JP6828425B2 - Power converter - Google Patents

Description

Embodiments of the present invention relates to a power conversion device.

The inverter circuit or chopper cell circuit of the power converter includes a semiconductor element having a switching function such as an insulated gate bipolar transistor (hereinafter referred to as an IGBT: Insulated Gate Bipolar Transistor). A multi-chip semiconductor device in which a plurality of semiconductor elements (for example, IGBTs) are housed in one package is known. Multi-chip semiconductor devices are a module type in which a plurality of semiconductor elements are connected using solder and the whole is hardened with resin, and two electrode plates are pressure-welded from both sides of the semiconductor element to electrically parallelize the plurality of semiconductor elements. Includes a pressure welding type that is designed to connect to. In a pressure-welded multi-chip semiconductor device (hereinafter, may be simply referred to as a pressure-welded semiconductor device), when a semiconductor element is damaged, the electrodes are short-circuited.

Japanese Unexamined Patent Publication No. 2013-236004

In a power conversion device using a pressure welding type multi-chip semiconductor device, all of the plurality of semiconductor elements included in the pressure welding type semiconductor device are turned on or off during normal operation, so that the current flowing through the pressure welding type semiconductor device is each semiconductor. It is evenly distributed in the elements.

However, if at least one of the semiconductor elements included in the pressure welding type semiconductor device fails and the electrodes are short-circuited, the short-circuited semiconductor element does not turn off even during the period when all of them are turned off. Current is concentrated and flows in the element. For this reason, silicon, which is a material for a semiconductor element that has suffered a short-circuit failure, sublimates into a gas, which causes a rapid increase in internal pressure and may damage the package of the pressure-welded semiconductor device. In addition, the debris generated by the breakage can damage other peripheral components in the power converter. This phenomenon can occur not only in the pressure-welding semiconductor device applied to the power conversion device but also in the pressure-welding semiconductor device applied to other devices.

An object of the present invention is to prevent damage to a pressure-welded semiconductor device in the event of a short-circuit failure of a semiconductor element included in the pressure-welding semiconductor device.

According to one aspect of the present invention, two pressure-welded semiconductor devices , each of which is composed of a plurality of semiconductor elements having a switching function connected in parallel, are connected in series, and the two pressure-welded types connected in series. A power conversion unit composed of a capacitor connected in parallel with a semiconductor device, a driving means for alternately turning on the two pressure-welded semiconductor devices, and a pressure-welding semiconductor device of either of the two pressure-welding semiconductor devices. A detection means for detecting a short circuit of any one of the plurality of semiconductor elements, and a plurality of the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected when the detection means detects the short circuit. A control means for turning on the semiconductor element of the above is provided, and a plurality of positive power conversion units connected in series and a plurality of power conversion units connected in series are connected to the positive side arm. The detection means is individually provided for each of the plurality of power conversion units included in the positive side arm and the negative side arm, and each of the power conversion units is provided with an arm circuit including the negative side arm. A detection signal including identification information for distinguishing each other is transmitted to the control means, and the control means transmits a power conversion unit other than the power conversion unit including the pressure-welding semiconductor device including the semiconductor element in which the short circuit is detected. Use to continue conversion operation .
According to one aspect of the present invention, two pressure-welded semiconductor devices, each of which is composed of a plurality of semiconductor elements having a switching function connected in parallel, are connected in series, and the two pressure-welded types connected in series. A power conversion unit composed of a capacitor connected in parallel with a semiconductor device, a driving means for alternately turning on the two pressure-welded semiconductor devices, and a pressure-welding semiconductor device of either of the two pressure-welding semiconductor devices. A detection means for detecting a short circuit of any one of the plurality of semiconductor elements, and a plurality of the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected when the detection means detects the short circuit. A first-phase positive electrode side arm in which a plurality of the power conversion units are connected in series and a plurality of the power conversion units connected in series are provided with a control means for turning on the semiconductor element of the first phase. A first-phase arm circuit including a first-phase negative-side arm connected to a positive-side arm, a second-phase positive-side arm in which a plurality of the power conversion units are connected in series, and the power conversion unit are connected in series. A second-phase arm circuit including a second-phase negative-side arm that is connected to a plurality of the second-phase positive-side arms and a third-phase positive-side arm in which a plurality of the power conversion units are connected in series. A third-phase arm circuit including a plurality of arms and a third-phase negative-side arm in which a plurality of the power conversion units are connected in series and connected to the third-phase positive-side arm is further provided.
The first-phase arm circuit, the second-phase arm circuit, and the third-phase arm circuit form a three-phase power conversion circuit, and the detection means is the first-phase positive side arm and the first-phase negative side. A plurality of power conversion units included in the arm, the second phase positive side arm, the second phase negative side arm, the third phase positive side arm, and the third phase negative side arm are individually provided. A detection signal including identification information for distinguishing each of the power conversion units is transmitted to the control means, and the control means is a power conversion unit including the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected. Continue the conversion operation using a power conversion unit other than.

According to the present invention, when any of a plurality of semiconductor elements connected in parallel is short-circuited, the remaining semiconductor elements are turned on, so that the current is concentrated and flows only in the short-circuited semiconductor elements, and the semiconductor device is damaged. Is prevented.

FIG. 1 is a diagram showing an example of a configuration of a power conversion device including a control circuit of the pressure welding type semiconductor device according to the embodiment. FIG. 2 is a diagram showing an example of the configuration of a converter provided in the power converter according to the embodiment. FIG. 3 is a circuit diagram illustrating an example of a connection state of the IGBT and the diode included in the pressure welding type semiconductor device according to the embodiment. FIG. 4 is a diagram showing an example of a state in which a plurality of semiconductor chips are arranged in the pressure welding type semiconductor device according to the embodiment. FIG. 5 is a side view illustrating an example of connection between pressure-welded semiconductor devices in the embodiment. FIG. 6 is a diagram showing an example of the configuration of the converter in the modified example of the embodiment. FIG. 7 is a diagram showing an example of the configuration of the converter in another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Overview of power converter]
FIG. 1 is a diagram showing an example of a configuration of a power conversion device 30 including a control circuit of a pressure welding type semiconductor device according to an embodiment of the present invention.
The embodiment will be described by taking MMC (Modular Multilevel Converter) as an example of the power conversion device, but the power conversion device to which the control circuit of the embodiment can be applied is not limited to the MMC. The MMC is used for orthogonal converters and AC / DC converters that connect high-voltage DC power transmission and existing AC systems.

The power conversion device 30 includes a power conversion circuit 31 and a control device 32.

The power conversion circuit 31 includes six arms 21up, 21um, 21vp, 21vm, 21wp, 21wm and six buffer reactors 22up, 22um, 22vp, 22vm, 22wp, 22ww.

The AC side (left side in FIG. 1) of the power conversion device 30 is connected to the AC power system via a transformer 24. The DC side (right side of FIG. 1) of the power conversion device 30 is connected to the DC power system. The power conversion device 30 converts the DC power supplied from the DC power system into three-phase AC power. Alternatively, the power conversion device 30 converts the three-phase AC power supplied from the AC power system into DC power.

Each arm 21up, 21um, 21vp, 21vm, 21ww, 21wm has a configuration in which a plurality of converters 1 are connected in series. The U-phase positive electrode side arm 21up and the U-phase negative electrode side arm 21um are configured for the U-phase of three-phase alternating current. The V-phase positive electrode side arm 21 bp and the V-phase negative electrode side arm 21 vm are configured for the V-phase of three-phase AC. The W-phase positive electrode side arm 21 hp and the W-phase negative electrode side arm 21 ww are configured for the W phase of three-phase alternating current.

The buffer reactors 22up, 22um, 22bp, 22vm, 22wp, and 22wm are impedances for passing a constant direct current through the circuit of the power converter 30 in order to suppress the short-circuit current.

The U-phase positive electrode side buffer reactor 22up and the U-phase negative electrode side buffer reactor 22um are connected in series. The connection point between the U-phase positive electrode side buffer reactor 22up and the U-phase negative electrode side buffer reactor 22um is connected to the U-phase of three-phase alternating current. A U-phase positive electrode side arm 21up is connected to the positive electrode side of the U-phase positive electrode side buffer reactor 22up. A U-phase negative electrode side arm 21um is connected to the negative electrode side of the U-phase negative electrode side buffer reactor 22um.

The V-phase positive electrode side buffer reactor 22 bp and the V-phase negative electrode side buffer reactor 22 vm are connected in series. The connection point between the V-phase positive electrode side buffer reactor 22 bp and the V-phase negative electrode side buffer reactor 22 vm is connected to the three-phase AC V phase. A V-phase positive electrode side arm 21vp is connected to the positive electrode side of the V-phase positive electrode side buffer reactor 22vp. A V-phase negative electrode side arm 21 vm is connected to the negative electrode side of the V-phase negative electrode side buffer reactor 22 vm.

The W-phase positive electrode side buffer reactor 22 hp and the W-phase negative electrode side buffer reactor 22 ww are connected in series. The connection point between the W-phase positive electrode side buffer reactor 22 hp and the W-phase negative electrode side buffer reactor 22 pm is connected to the W phase of three-phase alternating current. A W-phase positive electrode side arm 21 pp is connected to the positive electrode side of the W-phase positive electrode side buffer reactor 22 pp. A W-phase negative electrode side arm 21wm is connected to the negative electrode side of the W-phase negative electrode side buffer reactor 22wm.

The control device 32 exchanges various signals with the power conversion circuit 31, and executes a protection operation when it detects that a short-circuit failure has occurred in the power conversion circuit 31. Details will be described later.

[Chopper cell circuit]
FIG. 2 is a diagram showing an example of the configuration of the converter 1. All the converters 1 in the power conversion circuit 31 have the same configuration.

The converter 1 includes gate drivers 2a and 2b and a chopper cell circuit 3. The chopper cell circuit 3 includes semiconductor devices 4a and 4b that are alternately conductive. Each of the semiconductor devices 4a and 4b is realized by a pressure welding type semiconductor device composed of a large number of semiconductor elements connected in parallel in order to increase the current.

[Pressure welding type semiconductor device]
FIG. 3 shows an example of an equivalent circuit of the pressure welding type semiconductor device 4a. Since the pressure welding type semiconductor device 4b has the same structure as the pressure welding type semiconductor device 4a, the description thereof will be omitted. The pressure welding type semiconductor device 4a includes IGBTs 8 ₁ to 8 _N as switching elements connected in parallel and freewheeling diodes 9 _{1 to} 9 _N connected in antiparallel to IGBTs 8 ₁ to 8 _N , respectively. N is any positive integer greater than or equal to 2, for example 42. Assuming that a current of I [A] flows through the pressure-welding semiconductor device 4a, a current of I / N [A] flows through each of the IGBTs 8 ₁ to 8 _N of the pressure-welding semiconductor device 4a. The output of the gate driver 2a is supplied to the gates of the IGBTs 8 ₁ to 8 _N. Therefore, all the IGBTs of one pressure welding type semiconductor device are commonly on / off controlled.

FIG. 4 shows an example of the structure inside the package of the pressure welding type semiconductor device 4a (the same applies to 4b). FIG. 4A shows a planar structure, and FIG. 4B shows a cross-sectional structure. Each of the pressure-welded semiconductor elements 4a is contained in a columnar package having a height of about several centimeters (only the outline is shown in FIG. 4A but not shown in FIG. 4B), and each of them is IGBT 8 ₁ to _N semiconductor chips 10 ₁ to 10 _N constituting 8 _N are arranged on the same plane without a gap. The gate terminal plate 404 is connected to the semiconductor chips 10 ₁ to 10 _N via the spring pin 405. The semiconductor chips 10 ₁ to 10 _N are pressure-welded from above and below by the emitter copper electrode 401 and the collector copper electrode 402 via the molybdenum plate 403, respectively. The collector and emitter electrodes of the semiconductor chips 10 ₁ to 10 _N are brought into contact with the collector copper electrode 402 and the emitter copper electrode 401 by mechanical pressure contact force, respectively, via the molybdenum plate 403, and electrical connection and heat dissipation are performed.

Although not shown, semiconductor chips constituting the diodes 9 _{1 to} 9 _N are also arranged in the package. The semiconductor chip constituting the diode is the same as the semiconductor chip 10 constituting the IGBT from which the gate terminal plate 404 and the spring pin 405 are removed.

By adopting the double-sided heat dissipation structure in this way, it is possible to cool both sides of the collector side and the emitter side. Although not shown, the inert gas is hermetically sealed in the package to prevent deterioration of the electrode surface due to oxidation, and high thermal reliability is realized. In this way, all electrical connections are realized by pressure welding, and bonding by bonding is not used, so high reliability against thermal fatigue can be expected. If the package is made of ceramic, it has a high moisture resistance due to the airtight sealing structure made of ceramic and metal, and can be directly immersed in the coolant, so that efficient cooling is possible.

In FIG. 4, it was explained that the semiconductor chips constituting the IGBT and the semiconductor chips constituting the diode are arranged in a mixed manner in one package, but the semiconductor chips constituting the IGBT and the semiconductor chips constituting the diode are separately arranged. It may be packaged in.

The pressure-welded semiconductor device 4a and the pressure-welded semiconductor device 4b are connected in series. FIG. 5 shows an example of a series connection between the pressure-welded semiconductor devices 4a and 4b. Here, the pressure-welded semiconductor devices 4a and 4b are also connected in series by pressure-welding. The cooling fins 7, the pressure-welded semiconductor device 4a, the cooling fins 7, the pressure-welding semiconductor device 4b, and the cooling fins 7 are arranged in this order from the top, and the cooling fins 7 are pressure-welded from the top and bottom. Since the cooling fins 7 are conductors, the pressure-welded semiconductor devices 4a and 4b are electrically connected in series without wiring. Hereinafter, a pressure-welded semiconductor device 4a and a pressure-welding semiconductor device 4b connected in series are referred to as a series connector. In FIG. 4, two pressure-welded semiconductor devices are connected in series, but three or more pressure-welded semiconductor devices may be connected in series.

Returning to the description of FIG. 2, the capacitor 5 is connected in parallel to the series connector. The current detector 6 is provided between the series connector and the DC capacitor 5. The current detector 6 detects the current flowing through the wiring connecting the series connector and the DC capacitor 5, and outputs a detection signal 60 including the current value as the detection result to the control device 32. The detection signal 60 also includes identification information of the chopper cell circuit 3 (or converter 1) including the current detector 6 that outputs the detection signal 60.

The control device 32 includes on control signals 40a and 40b including an instruction to turn on all the IGBTs 8 ₁ to 8 _N included in the pressure welding type semiconductor devices 4a and 4b included in the chopper cell circuit 3, and an off control including an instruction to turn them off. The signals 41a and 41b are output to the gate drivers 2a and 2b of each converter 1 of the power conversion circuit 31. The control device 32 also detects that a short-circuit failure has occurred in any of the IGBTs included in the pressure-welded semiconductor devices 4a and 4b based on the detection signal 60 from the current detector 6. Further, the control device 32 identifies a pressure-welded semiconductor device having a short-circuited IGBT, and outputs on control signals 40a and 40b and off control signals 41a and 41b to the gate drivers 2a and 2b according to the result.

The gate drivers 2a and 2b are provided corresponding to the two pressure contact type semiconductor devices 4a and 4b included in the chopper cell 3. The gate driver 2a, 2b is ON control signal 40a from the controller 32, 40b or off control signal 41a, when receiving the 41b, corresponding pressure-contact type semiconductor device 4a, the gate of the IGBT 8 ₁ to 8 _N of 4b, IGBT 8 ₁ ~ drive signal 50a to the 8 _N on / off, supplies 50b. Specifically, the gate driver 2a, 2b is ON control signal 40a from the controller 32, when receiving the 40b, it is applied to IGBT 8 ₁ to 8 higher than the threshold gate voltage to the gate of the _N, the IGBT 8 ₁ to 8 _N turn on. The gate driver 2a, 2b, when the controller 32 receives off control signal 41a, a 41b, a reverse bias is applied to the IGBT 8 ₁ to 8 _N, to turn off the IGBT 8 ₁ to 8 _N.

Next, an operation example of the power conversion device will be described.

[Normal operation]
During normal power conversion, the control device 32 turns on the IGBTs 8 ₁ to 8 _N included in one of the pressure-welding semiconductor devices 4a (or 4b) of one chopper cell circuit 3, and the other pressure-welding semiconductor. An on control signal or an off control signal is output to the gate drivers 2a and 2b so as to turn off the IGBTs 8 ₁ to 8 _N included in the device 4b (or 4a). Further, the control device 32 alternately outputs an on control signal or an off control signal to the gate drivers 2a and 2b so that the on / off of the IGBTs 8 ₁ to 8 _N included in the pressure contact type semiconductor devices 4a and 4b are alternately switched. ..

That is, the control device 32 outputs (1) an on control signal 40a to the gate driver 2a and an off control signal 41b to the gate driver 2b. After a certain period of time, the control device 32 outputs (2) an off control signal 41a to the gate driver 2a and an on control signal 40b to the gate driver 2b. The control device 32 alternately repeats (1) and (2). The voltage value can be adjusted by adjusting the period during which the IGBT is turned on.

When one of the gate drivers 2a (or 2b) receives the on-control signal 40a (or 40b), it applies a gate voltage equal to or higher than the threshold value to the gates of the IGBTs 8 ₁ to 8 _N included in the pressure welding type semiconductor device 4a (or 4b). To do. At this time, the other gate driver 2b (or 2a) receives the off control signal 41a (or 41b) and applies a reverse bias to the IGBTs 8 ₁ to 8 _N. Thus, IGBT 8 ₁ to 8 _N contained in the pressure-contact type semiconductor device 4a (or 4b) is turned on from off, IGBT 8 ₁ to 8 _N contained in the pressure-contact type semiconductor device 4b (or 4a) is turned off from on .. Here, assuming that a current of I [A] flows through the pressure-welding semiconductor device 4a (or 4b), I / N [A] is applied to each IGBT 8 ₁ to 8 _N included in the pressure-welding semiconductor device 4a (or 4b). Current flows.

[Operation at the time of short circuit failure]
Next, an operation example of the power conversion device 30 at the time of a short circuit failure will be described. It is assumed that _one of the IGBTs included in the pressure welding type semiconductor device 4a of one converter 1, for example 81, has a short-circuit failure.

In that transducer 1, one of the gate driver, for example 2b outputs a driving signal 50a to turn on the IGBT 8 ₁ to 8 _N. At this time, the other gate driver 2a outputs a drive signal 50a that turns off the IGBTs 8 ₁ to 8 _N , but since the IGBT 8 ₁ included in the pressure welding type semiconductor device 4a has a short-circuit failure, the IGBTs 8 ₂ to 8 _N are It turns off, but the IGBT 8 ₁ does not. Therefore, short-circuit current flows in the IGBT 8 _1. When normal state and pressure-contact type semiconductor device 4a, a current of I [A] and 4b flows, flows short-circuit current I [A] is concentrated on IGBT 8 _1. When the current concentrates on IGBT 8 _1, becomes a gas by sublimation silicon is the material, leading to rapid increase in pressure, pressure-contact type semiconductor device is damaged, furthermore, broken pieces of the power converter Other peripheral parts may be damaged.

At this time, the IGBTs 8 ₁ to 8 _N included in the pressure-welded semiconductor device 4b are turned on, and the short-circuit current of the pressure-welding semiconductor device 4a is dispersed and flows in all the IGBTs in the pressure-welding semiconductor device 4b.

The current detector 6 detects a current (short-circuit current) flowing in the wiring connecting the DC capacitor 5 and the series connector composed of the pressure welding type semiconductor devices 4a and 4b, and includes the current value and the current detector 6 in a chopper cell circuit. The detection signal 60 including the identification information of 3 (or the converter 1) is output to the control device 32.

Next, the operation of the control device 32 that receives the detection signal 60 from the current detector 6 will be described.

When the control device 32 receives the detection signal 60 from the current detector 6 of each chopper cell circuit 3 in the power conversion circuit 31, the control device 32 compares the current value included in the detection signal 60 with a predetermined threshold value. When the current value is equal to or higher than a predetermined threshold value, the control device 32 is short-circuited to any of the IGBTs 8 ₁ to 8 _N included in the pressure-welding semiconductor devices 4a and 4b included in the chopper cell circuit 3 indicated by the identification information included in the detection signal 60. It is judged that a failure has occurred and a short-circuit current has flowed.

Subsequently, the control device 32 outputs the on control signals 40a and 40b to the gate drivers 2a and 2b.

As a result, the gate drivers 2a and 2b that have received the on control signal 40a output drive signals 50a and 50b to be turned on for the IGBTs 8 ₁ to 8 _N included in the corresponding pressure-welding semiconductor devices 4a and 4b. For this reason, the other IGBT 8 ₁ to 8 _N is on or short-circuit condition included in the pressure-contact type semiconductor device 4a comprising IGBT 8 ₁ a short-circuit failure occurs, not flow only in IGBT 8 ₁ short-circuit current is short-circuited, pressure It is dispersed and flows in all the IGBTs 8 ₁ to 8 _N of the type semiconductor device 4a. Therefore, it becomes a gas IGBT 8 ₁ of silicon short-circuited sublimes, the internal pressure rapidly increases, pressure-contact type semiconductor device is damaged, or broken pieces is other peripheral components in the power converter It will not be damaged.

Even if any of the IGBTs has a short-circuit failure, the power converter 30 can continue the conversion operation by using a converter 1 other than the converter including the short-circuited IGBT. The conversion operation of the power conversion device 30 is stopped at an arbitrary timing such as maintenance and inspection, and the pressure welding type semiconductor device 4a having a short-circuit failure is replaced.

According to the embodiment, when a short-circuit failure of the IGBT included in a certain pressure-welding semiconductor device is detected in the power conversion device, the IGBTs other than the short-circuited IGBT included in the pressure-welding semiconductor device are turned on and short-circuited. The current is distributed and flows in a plurality of IGBTs. Therefore, it is prevented that the short-circuit current is concentrated and flows in the IGBT in which the short-circuit failure occurs, and the internal pressure due to the sublimation of silicon does not suddenly increase. This makes it possible to prevent damage to the pressure welding type semiconductor device and damage or failure of other peripheral parts in the power conversion device to which the pressure welding type semiconductor device is applied. In addition, the burden on workers when replacing parts is reduced. In a device including a large number of pressure-welded semiconductor devices, for example, a power conversion device, the power conversion operation of the power conversion device is stopped by turning off the IGBTs of all the other pressure-welding semiconductor devices that do not include the short-circuited IGBT. be able to.

In the example of FIG. 2, a short-circuit failure occurs by providing a current detector 6 in the current passage of the pressure-welding semiconductor devices 4a and 4b of the chopper cell circuit 3 and detecting a short-circuit current based on the current detected by the current detector 5. It was judged. The example of short circuit detection is not limited to this, and a modified example relating to the detection of short circuit failure will be described below.

[Modification example 1 of short circuit detection]
In this modification, the short circuit of the IGBT is detected by detecting the change in the voltage generated in the capacitor 5.

An example of the configuration of the converter 1 in this modification is shown in FIG. 6A. A voltage detector 12 is provided in the chopper cell circuit 3 of each converter 1. The voltage detector 12 detects the voltage of the capacitor 5 and outputs a detection signal 60 including the voltage value and identification information of the chopper cell circuit 3 (or the converter 1) including the voltage detector 12 to the control device 32. .. It is the same as FIG. 2 except that the voltage detector 12 is provided instead of the current detector 6.

The control device 32 monitors the voltage value included in the detection signal 60 from the voltage detector 12 included in each converter 1. At the time of a short circuit, the voltage of the capacitor 5 changes abruptly. The control device 32 calculates the current i of the chopper cell circuit 3 from the time derivative dv / dt of the voltage value and the capacitance C of the capacitor 5 according to the equation of i = C · dv / dt. When the voltage of the capacitor 5 changes abruptly and the current i is equal to or higher than a predetermined threshold value, the control device 32 is a chopper cell circuit indicated by identification information included in a detection signal 60 including a voltage value used for calculating the current i. It is determined that a short-circuit failure has occurred in any of the IGBTs included in the pressure-welded semiconductor devices 4a and 4b included in 3.

When any of the IGBTs included in the pressure-welded semiconductor devices 4a and 4b fails in a short circuit in a certain converter 1, both the pressure-welded semiconductor devices 4a and 4b are turned on and a short-circuit current flows through the chopper cell circuit 3. The voltage of the capacitor 5 rises due to the short-circuit current. Therefore, when a sudden change occurs in the voltage, it can be determined that a short-circuit failure has occurred in any of the IGBTs included in the pressure-welding semiconductor devices 4a and 4b of the converter 1.

As described above, it is also possible to detect that a short-circuit failure has occurred in the IGBT by detecting the voltage of the capacitor 5 with the voltage detector 12.

[Modification 2 of short circuit detection]
In this modification, the on voltage of the pressure-welding semiconductor devices 4a and 4b when the IGBTs 8 ₁ to 8 _N included in the pressure-welding semiconductor devices 4a and 4b of the converter ₁ are on is detected to short-circuit the IGBT. Is detected. Since the on-voltage during the on-period is substantially proportional to the current, it can be determined that the current is also large when the on-voltage is large.

An example of the configuration of the converter 1 in this modification is shown in FIG. 6 (b). Voltage detectors 12a and 12b are provided in the chopper cell circuit 3 of each converter 1. The voltage detectors 12a and 12b detect the on-voltage during the on-period of the pressure-welding semiconductor devices 4a and 4b, respectively, and identify the voltage value and the chopper cell circuit 3 (or converter 1) including the voltage detectors 12a and 12b. The detection signal 60 including the information is output to the control device 32. It is the same as FIG. 2 except that the voltage detector 12 is provided instead of the current detector 6.

When a short-circuit current flows through the chopper circuit 3, the on-voltage of the pressure-welding semiconductor devices 4a and 4b becomes larger than when the short-circuit current does not flow. The control device 32 monitors the on-voltage value included in the detection signal 60a or 60b from the pressure welding type semiconductor device 4a or 4b during the on-period of each converter 1, and if the on-voltage value is equal to or higher than a predetermined threshold value, the detection is performed. It is determined that a short-circuit failure has occurred in any of the IGBTs included in the pressure welding type semiconductor device 4a or 4b included in the chopper cell circuit 3 indicated by the identification information included in the signal 60a or 60b.

As described above, it is also possible to detect that a short-circuit failure has occurred in the IGBT by detecting the on-voltage of the pressure-welding semiconductor devices 4a and 4b with the voltage detector 12.

[Modification 3 of short circuit detection]
In this modification, the short circuit of the IGBT is detected by detecting the voltage due to the one-circular inductance (also referred to as parasitic inductance) generated in the conducting wire between the capacitor 5 and the pressure-welded semiconductor devices 4a and 4b.

An example of the configuration of the converter 1 in this modification is shown in FIG. 6 (c). A voltage detector 12 is provided in the chopper cell circuit 3 of each converter 1. The voltage detector 12 detects a voltage generated in a circular inductance generated in the wiring connecting the series connection of the pressure welding type semiconductor devices 4a and 4b and the capacitor 5, and the voltage value and the chopper cell circuit 3 including the voltage detector 12 are included. (Or, the detection signal 60 including the identification information of the converter 1) is output to the control device 32. It is the same as FIG. 2 except that the voltage detector 12 is provided instead of the current detector 6.

The control device 32 monitors the voltage value included in the detection signal 60 from each converter 1, and when the voltage value is equal to or higher than a predetermined threshold value, the pressure welding of the chopper cell circuit 3 indicated by the identification information included in the detection signal 60. It is determined that a short-circuit failure has occurred in any of the IGBTs included in the type semiconductor devices 4a and 4b.

In the wiring connecting the series connection of the pressure-welded semiconductor devices 4a and 4b and the capacitor 5, a voltage V represented by V = Ldi / dt is generated by using a one-round inductance L and a current i. That is, when a sudden current (short-circuit current) flows, a voltage having a magnitude equal to or larger than a predetermined threshold value is generated in the wiring between the capacitor 5 and the pressure-welding semiconductor devices 4a and 4b. Therefore, if the voltage is detected, a short circuit failure can be detected.

As described above, it is also possible to detect that a short-circuit failure has occurred in the IGBT by detecting the voltage due to the circular inductance generated in the wiring connecting the series connector and the capacitor 5 by the voltage detector 12.

The method for detecting a short-circuit failure of the IGBT is not limited to the methods of the above-described embodiments and modifications 1 to 3. Other similar detection methods may be used. Further, two or more detection methods may be combined and executed, and if any of the methods is detected, short-circuit detection may be performed, or only when all methods are detected, short-circuit detection may be performed.

This embodiment can also be applied to a circuit in which a plurality of series connectors are connected in parallel. For example, it can be applied to a single-phase inverter circuit and a three-phase inverter circuit. As an example, a circuit diagram of a single-phase inverter circuit is shown in FIG. Single-phase inverter circuit includes four pressure-contact type semiconductor device _{63 1,} 63 _2, 63 3, 63 ₄ are bridge-connected. Each pressure-contact type semiconductor device _{63 1,} 63 _2, 63 3, 63 _4, as shown in FIG. 3, including the IGBT62 connected to a number of parallel and reflux diode 64. Pressure-contact type semiconductor device ₆₃ 1, 63 ₂ are connected in series, pressure-contact type semiconductor device ₆₃ 3, 63 ₄ are connected in series. A pressure-contact type semiconductor device ₆₃ 1, 63 ₂ connected in series, the pressure contact type semiconductor device ₆₃ 3, 63 ₄ connected in series, the capacitor 61 is connected in parallel. The DC power supply 66 is connected in parallel with the capacitor 61. A connection point of the pressure-contact type semiconductor device ₆₃ 1, 63 _2, a connection point of the pressure-contact type semiconductor device ₆₃ 3, 63 ₄ are connected to the AC terminal 68. In such a single-phase inverter circuit, if any of the IGBT included in the pressure-contact type semiconductor device _{63 1,} 63 _2, 63 3, 63 ₄ are short-circuited, it is possible to prevent damage to the pressure-contact type semiconductor device.

If it is a pressure welding type semiconductor device, the semiconductor element included in the device is not limited to the IGBT, but a semiconductor device having a switching function, for example, IEGT (Injection Enhanced Gate Transistor), MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). ) Etc. may be used.

According to the embodiment described above, when any of the semiconductor elements connected in parallel included in the pressure welding type semiconductor device is short-circuited, the current is prevented from concentrating and flowing through the semiconductor element having the short-circuit failure, and the pressure welding type Damage to the semiconductor device is prevented.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... transformer, 2a, 2b ... gate driver, 3 ... Choppaseru circuit, 4a, 4b ... pressure-contact type semiconductor device, 5 ... capacitor, 6 ... current detector, 7 ... cooling _fins, 8 ₁ to 8 N ... IGBT, 9 _{1 to} 9 _N ... diode, 10 ₁ to 10 _N ... semiconductor chip, 12 ... voltage detector, 30 ... power converter, 31 ... power conversion circuit, 32 ... control device, 40a, 40b ... on control signal, 41a, 41b ... Off control signal, 50a, 50b ... On signal, 60 ... Detection signal

Claims (4)

A capacitor composed of a plurality of semiconductor elements, each of which has a switching function connected in parallel, and connected in parallel with two pressure-welded semiconductor devices connected in series and the two pressure-welded semiconductor devices connected in series. Power conversion unit consisting of
A driving means for alternately turning on the two pressure-welded semiconductor devices and
A detection means for detecting a short circuit of any one of the plurality of semiconductor elements of the pressure-welding semiconductor device of either of the two pressure-welding semiconductor devices,
When the detection means detects the short circuit, the control means for turning on the plurality of semiconductor elements of the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected, and
Equipped with
An arm circuit including a positive electrode side arm in which a plurality of the power conversion units are connected in series and a negative electrode side arm in which a plurality of the power conversion units are connected in series and connected to the positive electrode side arm is provided.
Said detecting means, said positive electrode-side arm negative electrode side each of the plurality of the power conversion unit to be provided separately included in the arm, said including detection signals of the power conversion unit distinguishing identification information respectively from each other Send to control means
The control means is a power conversion device that continues a conversion operation by using a power conversion unit other than the power conversion unit including the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected . A capacitor composed of a plurality of semiconductor elements, each of which has a switching function connected in parallel, and connected in parallel with two pressure-welded semiconductor devices connected in series and the two pressure-welded semiconductor devices connected in series. Power conversion unit consisting of
A driving means for alternately turning on the two pressure-welded semiconductor devices and
A detection means for detecting a short circuit of any one of the plurality of semiconductor elements of the pressure-welding semiconductor device of either of the two pressure-welding semiconductor devices,
When the detection means detects the short circuit, the control means for turning on the plurality of semiconductor elements of the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected, and
Equipped with
A first-phase positive electrode side arm in which a plurality of the power conversion units are connected in series, and a first-phase negative electrode side arm in which a plurality of the power conversion units are connected in series and connected to the first-phase positive electrode side arm. 1st phase arm circuit including
A second-phase positive electrode side arm in which a plurality of the power conversion units are connected in series, and a second-phase negative electrode side arm in which a plurality of the power conversion units are connected in series and connected to the second-phase positive electrode side arm. Two-phase arm circuit, including
A third-phase positive electrode side arm in which a plurality of the power conversion units are connected in series, and a third-phase negative electrode side arm in which a plurality of the power conversion units are connected in series and connected to the third-phase positive electrode side arm. With a three-phase arm circuit, including
With more
The first-phase arm circuit, the second-phase arm circuit, and the third-phase arm circuit form a three-phase power conversion circuit.
The detection means includes the first phase positive electrode side arm, the first phase negative electrode side arm, the second phase positive electrode side arm, the second phase negative electrode side arm, the third phase positive electrode side arm, and the third phase negative electrode side arm. each of the plurality of the power conversion unit to be provided separately contained in a side arm, sends including detection signals of the power conversion unit distinguishing identification information respectively from each other to the control means,
The control means is a power conversion device that continues a conversion operation by using a power conversion unit other than the power conversion unit including the pressure welding type semiconductor device including the semiconductor element in which the short circuit is detected . The two pressure-welded semiconductor devices are composed of a first pressure-welded semiconductor device and a second pressure-welded semiconductor device connected in series with the first pressure-welded semiconductor device.
The detection means is based on the first detection means that outputs a first detection signal when a short circuit is detected based on the on voltage of the first pressure contact type semiconductor device and the on voltage of the second pressure contact type semiconductor device. The power conversion device according to claim 1 or 2 , further comprising a second detection means that outputs a second detection signal when a short circuit is detected. The power conversion device according to any one of claims 1 to 3 , wherein the two pressure welding type semiconductor devices constitute a chopper cell or a single-phase inverter circuit.

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