JP2812123B2 - Power semiconductor device protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a power semiconductor device.

[0002]

2. Description of the Related Art An example in which a protection fuse is inserted in each arm as a conventional protection device for a power semiconductor device will be described. That is, FIG. 4 is a configuration diagram showing a protection device for a power semiconductor device of a voltage source converter. FIG. 5 shows the connection relationship with the AC power supply line when the power semiconductor device of FIG. 4 is used as an automatic reactive power compensator. In FIG. 4, reference numeral 1 denotes a DC capacitor serving as a DC voltage source, which is charged from a DC power supply on the DC side when handling active power. The DC capacitor 1 is charged from the AC side, and is controlled to a constant value by controlling a power semiconductor device described later. Reference numerals 2a to 21 denote protection fuses provided above and below each arm, and reference numerals 3a to 31 denote power semiconductor devices as voltage-source converters, for example, thyristors, GTOs, and transistors. Reference numerals 4A to 4C denote six-phase inverters, and the insides of the six-phase inverters 4A and 4C are omitted. Reference numeral 5 denotes a series multiplex transformer for synthesizing the respective phase voltages of the six-phase inverters 4A to 4C. Reference numeral 6 denotes a control device, 7 denotes a circuit breaker, and 8 denotes a power supply.

Next, the operation will be described. The DC voltage of the DC capacitor 1 is converted into an AC voltage by applying the ignition signal generated by the control device 6 to the power semiconductor devices 3a to 3l. 6-phase inverter 4A-4
C is connected to the winding 5A-1 of the series multiplex transformer 5.
5A-3, 5B-1 to 5B-3, 5C-1 to 5C-3
, The primary side output voltage has a shape close to a sine wave.

The primary output voltage is connected to a power supply 8 through a circuit breaker 7. In the case of such a voltage source converter, a 180 ° pulse using a short-circuit prevention period is given to the upper and lower arms, but the upper and lower arms are short-circuited due to an overcurrent, an ignition signal abnormality, a fluctuation in the power supply 8, and the like. If this occurs, a large amount of current will flow because the large-capacity DC capacitor 1 is a voltage source. For this reason, the protection fuse 2 of the upper and lower arms
The short circuit current is interrupted by a to 21 to protect the power semiconductor devices 3a to 3e and other devices, and the current flowing from the DC capacitor 1 through the anti-parallel circuit of the power semiconductor devices 3a to 3l. doing.

[0005]

Since the conventional protection device for a power semiconductor device is constructed as described above, the number of necessary protection fuses is 12 for a 6-phase inverter, which is expensive. In addition, with the increase in the capacity and the voltage of the power semiconductor device, in the conventional method, the same current flows through the applicable protective fuse and the element of the power semiconductor device. Allowable I ² T
(I is the current flowing through the protection fuse, T is the time and I ²
T is the Joule integral value. ), The I ² T of the protection fuse becomes larger, and there is a problem that the protection coordination with the protection fuse becomes impossible. The present invention has been made in order to solve the above-described problems, and enables protection of a power semiconductor device, in particular, a power semiconductor device used in a voltage-source converter, and the number of protection fuses. And an inexpensive power semiconductor device protection device.

[0006]

According to the first aspect of the present invention, there is provided a protection device for a power semiconductor device, comprising: a series multiplex transformer; a group of polyphase inverters connected to the series multiplex transformer; A DC capacitor that becomes a DC power supply for the inverter group and is connected to the DC side, a protective fuse installed only on the DC side, a short-circuit detector that detects a short-circuit of the DC arm of the multi-phase inverter group, and a short-circuit detector that detects the short-circuit. An adder for adding a signal for each inverter group, a fault selection circuit for selecting whether to perform forced ignition or gate cutoff based on the signal of the adder, and an inverter group based on the result of the fault selection circuit. And a gate generation circuit that generates the gate signal of

According to a second aspect of the present invention, there is provided a protection device for a power semiconductor device, comprising: a series multiplex transformer; a group of polyphase inverters connected to the series multiplex transformer; A large number of connected DC capacitors, a protective fuse connected in series to each DC capacitor, a short-circuit detector for detecting a short-circuit of the DC arm of the polyphase inverter group, and a signal detected by the short-circuit detector. An adder for adding for each inverter, a fault selection circuit for selecting whether to perform forced ignition or gate cutoff based on the signal of the adder, and a gate signal for each inverter based on the result of the fault selection circuit. And a gate generation circuit that generates the signal.

Further, a protection device for a power semiconductor device according to a third aspect of the present invention is a series multiplex transformer, a group of polyphase inverters connected to the series multiplex transformer, and a DC power source for the group of polyphase inverters, and A large number of connected DC capacitors, a protective fuse connected in series to each DC capacitor, a short-circuit detector for detecting a short-circuit of the DC arm of the multi-phase inverter group, and an inverter for detecting a signal detected by the short-circuit detector. An adder for adding for each group, a fault selection circuit for selecting whether to perform forced ignition or gate cutoff based on the signal of the adder, and a gate signal for each inverter group based on the result of the fault selection circuit. And a series connection of a semiconductor switch and a resistor between the DC terminals to prevent DC overvoltage during protection fuse operation. It includes those were.

[0009]

According to the first aspect of the present invention, since the protection fuse on the DC side forcibly fires each arm of the polyphase inverter to which the arm belongs after the short-circuit detection of the arm, the fuse passing current is reduced. It will increase and be cut off quickly. As a result, the passing current of each power semiconductor device is divided and reduced, so that protection coordination of the power semiconductor devices becomes possible. Also, since the other polyphase inverters are gated off at the same time, the current flowing from the power supply through the anti-parallel circuit of the power semiconductor device does not increase due to the winding effect of the series multiple transformer. According to the second aspect of the present invention, each capacitor is provided with a protective fuse,
The DC capacitor is protected while maintaining protection coordination. Furthermore, according to the third aspect of the present invention, since the resistor and the semiconductor switch are provided in parallel with the DC capacitor, DC overvoltage during operation of the protection fuse is prevented.

[0010]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention, and is a configuration diagram of a protection device for a power semiconductor device of a voltage source converter (18 groups of 6-phase inverters 3 groups) connected to a series multiplex transformer. . In FIG. 1, 1 is a DC capacitor serving as a DC voltage source, 2A to 2C are protection fuses which are provided above and below each arm and have only one DC side, 3a
Reference numerals 31 to 31 denote power semiconductor devices that are turned on / off by the ignition signal output by the control device 6, 4A to 4C are six-phase inverters, and 5 is a composite of output voltages of these six-phase inverters 4A to 4C. A series multiplex transformer having a voltage close to a sine wave, the output of which is connected to a power supply 8 by a circuit breaker 7. 9a to 9l are d of the power semiconductor devices 3a to 3l.
i / dt suppressing anode reactor, 10a to 10f short-circuit detectors for detecting arm short-circuits, 11A to 11C short-circuit fault signal adders for adding arm short-circuit signals for each of the 6-phase inverters 4A to 4C, 12 A fault selection circuit for selecting forced firing or gate cut-off based on the arm short-circuit signal of each of the six-phase inverters 4A to 4C, 13 is a normal signal, 14 is an ignition based on the normal signal 13 and the output of the fault selection circuit 12, This is a gate generation circuit that generates a signal.

Next, the operation will be described. In the power semiconductor device protection device of the present invention having the above-described configuration, in order to enable protection of a large-capacity power semiconductor device, the protection fuses 2 </ b> A to 2 </ b> C need to have an increased current passing therethrough. It is necessary to cut off 2A to 2C quickly, to reduce the current passing through each of the power semiconductor devices 3a to 3l, and to reduce the sneak current from the power supply 8 side. Therefore, in the present embodiment, short-circuits of the upper and lower arms are detected in a short time by the short-circuit detectors 10a to 10f, and added by the short-circuit fault signal adders 11A to 11C for each of the six-phase inverters 4A to 4C. , Each 6-phase inverter 4
Detects arm short circuits every A to 4C. That is, taking the short-circuit fault signal adder 11B as an example, the six-phase inverter 4
B are connected to the respective short-circuit detectors 10a.
Ｆ10f, and the logical sum of these short-circuit detection signals is taken by the short-circuit fault signal adder 11B (ON when one or more are detected), and the arm short-circuit detection signals for six phases are sent to the control device 6. The same applies to each of the six-phase inverters 4A and 4C.
The power semiconductor devices of the six-phase inverter whose arms are short-circuited by the fault selection circuit 12 are forcibly fired on all arms, and all the power semiconductor devices of the other six-phase inverters are gated off. By such an operation, the protection fuses 2A to
The current flowing through the 2C increases, the cutoff becomes faster, and the first short-circuited arm current is reduced by forcibly firing all the arms of the same group to the other 5 in the same 6-phase inverter.
Since the current is divided into the current of the arm, the current passing through the power semiconductor device can be reduced. At this time, looking at the series multiplex transformer 5 from the current side, the windings of the inverter group performing the forced ignition are short-circuited due to the anti-parallel circuit of the power semiconductor device. Since the inverter group connected to the series winding blocks the gate, a large short-circuit current does not flow. Therefore, a large sneak current from the current side can be prevented.

As described above, the power semiconductor devices 3a to 3l
The protection fuses 2A to 2C are cut off before reaching the breakdown passing current to cut off the circuit, and protection is performed by preventing a sneak current from the power supply 8 side. In the above embodiment, the six-phase inverters 4A to 4A
Although the example of the C, 3 series multiplex transformer 5 is shown, the same effect can be obtained with an n-phase inverter and an m series multiplex transformer.

[Embodiment 2] In Embodiment 1 described above, one having one DC capacitor 1 is shown. However, when the capacity becomes large, the DC capacitor 1 is often connected in multiple parallel. As shown in FIG.
By providing protection fuses 15a to 15f individually for a to 1f and combining them, protection of the capacitor alone and protection of the power semiconductor devices 3a to 31 can be performed. In other words, if a short-circuit fault occurs in one of the individual DC capacitors, the other capacitor current concentrates on the protective fuse on the faulty capacitor, so that it can be cut off quickly and prevent the DC capacitor from exploding. it can. When the arm short-circuit of the six-phase inverters 4A to 4C occurs, current flows from each of the DC capacitors 1a to 1f. However, according to the above embodiment, the protection fuses 2A to 2C on the inverter side are cut off and the DC capacitor 1a
The protection fuses 15a to 15f on the side of .about.1f can perform protection coordination so as not to be blown, and the same effects as in the first embodiment can be obtained. Also, the case where the number of divisions of the DC capacitor 1 is set to six has been described, but the same effect can be obtained when the number of divisions is n.

[Embodiment 3] Furthermore, in the first embodiment, the sneak current from the power supply 8 can be prevented by the effect of the series multiplex winding. In order to prevent this, the third embodiment shown in FIG. 3 uses a semiconductor switch (SW) 16, for example, a GTO and a resistor 17, to prevent DC overvoltage during protection. That is, the series multiplex transformer 5
Is m / (m-1) times, and if m is small, the voltage per winding is m / (m-1). As the sharing increases, the output of the secondary winding increases, and the power semiconductor device 3
DC capacitors 1a to 1f by the anti-parallel circuit of
May be charged at a peak, resulting in a DC overvoltage. Therefore, a semiconductor switch 16, for example, a GTO and a resistor 17 are installed in series on the DC bus, and the short-circuit detectors 10a to 10f
By turning on the semiconductor switch 16 in response to the DC short-circuit signal detected by the above, an increase in the DC voltage can be suppressed, and the same effects as in the first and second embodiments can be obtained.

[0015]

As described above, according to the first aspect of the present invention,
According to the invention described in (1), in the inverter device of the series multiplex transformer, one protection fuse is provided on the DC side for each group of n-phase inverters, the short-circuit of the DC arm is quickly detected, the forced ignition and the gate are provided for each inverter. Since the configuration is such that the cutoff is performed, it is possible to protect a large-capacity power semiconductor device, and the number of protection fuses installed above and below each arm is reduced to one with a group of inverters. There is. According to the second aspect of the present invention, by providing a protection fuse for each DC capacitor, the DC capacitor can be protected while maintaining protection coordination. Furthermore, according to the third aspect of the present invention, even when the number of series multiplex transformers is small, a DC overvoltage is prevented by installing a resistor and a semiconductor switch in parallel with a DC capacitor and controlling them in parallel. This has the effect of protecting the inverter.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing Embodiment 1 of a protection device for a power semiconductor device of the present invention.

FIG. 2 is a configuration diagram showing Embodiment 2 of the protection device for a power semiconductor device of the present invention.

FIG. 3 is a configuration diagram showing Embodiment 3 of a protection device for a power semiconductor device of the present invention.

FIG. 4 is a configuration diagram showing a conventional protection device for a power semiconductor device.

FIG. 5 is a detailed connection diagram of main parts in the conventional example of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 DC capacitor 2A to 2C Protective fuse 3a to 3l Power semiconductor device 4A to 4C 6-phase inverter 5 Series multiplex transformer 6 Control device 7 Breaker 8 Power supply 9a to 9l Anode reactor 10a to 10f Short circuit detector 11A to 11C Short circuit fault Signal adder 12 Failure selection circuit 13 Normal signal 14 Gate generation circuit 15a to 15f Protective fuse 16 Semiconductor switch 17 Resistance

Claims (3)

(57) [Claims] 1. A series multiplex transformer, a multi-phase inverter group connected to the series multiplex transformer, a DC capacitor serving as a DC power supply of the multi-phase inverter group and connected to a DC side,
A protection fuse installed only on the DC side, a short-circuit detector for detecting a short-circuit of the DC arm of the polyphase inverter group, an adder for adding a signal detected by the short-circuit detector for each inverter group, A fault selection circuit that selects whether to perform forced ignition or gate cutoff based on a signal from a heat generator, and a gate generation circuit that generates a gate signal for each inverter group based on the result of the fault selection circuit. A protection device for a power semiconductor device, characterized in that: 2. A series multiplex transformer, a multi-phase inverter group connected to the series multiplex transformer, a plurality of DC capacitors serving as a DC power source of the multi-phase inverter group and connected to the DC side, and a series connected to each DC capacitor. , A short-circuit detector for detecting a short-circuit of the DC arm of the group of polyphase inverters, an adder for adding a signal detected by the short-circuit detector for each inverter, and a signal of the adder. A fault selection circuit that selects whether to perform forced ignition or gate cutoff, and a gate generation circuit that generates a gate signal for each inverter based on the result of the fault selection circuit. Power semiconductor device protection device. 3. A series multiplex transformer, a multi-phase inverter group connected to the series multiplex transformer, a plurality of DC capacitors serving as a DC power source of the multi-phase inverter group and connected to the DC side, and a series connected to each DC capacitor. And a short-circuit detector for detecting a short-circuit of the DC arm of the polyphase inverter group, an adder for adding a signal detected by the short-circuit detector for each inverter group, and a signal of the adder. A fault selection circuit for selecting whether to perform forced ignition or gate cutoff, and a gate generation circuit for generating a gate signal for each inverter group based on the result of the fault selection circuit. A protection device for a power semiconductor device, comprising, in series, a semiconductor switch and a resistor for preventing a DC overvoltage during operation of a protection fuse.