JP4518971B2 - DC power supply - Google Patents

Description

  The present invention relates to a DC power supply apparatus that uses a DC power supply by stepping down, and more particularly to a DC power supply apparatus having an improved overvoltage protection function.

  In general, in a DC power supply device, particularly a DC power supply device having an inductive load as a load, the energy accumulated in the load is released due to a failure of a converter for generating DC, and the circuit voltage rapidly increases. Overvoltage may cause damage to equipment.

Since such overvoltage protection requires high speed, a method has been proposed in which a reflux path is provided by an overvoltage protection thyristor element, and the overvoltage protection thyristor element is ignited by an overvoltage of the circuit ( For example, see Patent Document 1.)
Japanese Utility Model Publication No. 6-2625 (page 5-6, FIG. 1)

  When the protection circuit shown in Patent Document 1 is applied to a DC-DC conversion type DC power supply device, there are the following problems.

  That is, when the main circuit element for conversion becomes abnormal and the input / output is short-circuited, the protective thyristor is turned on by automatic detection of overvoltage, but until the fuse provided in series with the main circuit is blown (for several ms) Short circuit current flows through the protective thyristor. Therefore, the protective thyristor needs an element capacity that does not cause a problem even if a short-circuit current flows between them. In addition, when a short-circuit current flows through the protective thyristor, the DC power supply is in a short-circuited state, and there is a problem of affecting the life of the DC power supply.

The present invention has been made in view of the above, and an object of the present invention is to provide a DC power supply device including an overvoltage protection circuit that minimizes a short-circuit current even when the main circuit element for conversion is abnormal.

In order to achieve the above object, a DC power supply device according to a first aspect of the present invention includes a DC voltage source,
Two main circuit elements connected in series to the DC voltage source, a freewheeling diode connected in parallel to the output side of the main circuit element, a series reactor for smoothing the voltage on the output side of the main circuit element, and A smoothing capacitor connected in parallel to the output side of the series reactor, a protective main circuit element connected in parallel to the smoothing capacitor, and an output voltage detection means for detecting a voltage applied to the protective main circuit element; And a control unit for controlling the main circuit element and the protection main circuit element. The control unit turns on and off the main circuit element in order to set a detection voltage by the output voltage detection means to a desired value. Gate pulse supply means for controlling, overvoltage protection means for turning on the main circuit element for protection when a detection voltage by the output voltage detection means exceeds a predetermined value, and the output When the detected voltage by the pressure detecting means exceeds a predetermined value, it is characterized by having a first gate block means for blocking the gate pulse supply means.

  The DC power supply device according to the second aspect of the present invention includes a DC voltage source, two main circuit elements connected in series to the DC voltage source, and a parallel connection on the output side of the main circuit element. A freewheeling diode, a series reactor for smoothing the output side voltage of the main circuit element, a smoothing capacitor connected in parallel to the output side of the series reactor, and an output voltage detection for detecting a voltage applied to the smoothing capacitor And a control part for controlling the main circuit element. The control part supplies a gate pulse for controlling on / off of the main circuit element in order to set a detection voltage by the output voltage detecting means to a desired value. Means, a first switching monitoring means for monitoring the on / off operation of the main circuit element during normal operation, and a main circuit in which the first switching monitoring means is connected in two series. When detecting any abnormality of the elements is characterized by having a second gate block means for blocking the gate pulse supply means.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the main circuit element for conversion is abnormal, it becomes possible to provide the direct-current power supply device provided with the overvoltage protection circuit which suppresses a short circuit current to the minimum.

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

  A DC power supply apparatus according to Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a DC power supply apparatus according to Embodiment 1 of the present invention.

  The DC voltage Vd1 of the DC voltage source 1 is supplied to the main circuit element 3A and the main circuit element 3B that are connected in series via the fuse 2. The main circuit elements 3A and 3B are each composed of a main switching element typified by an IGBT or the like and a free-wheeling diode connected in reverse parallel thereto. The output of the series circuit of the main circuit element 3A and the main circuit element 3B is smoothed by the ripple by the series reactor 5 and the smoothing capacitor 6 via the free-wheeling diode 4 connected in parallel, and the DC output voltage Vd2 is supplied to the load 7 Power is supplied. A voltage detector 8 for detecting the output voltage Vd2 is provided on the input side of the load 7, and a protection main circuit element 9 for overvoltage protection is connected in parallel. Further, a reverse voltage protection diode 8B is connected in reverse parallel to the protection main circuit element 9.

  The above is the main circuit configuration of the DC power supply device. Next, the internal configuration of the control unit 10 for controlling the main circuit elements 3A and 3B and the protection main circuit element 9 of the DC power supply device will be described.

  The output control device 11 performs on / off control of the main circuit element 3A and the main circuit element 3B so that the output voltage Vd2 detected by the voltage detector 8 becomes a desired value. The gate pulse Gch that is the output of the output control device 11 is supplied to the pulse distributor 12, and the gate distributor Gch_a and Gch_b of the main circuit element 3A and the main circuit element 3B are supplied from the pulse distributor 12, respectively.

  The output voltage Vd2 detected by the voltage detector 8 is given to the overvoltage detector 13, and when the output voltage Vd2 exceeds a predetermined value, the protection main circuit element 9 is turned on via the short-circuit pulse generator 14. Thus, this short circuit operation prevents overvoltage. The reverse voltage protection diode recirculates the energy stored in the smoothing capacitor 6 at this time. When the output voltage Vd2 detected by the voltage detector 8 exceeds a predetermined value, the overvoltage detector 13 outputs a gate block signal to the pulse distributor 12, and the gate pulses of the main circuit element 3A and the main circuit element 3B. Shut off.

  The detailed operation of the control unit 10 described above will be described with reference to FIG. FIG. 2 is an explanatory diagram of a control operation according to the first embodiment.

  The output control device 11 outputs a gate pulse Gch, which is an on / off signal when the main circuit element is not a serial configuration but a single device so that the output voltage Vd2 is obtained, and the pulse distributor 12 In response to this signal, two on / off gate signals whose frequency is half and whose phase is shifted by a half cycle are generated and supplied to the gates of the main circuit element 3A and the main circuit element 3B as the gate pulse Gch_a and the gate pulse Gch_b, respectively. Yes. When the overvoltage protection signal from the overvoltage detector 13 is received, the gate pulse Gch_a and the gate pulse Gch_b are blocked and blocked.

  According to the configuration of the first embodiment described above, since the probability that both the main circuit element 3A and the main circuit element 3B connected in series are short-circuited at the same time is extremely low, the above-described gate is obtained when the DC output Vd2 becomes an overvoltage. The block operation prevents the DC voltage Vd1 of the DC voltage source 1 from being applied to the output voltage Vd2 side.

  Further, since the above gate block operation is one digit or more faster than the operation in which the fuse 2 is cut off, the time during which the main circuit element for protection 9 is turned on depends on the cut-off operation of the fuse 2 to prevent the application of the high voltage. Compared with the case where it is, the element rating of the main circuit element 9 for protection can be reduced.

  Further, since the main circuit element 3A and the main circuit element 3B connected in series are alternately switched, the loss at the time of switching can be equally shared between the main circuit element 3A and the main circuit element 3B to be minimized. it can.

  Hereinafter, a DC power supply according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram of a DC power supply apparatus according to Embodiment 2 of the present invention.

  The same parts of the second embodiment as those of the direct-current power supply apparatus according to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. The second embodiment is different from the first embodiment in that the main circuit element 9 for protection, the reverse voltage protection diode 8A and the short-circuit pulse generator 14 are omitted, and the input voltage of the main circuit element 3A to the control unit 10A. The switching monitoring device 15 that operates by receiving five signals of Vfa, the output voltage Vfb of the main circuit element 3A, the output voltage Vfc of the main circuit element 3B, and the gate pulses Gch_a and Gch_b, and the gate pulse at the output of the switching monitoring device 15 It is the point which added protection device 16A and 16B which performs interruption | blocking operation | movement of Gch_a and Gch_b.

  Hereinafter, the detailed operation of the control unit 10A will be described with reference to FIG. FIG. 4 is an explanatory diagram of a control operation according to the second embodiment.

  As shown in FIG. 4, the switching monitoring device 15 receives ON / OFF timings of the main circuit elements 3 </ b> A and 3 </ b> B by gate pulses Gch_a and Gch_b that are outputs of the pulse distributor 12. On the other hand, the voltage detector 51A detects the voltage across the main circuit element 3A from the difference between Vfa and Vfb, and the voltage detector 51B detects the voltage across the main circuit element 3B from the difference between Vfb and Vfc.

  When the gate pulse Gch_a is on, the main circuit element 3A is turned on if it is operating normally. Therefore, the monitoring circuit 52A outputs 0 when Vfa-Vfb is equal to or lower than a predetermined on-voltage. When the gate pulse Gch_a is off, the main circuit element 3A is normally turned off, and the voltage Vd1-Vd2 is applied to both ends of the main circuit element 3A. When it is equal to or higher than the voltage, 0 is output. With this configuration, the monitor circuit 52A outputs 0 when the main circuit element 3A is operating normally and 1 when the main circuit element 3A becomes abnormal.

  Similarly, the monitoring circuit 52B outputs 0 when the main circuit element 3B is operating normally and 1 when the main circuit element 3B becomes abnormal. If the output of the monitoring circuit 52A and the output of the monitoring circuit 52B are input to the flip-flop circuit 54 via the OR circuit 53, the output of the flip-flop circuit 54 is either the main circuit element 3A or the main circuit element 3B. When an abnormality occurs, 1 is output, and both the protection devices 16A and 16B are operated by this signal to cut off the gate pulses Gch_a and Gch_b.

  The monitoring circuits 52A and 52B may be configured to have a filter function so as to prevent malfunction due to an oscillating voltage or the like generated at the switching transition of each main circuit element.

  The protection devices 16A and 16B can also be used as a gate block function provided in the pulse distributor 12.

  With the above configuration and operation, the abnormality of the main circuit element 3A and the main circuit element 3B is monitored every time switching is performed. Therefore, the protective operation is performed before the overvoltage detector 13 detects the overvoltage of the output voltage Vd2. It becomes possible. Accordingly, since the overvoltage at this time can be limited to a slight increase corresponding to one switching, the protection main circuit element 8 provided in the first embodiment is not necessary.

  Hereinafter, a DC power supply according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram of a DC power supply apparatus according to Embodiment 3 of the present invention.

  Regarding the respective parts of the third embodiment, the same parts as those of the DC power supply apparatus according to the second embodiment of FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted. The third embodiment is different from the second embodiment in that the gate pulse Gch of the output control device 11A is input, and the abnormal-time pulse distributor is configured to switch the gate pulse in order to reconfirm the abnormal state of the main circuit element at the time of abnormality. 17 is inserted on the output side of the protection devices 16A and 16B in the control unit 10B, and the gate pulse input signal of the switching monitoring device 15 is set as gate pulses Gch_a2 and Gch_b2 which are outputs of the pulse distributor 17 at the time of abnormality, In addition, when an abnormality occurs, a signal from the switching monitoring device 15A is received to reconfirm the abnormal state, and when this abnormal state can be determined as a malfunction such as noise, the output control device 11A has a function of resetting the abnormal output of the switching monitoring device 15A. It is the point that it was made to have.

  Hereinafter, the detailed operation of the control unit 10B will be described with reference to FIG. FIG. 6 is an explanatory diagram of the control operation of the third embodiment.

  In FIG. 6, the operation of monitoring the abnormality of the main circuit elements 3A and 3B by the switching monitoring device 15A and shutting off the gate pulse by the protection devices 16A and 16B in the case of abnormality is the same as that of the second embodiment shown in FIG. The description will be omitted, and the operation of resetting the abnormal output of the switching monitoring device 15A when the abnormal state of the main circuit elements 3A and 3B is reconfirmed at the time of abnormality and this abnormal state can be determined as malfunction such as noise will be described.

  When the switching monitoring device 15A detects an abnormality in one of the main circuit elements 3A and 3B and the output of the flip-flop circuit 54A becomes 1, the protection devices 16A and 16B cut off the gate pulse, and at the same time, the abnormal pulse distribution A signal is given to the device 17 to switch the gate pulses of the main circuit elements 3A and 3B. Of the outputs of the abnormal-time pulse distributor 17 at the time of abnormality, the gate pulse Gch_a2 for the main circuit element 3A is given as it is the output Gch of the output control device 11B, and the gate pulse Gch_b2 for the main circuit element 3B is output controlled. The output Gch of the device 11B is configured to be delayed by a delay circuit 61 for a predetermined time.

  When the switching monitoring device 15A detects any abnormality of the main circuit elements 3A and 3B and the output of the flip-flop circuit 54A becomes 1, this abnormality signal is sent to the element monitoring circuit 71 provided in the output control circuit 11B. Entered. Then, since the switching gate pulses Gch_a2 and Gch_b2 are given to the monitoring circuits 52A and 52B, the switching monitoring device 15A is similar to the monitoring operation described in the second embodiment in a state where the gate pulses are switched. The monitoring operation is performed on the main circuit elements 3A and 3B.

  Then, the output of the OR circuit 53 in the switching monitoring device 15A is monitored by the element monitoring circuit 71, and if the output of the OR circuit 53 is 0, the element monitoring circuit 71 gives a reset signal to the flip-flop circuit 54A to cause an abnormality. In addition to resetting the state, the output of the abnormal pulse distributor 17 is switched to the original output of the pulse distributor 12. If the output of the OR circuit 53 is 1 even when the gate pulse is switched, there is no malfunction due to noise or the like, and it is determined that one of the main circuit elements 3A and 3B is abnormal and provided in the output control circuit 11B. The gate block circuit 72 is operated to cut off the gate pulse Gch. For safety, the gate block circuit 72 may be operated by an overvoltage protection signal.

  According to the third embodiment, when the switching monitoring device 15A is activated in the operation state and the protection devices 16A and 16B block the gate pulse, the health check of the main circuit elements 3A and 3B is performed in the normal operation gate. When the main circuit elements 3A and 3B are healthy, the operation is continued even when the main circuit element malfunctions due to noise or the like. be able to.

1 is a block configuration diagram of a DC power supply device according to Embodiment 1 of the present invention. Explanatory drawing of control operation | movement of the DC power supply device which concerns on Example 1 of this invention. The block block diagram of the DC power supply device which concerns on Example 2 of this invention. Explanatory drawing of control operation | movement of the DC power supply device which concerns on Example 2 of this invention. The block block diagram of the DC power supply device which concerns on Example 3 of this invention. Explanatory drawing of control operation | movement of the DC power supply device which concerns on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC voltage source 2 Fuse 3A, 3B Main circuit element 4 Free-wheeling diode 5 Series reactor 6 Smoothing capacitor 7 Load 8 Protection main circuit element 8A Reverse voltage protection 9 Voltage detector 10, 10A, 10B Control part 11, 11A Output control Device 12 Pulse distributor 13 Overvoltage detector 14 Short-circuit pulse generator 15, 15A Switching monitoring device 16A, 16B Protection device 17 Abnormal pulse distributor 51A, 51B Voltage detector 52A, 52B Monitoring circuit 53 OR circuit 54, 54A Flip-flop Circuit 61 Delay circuit 71 Element monitoring circuit 72 Gate block circuit

Claims (6)

A DC voltage source;
Two main circuit elements connected in series to the DC voltage source;
A free-wheeling diode connected in parallel to the output side of the main circuit element;
A series reactor for smoothing the voltage on the output side of the main circuit element and a smoothing capacitor connected in parallel to the output side of the series reactor;
A protective main circuit element connected in parallel to the smoothing capacitor;
Output voltage detection means for detecting a voltage applied to the protective main circuit element;
A control unit for controlling the main circuit element and the protective main circuit element;
The controller is
Gate pulse supply means for controlling on / off of the main circuit element in order to set the detection voltage by the output voltage detection means to a desired value;
Overvoltage protection means for turning on the main circuit element for protection when a detection voltage by the output voltage detection means exceeds a predetermined value;
A DC power supply apparatus comprising: a first gate block unit that shuts off the gate pulse supply unit when a voltage detected by the output voltage detection unit exceeds a predetermined value. A DC voltage source;
Two main circuit elements connected in series to the DC voltage source;
A free-wheeling diode connected in parallel to the output side of the main circuit element;
A series reactor for smoothing the voltage on the output side of the main circuit element and a smoothing capacitor connected in parallel to the output side of the series reactor;
Output voltage detecting means for detecting the voltage applied to the smoothing capacitor;
A control unit for controlling the main circuit element;
The controller is
Gate pulse supply means for controlling on / off of the main circuit element in order to set the detection voltage by the output voltage detection means to a desired value;
First switching monitoring means for monitoring on / off operation of the main circuit element during normal operation;
The first switching monitoring means includes a second gate block means for shutting off the gate pulse supply means when detecting an abnormality of any of the two series-connected main circuit elements. Power supply. The controller is
When the second gate block means is activated, the second switching monitoring means for monitoring the on / off operation at the time of abnormality of the two main circuit elements connected in series;
When the second switching monitoring means detects normal operation of the two main circuit elements connected in series,
Canceling the gate blocking by the second gate blocking means,
The DC power supply device according to claim 2, wherein the DC power supply device is returned to normal operation. The gate pulse supply means includes
Means for generating a reference gate pulse for the two series-connected main circuit elements;
Pulse distribution means for distributing the reference gate pulse into two pulses having a half frequency and shifted by a half cycle;
4. The device according to claim 1, wherein two gate pulse outputs of the pulse distribution means are given as gate pulses during normal operation to each of the two main circuit elements connected in series. The direct current power supply device according to item. The switching monitoring means includes
When an on-pulse is applied to each of the two main circuit elements connected in series, and the voltage across the main circuit element is a predetermined value or more
Or, in a state where an off pulse is applied to each of the main circuit elements connected in series, when the voltage across the main circuit element is a predetermined value or less,
4. The DC power supply device according to claim 2, wherein the main circuit element is determined to be abnormal. The second switching monitoring means includes:
4. The DC power supply device according to claim 3, wherein the on / off operation of the main circuit element is monitored by a gate pulse supply means at the time of abnormality different from the gate pulse supply means at the time of normal operation.

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