JP2005192354A - Alternating-current switch device and power supply device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accomplish reduction in both the turn-off delay in alternating-current switches and cost of the alternating-current power supply device. <P>SOLUTION: Each of the alternating-current switches 2a, 2b, and 2c connected in series with the power lines 3a, 3b, and 3c of the alternating-current power supply device comprises an inverse-parallel connection circuit of two thyristors and a series circuit of IGBT and a diode connected in inverse-parallel with one of the two thyristors. At normal power supply times, one thyristors S1a, S1b, and S1c and the IGBTs Qa, Qb, and Qc are on-controlled. At overcurrent or IGBT failure times, the other thyristors S2a, S2b, and S2c are on-controlled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an AC switch device suitable for disconnecting an AC power source in an AC uninterruptible power supply device, and a power supply device using the AC switch device.

  A conventional representative AC uninterruptible power supply is connected to a commercial AC power supply terminal via an AC switch connected between a commercial AC power supply terminal and a load, and an AC switch. A bidirectional power converter connected to a load; a storage battery connected to a DC terminal of the bidirectional power converter; and a power supply abnormality detection device that detects an abnormality in the voltage of the commercial AC power supply terminal and controls the AC switch to be turned off. have.

  The AC switch of the AC uninterruptible power supply device includes an anti-parallel connection circuit of two thyristors as shown in Patent Documents 1 and 2 to be described later. Although the AC switch using this thyristor has the advantages of low cost and large instantaneous load capacity, it is not immediately turned off even if an OFF command is given for extinction by natural commutation, resulting in a delay of the maximum AC half cycle. It has the disadvantages.

As another AC switch, a circuit in which two IGBTs, that is, insulated gate bipolar transistors are connected in antiparallel, is known. Since the IGBT is a self-extinguishing semiconductor switch, the power supply can be turned off with a smaller delay than the thyristor. However, the instantaneous overcurrent capability of the IGBT is smaller than that of the thyristor. For this reason, for example, when a high instantaneous overload capability that can withstand 600% of the rated current for 2 seconds is required, an element having a current capacity sufficiently larger than the current in a steady state must be used. High cost. Further, the voltage drop and loss when the IGBT is on are larger than those of the thyristor.
In addition, although a high-speed circuit breaker may be used instead of a semiconductor switch such as a thyristor or IGBT, it has the disadvantages of large external dimensions and weight and high cost.
JP 2003-87999 A JP-A-5-292686

  The problem to be solved by the present invention is that it is difficult to easily provide an AC switch device and a power supply device that satisfy both the cost and the breaking speed.

  The present invention for solving the above-mentioned problems has a first thyristor for connection between an AC power supply terminal and a load, and a directionality for flowing a current in a direction opposite to that of the first thyristor. The present invention relates to an AC switch device comprising a self-extinguishing semiconductor switch connected in reverse parallel to one thyristor.

In addition, as shown in claim 2, it is desirable to further include a second thyristor connected in reverse parallel to the first thyristor.
According to a third aspect of the present invention, it is preferable that the self-extinguishing semiconductor switch comprises a series circuit of an IGBT and a backflow prevention diode.
According to a fourth aspect of the present invention, at least first and second AC power supply terminals for supplying an AC voltage to the load, and a first connected between the first AC power supply terminal and the load. And a second AC switch device connected between the second AC power supply terminal and the load, each of the first and second AC switch devices. Are connected in reverse parallel to the first thyristor with a first thyristor connected between the AC power supply terminal and the load, and having a direction of flowing a current in a direction opposite to that of the first thyristor. It is desirable to comprise a self-extinguishing semiconductor switch.
According to a fifth aspect of the present invention, each of the first and second AC switch devices further includes a second thyristor connected in reverse parallel to the first thyristor, and the first thyristor during normal power supply. Control means for turning on the first thyristor and the self-extinguishing semiconductor switch, keeping the second thyristor in an off state, and turning on the second thyristor only when power supply is abnormal. It is desirable.
According to a sixth aspect of the present invention, it is desirable that the self-extinguishing type semiconductor switch comprises a series circuit of an IGBT and a backflow prevention diode.
Further, according to a seventh aspect of the present invention, the control means includes an overcurrent detection circuit for detecting that a current supplied from the AC power supply terminal to the load is greater than a predetermined value, and the overcurrent The first thyristor is turned on when the overcurrent is not detected by the detection circuit, and the second thyristor is not turned on. When the overcurrent is detected by the overcurrent detection circuit, the first thyristor is turned on. A thyristor control circuit that turns on both the first and second thyristors; and a switch control circuit that turns on the self-extinguishing semiconductor switch in both a normal state and an overcurrent detection state. desirable.
According to another aspect of the present invention, the control means includes an abnormality detection circuit that detects that the current supply through the self-extinguishing semiconductor switch has stopped due to an abnormality, and an output of the abnormality detection circuit indicates an abnormality. The first thyristor is on-controlled when not normal, the second thyristor is not on-controlled, and both the first and second thyristors are controlled when the output of the abnormality detection circuit indicates an abnormality. It is desirable to have a thyristor control circuit that performs on-control.
According to a ninth aspect of the present invention, the control means detects a voltage abnormality of the AC power supply terminal, and stops the on control of the first thyristor and the self-extinguishing semiconductor switch when the abnormality is detected. It is desirable to have a power supply abnormality detection circuit.

The AC switch composed of the anti-parallel connection of the thyristor and the self-extinguishing semiconductor switch according to the present invention can compensate for the disadvantage of delay in turn-off due to the natural commutation of the thyristor with the self-extinguishing semiconductor switch. This can provide an AC switch with low turn-off delay despite low cost.
Further, according to the inventions of claims 2 and 5, it is possible to easily achieve the countermeasure or protection of the abnormality of the self-extinguishing semiconductor switch.
Moreover, according to the invention of Claim 3 and 6, the self-arc type semiconductor switch which flows only the electric current of one direction can be comprised easily.
According to the fourth aspect of the invention, the combination of the self-extinguishing semiconductor switch and the thyristor can cut off the power supply with little delay and reduce the cost of the power supply device.
According to the invention of claim 7, the self-extinguishing semiconductor switch can be easily protected from overcurrent.
According to the invention of claim 8, it is possible to easily achieve the continuation of power supply when the self-extinguishing semiconductor switch or the control circuit is abnormal.
According to the ninth aspect of the present invention, it is possible to quickly cut off the power supply when the power supply is abnormal.

  Next, an embodiment of the present invention will be described with reference to FIGS.

  The power supply apparatus having an uninterruptible power supply function according to the first embodiment of the present invention shown in FIG. 1 includes first, second and third AC power supply terminals 1a and 1b connected to a 200V three-phase commercial AC power supply. 1c, first, second and third AC switches 2a, 2b and 2c as AC switch devices, first, second and third power supply lines 3a, 3b and 3c, and three-phase bidirectional Power converter 4, 300-400V storage battery 5, thyristor control circuit 6, IGBT control circuit 7, power supply abnormality detection circuit 8, first, second and third current detectors 9a, 9b, 9c The overcurrent detection circuit 10 and the IGBT abnormality detection circuit 11 are configured to supply power to the load 12 substantially without a power failure.

  The first, second and third AC switches 2a, 2b and 2c are connected to the first, second and third AC power terminals 1a, 1b and 1c and the load 12, respectively. The power supply lines 3a, 3b, and 3c are connected in series. Since the first, second and third AC switches 2a, 2b and 2c have the same configuration, the reference numerals of the circuit elements constituting them are distinguished by the subscripts a, b and c, and the first AC switch Only the configuration and operation of the switch 2a will be described in detail, and detailed description of the configuration and operation of the second and third AC switches 2b and 2c will be omitted.

  The first AC switch 2a includes first and second thyristors S1a and S2a, an IGBT (insulated gate bipolar transistor) Qa, and a backflow prevention diode Da. The first and second thyristors S1a and S2a are called reverse-blocking three-terminal thyristors, SCRs, or control rectifiers, and are connected in reverse parallel to each other and connected in series to the first power supply line 3a. . The first and second thyristors S1a and S2a are incapable of self-extinguishing and have a characteristic that the current continues to flow until the current flowing therethrough becomes equal to or lower than the holding current. Accordingly, the turn-off of the first and second thyristors Sla and Slb is delayed by a maximum of half an alternating cycle.

  The IGBT Qa as a self-extinguishing semiconductor switch is connected in reverse parallel to the first thyristor S1a via a backflow prevention diode Da. As is well known, the IGBT Qa incorporates a diode called a parasitic diode or a body diode, so that a current can flow in the reverse direction. For this reason, in this embodiment, a backflow prevention diode Da is connected in series to the IGBT Qa. A self-extinguishing semiconductor switch such as a bipolar transistor, FET, or SIT (electrostatic induction transistor) can be used in place of the IGBT Qa. When the self-extinguishing semiconductor switch has a reverse blocking function, the reverse flow blocking diode Da shown in FIG. 1 can be omitted.

  The second thyristor S2a has the same direction as the IGBT Qa. Therefore, even if the second thyristor S2a is omitted, it functions as an AC switch. For this reason, the second thyristor S2a can be omitted in the case of a power supply apparatus that is less likely to cause an abnormal state or an overcurrent state. However, in the present embodiment, the second thyristor S2a is provided to cope with the abnormality of the IGBT Qa and the overcurrent.

  The IGBT Qa can turn off only one-way current in a self-extinguishing manner. However, the first, second, and third IGBTs Qa, Qb, and Qc are connected to the first, second, and third power supply lines 3a, 3b, and 3c. The currents in both the positive direction and the negative direction of the power supply lines 3a, 3b, and 3c can be turned off with a small delay.

  The bidirectional power converter 4 for constituting the uninterruptible power supply has an AC-DC conversion function, a DC-AC conversion function, and a power factor improvement function, and this three-phase AC terminal is connected to the load 12. And connected to the first, second and third AC power supply terminals 1a, 1b and 1c via the first, second and third AC switches 2a, 2b and 2c having the same configuration. The terminal is connected to the storage battery 5. Therefore, when electric power is normally supplied from the first, second and third AC power supply terminals 1a, 1b and 1c, the three-phase AC voltage is converted into a DC voltage to charge the storage battery 5. When the voltage supplied from the first, second and third AC power supply terminals 1a, 1b and 1c is reduced or stopped, or abnormally increased, the first, second and third AC switches 2a, Since 2b and 2c are simultaneously turned off and the bidirectional power converter 4 is simultaneously inverter controlled, the direct current of the storage battery 5 is converted into alternating current and supplied to the load 12.

  The power supply abnormality detection circuit 8 is connected to the first, second and third AC power supply terminals 1a, 1b and 1c, and when the detected value of the power supply voltage falls below a predetermined lower limit reference value, and the power supply voltage When the detected value of the signal becomes higher than a predetermined upper limit reference value, signals for simultaneously turning off the first, second and third AC switches 2a, 2b and 2c are sent to the thyristor control circuit 6 and the IGBT control circuit 7. And an inverter command, that is, a DC-AC conversion command is sent to the bidirectional power converter 4. When the power supply voltage returns to normal, the power supply abnormality detection circuit 8 sends a command to turn on the first, second and third AC switches 2a, 2b and 2c simultaneously to the thyristor control circuit 6 and the IGBT control circuit 7, and An AC-DC conversion command is sent to the bidirectional power converter 4.

  The first, second, and third current detectors 9a, 9b, 9c are made of, for example, a CT (current transformer), and are connected to the first, second, and third power supply lines 3a, 3b, 3c. Therefore, a current detection signal indicating the current of the power supply lines 3a, 3b, 3c is obtained from the current detectors 9a, 9b, 9c.

  The overcurrent detection circuit 10 detects whether or not the power supply lines 3a, 3b, 3c are in an overcurrent state based on the outputs of the first, second, and third current detectors 9a, 9b, 9c. The result is sent to the thyristor control circuit 6. FIG. 2 schematically shows one phase of the overcurrent detection circuit 10 of FIG. The overcurrent detection circuit 10 includes a rectifying / smoothing circuit 10a connected to the current detector 9a, a reference voltage source 10b, and a comparator 10c. The reference voltage source 10b generates a predetermined reference value of the overcurrent level. The comparator 10c outputs a first signal such as a low level signal when the voltage level of the current detection signal obtained from the rectifying and smoothing circuit 10a is lower than the reference voltage of the reference voltage source 10b, and a second signal such as high when the voltage level is high. Output level signal. The second-phase and third-phase overcurrent detection circuits omitted in FIG. 2 are also formed in the same manner as the first phase.

  An IGBT abnormality detection circuit 11 as an abnormality detection circuit of a self-extinguishing semiconductor switch or its control circuit includes first, second and third current detectors 9a, 9b and 9c and first, second and third current detectors. Connected to the AC power supply terminals 1a, 1b, 1c and the power supply abnormality detection circuit 8, the failure of the IGBTs Qa, Qb, c and the failure of the control circuit 7 are detected, and the thyristor control circuit 6 is controlled. FIG. 2 schematically shows one phase of the IGBT abnormality detection circuit 11 of FIG. The extraction circuit 11a connected to the current detector 9a, the AC power supply terminals 1a, 1b, and 1c and the power supply abnormality detection line 8a supplies current to the IGBT Qa by the power supply voltage Vin when the output of the power supply abnormality detection circuit 8 indicates normal. Determine the duration of the flow. For example, the positive half cycle of the voltage supplied from the first AC power supply terminal 1a is set as a period during which the current of the IGBT Qa flows and this is set as the extraction period. The extraction switch included in the extraction circuit 11a is turned on only during the extraction period to extract the output of the current detector 9a and send it to the smoothing circuit 11b. The smoothing circuit 11b integrates the current of the IGBTQa of a plurality of cycles of AC voltage and sends it to the comparator 11c. The reference voltage of the reference voltage source 11d is set so as to correspond to a value slightly higher than zero of the current of the power supply line 3a. When the output of the smoothing circuit 11b is normal, which is higher than the reference value of the reference voltage source 11d, the output of the comparator 11c is kept in the first signal (for example, low level signal) state. 2 (for example, a high level signal), and the abnormality of the IGBT Qa is detected. In short, in this embodiment, the abnormality is determined by detecting that no current flows in the IGBT Qa during the period in which the current should flow. The abnormality detection of the IGBT Qa and the IGBT control circuit 7 is not limited to the method shown in FIG. 2. For example, a failure of the IGBT Qa is caused by connecting a current detector to the current path of only the IGBT Qa and no current is flowing through the IGBT Qa. Alternatively, it can be regarded as a failure of the IGBT control circuit 7. Further, the temperature of the IGBT Qa is detected, and when this temperature is lower than a predetermined temperature, it can be determined that the IGBT Qa or the control circuit 7 is faulty. It should be noted that the second and third phase IGBTs Qb and Qc are detected in the same manner as the first phase IGBT Qa is detected.

  The thyristor control circuit 6 forms gate control signals V1a, V2a, V1b, V2b, V1c, and V2c for the six thyristors S1a, S2a, S1b, S2b, S1c, and S2c by a well-known method. Send to terminal. In this embodiment, the transmission of the gate control signals of the thyristors S2a, S2b, and S2c is controlled based on the output of the overcurrent detection circuit 10 and the output of the IGBT abnormality detection circuit 11.

  FIG. 2 schematically shows only one phase of the thyristor control circuit 6 of FIG. In FIG. 2, in order to control the first and second thyristors S1a and S2a separately, first and second thyristor control circuits 6a and 6b are provided. The first thyristor control circuit 6a outputs a first gate control signal V1a for controlling the first thyristor S1a in FIG. 1, and is based on the signal on the output line 8a of the power supply abnormality detection circuit 8. The transmission of one gate control signal V1a is controlled. That is, the first thyristor control circuit 6a sends out the first gate control signal V1a for continuously turning on the first thyristor S1a when the output of the power supply abnormality detection circuit 8 indicates normality. When the output of the power supply abnormality detection circuit 8 indicates an abnormality, the transmission of the first gate control signal V1a is stopped.

The second thyristor control circuit 6b sends out the second gate control signal V2a only when the conduction of the second thyristor S2a is required due to an overcurrent or IGBT abnormality. For this reason, the overcurrent detection circuit 10 and the IGBT abnormality detection circuit 11 are connected to the second thyristor control circuit 6b.
Further, a power supply abnormality detection circuit 8 is connected to the second thyristor control circuit 6b in order to keep the second thyristor S2a off when a power supply abnormality occurs.

  The thyristor control circuits for the second phase thyristors S1b and S2b and the third phase thyristors S1c and S2c are also configured in the same manner as the first phase thyristor control circuits 6a and 6b in FIG.

FIG. 3 shows the state of each part when the output line 8a of the power supply abnormality detection circuit 8 is changed from the low level to the high level indicating abnormality as shown in FIG. 3 (K) in the power supply apparatus of FIG. . In FIG. 3, when the power supply voltage Vin drops below the predetermined level Vr just before t1, as shown in FIG. 3A, the predetermined level Vr and the power supply voltage in the lower limit detection comparator included in the power supply abnormality detection circuit 8 A high-level output indicating an abnormality based on the comparison with Vin occurs at time t1 as shown in FIG. The thyristor control circuit 6 and the IGBT control circuit 7 respond to the abnormality detection signal shown in FIG. 3 (K) at the time t1 and control the gate control signals V1a, V2a, V1b of all thyristors S1a, S2a, S1b, S2b, S1c, S2c. Transmission of V2b, V1c, and V2c is prohibited, and IGBTs Qa, Qb, and Qc are turned off. The gate control signals V2a, V2b, and V2c of the thyristors S2a, S2b, and S2c kept in the off state before t1 due to the normal state are the power failure occurrence points as shown in FIGS. 3 (C), (F), and (I). The gate control signals V1a, V1b, and V1c of the thyristors S1a, S1b, and S1c that have not been changed at t1 but were turned on in the normal state before t1 are as shown in FIGS. 3B, 3E, and 3H. At a time point t1, the level is changed to a low level, and the thyristors S1a, S1b, S1c are turned off. Further, the control signals Vqa, Vqb, and Vqc of the IGBTs Qa, Qb, and Qc change from a high level to a low level at t1 as shown in FIGS. 3D, 3G, and 3J, and are turned off.
As already described, since the thyristors S1a, S1b, and S1c are not self-extinguishing types but are natural commutation types, current tends to flow until the holding current becomes lower than the holding current. However, since IGBTs Qa, Qb, Qc of different phases are connected in series to the thyristors S1a, S1b, S1c via the load 12 or the bidirectional power converter 4, the IGBTs Qa, Qb, Qc are turned off simultaneously. The currents of the thyristors S1a, S1b, and S1c are also zero or less than the holding current. As a result, the thyristors S1a, S1b, S1c, and the IGBTs Qa, Qb, Qc can be turned off within a quarter cycle of the AC power supply voltage that is generally regarded as an uninterrupted time from the abnormality detection time t1. As described above, when the first, second and third AC switches 2a, 2b and 2c are quickly turned off, the power of the storage battery 5 is switched between the bidirectional power converter 4 and the AC switches 2a, 2b and 2c. Therefore, it is possible to prevent wasteful supply to the AC power supply terminals 1a, 1b, and 1c, and to increase the power supply possible time for the load 12 based on the storage battery 5.

  FIG. 4 shows the state of each part of FIG. 1 when overcurrent is detected and when the IGBT is abnormal. As shown in FIG. 4 (A), when the output Voc of the overcurrent detection circuit 10 changes to a high level indicating an overcurrent state at time t1, the gate control signal V2a of the second thyristor S2a is shown in FIG. 4 (D). So that the second thyristor S2a is turned on. At the same time, the gate control signals V2b and V2c, not shown in FIG. The thyristors S2a, S2b, and S2c have a polarity that allows current to flow in the same direction as the IGBTs Qa, Qb, and Qc, and the on-voltage drop of the thyristor is lower than the on-voltage drop of the series circuit of IGBT and diode. Most of the current that flows to the IGBT side flows to the thyristor side. Thereby, destruction of IGBTQa, Qb, Qc can be prevented. As described above, the IGBT's instantaneous overcurrent withstand capability is inferior to that of the thyristor. Therefore, the IGBT Qa, Qb, and Qc are not easily destroyed by passing the current that has flowed on the IGBT side to the thyristor side.

  After the time t2 in FIG. 4, the operation when the IGBTs Qa, Qb and Qc are abnormal will be described. For example, as shown in FIG. 4E, the control signal Vqa is supplied to the IGBT Qa from the time t3 when the IGBT Qa is in an open state, that is, a switch-off state, even though the control signal Vqa of the IGBT Qa indicates ON control. When the failure of the IGBT control circuit 7 that cannot be performed occurs, the current passing through the IGBT Qa becomes zero. As a result, the output Vdef of the IGBT abnormality detection circuit 11 is changed to a high level at time t3 as shown in FIG. 4B, and the gate control signal V2a of the second thyristor S2a is as shown in FIG. 4D. It becomes a high level, a current flows through the second thyristor S2a instead of the IGBT Qa, and it is possible to prevent the power supply from the AC power supply terminals 1a, 1b and 1c from being stopped. In the case of the abnormality of the second and third IGBTs Qb and Qc, the same operation as that in the case of the abnormality of the first IGBT Qa occurs.

This embodiment has the following effects.
(1) Since the IGBTs Qa, Qb, Qc as self-extinguishing semiconductor elements are connected in reverse parallel to the thyristors S1a, S1b, S1c, the AC power supply terminals 1a, 1b, 1c are quickly connected to the load 12 and It can be disconnected from the bidirectional power converter 4.
(2) By turning on the thyristors S2a, S2b, and S2c at the time of overcurrent, the IGBTs Qa, Qb, and Qc having relatively small instantaneous overcurrent immunity can be protected.
(3) When the IGBT Qa, Qb, Qc or the IGBT control circuit 7 fails, the power supply can be continued by turning on the thyristors S2a, S2b, S2c, and the reliability is improved.
(4) By connecting AC switches 2a, 2b, and 2c in series to a plurality of power supply lines 3a, 3b, and 3c, only one IGBT Qa, Qb, and Qc is included in each of the AC switches 2a, 2b, and 2c. Thus, the positive and negative currents can be cut off with a small delay.
(5) At a constant time, the loss of the AC switches 2a, 2b, and 2c of this embodiment is smaller than the loss of the conventional AC switch in which two IGBTs are connected in antiparallel. For this reason, the efficiency of an electric power supply apparatus can be improved.

The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible.
(1) Instead of IGBTs Qa, Qb, Qc, IGBTs, transistors, etc. that do not incorporate antiparallel diodes can be used.
(2) The reverse current blocking diodes Da, Db, Dc can be omitted when a self-extinguishing semiconductor element such as a transistor having a reverse blocking function is used instead of the IGBTs Qa, Qb, Qc.
(3) As shown in FIG. 5, a series circuit of another IGBT Qa 'and another backflow prevention diode Da' can be added to the first AC switch 2a. That is, the series circuit of the second IGBT Qa 'and the second backflow prevention diode Da' can be connected in reverse parallel to the series circuit of the first IGBT Qa and the first backflow prevention diode Da. In this case, the second and third AC switches 2b and 2c are also modified to have the same configuration as the first AC switch 2a in FIG. The second IGBT Qa 'in FIG. 5 is turned on only when the first thyristor S1a is faulty or overcurrent, or both the first and second IGBTs Qa, Qa' are turned on during normal power supply. The second thyristors S1a and S2a can be turned on only when the IGBTs Qa and Qb are out of order or overcurrent. The IGBTs Qa and Qa 'in FIG. 5 can be replaced with other self-extinguishing semiconductor switches such as transistors, FETs, and SITs.
(4) As shown in FIG. 6, in the first AC switch 2a, another IGBT Qa 'can be connected in series to the IGBT Qa. The second and third AC switches Qb and Qc can also be configured in the same way as in FIG. In FIG. 6, the first and second IGBTs Qa and Qa 'have first and second built-in diodes D1 and D2 connected in reverse parallel to the first and second main switches Q1 and Q2. When the first IGBT Qa is on-controlled during normal power supply as in FIG. 1, the built-in diode D2 of the second IGBT Qa 'functions in the same manner as the backflow prevention diode Da in FIG. The first and second IGBTs Qa and Qa 'can be simultaneously on-controlled and simultaneously off-controlled. Further, the second IGBT Qa 'can be kept off during normal power feeding, and can be controlled to be turned on only during overcurrent or when the first thyristor S1a is abnormal. In place of the first and second IGBTs Qa and Qa 'in FIG. 6, another self-extinguishing semiconductor switch such as a transistor, FET, SIT or the like having a built-in diode D1, D2 can be used. When using a self-extinguishing semiconductor switch that does not include diodes D1 and D2, individual diodes can be connected in place of the diodes D1 and D2 in FIG.
(5) The second thyristors S2a, S2b, S2c of each AC switch 2a, 2b, 2c can be omitted.
(6) Instead of the storage battery 5, an electric storage device such as an electrolytic capacitor, an accumulator such as an electric double layer, an accumulator for a cycle, or the like can be used.

  The present invention can be used for a power supply device such as an uninterruptible power supply.

It is a circuit diagram which shows the electric power supply apparatus according to Example 1 of this invention. It is a circuit diagram which shows a part of FIG. 1 in detail. It is a wave form diagram which shows the state of each part of FIG. 1 for demonstrating the OFF control of an alternating current switch. It is a wave form diagram which shows the state of each part of FIG. 1 at the time of overcurrent and IGBT abnormality. It is a circuit diagram which shows the alternating current switch of a modification. It is a circuit diagram which shows the alternating current switch of another modification.

Explanation of symbols

1a, 1b, 1c AC power supply terminal 2a, 2b, 2c AC switch S1a, S2a, S1b, S2b, S1c, S2c Thyristor Qa, Qb, Qc IGBT
4 Bidirectional power converter 5 Storage battery 6 Thyristor control circuit 7 IGBT control circuit 8 Power supply abnormality detection circuit 10 Overcurrent detection circuit 11 IGBT abnormality detection circuit 12 Load

Claims (9)

A first thyristor for connection between the AC power supply terminal and the load;
An AC switching device comprising a self-extinguishing type semiconductor switch connected in reverse parallel to the first thyristor and having a direction to flow a current in the opposite direction to the first thyristor.   2. The AC switch device according to claim 1, further comprising a second thyristor connected in reverse parallel to the first thyristor.   3. The AC switch device according to claim 1, wherein the self-extinguishing type semiconductor switch comprises a series circuit of an IGBT and a backflow prevention diode. At least first and second AC power supply terminals for supplying an AC voltage to a load; a first AC switch device connected between the first AC power supply terminal and the load; and the second A second AC switch device connected between the AC power supply terminal and the load;
Each of the first and second AC switch devices includes:
A first thyristor connected between the AC power supply terminal and the load;
A power supply device comprising a self-extinguishing semiconductor switch connected in reverse parallel to the first thyristor and having a directivity for passing a current in a direction opposite to that of the first thyristor. Each of the first and second AC switch devices further includes:
A second thyristor connected in antiparallel to the first thyristor;
When the power is normally supplied, the first thyristor and the self-extinguishing semiconductor switch are turned on, the second thyristor is kept off, and the second thyristor is turned on only when power supply is abnormal. The power supply apparatus according to claim 4, further comprising a control unit.   6. The power supply apparatus according to claim 4, wherein the self-extinguishing type semiconductor switch comprises a series circuit of an IGBT and a backflow prevention diode. The control means includes
An overcurrent detection circuit for detecting that the current supplied from the AC power supply terminal to the load is greater than a predetermined value;
When the overcurrent is not detected by the overcurrent detection circuit, the first thyristor is turned on in the normal state, the second thyristor is not turned on, and the overcurrent detection circuit detects the overcurrent. Sometimes a thyristor control circuit for turning on both the first and second thyristors;
6. The power supply apparatus according to claim 5, further comprising a switch control circuit that controls the self-extinguishing semiconductor switch to be turned on in both a normal state and an overcurrent detection state. The control means includes
An abnormality detection circuit for detecting that the current supply through the self-extinguishing semiconductor switch has stopped due to an abnormality, and
The first thyristor is on-controlled when the output of the abnormality detection circuit does not indicate an abnormality, and the second thyristor is not controlled on, and the output of the abnormality detection circuit indicates an abnormality when the output is abnormal 6. The power supply apparatus according to claim 5, further comprising a thyristor control circuit that controls both of the first and second thyristors. The control means includes
It has a power supply abnormality detection circuit for detecting a voltage abnormality of the AC power supply terminal and stopping on-control of the first thyristor and the self-extinguishing semiconductor switch when the abnormality is detected. The power supply device according to claim 5.

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