JPH08214538A - Power converter - Google Patents

Abstract

PURPOSE: To obtain a power converter which has high reliability and facilitates the recovery of a fault. CONSTITUTION: A plurality of power devices Q1 to Q3 in which the voltage drop voltage is varied according to the increasing or decreasing operation of the level of a gate control signal from a gate controller 10 are connected in parallel. The predetermined device of the devices Q1 to Q3 is separated from the other devices except the predetermined device, the operating timing of the signal given from the controller is differentiated at each separated device, and a current detector for detecting the current flowing to the device is provided. The part of the devices connected in parallel is turned OFF by the operation of the level of the signal when the current detected by the detector becomes an overcurrent exceeding the predetermined level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion apparatus constructed by connecting in parallel a plurality of self-extinguishing power devices whose voltage drop voltage VcE changes according to the operation of increasing or decreasing the level of a gate control signal.

[0002]

2. Description of the Related Art Recently, as a power device used in a power conversion device such as an inverter or a PWM (pulse width modulation control system) converter, a conventional thyristor or GTO (gate turn-off thyristor) is changed to an IGBT (insulated gate bipolar transistor). And power MOSFET
It is often used in place of a self-extinguishing device with high-speed switching operation such as (static induction transistor).
In particular, it has been widely used in the field of small and medium-capacity power conversion devices.

Here, as an example of a conventional power converter, a power device using an IGBT will be described with reference to FIGS. 7 and 8. FIG. FIG. 7 shows one in the power converter
Shows the main circuit of the arm component, IGBTQ ₁ ~Q ₅ are connected in parallel, respectively, connected to the gate control terminal G ₁ each ~G ₅ is common gate control circuit (GATE) 11 of IGBTQ ₁ ~Q ₅ The gate control terminal G ₁ ~
The gate control signal e _G from the gate control circuit 11 is applied to each G ₅ . Main circuit terminal C,
A power supply (not shown) is connected to E, and a main circuit current ic flows between the main circuit terminals C and E.

In general, it is known that a power conversion device uses four parallel circuits shown in FIG. 7 to form a single phase, and uses six parallel circuits to form a three-phase circuit. IGBTs Q _{1 to} Q connected in parallel
₅ is a gate control signal e _G output from the gate control circuit 11.
Turn on the IGBTs Q _{1 to} Q ₅ at the same timing,
Turn off. IG is controlled by controlling the gate control signal e _G
When the BTQ _{1 to} Q ₅ are turned on all at once, the main circuit current ic
Flows in the direction from the main circuit terminal C to E, and IGBTs Q _{1 to} Q
_{When 5} is turned off, the main circuit current ic becomes zero, which controls the output current of the power converter.

FIG. 8 shows IGBTs connected in parallel as shown in FIG.
This is for explaining a conventional overvoltage protection method for Q _{1 to} Q ₅ . Now, from the gate control circuit 11 to the gate control signals G _{1 to} G ₅ in FIG. 7, the gate control signal e shown in FIG.
From the time when the G is supplied and the IGBTs Q _{1 to} Q ₅ are turned on all at once until the time t ₁ , between the main circuit terminals C and E of FIG.
Consider a case where a main circuit current ic as shown in (1) is flowing. When the main circuit current ic increases for some reason at time t _1, the main circuit current ic is detected and the level of the gate control signal e _G is decreased by the action of the gate control circuit 11 at time t ₂ , so that the IGBTQ The voltage drop voltage VcE between both terminals of _{1 to} Q ₅ increases.

This voltage drop voltage VcE is from IGBTQ ₁ to
When a sufficiently large gate control signal e _G is applied to the gate control terminals G _{1 to} G _{5 of} Q ₅ , the voltage drop voltage VcE across it is saturated and small, but the gate control signal e It is known that when _G becomes smaller than a predetermined value, the voltage drop voltage VcE increases.

From the above, the gate control signal e _G
When the gate control signal e _G is decreased from the time t ₂ using the characteristic that the voltage drop voltage VcE increases due to the decrease of
At time t ₃ , the increase of the main circuit current ic disappears, and time t ₄
By setting the gate control signal e _G to zero, the main circuit current ic can also be zero.

As described above, the switching speed of the IGBT and the power MOSFET whose voltage drop voltage VcE across the gate control signal e _G can be varied by the increase and decrease of the gate control signal e _G is very high.
As described above, even if the main circuit current ic becomes the overcurrent level, the main circuit current i can be changed by increasing or decreasing the gate control signal e _G.
It is known that the protection reliability of the power conversion device is significantly improved as compared with the conventional power conversion device because the protection can be performed by setting c to zero.

However, power devices such as IGBTs and power MOSFETs have small individual rated voltage and rated current, and even an IGBT having a relatively large rated capacity is 1200V-
The device rated capacity is about 600A. With this rated capacity, the output capacity of the three-phase inverter circuit using the IGBT in 11 parallel circuits is only about 100 KVA,
It is necessary to connect 6 parallel circuits with 0 KVA output and 12 parallel circuits with 1000 KVA output.

As described above, power devices such as IGBTs and power MOSFETs whose voltage drop voltage VcE can be manipulated by increasing / decreasing the gate control signal e _G are used in medium-capacity class power converters because the rated capacity of the power device is small. If used, a large number of power devices can be used.
As described above, it is necessary to connect them in parallel to form a power conversion device.

[0011]

In the conventional power converter, it is necessary to connect a large number of power devices in parallel as described above. Therefore, the current tends to be unbalanced between the power devices connected in parallel due to the difference in the characteristics of the power devices and the inductance difference in each circuit. It is designed so that the rated overload current also has a predetermined allowable value.

However, when the number of power devices connected in parallel increases, the main circuit current ic of all the power devices connected in parallel becomes an overcurrent as shown in FIG. When an overcurrent flows in the parallel circuit, it is difficult to protect it by reducing the level of the common gate control signal e _G.

When an overcurrent flows in a parallel circuit of a large number of power devices connected in parallel as described above, some power devices may be damaged due to the overcurrent because of insufficient protection. In this case, the remaining power devices that were connected in parallel to the destroyed power device were not able to determine whether the characteristics were about to deteriorate or were healthy, and it was necessary to replace all the power devices connected in parallel.

That is, in the conventional power converter, when the power devices are destroyed due to the overcurrent, it is necessary to replace all the power devices in parallel connection, and this replacement requires a large failure recovery time and There was a costly problem.

Therefore, an object of the present invention is to solve the conventional problems. Even if a part of the power device group is destroyed due to overcurrent, all the power devices connected in parallel are replaced. It is an object of the present invention to provide a power conversion device with improved protection that does not need to be performed.

[0016]

In order to achieve the above-mentioned object, the invention according to claim 1 is a power device whose voltage drop voltage is changed by increasing or decreasing the level of a gate control signal from a gate control device. In a power conversion device configured by connecting a plurality of the above in parallel with each other, a predetermined power device among the power devices and a power device other than the predetermined power device are separated, and It is a power conversion device comprising means for varying the operation timing of a gate control signal given from a gate control device.

In order to achieve the above object, the invention according to claim 2 is the power converter according to claim 1, wherein a current detector for detecting a current flowing through the power device is provided, and this current detector is used. When the detected current is an overcurrent exceeding a predetermined value, a part of the plurality of power devices connected in parallel is controlled to be turned off by operating the level of the gate control signal. It is a conversion device.

To achieve the above object, the invention according to claim 3 provides the power converter according to claim 2, wherein an overcurrent flowing through the remaining power device which is not turned off by the operation of the gate control signal is generated. The power converter is characterized in that a fast-acting fuse is provided in the loop through which the overcurrent flows for the purpose of protection when a predetermined value is exceeded.

In order to achieve the above object, the invention according to claim 4 is the power conversion device according to claim 1, wherein the voltage drop voltage of each of a plurality of power devices connected in parallel flows to each power device. The power converter is characterized in that a detector for detecting a current is provided, and a gate control signal is operated so as to turn off only a power device whose detected voltage or detected current exceeds a predetermined value.

In order to achieve the above-mentioned object, the invention corresponding to claim 5 is the power conversion device according to any one of claims 1 to 4, wherein the power device parallel provided in the power conversion device is provided. Among the plurality of circuits, only a parallel circuit of a predetermined power device can be turned off by dividing only a part of the power devices connected in parallel by operating a gate control signal. It is a power converter.

In order to achieve the above object, the invention according to claim 6 is the power converter according to any one of claims 1 to 5, wherein the discharge current of a DC filter capacitor provided in a DC circuit is provided. Or a circuit for detecting a fault current flowing in the parallel circuit, and a circuit for determining whether to turn off all or only a part of the power devices connected in parallel is provided. It is a device.

In order to achieve the above object, the invention corresponding to claim 7 is the power conversion device according to any one of claims 1 to 6, wherein the power devices connected in parallel are in a steady conduction state. Then, the power conversion device is characterized in that it is a static induction type composite device in which characteristic modes are switched between thyristor characteristics and self-extinguishing insulated gate bipolar transistor characteristics during turn-off operation.

[0023]

According to the invention corresponding to claim 1, as a result of not controlling all the power devices connected in parallel at the same timing, the influence of overcurrent on the parallel connection circuit can be made different for each power device.

According to the invention corresponding to claim 2, when an overcurrent flows through the power devices connected in parallel, only a part of the power devices is turned off to concentrate the overcurrent on a specific power device side, and The reliability against overvoltage can be improved by preventing the influence of overvoltage on the power device to be turned off.

According to the invention according to claim 3, even if the overcurrent is concentrated on a part of the power devices connected in parallel, the protection can be backed up by the fast-acting fuse. The reliability can be further improved.

According to the fourth aspect of the invention, the power device itself detects an overcurrent and sequentially turns off, such as sequentially turning off the power devices whose voltage drop voltage reaches a predetermined value. It is possible to prevent the influence on all power devices connected in parallel.

According to the invention corresponding to claim 5, even if the turn-off timing is similarly shifted not in all the parallel connection circuits constituting the power conversion device but in the parallel connection circuits, the protection reliability due to the overcurrent is also increased. Can be improved as well.

According to the invention of claim 6, only a part of the power devices connected in parallel is turned off only when it is detected that the fault current exceeds a predetermined value. The number of power devices to be used can be minimized.

According to the invention corresponding to claim 7, since the electrostatic induction type composite device is preferentially turned off from the one which is switched to the insulated gate bipolar transistor mode, a power device which is deteriorated by an overcurrent occurs. However, the number can be minimized.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG 1 shows a part of a main circuit of the power converter, IGBT (insulated gate bipolar transistor) Q ₁ to Q ₃ is a total of three parallel-connected main to the connection point of the collectors The circuit terminal C is connected, and the main circuit terminal E is connected to the connection point of each emitter. Also, the IGBTQ
_A fast-acting fuse 12 is connected to the connection point of the collectors of ₂ and Q ₃ . Furthermore, a current detector 8 is provided between the connection point of the main circuit terminal C and the collector of the IGBT, and the detection current of this current detector 8 is input, and only when this detection current is an overcurrent exceeding a predetermined value. A current determination circuit 9 that outputs a signal to the gate control device 10 is provided.

The gate control device 10 supplies a common gate control signal to the gate control terminals G ₁ , G ₂ and G ₃ in the same manner as the conventional gate control circuit 11 when there is no output from the current discrimination circuit 9. Alternatively, when there is an output from the current discrimination circuit 9, only a part of the gate control terminals G ₁ , G ₂ and G ₃ , for example, the gate control terminal G ₃ is separated and the gate control terminal G ₃ is controlled. It has a function of giving a gate control signal e _{G 3} different from the stop timing of the gate control signals e _{G 1} and e _{G 2} given to the terminals G ₁ and G ₂ .

The number of connected IGBTs Q _{1 to} Q ₃ is 3
Not limited to individual pieces, any number may be used. Next, the operation of the first embodiment configured as described above will be described with reference to FIG. 2. The main circuit current ic [FIG. 2 (1)] is the current flowing through the main circuit terminals C and E of FIG. And shunt currents ic ₁ , ic ₂ , ic
₃ shows a current flowing through each IGBTQ ₁ ~Q _3, further IGBTQ ₁ gate control signal ~Q ₃ e _{G 1} ~e _{G 3}
2 (2), (3) and (4) are signals given to the gate control terminals G ₁ , G ₂ and G ₃ of FIG.

FIG. 1 shows that under normal general load conditions (when the main circuit current ic is at the rated value), the IGBTs Q _{1 to} Q ₃ have the same timing as the gate control signals e _{G 1} to Q ₃ as in the prior art described above. Controlled by e _{G 3} , the IGBTs Q _{1 to} Q ₃ are on / off controlled at the same timing.

However, when the main circuit current ic in FIG. 1 becomes higher than the rated value, an output signal is output from the current discriminating circuit 9 to the gate control device 10, so that the gate control device 10 operates as follows. That is, when the main circuit current ic flowing through the main circuit terminals C and E begins to become an overcurrent at time t ₁ and the main circuit current ic reaches a predetermined value at time t ₂ as shown in FIG. 2 Decrease the levels of the gate control signals e _{G 1} and e _{G 2} shown in (2) and (3).
As a result, the currents ic ₁ and ic ₂ of the IGBTs Q ₁ and Q ₂ start decreasing at time t ₃ , and the gate control signals e _{G 1} e and e
_At time t ₄ when _{G 2} is controlled to zero, the currents ic ₁ and ic ₂ become zero, the IGBTs Q ₁ and Q ₂ are turned off at time t ₄ , and as shown by VCE ₁ in FIG. Recover the withstand voltage of.

[0035] Since IGBTQ ₃ at time t ₄ the gate control signal e _{G 3} in FIG. 2 (4) remains the same as on-state, the actual voltage is IGBTQ _1, Q ₂ as VCE ₁ in FIG. 2 Is not applied, the main circuit current ic starts to move to the IGBTQ ₃ side from time t ₃ , and at time t ₄ , the shunt current ic
And ic ₃ become equal, and all the shunt currents concentrate on the IGBT Q ₃ after time t ₄ . If the main circuit current ic concentrated in the IGBT Q ₃ is suppressed within a predetermined value, the fast-acting fuse 12
Is not blown, but if the overcurrent is excessive, the fast-acting fuse 1
2 melts and the overcurrent is cut off.

At this time, the main circuit current ic becomes excessive and
Even if IGBTQ ₃ is destroyed by overcurrent, IGBTQ ₁ and Q
_{Since 2} is surely turned off at a fast timing, the influence of destruction due to overcurrent can be limited to the IGBT Q ₃ . Therefore, it is not necessary to replace all the IGBTs connected in parallel, and failure recovery can be performed in a short time.

<Second Embodiment> FIG. 3 shows one phase of the power converter, which includes a fast-acting fuse 12, a gate controller 13, a DC filter capacitor 14, current detectors 15 and 16, and current discrimination. Vessel (PRO) 17, IGBTQ ₁
~Q _3, IGBTQ ₁₁ ~Q _13, DC terminals P, and includes N, an output terminal R.

The current detector 15 detects the discharge current of the DC filter capacitor 14, and the current detector 16 is the IGBT.
Detecting a current flowing through _{Q 1 ~Q 3, IGBTQ 11 ~Q} 13. The current discriminator (PRO) 17 discriminates whether or not the detected current detected by the current detector 15 or 16 exceeds a predetermined value, and when it exceeds the predetermined value, the gate controller 13
The output signal is output to. When the gate controller 13 receives no output signal from the current discriminator 17, the IGBT Q ₁
To Q ₃ and IGBTQ _{11 to} Q ₁₃ are given the same gate control signal for turning off the gates, and when the output signal is input from the current discriminator 17, only the IGBTQ ₃ and the other IGBTQ are excluded. ₁ , Q
The timing of the gate control signal applied to the _second and IGBTQ ₁₁ ~Q ₁₃ is intended to provide a different gate control signal.

In such a structure, the IGBT
By controlling the gate control signals supplied to the gate terminals of Q _{1 to} Q ₃ and the IGBTs Q _{11 to} Q ₁₃ , the power is converted into a predetermined power, which is output from the output terminal R. At this time, the parallel circuit of the IGBTs Q _{1 to} Q ₃ or the IGBTs Q _{11 to} Q 3
_{When the} current flowing in the parallel circuit of ₁₃ becomes an overcurrent more than a predetermined value, it is detected by the current detector 15 or 16 and the current discriminator 17
In discriminated current through only the gate control device 13 when it becomes more than a predetermined value, IGBTQ ₁ gate control signal as in the embodiment of FIG 1 and FIG 2 a parallel circuit of to Q ₃ e _{G 1} and e
The stop timings of _{G 2} and e _{G 3} are shifted and controlled.
By doing so, even if the power devices deteriorate in the parallel circuit as in the case of the above-described embodiment, there is no need to replace all the power devices, and therefore reliability is high and failure recovery can be easily performed.

[0040] In the embodiment of FIG. 3, the parallel circuit of the DC filter capacitor 14-IGBTQ ₁ ~Q ₃ - IGBTQ in the power conversion device such that the that in the case of an overcurrent through the load side at the root of the output terminal R ₁ , Q ₂ , Q _{11 to} Q ₁₃
The power conversion device can be protected even if only a part of the parallel circuit (IGBTQ ₃ ) is controlled by shifting the gate control signal.

<Third Embodiment> As shown in FIG. 4, a gate control device 18 having a memory circuit (not shown), a gate resistor 19, a voltage detection circuit (V / D) 20, a voltage discrimination circuit (OFF) 21, It has a IGBTQ _4.

The gate controller 18 is an IGBT connected in parallel such as an IGBT Q ₄ like the gate controller 13 of FIG.
A gate control signal is applied to each to control each IGBT. IG
The voltage detection circuit 20 detects the voltage drop voltage VcE of the BTQ ₄ , and when the voltage drop voltage VcE becomes a predetermined value or more, the voltage detection circuit 21 determines the voltage drop voltage VcE and outputs a gate control signal to turn off the IGBTQ _4. Gate control device 18,
It operates via the gate resistor 19.

IGs connected in parallel as shown in FIG.
Each of the BTs is provided with a voltage detection circuit 20 for detecting an overcurrent, and the voltage drop voltage VcE rises due to the overcurrent flowing through the IGBT. When the turn-off operation is started from the IGBT, the IGBTs are sequentially turned on in case of an excessive overcurrent.
Since T is turned off, the specific IGBT is turned off lastly, so that all the parallel-connected IGBTs are not deteriorated by the overcurrent.

At this time, when the IGBTs which are sequentially turned off are recorded in the memory circuit included in the gate control device 18, it is possible to determine which of the IGBTs connected in parallel is most affected by the overcurrent, and the IGBTs Exchange failure recovery is also easy. Incidentally, a method of recording such an operation sequence in the memory circuit is publicly known, and therefore its explanation is omitted here.

<Fourth Embodiment> As shown in FIG.
Composite device (static induction composite device) Q ₆ and MO
When the voltage detected by the voltage detection circuit 20 that detects the voltage between the collector C and the emitter E of the S composite device Q ₆ and the voltage detected by the voltage detection circuit 20 exceeds a predetermined value, Voltage discriminating circuit 21 for outputting a signal only
And the output signal from the voltage discrimination circuit 21 is input,
A gate control device 22 for outputting a gate on / off control signal G (ON / OFF) shown in (1) and a turn off mode control signal G (MODE) shown in FIG. 6 (2) is provided.

A specific example of the MOS composite device Q ₆ is DGMOS (Doub) described in Electronic Technology, 1993-8 p55-p56.
le Gate MOS Device: A power device aiming to demonstrate the characteristics when each power device is turned on and off with a dual gate.It has a thyristor characteristic in the steady conduction state and a self-extinguishing IG in the turn-off operation.
BT characteristics and those that can be switched).

[0047] will be described with reference to FIG. 6 the operating characteristics of the MOS composite device Q _6. If the gate on / off control signal G (ON / OFF) is applied until the turn-off mode control signal G (MODE) is switched as shown in the figure at the time t ₅ , conduction is performed at a low voltage drop voltage VcE. This normal mode is a conduction mode with a general thyristor characteristic. When the turn-off mode control signal G (MODE) is switched at time t ₅ , the MOS composite device Q ₆ is switched to the conduction mode with the IGBT characteristic having the self-extinguishing characteristic because the voltage drop voltage VcE rises.

After switching to the conduction mode by the IGBT characteristic, when the gate on / off control signal G (ON / OFF) is switched at time t ₆ , the MOS composite device Q ₆ is turned off at high speed. The period TM from time t ₅ to time t ₆ is about several microseconds.

The gate control circuit 2 determines by the voltage detection circuit 20 and the voltage determination circuit 21 that the voltage drop voltage VcE of the MOS composite device Q ₆ has increased to a predetermined value during the period TM.
By switching the turn-off control signal G (ON / OFF) via 2, it is possible to surely turn off with the IGBT characteristic even if a large number of MOS composite devices Q ₆ are connected in parallel.

In the parallel circuit of the MOS composite device Q ₆ , even if the overcurrent as described in FIGS. 1 and 2 exceeds a predetermined value, the device switched to the IGBT characteristic is turned off preferentially. Therefore, the overcurrent is concentrated on a specific device side in the parallel circuit, and the total M of the parallel circuit is increased.
The OS composite device Q ₆ is not affected by the overcurrent.

<Modifications> The present invention is not limited to the above-described embodiments and can be modified in various ways. That is, the gate control of each of the power devices connected in parallel described in the embodiment is not limited to be controlled separately, and may be controlled in several groups, and the flowing current ic It is also possible to control up to a predetermined value at the same time, and to control each separately in some cases only when the overcurrent exceeds a predetermined value.

In FIG. 4, the method of detecting the voltage drop voltage VcE of the IGBTQ ₄ by the voltage detector 20 has been described as a means for detecting the overcurrent of the IGBTQ ₄ . There are other known methods of intelligent detection, and the power devices that have detected an overcurrent of a predetermined value or more by these known methods may be sequentially turned off.

In the above-mentioned embodiments, the IGBT is described as an example of the power device, but the present invention is not limited to the IGBT as the power device, but is a power MOSFET, SIT (static induction transistor), or DGMOS being developed as a next-generation device. , IEGT and other MOS composite devices. In addition, it is apparent that various modifications can be applied to the power conversion device without changing the gist of the present invention.

[0054]

According to the present invention, a plurality of power devices whose voltage drop voltage is changed in parallel by increasing or decreasing the level of a gate control signal are connected in parallel, and are connected in parallel by an overcurrent. It is possible to provide a power conversion device that is highly reliable and that is easy to recover from failure because it does not deteriorate all of the power devices and eliminates the need for 100% replacement even if the power devices deteriorate in the parallel circuit.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram for explaining a first embodiment of a power conversion device of the present invention.

FIG. 2 is a waveform chart of each part for explaining the operation of the embodiment of FIG. 1 of the present invention.

FIG. 3 is a schematic circuit diagram for explaining a second embodiment of the power conversion device of the present invention.

FIG. 4 is a schematic circuit diagram for explaining a third embodiment of the power conversion device of the present invention.

FIG. 5 is a schematic circuit diagram for explaining a fourth embodiment of the power conversion device of the present invention.

FIG. 6 is a waveform chart of each part showing the operation of FIG. 5 which is an embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of a conventional power converter.

FIG. 8 is a waveform chart of each part showing the operation of the conventional power converter.

[Explanation of symbols]

9 ... Current detector, 10 ... Gate control device, 12 ... Fast-acting fuse, 13 ... Gate control device, 14 ... DC filter capacitor, 15 ... Current detector, 16 ... Current detector, 17
... current discriminator, 18 ... gate control device, 19 ... gate resistor, 20 ... voltage detection circuit, 21 ... voltage discrimination circuit, 22
... gate control _{unit, Q 1 ~Q 5, Q 11} ~Q 13 ... IGB
T, Q ₆ ... MOS composite device, C, E ... Main circuit terminal,
P, N ... DC terminal, R ... Output terminal, G, G ₁ , G ₂ , G
₃ ... gate control terminal of the _{IGBT, eG, e G 1,} e G
₂ , e _{G 3} ... Gate control signal, G (ON / OFF) ... Gate on / off control signal, G (MODE) ... Turn-off mode control signal,
ic ... Main circuit current, ic ₁ , ic ₂ , ic ₃ ... IGBT
Current, VCE, VCE ₁ ... Voltage drop of power device.

Claims (7)

[Claims] 1. A power converter comprising a plurality of power devices whose voltage drop voltage changes in parallel according to an increase / decrease operation of the level of a gate control signal from the gate control device, wherein A predetermined power device,
A power conversion device comprising means for separating the power device other than the predetermined power device, and varying the operation timing of the gate control signal given from the gate control device for each of the separated power devices. . 2. The power conversion device according to claim 1,
A current detector for detecting a current flowing through the power device is provided, and when a current detected by the current detector becomes an overcurrent exceeding a predetermined value, a part of the power devices connected in parallel is An electric power converter characterized by being controlled so as to be turned off by operating a level of a gate control signal. 3. The power conversion device according to claim 2, wherein
When the overcurrent flowing through the remaining power devices that are not turned off by the operation of the gate control signal exceeds a predetermined value, a fast-acting fuse is provided in the loop through which the overcurrent flows for the purpose of protection. apparatus. 4. The power conversion device according to claim 1,
A detector that detects the voltage drop voltage of each of the multiple power devices connected in parallel or the current flowing through each power device is provided, and the gate is used to turn off only the power device whose detection voltage or current exceeds a specified value. A power converter in which a control signal is operated. 5. The power converter according to claim 1, wherein a parallel circuit of a predetermined power device is included in a plurality of circuits of the power device parallel circuit provided in the power converter. A power conversion device characterized in that only a part of power devices connected in parallel can be divided and turned off by operating a gate control signal. 6. The power conversion device according to claim 1, further comprising a circuit that detects a discharge current of a DC filter capacitor provided in a DC circuit or a fault current flowing in the parallel circuit. A power conversion device comprising a circuit for determining whether all of the power devices connected in parallel are turned off or only some of them are turned off. 7. The power conversion device according to claim 1, wherein the power devices connected in parallel have thyristor characteristics in a steady conduction state and self-extinguishing insulated gate bipolar in a turn-off operation. A power conversion device, which is an electrostatic induction composite device in which characteristic mode switching of transistor characteristics is performed.