JPH10243660A - Power converter - Google Patents

Abstract

(57) [Problem] To improve operation reliability against a failure of a switching element or the like remarkably even if one switching arm is constituted by connecting a plurality of switching elements in parallel. In a power converter in which each switching arm (15) is configured by connecting a plurality of switching elements (17) in parallel, a plurality of switching elements (17) constituting one switching arm (15) are connected in parallel. The protection fuse 19 is provided in each of the divided units of the switching element 17 in parallel, and when any one of the switching elements 17 in one switching arm 15 fails, the protection unit 19 is connected in parallel. The failed switching element 17 is separated by the protective fuse 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter in which a plurality of switching elements are equivalently connected in parallel to form a single switching arm, and in particular, has a remarkable operational reliability against a failure of the switching element. The present invention relates to a power conversion device that is improved.

[0002]

2. Description of the Related Art Conventionally, since a switching element constituting a power conversion device main body has a shortage of current rating, a power conversion device in which a plurality of switching elements are equivalently connected in parallel to form one switching arm. Various types are known, and as a typical example, a PWM inverter device is well known.

FIG. 6 is a circuit diagram showing an example of the configuration of a power converter that is already frequently used in general-purpose inverters and the like.
In FIG. 6, in the power converter, an input AC power supply terminal 1
The AC power is input from 1, converted into DC power by the rectifier 12, and smoothed by the DC filter capacitor 13.

[0004] The smoothed DC power is converted into AC power of an arbitrary frequency by a three-phase PWM inverter 14 composed of six switching arms 15, and a load 16 is driven.

[0005] P and N indicate DC power supply buses on the positive electrode side and the negative electrode side, respectively. Now, such a power converter as described above is widely used as a PWM inverter device because AC power of an arbitrary frequency can be obtained by the three-phase PWM inverter 14.

In FIG. 6, the capacity of the load 16 is generally 1
In the region of 00 KVA or less, the switching arm 15 can apply one switching element in current rating.
In a device capacity region exceeding this range, it is common to connect switching elements in parallel in terms of current capacity.

FIG. 7 is a circuit diagram showing an example in which the switching arm 15 is configured by connecting switching elements in parallel. In FIG. 7, reference numeral 17 denotes an IGBT element as a switching element, and reference numeral 18 denotes a diode connected to the IGBT element 17 in anti-parallel.

In FIG. 6, the capacity of the power converter is 50
If it is set to 0 to 600 KVA, the switching arm 15
As shown in FIG. 7, six IGBTs 17 as switching elements are connected in parallel in terms of current rating.

As shown in FIGS. 6 and 7, a recent switching element I which can perform high-speed switching operation is provided.
When configuring a power converter having a large capacity, GBTs and MOSFETs are generally used by connecting a switching element to the switching arm 15 in parallel. Not only a PWM inverter device but also various power converters are already used. Has been applied to

IGBT element 17 as a switching element
Is taken as an example, the IGBT element 17 and the diode 18
One set is stored in one package and used in a package called an IGBT module. Therefore, in the case of the configuration shown in FIG. 7, the configuration is such that six IGBT modules are connected in parallel.
The GBT element 17 and the diode 18 are illustrated separately.

On the other hand, the failure rate of an IGBT module having a rated current of about 300 to 600 A is slightly different depending on various applied circuits, but is generally 50 to 100 fi.
about t. Therefore, when six IGBT modules are connected in parallel to the switching arm 15 as shown in FIG. 7, the failure rate of the switching arm 15 at this time becomes 300 to 600 feet.

When a conventionally used GTO element is applied to the switching arm 15 as a switching element, a single GTO element having a high current rating is manufactured. For,
Even if the device capacity is 500 to 600 KVA, the switching arm 15 can be constituted by one GTO element. The failure rate of a switching element having a large current rating, such as such a GTO element, is generally about 100 feet or less.

Compared to the GTO element, the use of IGBTs and MOSFETs, which are recent switching elements, enables high-speed switching operation, so that clean AC power can be supplied to the load 16 and the operating efficiency of the entire system can be reduced. It is known that many advantages such as improvement and reduction of the noise of the load 16 can be obtained.

However, as described above, IGBTs and MOSFETs, which are new switching elements, have a small rated current, so they need to be used in parallel connection according to the capacity of the power converter, as shown in FIG. Switching arm 1 by connecting six IGBT elements 17 in parallel
4, the failure rate is increased three to six times as compared with the conventional case. Further, there is a problem that such an increase in the failure rate increases as the capacity of the power converter increases.

[0015]

SUMMARY OF THE INVENTION As outlined above,
In recent power converters, switching elements such as IGBTs and MOSFETs that can perform high-speed switching operation are used. In the example of the three-phase PWM inverter 14, the load 16 has less harmonic components by PWM control using high-speed switching operation. It can be operated by supplying clean AC power.

The switching element capable of performing these high-speed switching operations has an upper limit of a rated current of about 300 to 600 A, for example, an apparatus rating of 500 to 600 KVA.
In the case of (1), it is necessary to configure one switching arm 15 by connecting six IGBT elements 17 in parallel.

In terms of current rating and electric performance of the power converter, even if the switching arm 15 is configured by connecting six IGBT elements 17 in parallel, the function can be sufficiently satisfied, and the three-phase PWM inverter 14 and many others have been produced.

However, in terms of operational reliability of the power converter, one switching arm 15 is composed of a plurality of IGBT elements 17 as compared with a case where the switching arm 15 is composed of one power device. ,
As compared with one switching arm 15, the failure rate is 3
There is a problem of increasing by up to 6 times.

The three-phase PWM inverter 14 is a high-speed switching element such as an IGBT or MO
With the advent of SFETs, their application fields have expanded, and today they are being applied to all fields. However, due to the increase in the number of parallel-connected switching elements constituting the switching arm 15, failures in switching elements and the like are prevented. Operational reliability may be reduced for large capacity devices.

An object of the present invention is to provide a power converter capable of significantly improving the operational reliability against a failure of a switching element or the like even when a plurality of switching elements are connected in parallel to form one switching arm. Is to provide.

[0021]

In order to achieve the above object, according to the first aspect of the present invention, each switching arm includes a plurality of switching elements connected in parallel. A plurality of switching elements constituting a plurality of switching arms are divided into a plurality of switching elements, and protection fuses are respectively provided in parallel units of the plurality of divided switching elements, and any one of the one switching arm is provided. When a failure occurs in the switching element, the failed switching element is separated by the protection fuse of the parallel unit.

Therefore, in the power conversion apparatus according to the first aspect of the present invention, even if a failure occurs in the switching element in any one of the parallel units, the failed switching unit in the plurality of divided switching elements is used. Parallel units of elements can be separated.

Thus, the operation of the power converter can be continued using the remaining parallel units other than the parallel unit that has been separated due to the occurrence of the failure, and the operation reliability against the failure of the power converter can be improved. be able to.

According to the second aspect of the present invention, the first aspect is provided.
In the power converter of the invention, when at least two switching arms are connected in series between the respective DC power supply buses on the positive electrode side and the negative electrode side to form a power converter main body,
The switching arms to be connected in series are connected in series for each of a plurality of parallel units of the switching elements, and the series connection circuits of the parallel units are connected between the respective DC power supply buses via respective protective fuses, so that the switching arms are connected in series. Constructs a connection circuit.

Therefore, in the power converter according to the second aspect of the present invention, even if a failure occurs in any one of the switching elements, the failure occurs in the series connection circuit connected in series for each parallel unit. The connection circuit can be disconnected from the DC power supply bus by blowing the protection fuse with the short-circuit current.

As a result, the operation of the power converter can be continued by the remaining series connection circuits of sound parallel units, and the operation reliability against failure of the power converter can be improved.

According to a third aspect of the present invention, in the power converter according to the first aspect of the present invention, a series connection circuit connected in series for each of a plurality of parallel units is provided between each of the positive and negative DC power supply buses. When connecting, protection fuses are inserted into at least one of the DC terminal side and the AC terminal side, respectively, to form a switching arm series connection circuit.

Therefore, in the power converter according to the third aspect of the present invention, even if a failure occurs in any one of the switching elements, the failure occurs in the series connection circuit connected in series for each parallel unit. Only the connection circuit can be disconnected from at least one of the DC power supply buses and the AC terminal side by blowing the protective fuses on the DC terminal side and the AC terminal side with the short-circuit current.

[0029] Thus, the operation of the power converter can be continued by the remaining healthy parallel-connected series connection circuits, and the operation reliability against the failure of the power converter can be improved.

According to a fourth aspect of the present invention, in the power converter according to the first aspect of the present invention, a plurality of unit power conversion circuits are configured in parallel with the switching elements, and a failure of the switching elements occurs. Then, a plurality of unit power conversion circuits are separated by a protective fuse.

Therefore, in the power converter according to the fourth aspect of the present invention, even if a failure occurs in any one of the switching elements, the failure occurs in the plurality of unit power conversion circuits divided for each parallel unit. Only the unit power conversion circuit portion that has generated can be disconnected by fusing the protection fuse with the short-circuit current.

Thus, the operation of the power converter can be continued by the remaining healthy unit power conversion circuits,
It is possible to improve the operation reliability against the failure of the power converter.

On the other hand, according to the invention of claim 5, the above-mentioned claim 1 is provided.
The power converter according to any one of claims 4 to 4, wherein an on / off control signal for each switching element is supplied to a parallel unit of a plurality of divided switching elements constituting one switching arm. A protection unit is provided for each parallel unit with respect to the control line, and when a failure of the switching element occurs, the control line of the failed parallel unit is disconnected by the protection unit.

Therefore, in the power converter according to the fifth aspect of the present invention, when a failure occurs in one of the switching elements and the parallel unit is disconnected in a main circuit, the influence of the disconnection of the parallel unit is obtained. Even if the on / off control signal is affected by the main circuit potential, etc., and the on / off control signal of another parallel unit is to be influenced, the protection means provided on the control line controls the failed switching element. The line can be cut off.

As a result, the operation of the power converter can be continued without affecting the remaining healthy control units of the parallel unit, and the operation reliability against failure of the power converter can be further improved. .

According to the invention of claim 6, in the above-mentioned claim 1,
The power converter according to any one of claims 5 to 5, wherein a failure occurs in any one of the parallel units of the switching element divided into a plurality of parts constituting the switching arm, and Detecting means for detecting that the unit has been disconnected by the protective fuse is provided. When the detecting means detects that the parallel unit has been disconnected, the power conversion device main body corresponds to the disconnected parallel unit. Output is restricted.

Therefore, in the power converter of the present invention, when the faulty parallel unit is cut off by the protection fuse, this is detected by the detecting means, and the output of the power converter main body is limited. it can.

Thus, the output of the power conversion device main body can be limited to the output power corresponding to the remaining sound parallel units, and the problem of the overload current can be eliminated and the failure of the power conversion device can be safely performed. , The driving reliability can be improved.

According to a seventh aspect of the present invention, in the power conversion device according to any one of the first to sixth aspects of the present invention, each switching element constituting the parallel unit has a protection function in place of a protection fuse. A switching arm with a built-in protection function is used.A plurality of switching elements with a protection function are connected in parallel to form a switching arm, and the protection function of the switching element with a protection function against failures that occur in each switching element. Operate and separate.

Therefore, in the power converter of the present invention, even if a failure occurs in the switching element, the failed switching element can be separated by the protection function built in the switching element.

As a result, the operation of the power converter can be continued without affecting the remaining healthy switching elements, and the operation reliability against the failure of the power converter can be improved.

[0042]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment: Corresponding to Claims 1 and 2) FIG.
6 is a circuit diagram showing a configuration example of a power conversion device according to the present embodiment. The same parts as those in FIGS. 6 and 7 are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described here.

In FIG. 1, the three-phase PWM inverter 1
Reference numeral 4 shows only one of the three phases in detail. In FIG. 1, two switching arms 15 are
It is connected in series between DC power supply buses P and N.

Each switching arm 15
Is constructed by connecting four IGBT elements 17 and diodes 18 in parallel as shown in the figure. Further, the switching arm 15 includes four IGBT elements 17 connected in parallel.
And the diode 18 are divided into two parallel units, and each parallel unit is composed of two IGBT elements 17 and two diodes 18 connected in parallel.

Also, by connecting two parallel units in series,
As shown in the figure, the protective fuse 19 is connected between the DC power buses P and N.
Connect through. Further, the midpoint of the series connection circuit of the parallel units connected in series is an AC terminal, which is connected to supply power to the load 16.

Next, the operation of the power converter of the present embodiment configured as described above will be described. In FIG. 1, when one IGBT element 17 or a diode 18 fails in the switching arm 15, the DC power supply bus PN is connected through another parallel unit connected in series.
IGBT element 1 in which a fault current has flowed and a fault has occurred
The protection fuse 19 in a parallel unit including the diode 7 and the diode 18 is blown by the short-circuit current.

As a result, the faulty parallel unit is disconnected from the DC power supply bus P or N, and the operation of the power converter can be continued with the remaining healthy parallel unit.

As described above, the IGBT 17 and the diode 1
By isolating the faulty part in parallel units for eight faults, the I / O ratio can be at least twice as large as that of the prior art.
The operation reliability against the failure of the GBT 17 and the diode 18 can be improved.

As described above, in the power converter according to the present embodiment, even if a failure occurs in the IGBT element 17 or the diode 18 which is a switching element in any one of the parallel units, the plurality of divided switching elements IG as an element
With the parallel unit of the BT element 17 and the diode 18, the parallel unit of the IGBT element 17 and the diode 18 which is a failed switching element can be separated.

Therefore, the operation of the power converter can be continued with the remaining parallel units other than the parallel unit disconnected due to the failure, and the switching element I
It is possible to improve the operation reliability against the failure of the GBT element 17 and the diode 18.

(Second Embodiment: Claims 1 and 3)
FIG. 2 is a circuit diagram showing a configuration example of a power conversion device according to the present embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. State.

That is, as shown in FIG. 2, the power converter according to the present embodiment omits the protection fuse 19 provided on the negative DC power supply bus N in FIG. 1 and replaces it with a parallel unit. The protective fuse 20 is inserted into the AC terminal side of the switching arm 15 to form a series circuit of the switching arm 15.

Next, the operation of the power converter of the present embodiment configured as described above will be described. In FIG. 2, when one IGBT element 17 or a diode 18 fails in the switching arm 15, the DC power supply bus P · N is connected through another parallel unit connected in series.
Then, a fault current flows from the load 16 and at least the protection fuse 19 or the protection fuse 20 is blown.

As a result, the faulty parallel unit is separated from other sound parallel units, and the operation of the power converter can be continued with the remaining sound parallel units. As described above, as in the case of FIG. 1, the IGBT 17 and the diode 18 are at least twice as large as the conventional one.
Operation reliability against failure of the vehicle can be improved.

As described above, in the power converter according to the present embodiment, any one of the switching elements IGB
Even if a failure occurs in the T element 17 or the diode 18, only the series connection circuit in which the failure has occurred in the series connection circuits connected in series for each parallel unit is replaced with the protective fuse 19 and the DC terminal side and the AC terminal side. By fusing with the short-circuit current of 20, at least one of the DC power supply buses P and N can be separated from the AC terminal side.

Therefore, the operation of the power converter can be continued by the remaining sound series connection circuit of the parallel unit, and the operation reliability against the failure of the IGBT element 17 or the diode 18 as the switching element can be improved. Becomes

(Third Embodiment: Claims 1 and 4)
FIG. 3 is a circuit diagram showing a configuration example of the power converter according to the present embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. Here, only different parts will be described. State.

That is, in the power converter of the present embodiment, as shown in FIG. 3, the switching arm 15 of the three-phase PWM inverter 14 is connected to the IGBT 17 and the diode 1.
8 instead of two parallel connections, a unit power conversion circuit 21 is configured without direct parallel connection, and this unit power conversion circuit 21 is connected between the DC power supply buses P and N via a protection fuse 22. The AC terminals are configured by connecting the AC terminals of each unit power conversion circuit 21 in parallel for each phase.

Next, the operation of the power converter of the present embodiment configured as described above will be described. 3, in the power converter in which a plurality of unit power conversion circuits 21 are connected in parallel, when a failure occurs in the IGBT 17 or the diode 18 which is a switching element, a fault current flows and the protection fuse 22 is blown.

As a result, the unit power conversion circuit 21 in which the failure has occurred is disconnected from the main circuit, and the operation of the power converter can be continued by the remaining healthy unit power conversion circuit 21.

Thus, as in the case of FIGS. 1 and 2, the IGBT 1 is at least twice as large as the conventional one.
It is possible to improve the operation reliability against the failure of the diode 7 or the diode 18.

As described above, in the power converter according to the present embodiment, any one of the switching elements IGB
Even if a failure occurs in the T element 17 or the diode 18, of the plurality of unit power conversion circuits 21 divided for each parallel unit,
The protection fuse 22 can be separated by fusing with a short-circuit current.

Therefore, the remaining sound unit power conversion circuit 2
1, the operation of the power converter can be continued,
It is possible to improve the operation reliability with respect to the failure of the IGBT element 17 and the diode 18 which are the switching elements.

(Fourth Embodiment: Claims 1 and 5)
FIG. 4 is a circuit diagram showing a configuration example of the power converter according to the present embodiment. The same reference numerals are given to the same portions as those in FIG. 1 or FIG. Only the part will be described.

FIG. 4 shows, for example, only one switching arm 15 in FIG. 1 or FIG. That is, as shown in FIG. 4, the power conversion device of the present embodiment has one switching arm 15
Each of the IGBT elements 17 and diodes 18 which are divided into a plurality of switching elements constituting
The control line for supplying the on / off control signal 23 of the GBT element 17 is provided with a protection fuse 25 as protection means for each parallel unit.

Reference numeral 24 denotes a gate resistor of the IGBT element 17. Next, the operation of the power converter of the present embodiment configured as described above will be described.

In FIG. 4, the switching element I
As described above, the failure of the GBT element 17 and the diode 18
The parallel unit of the BT element 17 and the diode 18 can be separated. However, if the IGBT element 17 fails, the potential of the DC power supply bus PN is also divided by the gate terminal of the IGBT element 17. The generated voltage may affect the on / off control signal 23 and the gate of the IGBT element 17 in another parallel unit via the gate resistor 24.

In such a case, in the present embodiment, the protection fuse 25 is inserted as shown in the control line to which the on / off control signal 23 is supplied, so that the IGBT 17 and the diode 18 as switching elements are provided. Occurs, a fault current flows and the protection fuse 25 is blown.

As a result, the faulty parallel unit IGBT element 17 can be disconnected also as a control signal so that the ON / OFF control signal 23 is not affected, and the power conversion is performed by the remaining sound parallel unit. The operation of the device can be continued.

As described above, even if any failure of the IGBT element 17 occurs, the operation of the power converter can be continued by using the remaining sound parallel units, so that the power converter can be operated as compared with the case of FIGS. , IGBT17 and diode 1
8 can further improve operation reliability.

As described above, in the power converter according to the present embodiment, any one of the switching elements IGB
When a failure occurs in the T element 17 or the diode 18 and the parallel unit is disconnected in the main circuit, the on / off control signal is affected by the main circuit potential due to the disconnection of the parallel unit, Even if an attempt is made to affect the on / off control signal 23 of another parallel unit, the protection fuse 25 provided on the control line causes the IGB, which is a failed switching element, to fail.
The control lines of the T element 17 and the diode 18 can be disconnected.

Therefore, the operation of the power converter can be continued without affecting the remaining healthy control units of the parallel unit, and the IGBT element 1 serving as a switching element can be operated.
It is possible to further improve the operational reliability against the failure of the diode 7 or the diode 18.

(Fifth Embodiment: Claims 1 and 6)
FIG. 5 is a circuit diagram showing a configuration example of a power conversion device according to the present embodiment, and the same parts as those in FIG. 1, FIG. 2, or FIG. Here, only different parts will be described.

That is, as shown in FIG. 5, the power converter according to the present embodiment is an IGBT which is a switching element divided into a plurality of parts constituting the switching arm 15 shown in FIG. 1, FIG. 2 or FIG. Element 17
Detecting means 26 for detecting that a failure has occurred in any one of the parallel units of the diode 18 and that the parallel unit has been disconnected by the protection fuse 19 (detects the fusing of the protection fuse 19). When the detection unit 26 detects that the parallel unit has been disconnected, the detection signal is input to the control circuit 27 of the power conversion device, and 3 corresponding to the disconnected parallel unit is output. The configuration is such that the output power of the phase PWM inverter 14 is limited.

Next, the operation of the power converter of the present embodiment configured as described above will be described. In FIG. 5, when a failure of one IGBT element 17 or diode 18 occurs in switching arm 15, DC power supply bus P · N is connected through another parallel unit connected in series.
IGBT element 1 in which a fault current has flowed and a fault has occurred
The protection fuse 19 in a parallel unit including the diode 7 and the diode 18 is blown by the short-circuit current.

When the detecting means 26 detects that the faulty IGBT element 17 or diode 18 has been disconnected in parallel units, this detection signal is input to the control circuit 27 of the power conversion device, and the three-phase The output power of the PWM inverter 14 is limited.

As a result, the output power of the three-phase PWM inverter 14 can be limited to a predetermined value in response to disconnection of the parallel unit due to a failure, and power conversion is performed using the remaining sound parallel unit. Even when the operation of the device is continued, it is possible to prevent a trouble due to an overload or the like and continue the operation safely.

As described above, the output power of the three-phase PWM inverter 14 is limited to a predetermined value in response to disconnection of the parallel unit due to a failure, so that the power converter of the remaining healthy parallel unit can be used. Even if the operation is continued, troubles due to overload and the like are prevented and the operation is continued safely,
As compared with the case of, the operation reliability against the failure of the IGBT 17 and the diode 18 can be further improved.

As described above, in the power converter of the present embodiment, the parallel unit in which a failure has occurred is connected to the protection fuse 19.
When the power supply is disconnected, the output of the three-phase PWM inverter 14 can be limited.

Therefore, the output of the three-phase PWM inverter 14 can be limited to the output power corresponding to the remaining sound parallel units, and the problem of the overload current can be eliminated, and
The operation of the power converter can be continued, and the operation reliability against the failure of the IGBT element 17 or the diode 18 as the switching element can be further improved.

(Sixth Embodiment: Corresponding to Claim 7) That is, the power converter of the present embodiment is the same as the first embodiment.
In each of the fifth to fifth embodiments, a switching element with a protection function having a built-in protection function in place of the above-described protection fuse is used as each switching element constituting the parallel unit, and a plurality of the switching elements with the protection function are connected in parallel. The switching arm 15 is configured by being connected.

In the power converter of the present embodiment configured as described above, even if a failure occurs in the switching element, the failed switching element can be separated by the protection function built in the switching element. .

Therefore, the operation of the power converter can be continued without affecting the remaining healthy switching elements, and the switching can be performed in the same manner as in the first to fifth embodiments described above. It is possible to improve the operational reliability against the element failure.

(Other Embodiments) (a) In the embodiment described above, when the unit power conversion circuits 21 are connected in parallel as shown in FIG. 3, the AC terminal side of the unit power conversion circuit 21 is also protected. Install a fuse,
You may make it connect in parallel.

(B) In the embodiment described above, FIG.
As shown in FIG.
May be provided with a small-capacity resistor or the like that disconnects due to a fault current in the control line. Any protection function element having the same function as the protection fuse 25 may be used.

(C) In the above embodiments, the case where the present invention is applied to the power converter using the three-phase PWM inverter using the IGBT element has been described. However, the switching element is not particularly limited. It does not limit the circuit system to be configured.

(D) The number of the switching elements constituting the switching arm 15 is not limited in parallel. When dividing the switching elements connected in parallel into parallel units, it is sufficient to use two or more switching elements. The number of parallel units is not particularly limited.

[0088]

As described above, according to the power converter of the first aspect, even if a failure occurs in a switching element in any one of the parallel units, the switching element divided into a plurality of switching elements can be used. Since the parallel unit of the failed switching element can be disconnected in the parallel unit, the operation of the power converter can be continued by the remaining healthy parallel units other than the disconnected parallel unit in which the failure has occurred. Therefore, it is possible to improve the operation reliability against the failure of the power converter.

According to the power converter of the second aspect, even if a failure occurs in any one of the switching elements, a failure occurs in the series connection circuit connected in series for each parallel unit. Since the series connection circuit can be disconnected from the DC power supply bus by blowing the protection fuse with the short-circuit current, the operation of the power converter can be continued by the remaining sound parallel unit series connection circuit, It is possible to improve the operation reliability against the failure of the power converter.

Further, according to the power converter of the present invention, even if a failure occurs in any one of the switching elements, a failure occurs in the series connection circuit connected in series for each parallel unit. Only the series connection circuit can be disconnected from at least one of the DC power supply buses and the AC terminal side by fusing the protective fuses on the DC and AC terminal sides with the short-circuit current. The operation of the power converter can be continued by the connection circuit, and thus, the operation reliability against the failure of the power converter can be improved.

Further, according to the power converter of the present invention, even if a failure occurs in any one of the switching elements, the power conversion circuit is divided into a plurality of unit power conversion circuits divided for each parallel unit. Since only the unit power conversion circuit part in which a failure has occurred can be disconnected by fusing the protection fuse with the short-circuit current, the operation of the power conversion device can be continued by the remaining sound unit power conversion circuits, Therefore, it is possible to improve the operation reliability against the failure of the power converter.

On the other hand, according to the power converter of the present invention, when a failure occurs in one of the switching elements and the parallel unit is disconnected in the main circuit, the disconnection of the parallel unit is performed. The influence of the main circuit potential on the ON / OFF control signal due to the influence of the influence causes the ON / OFF control signal of another parallel unit to be affected. Since the control line can be disconnected, the operation of the power converter can be continued without affecting the remaining sound parallel unit control lines, thereby further improving the operational reliability against failure of the power converter. It is possible to improve.

Further, according to the power converter of the present invention, when the faulty parallel unit is cut off by the protection fuse, this is detected by the detecting means, and the output of the power converter main body is limited. Therefore, it is possible to limit the output of the power conversion device main body to the output power corresponding to the remaining healthy parallel units, thereby safely removing the problem of the overload current, etc. Operation reliability can be improved.

Further, according to the power converter of the present invention, even if a failure occurs in the switching element, the failed switching element can be separated by the protection function built in the switching element. The operation of the power converter can be continued without affecting the healthy switching element, and the operation reliability against the failure of the power converter can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a power converter according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the power converter according to the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the power converter according to the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of the power converter according to the present invention.

FIG. 5 is a circuit diagram showing a fifth embodiment of the power converter according to the present invention.

FIG. 6 is a circuit diagram showing a configuration example of a conventional power converter.

FIG. 7 is a circuit diagram showing a configuration example of a switching arm of a conventional power converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Input AC power supply terminal, 12 ... Rectifier, 13 ... DC filter capacitor, 14 ... 3-phase PWM inverter, 15 ... Switching arm, 16 ... Load, 17 ... IGBT element as a switching element, 18 ... Diode, 19 ... Protective fuse Reference numeral 20: protection fuse, 21: unit power conversion circuit, 22: protection fuse, 23: ON / OFF control signal, 24: gate resistor, 25: protection means, 26: detection means, 27: control circuit

Claims (7)

[Claims] 1. A power converter in which each switching arm is configured by connecting a plurality of switching elements in parallel, wherein the switching elements connected in parallel constituting one switching arm are divided into a plurality of switching elements. A protection fuse is provided for each of the plurality of divided switching elements in parallel, and when any one of the switching elements fails in the one switching arm, the protection fuse for each of the parallel units is provided. A power conversion device characterized in that a failed switching element portion is separated from the power conversion device. 2. The power converter according to claim 1, wherein at least two power supply lines are provided between each of the DC power supply buses on the positive electrode side and the negative electrode side.
When the power conversion device main body is configured by connecting the switching arms in series, the switching arms to be connected in series are connected in series for each of the plurality of parallel units of the switching element, and the series connection circuits of the parallel units are respectively connected. A power converter, wherein a series connection circuit of the switching arms is configured by connecting between the DC power buses via a protection fuse. 3. The power converter according to claim 1, wherein a series connection circuit connected in series for each of the plurality of parallel units is connected between each of the positive and negative DC power supply buses. A power converter, wherein a protective fuse is inserted into one of a DC terminal side and an AC terminal side to form a series connection circuit of switching arms. 4. The power conversion device according to claim 1, wherein a plurality of unit power conversion circuits are configured in parallel units of the switching elements, and when a failure of the switching elements occurs, the plurality of unit power conversion circuits are configured. A power conversion device characterized in that a protection fuse is cut off in units of a power conversion circuit. 5. The method according to claim 1, wherein
The power conversion device according to any one of the preceding claims, wherein a control unit that supplies an on / off control signal for each switching element to a parallel unit of a plurality of divided switching elements constituting the one switching arm is provided. A power converter, wherein a protection unit is provided for each parallel unit, and when a failure of the switching element occurs, the control line of the failed parallel unit is disconnected by the protection unit. 6. The method according to claim 1, wherein
In the power conversion device according to the item, among the parallel units of the plurality of switching elements constituting the switching arm, a failure occurs in one of the parallel units and the parallel unit is blown by the protection fuse. Detecting means for detecting that the parallel unit has been separated, and when the detecting means detects that the parallel unit has been separated, limiting the output of the power conversion device main body corresponding to the separated parallel unit. A power converter characterized by the above. 7. The method according to claim 1, wherein
In the power converter described in the paragraph, a switching element with a protection function having a built-in protection function instead of the protection fuse is used as each switching element constituting the parallel unit, and a plurality of the switching elements with a protection function are connected in parallel. To constitute a switching arm, and for a failure occurring in the individual switching element,
A power converter wherein the protection function of the switching element with protection function is operated to disconnect the switching element.