion apparatus according to Embodiment 2 of the present invention.

  The same parts as those in the internal circuit configuration diagram of the DC voltage detector used in the power converter according to Embodiment 1 of the present invention in FIG. Is omitted. The difference between the second embodiment and the first embodiment is that the polarity on the secondary side of the insulation amplifier 63A is reversed. The output of the insulation amplifier 63A and the output of the reference power supply 64 are added by an adder 66. The result is that the output is the output of the DC voltage detector 6A.

  Since the output characteristics of the DC voltage detector 6A according to the second embodiment are the same as the output characteristics of the DC voltage detector 6 according to the first embodiment shown in FIG. 2B, the DC voltage is also detected before the power converter is started. It is possible to detect breakage of the detector 6A and disconnection of the wiring on the output side of the DC voltage detector 6A.

  FIG. 4A is an internal circuit configuration diagram of a DC voltage detector 6B used in the power conversion apparatus according to Embodiment 3 of the present invention.

  About each part of this Example 3, the part same as each part of the internal circuit block diagram of the direct-current voltage detector used for the power converter device which concerns on Example 1 of this invention of Fig.2 (a) is shown with the same code | symbol, The description Is omitted. The third embodiment is different from the first embodiment in that an amplifier 63B is provided in place of the insulation amplifier 63, the output of the subtractor 65 is converted into a frequency by a VF converter 67, and the output is converted by an optical converter 68. This is the point that the output of the DC voltage detector 6B is obtained by converting into an optical signal.

  Here, the amplifier 63B may be an operational amplifier using a normal electronic circuit. The output of the amplifier 63B is subtracted from the reference voltage of the reference power supply 64 by the subtractor 65. The reference power supply 64 is set to the absolute value full scale output of the amplifier 63B, and is given to the subtractor 65 with positive polarity. The VF converter 67 generally uses a type that outputs a frequency corresponding to an input voltage and outputs 0 Hz when there is no input voltage.

  As described above, as shown in FIG. 4B, when the DC voltage is 0V, the optical output of the DC voltage detector 6B outputs the full scale voltage e of the amplifier 63B. Further, when the DC voltage increases and becomes the full scale input B of the amplifier 63B, the output of the DC voltage detector 6B is set to 0V. At this time, the overvoltage detector 9 determines that it is a DC overvoltage when the output frequency of the DC voltage detector 6 falls below a predetermined value f.

  As a result, when the DC voltage becomes A or higher, the output of the DC voltage detector 6B becomes f or lower, so that the power conversion device can stop overvoltage, and the DC voltage detector 6B is damaged by the DC voltage detector 6B. When the output of 6B becomes 0, or when the disconnection of the wiring on the output side after the VF converter 67 occurs, the frequency becomes 0 Hz. Therefore, the DC voltage detector 6B is damaged even before the power converter is started. In addition, it is possible to detect disconnection of the output side wiring.

  Further, since the DC voltage detection is performed at the frequency, the output frequency of the DC voltage detector 6B becomes 0 Hz even when the failure of the DC voltage detector 6B stops at a high level (latch-up). It becomes possible to stop processing.

  Furthermore, by optically isolating the output with the optical converter 68, it is applicable to an insulation specification having a higher withstand voltage than an insulation amplifier that performs electrical insulation, and a power converter with a higher withstand voltage can be provided.

The circuit block diagram of the power converter device which concerns on Example 1 of this invention. The internal circuit block diagram of the DC voltage detector used for the power converter device which concerns on Example 1 of this invention, and its input-output characteristic. The internal circuit block diagram of the direct-current voltage detector used for the power converter device which concerns on Example 2 of this invention. The internal circuit block diagram of the DC voltage detector used for the power converter device which concerns on Example 3 of this invention, and its input-output characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Power converter 3 Filter circuit 4 Load 5 DC smoothing capacitor 6, 6A, 6B DC voltage detector 61, 62 Voltage dividing resistor 63, 63A Insulation amplifier 63B Amplifier 64 Reference power supply 65 Subtractor 66 Adder 67 VF Converter 68 Optical converter

7 Input current detector 8 Control circuit 9 Overvoltage detector 10 Undervoltage detector

Claims (6)

A power converter having DC voltage detecting means for a DC section on the input or output side of the power converter, and stopping the operation of the power converter when the output of the DC voltage detecting means is equal to or lower than an overvoltage set value. Because
The DC voltage detecting means includes
An insulation amplifier that receives the voltage of the DC section as an input;
A reference power supply whose output is a reference voltage set to the full-scale output of the isolation amplifier, and
Subtracting means for subtracting the output of the insulation amplifier from the reference voltage,
An output of the subtracting means is used as an output of the DC voltage detecting means. A power converter having DC voltage detecting means for a DC section on the input or output side of the power converter, and stopping the operation of the power converter when the output of the DC voltage detecting means is equal to or lower than an overvoltage set value. Because
The DC voltage detecting means includes
An insulation amplifier that takes the voltage of the DC section as an input and outputs a polarity opposite to the input;
A reference power supply whose output is a reference voltage set to the full-scale output of the isolation amplifier, and
Adding means for adding the reference voltage and the output of the insulation amplifier;
An output of the adding means is used as an output of the DC voltage detecting means. Electric power having DC voltage detection means for the DC part on the input or output side of the power converter, and stopping the operation of the power converter when the frequency output by the DC voltage detection means is equal to or lower than the overvoltage set value A conversion device,
The DC voltage detecting means includes
An amplifier that receives the voltage of the DC section;
A reference power supply whose reference voltage is set to the full-scale output of the amplifier, and
Subtracting means for subtracting the output of the isolation amplifier from the reference voltage;
VF conversion means such that the output frequency is zero when the output of the subtraction means is zero, and the output frequency is full scale when the output of the subtraction means is full scale,
The power converter according to claim 1, wherein the output of the VF converter is the output of the DC voltage detector. The DC voltage detecting means includes
Furthermore, it has a light conversion means for converting the output frequency of the VF conversion means into light,
4. The power converter according to claim 3, wherein the output of the light conversion means is the output of the DC voltage detection means.   5. The operation of the power converter is stopped when the output voltage or frequency of the DC voltage detection means exceeds an undervoltage set value. 6. The power converter described.   When the output voltage or frequency of the DC voltage detection means exceeds a predetermined value before starting the power converter, it is determined that the DC voltage detection means or the wiring on the output side thereof is abnormal. The power converter according to any one of claims 1 to 5.

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