CN102263489B

CN102263489B - Electric power switching device and its abnormal test method

Info

Publication number: CN102263489B
Application number: CN2011101195323A
Authority: CN
Inventors: 松田敏彦; 小林清隆; 执行正谦
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2006-08-22
Filing date: 2007-08-09
Publication date: 2013-04-10
Anticipated expiration: 2027-08-09
Also published as: CN102263489A; JP4338721B2; CN101132145B; CN101707432A; JP2008054375A; CN101132145A; CN101707432B; KR101083188B1; KR20080018099A

Abstract

A power conversion apparatus and a malfunction detection method thereof are provided to prevent a failure of one IGBT(Insulated Gate Bipolar Transistor) device from influencing the damage of the other IGBT device, by detecting abnormality of a gate driving circuit and the IGBT device. A power conversion apparatus uses a plurality of voltage controlled semiconductor devices. A pulse generation part(200) generates a command pulse to control on/off of the voltage controlled semiconductor device, on the basis of a command from a control circuit. A gate driving part(400a) receives the command pulse, and controls on/off operation of the voltage controlled semiconductor device by applying a voltage according to the command pulse as a gate voltage, and outputs a gate feedback signal indicating the on/off state of the voltage controlled semiconductor device. A failure detection part(300) detects a failure, by receiving the command pulse and the gate feedback signal. The failure detection part includes a detection part and a signal generation part for generating a signal to stop the command pulse for the voltage controlled semiconductor device.

Description

Power-converting device and method for detecting abnormality thereof

The application is to be that August 9, application number in 2007 are dividing an application of 2007101407636 patent application the applying date, and the invention and created name of this application is power-converting device and method for detecting abnormality thereof.

Technical field

The voltage that the present invention relates to a kind of control inputs that can be by imposing on element is controlled conducting state and is used a plurality of voltage driven type semiconductor elements to carry out the power-converting device of power converter, particularly has power-converting device and the method for detecting abnormality thereof of the unusual mechanism that detects the voltage driven type semiconductor element.

Background technology

Representational in the voltage driven type semiconductor element have an igbt (InsulatedGate Bipolar Transistor:IGBT), is widely used in power-converting device.Below, use IGBT as referring to all language of voltage driven type semiconductor element in this specification, describe.

As the protection of power-converting device, what extensively carry out is to detect the overcurrent that load short circuit because of power-converting device etc. produces, and cuts off the mode that overcurrent is protected by IGBT self.For example, the saturation voltage when detecting super-high-current from the collector voltage of IGBT rises, so that gate voltage descends, cuts off overcurrent by IGBT self, protects.In addition, the current detecting emission electrode that special use is set in IGBT that also has detects overcurrent, so that gate voltage descends, cuts off overcurrent by IGBT self, protects.

But, detect in the mode of rising of saturation voltage, if do not circulate super-high-current, collector voltage just can not rise, and therefore will inevitably detect delay.In addition, because the collector voltage of high pressure is connected with grid (gate) drive circuit, so the circuit structure complicated, and use because of the on/off action of the IGBT collector voltage of change sharp, so sometimes misoperation can occur.In addition, current detecting is set with the mode of emitter, need in IGBT circuit self, electrode be set, in the power-converting device that uses general purpose I GBT, can't use.

In the patent documentation 1, a kind of fault detection method of insulated gate formula semiconductor element is disclosed, detect the gate current of insulated gate formula semiconductor element, from the rising signals of gate current, obtain the time that is equivalent to conducting, should the time and gate command signal compare, detect both inconsistent, by coming like this to detect rapidly the fault of element.

[patent documentation 1] JP 2002-281736 communique

But, in the former mode, all adopt the mode of cutting off overcurrent by IGBT self, therefore losing in the situation of failure of current function the problem that existence can't be protected because of the fault of IGBT self etc.And then, because of the misoperation of grid drive circuit, fault etc., and IGBT has been carried out in the situation of wrong on/off control, also there is the problem that can't protect.

In addition, in the power-converting device that a plurality of IGBT consist of, the failure of current of 1 IGBT element unsuccessfully becomes the reason of the overcurrent of other IGBT elements, and existence can feed through to the problem of the breakage of a plurality of IGBT elements.

Summary of the invention

The present invention is based on above problem; purpose is to provide a kind of power-converting device; in the power-converting device that this a plurality of IGBT elements consist of; have the unusual of the unusual and IGBT element that detects reliably the grid drive circuit and protect, feed through to the defencive function of the damage of other IGBT elements by the fault that prevents like this 1 IGBT element.

The present invention has: the control of carrying out power-converting device is processed, according to the instruction from control circuit, produce to specify pulse generation section to the command pulse of the on/off state of each switch element (the voltage-type driving elements of following representative IGBT etc.), corresponding to the state of the command pulse of inputting, change the size of the gate voltage of the grid that imposes on IGBT, by like this IGBT being carried out a plurality of grid drive divisions, the IGBT that is connected with each grid drive division of on-off action and the unusual abnormity detection portion that detects grid driving mechanism and IGBT.

Specifically, grid drive division (grid drive circuit) has: corresponding to the state of command pulse, change imposes on the grid drive division of size of gate voltage of the grid of IGBT; Detect gate voltage, its size is compared with threshold value, and the output expression is greater than (H) of threshold value or less than the gate voltage judging part of the signal of (L) of threshold value; Detect gate current, its size is compared with threshold value, and the output expression is greater than (H) of threshold value or less than the gate current judging part of the signal of (L) of threshold value; The output of input gate voltage judging part and the output of gate current judging part, grid feedback generating unit and the power supply unit of the grid feedback signal of the on/off state of output expression IGBT.

In addition, abnormity detection portion (abnormal detection circuit), input is exported to the command pulse of each grid drive division by pulse generation section, and the grid feedback signal exported of a plurality of grid drive divisions that are connected with pulse generating circuit, and whether the decision instruction pulse is consistent with each grid feedback signal.Detected in the unusual situation in the result who judges, output allows pulse generation section for example all command pulses are made as the instruction of the signal (suppressing (suppress) signal) of cut-off.By like this, each IGBT that consists of power-converting device becomes cut-off state, and power-converting device stops.

Like this; among the present invention; for example when abnormality detection; all end action among all IGBT of formation power-converting device; even therefore for example 1 IGBT does not carry out failure of current; other IGBT that are arranged in this current path also become cut-off state, cut off electric current, therefore can protect other IGBT.

According to the present invention, in the power-converting device that a plurality of IGBT consist of, detect the unusual of IGBT, and for example in all IGBT that consist of power-converting device, all end action, by like this, can prevent that the fault of 1 IGBT element from feeding through to the breakage of other IGBT elements.In addition, when abnormality detection, end action by impulse mechanism, even therefore have in the unusual situation at grid driving mechanism or IGBT self, for example also all IGBT can be made as cut-off state reliably, can protect other IGBT.

Here, the grid drive division carries out following action: when command pulse is the H level, apply positive fixed voltage for the grid of IGBT, apply the action of negative fixed voltage for the L level time.Therefore, in the not corresponding situation of the level of the gate voltage and instruction pulse of IGBT, think unusual or IGBT unusual of grid driving mechanism.In addition, in general, the voltage driven type semiconductor elements such as IGBT, in the short time after having changed the gate voltage that applies, circulation is used for gate current that gate capacitance is discharged and recharged, and does not circulate when other stable.Therefore, although do not allowing the gate voltage that applies change, in the situation of the gate current more than the certain hour that circulated, can judge it is the abnormality of IGBT.

In order to utilize the characteristic of aforesaid IGBT; detect unusual; and gate voltage judging part and gate current judging part are set in the grid drive division; the inconsistent situation of gate voltage and instruction pulse except IGBT; therefore can also detect the inconsistent of gate current and instruction pulse, can detect reliably unusual or IGBT element unusual of grid drive division and protect.

Description of drawings

Fig. 1 is the block diagram of the overall structure example of expression one embodiment of the present invention.

Fig. 2 is the key diagram of the operating characteristics example of the gate voltage judging part of expression one embodiment of the present invention.

Fig. 3 is the key diagram of the operating characteristics example of the gate current judging part of expression one embodiment of the present invention.

Fig. 4 is the key diagram of the structure example of the grid feedback generating unit of expression one embodiment of the present invention.

Fig. 5 is the block diagram of the structure example of the abnormal detection circuit of expression one embodiment of the present invention.

The key diagram of action case of Fig. 6 during for expression one embodiment of the present invention normal.

The key diagram of action case (1) of Fig. 7 during for expression one embodiment of the present invention unusual.

The key diagram of action case (2) of Fig. 8 during for expression one embodiment of the present invention unusual.

Among the figure: 100-control circuit, 200-pulse generating circuit, 300-abnormal detection circuit, the 301-oscillating circuit, 302-counter, 303-exclusive disjunction circuit, 304-XOR circuit, 400-grid drive circuit, 401-grid drive division, the 402-power supply unit, 403-gate voltage judging part, 404-gate current judging part, 405-grid feedback generating unit, the 406-gate resistance, 500-IGBT

Embodiment

Below, the contrast accompanying drawing describes one embodiment of the present invention.

Fig. 1 is the block diagram of the structure example of the power-converting device of expression one embodiment of the present invention.Contrast Fig. 1 describes the overall structure of the execution mode of this example.

This example has: the control circuit 100 of the action of control power-converting device; According to the indication of control circuit 100, carrying out the command pulse generating mechanism that the command pulse of the on/off of instruction IGBT occurs is pulse generating circuit 200; By pulse generating circuit 200 input command pulses, corresponding to the state of command pulse, change the size of the gate voltage of the grid that imposes on IGBT, be grid drive circuit 400a by the grid driving mechanism that is switched on or switched off action that carries out like this IGBT; IGBT element 500a; And detect the unusual of grid drive circuit or IGBT, when unusual the generation, it is abnormal detection circuit 300 that output is used for the abnormal detection mechanism of the signal SUP that pulse generation with pulse generating circuit 200 stops.In addition, power-converting device is by a plurality of IGBT (500a～500n) and a plurality of grid drive circuit (400a～400n) consist of, but because its structure and action are all identical, so only show 1 IGBT500a and grid drive circuit 400a thereof among Fig. 1, other have been omitted.

Grid drive circuit 400a has: the command pulse RPa that input is occured by pulse generating circuit 200, and apply voltage corresponding to command pulse RPa as gate voltage, the grid drive division 401a of the on/off action of control IGBT500a; The power supply unit 402a of needed power supply in each one of grid drive circuit 400a is provided; Input gate voltage Vga, the gate voltage judging part 403a that carries out the judgement of gate voltage; Input gate current Iga, the gate current judging part 404a that carries out the judgement of gate current; Be transfused to the gate voltage feedback pulse VFBa that is exported by gate voltage judging part 403a and the gate current feedback pulse IFBa that is exported by gate current judging part 404a, grid feedback generating unit 405a and the gate resistance 406a of output grid feedback pulse FBpA.

Next, the action of grid drive circuit 400a each several part described.

Grid drive division 401a, the command pulse RPa that input is occured by pulse generating circuit 200, in the situation of H level at command pulse RPa, apply positive fixed voltage for the grid of IGBT500a, carry out turn-on action, be in the situation of L level at command pulse RPa, apply negative fixed voltage, end action.

The gate voltage Vga of gate voltage judging part 403a input IGBT500a produces gate voltage feedback pulse VFBa.The operating characteristics of gate voltage judging part 403a has been shown among Fig. 2.In this example, set fixing decision level Vth in order to judge gate voltage, in the situation of gate voltage Vga less than Vth of inputting (Vga＜Vth), be judged as the L level, under Vga is situation more than the Vth (Vga 〉=Vth), be judged as the H level, generate gate voltage feedback pulse VFBa and output corresponding to this judged result.

Gate current judging part 404a, the gate current Iga of input IGBT500a produce gate current feedback pulse IFBa as the voltage of gate resistance 406a.The operating characteristics of gate current judging part 404a has been shown among Fig. 3.In this example, set fixing judgement grade Ith in order to judge gate current, in the situation of absolute value less than Ith of the gate current Iga that inputs (Ith＜Iga＜+Ith), be judged as the L level, under the absolute value of gate current Iga is situation more than the Ith (Iga≤-Ith, Iga 〉=+Ith), be judged as the H level, generate gate current feedback pulse IFBa and output corresponding to this judged result.

Next the action of grid feedback generating unit 405a described.The structure example of this routine grid feedback generating unit 405a has been shown among Fig. 4.Among the grid feedback generating unit 405a, be transfused to the gate voltage feedback pulse VFBa that is exported by gate voltage judging part 403a, with the gate current feedback pulse IFBa that is exported by gate current judging part 404a, get the XOR of the pulse of inputting, and be grid feedback pulse FBPa output with the result as the signal of H level or L level.Grid feedback pulse FBPa is with the on/off state notifying of the IGBT500a signal to abnormal detection circuit 300.About the detailed action of grid feedback generating unit 405a, will use Fig. 6～Fig. 8 to describe.

The structure example of the abnormal detection circuit 300 in this example has been shown among Fig. 5.With reference to Fig. 5, structure and the action of abnormal detection circuit 300 described.

Abnormal detection circuit 300 has: command pulse RPa～RPn and grid feedback pulse FBPa～FBPn that input is exported by pulse generating circuit 200 detect the inconsistent XOR circuit 304a～304n between it; Exclusive disjunction circuit 303; As inconsistently having continued the mechanism of certain hour and produce the oscillating circuit 301 of the clock signal of fixed frequency in that this having occured to detect in the inconsistent situation; And the counter 302 that clock signal is counted.Among XOR circuit 304a～304n, be transfused to respectively the command pulse RPa～RPn that exports to each grid drive circuit 400a～400n from pulse generating circuit 200, feed back grid feedback pulse FBPa～FBPn that generating unit 405a～405n exports, the XOR of instruction fetch pulse RPa～RPn and grid feedback pulse FBPa～FBPn with the grid of each grid drive circuit.In the exclusive disjunction circuit 303, the result of input XOR circuit 304a～304n gets itself or logic.

Counter 302 has clock input CLK, the counter action inputted from oscillating circuit 301 and allows input EN, counter to empty input CLR and counter overflow output OVF.Counter 302, allowing input EN in counting action is H level and counter when emptying input CLR and being the H level, counts action when each time clock input CLK changes.In addition, in case empty input CLR input L level signal to counter, just to the timer zero clearing.Be provided with in advance in the timer to detect the higher limit of overflowing, in case count value has reached higher limit, just export the counter overflow output OVF of H level signal.Counter overflow output becomes the signal SUP that the pulse generation with pulse generating circuit 200 stops.

Here, counter empties input CLR and allows input EN with the counting action, has been transfused to the output signal of exclusive disjunction circuit 303.Exclusive disjunction circuit 303 is transfused to the result of XOR circuit 304a～304n, is in the situation of H level in any of the result of this XOR circuit 304a～304n, and the output signal of exclusive disjunction circuit 303 becomes the H level.Therefore, be in the situation of H level in the output signal of exclusive disjunction circuit 303, can judge in any of instruction pulse RPa～RPn and grid feedback pulse FBPa～FBPn inconsistent state has occured.

Command pulse and the inconsistent state of grid feedback pulse have the inconsistent situation of on/off state of command pulse and IGBT.In addition, in general, among the IGBT, in the short time after having changed the gate voltage that applies, flow through gate current that gate capacitance is discharged and recharged, and when other constant, do not circulate.Therefore, in the generation of the gate current of the variation that is accompanied by gate voltage, the inconsistent of command pulse and grid feedback pulse can occur in some cases.But, under this inconsistent state has continued situation that certain hour do not have to restore, can be judged as and to have sent that certain is unusual.Therefore, be provided with the higher limit of timer in this example as the threshold value that is used for judging unusual generation.Exclusive disjunction circuit 303 be output as the H level during in, timer 302 continues counting, if the state continuance of H level certain hour, count value will reach higher limit, counter overflow output OVF becomes the H level.Counter overflow output OVF is as the output signal SUP output of paired pulses circuit for generating 200, be transfused to the pulse generating circuit 200 of the output signal SUP of H level, stop all command pulses, each IGBT that consequently consists of power-converting device becomes cut-off state, and power-converting device stops.

Like this, in this example, detect reliably unusually by abnormal detection circuit 300, and pulse generating circuit 200 stops all command pulses, IGBT is made as cut-off state, by protecting sound IGBT like this.

In addition, be provided with oscillating circuit and counter in this example as being used for detecting the mechanism that the inconsistent state between command pulse and the grid feedback pulse has continued certain hour, but also can be other mechanisms, be continuously the time of H level state as long as can judge the output of exclusive disjunction circuit 303, and the situation that has exceeded threshold value notified just passable.

Next, contrast Fig. 6～Fig. 8 describes the action of this example.Fig. 6 shows the action when normal, and Fig. 7, Fig. 8 show the action when unusual.

At first, the action when normal describes with reference to Fig. 6.Among Fig. 6, from top to bottom output signal, the output signal of exclusive disjunction circuit 303, the count value of timer 302 and the output signal SUP of abnormal detection circuit 300 of gate voltage Vga, the gate current Iga of the command pulse RPa, the IGBT500a that export of indicating impulse circuit for generating 200, gate voltage feedback pulse VFBa that gate voltage judging part 403a exports, gate current feedback pulse IFBa that gate current judging part 404a exports, grid feedback pulse FBPa, XOR circuit 304a that grid feedback generating unit 405a exports.

Among the t1, when command pulse RPa became the H level from the L level, gate voltage Vga became+V from-V.At this moment, for the gate capacitance to IGBT500a is charged, positive gate current Iga circulates.Because gate voltage Vga has become+V from-V, therefore become the moment more than the decision level Vth at gate voltage Vga, the output signal of gate voltage judging part 403a is that gate voltage feedback pulse VFBa becomes the H level from the L level.

In addition, in during more than gate current Iga circulation fixed value+Ith, the output signal of gate current judging part 404a is that gate current feedback pulse IFBa becomes the H level, and after charge end and gate current Iga had become less than fixed value+Ith, gate current feedback pulse IFBa became the L level.

The XOR that grid feedbacks generating unit 405a gets gate voltage feedback pulse VFBa and gate current feedback pulse IFBa, so as the grid feedback pulse FBPa of output signal as shown in the figure.

The XOR circuit 304a of abnormal detection circuit 300, input command pulse RPa and grid feedback pulse FBPa also gets XOR, so its output signal as shown in the figure.In addition, with the output signal of XOR circuit 304a as the output of the XOR circuit 300 of input also as shown in the figure.Here, showing as an example the XOR circuit is 1 situation, so becomes the output identical with the output signal of XOR circuit 304a.

Timer 302 the output signal of exclusive disjunction circuit 303 be the H level during, increase count value, but before reaching to detect the higher limit of overflowing, turn back to the L level, so count value be cleared.Consequently the output signal SUP of abnormal detection circuit 300 can not become the H level.

Among the t2, when command pulse RPa became the L level from the H level, gate voltage Vga became-V from+V.At this moment, for the gate capacitance to IGBT500a is discharged, the gate current Iga that circulation is negative.Because gate voltage Vga has become-V from+V, therefore when gate voltage Vga became lower than decision level Vth, the output signal of gate voltage judging part 403a was that gate voltage feedback pulse VFBa becomes the L level from the H level.

In addition, gate current Iga become below certain value-Ith during in, the output signal of gate current judging part 404a is that gate current feedback pulse IFBa becomes the H level, and after charge end and gate current Iga had become greater than fixed value-Ith, gate current feedback pulse IFBa became the L level.

Carry out later on same action, the output signal SUP of abnormal detection circuit 300 can not become the H level.

Next, the action during to unusual occur describes with reference to Fig. 7.In addition, the same with shown in Fig. 6 of the signal shown in Fig. 7.

Among Fig. 7, about t3 constantly in command pulse RPa become action in the situation of L level from the H level, the action during with normal shown in Fig. 6 is identical.

Here, establish t4 and constantly among the IGBT500a fault has occured.In case break down among the IGBT500a, gate current Iga just flows out.This electric current is by through the collector electrode of IGBT, the feedback capacity between grid, and perhaps collector electrode and grid become conducting state, and collector current flows to grid, or becomes conducting state between grid, emitting stage, and the IGBT's such as circulation gate current is unusually caused.

Consequently, in case gate current Iga becomes below fixed value-Ith, then the output signal of gate current judging part 404a is that gate current feedback pulse IFBa just becomes the H level, and the output signal of grid feedback generating unit 405a is that grid feedback pulse FBPa also becomes the H level.And input command pulse RPa and grid feedback pulse FBPa and the XOR circuit 304a that gets the abnormal detection circuit 300 of XOR also become the H level, and the output of XOR circuit 303 too.

The output signal of exclusive disjunction circuit 303 be the H level during in, counter 302 increases count values, if more than the H level state certain time of the output of exclusive disjunction circuit 303, just the count value of t5 hour counter 302 reaches higher limit.Consequently, the output signal SUP of abnormal detection circuit 300 becomes the H level, judges this moment to have occured unusually.

Be transfused to the pulse generating circuit 200 of the output signal SUP of abnormal detection circuit 300, stop pulse occurs, and command pulse RPa～RPn becomes the L level.Therefore IGBT500a～IGBT500n becomes cut-off state, and power-converting device stops action.By like this, comprise that all IGBT that unusual IGBT has occured stop, therefore can cut off overcurrent, can protect normal IGBT.

Next, with reference to Fig. 8, the action during to other unusual generations describes.In addition, the same with shown in Fig. 6 of the signal shown in Fig. 8.

Here, establish t6 grid drive division 401a misoperation in the moment, produced the gate voltage Vga of not corresponding command pulse RPa.By like this, the output of gate voltage judging part 403a is that gate voltage feedback pulse VFBa just becomes the H level, and the output signal of grid feedback generating unit 405a is that grid feedback pulse FBPa also becomes the H level.The result is the same with action illustrated in fig. 7 to move, and the output of the exclusive disjunction circuit 303 of abnormal detection circuit 300 also becomes the H level, and the t7 constantly count value of Counter 302 reaches higher limit.Afterwards, the output signal SUP of abnormal detection circuit 300 becomes the H level, and pulse generating circuit 200 stop pulses occur, and by like this, IGBT500a～IGBT500n becomes cut-off state, and power-converting device stops action.

In addition, except above-mentioned unusual routine, in power supply unit 402a, occured in the unusual situation, it is unusual that any of each circuit part all becomes.Consequently grid feedback pulse FBPa becomes waveforms different when normal, so detects unusually in the abnormal detection circuit 300, and power-converting device stops action.And then, in gate voltage judging part 403a, gate current judging part 404a, grid feedback generating unit 405a, having occured in the unusual situation, grid feedback pulse FBPa also becomes waveforms different when normal, is detected.

Like this; in any of IGBT element and the grid drive circuit that drives the IGBT element, occured in the unusual situation in this example; can both detect reliably unusual; when abnormality detection; the pulse of stop pulse circuit for generating is by protecting reliably power-converting device and IGBT element like this.

Claims

1. power-converting device uses a plurality of voltage type semiconductor elements and consists of,

Have:

The command signal generating unit according to the instruction from control circuit, is used for controlling the command signal of the on/off of above-mentioned voltage type semiconductor element;

The grid drive division is inputted above-mentioned command signal, by being applied to corresponding to the gate voltage of above-mentioned command signal above-mentioned voltage type semiconductor element;

Gate resistance is arranged between above-mentioned grid drive division and the above-mentioned voltage type semiconductor element;

The gate voltage judging part, from detecting above-mentioned gate voltage between above-mentioned grid drive division and the above-mentioned gate resistance, the output gate voltage is judged signal;

The gate current judging part detects the gate current that flows through above-mentioned gate resistance, and the output gate current is judged signal; And

Abnormity detection portion is judged signal and above-mentioned gate current judgement signal based on above-mentioned gate voltage, detects unusual.

2. power-converting device according to claim 1 is characterized in that,

The gate voltage of the voltage type semiconductor element of above-mentioned gate voltage judging part input control object, the height of judgement voltage,

The gate current of the voltage type semiconductor element of above-mentioned gate current judging part input control object, the size of judgement electric current,

According to the state of above-mentioned gate voltage and gate current, the state of above-mentioned voltage type semiconductor element is exported as the grid feedback signal, detect unusual.

3. the method for detecting abnormality of a power-converting device, this method for detecting abnormality is the command pulse that the input pulse generating unit occurs, by applying as gate voltage corresponding to the voltage of command pulse, control the grid drive division of the on/off action of voltage type semiconductor element, and the method for detecting abnormality of the voltage type semiconductor element of controlling by above-mentioned grid drive division

The grid feedback signal of the on/off state of more above-mentioned command pulse and the above-mentioned voltage type semiconductor element of expression detects both inconsistent, by detecting this inconsistent certain hour that continued, detects unusual.

4. the method for detecting abnormality of power-converting device according to claim 3 is characterized in that,

Judge the inconsistent method of grid feedback signal of above-mentioned command pulse and the on/off state of the above-mentioned voltage type semiconductor element of expression,

Detect gate voltage and the gate current of above-mentioned voltage type semiconductor element, under gate voltage is situation more than the fixed value, judgement is the H level, in the situation less than fixed value, judgement is the L level, under the absolute value of gate current is situation more than the fixed value, judgement is the H level, in the situation less than fixed value, judgement is the L level

Be in the situation of H level in any of gate voltage and gate current, judgement is the H level, gets the XOR of this judged result and above-mentioned command pulse, is in the situation of H level in the result, and it is inconsistent to judge both.

5. the method for detecting abnormality of power-converting device according to claim 3 is characterized in that,

During above-mentioned command pulse and above-mentioned grid feedback signal are inconsistent, with fixed cycle Measuring Time process, measure number of times by it and become more than the fixed value, thereby judge that inconsistent state has continued certain hour.