JP6618081B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device.

  Generally, it is known to control a power converter by driving a switching element by a gate drive circuit. Moreover, a power conversion device including a gate power supply system that supplies power to a plurality of gate drive circuits is disclosed (see Patent Document 1).

JP 2008-236994 A

  However, when the number of gate drive circuits is large, if an overcurrent detector or a disconnecting device is provided for short-circuit protection or the like in each power supply path of the gate drive circuit, the number of components constituting the power conversion device increases. . This leads to an increase in the size of the entire power conversion device or an increase in manufacturing cost, which is not preferable. In addition, when an overcurrent detector and disconnection device are provided only in the upper part of the gate power supply system, even if a failure such as a short circuit occurs in one of the power supply paths branched in the lower order, the upper There is a possibility that overcurrent cannot be detected.

  Accordingly, an object of the present invention is to provide a power conversion device that detects a failure with a simple configuration for each gate drive circuit.

A power conversion device according to an aspect of the present invention includes a switching element, a gate drive circuit that applies a gate trigger to the switching element, and a gate state detection unit that outputs a feedback signal corresponding to the state of the gate of the switching element. , A controller for controlling the switching of the switching element , a switching control unit for supplying a gate signal to the gate driving circuit, and a failure detecting unit for determining whether or not the switching element has failed And a controller including: The gate driving circuit applies a gate trigger to the switching element based on the gate signal supplied from the switching control unit , and the gate state detecting means is a feedback signal corresponding to the gate state of the switching element. Is output. The failure detection unit detects the presence or absence of a failure of the switching element by synchronizing the gate signal and the feedback signal and comparing the gate signal and the feedback signal.

  According to the present invention, there is provided a power conversion device that detects a failure with a simple configuration for each gate drive circuit.

The block diagram which shows the structure which detects the failure of the power converter device which concerns on the 1st Embodiment of this invention. The lineblock diagram showing the composition of the power converter concerning a 1st embodiment. The wave form diagram which shows the detection method of the failure by the failure detection part which concerns on 1st Embodiment. The block diagram which shows the structure of the power converter device which concerns on the 2nd Embodiment of this invention. The block diagram which shows the structure of the power converter device which concerns on the 3rd Embodiment of this invention.

(First embodiment)
FIG. 1 is a configuration diagram illustrating a configuration for detecting a failure of the power conversion device 10 according to the first embodiment of the present invention. FIG. 2 is a configuration diagram illustrating the configuration of the power conversion device 10 according to the first embodiment. In addition, the same code | symbol is attached | subjected to the same part in drawing, and a different part is mainly demonstrated.

  The power conversion device 10 includes a control device 1, N gate drive substrates 2, a power conversion circuit 3, N transformers 4, a switch 5, and a gate power supply 6. Here, the case where the gate power source supplied to the gate drive substrate 2 is AC power will be described, but the same configuration can be applied to the case of DC power.

  The N transformers 4, the switches 5, and the gate power supply 6 constitute a gate power supply system. The gate power supply 6 outputs AC power for supplying power to each gate drive substrate 2. The gate power source 6 may be anything such as a generator or an inverter as long as it outputs AC power. The AC power output from the gate power supply 6 is supplied to each power supply system branched to each gate drive substrate 2 via the switch 5. The switch 5 may be a circuit breaker such as an MCCB (molded case circuit breaker), a thermal contactor (electromagnetic switch), or a circuit protector. Each transformer 4 is provided in each branched power supply system. Each transformer 4 transforms the input AC power to a voltage suitable for supplying each gate drive substrate 2. AC power is supplied to each gate drive substrate 2 from a gate power supply 6 via each transformer 4.

  The power conversion circuit 3 includes N switching elements SW1, SW2,. Here, although the power converter circuit 3 is demonstrated as one, you may be comprised by the some power converter circuit. The switching elements SW1 to SWN are, for example, IGBTs (insulated gate bipolar transistors). The power conversion circuit 3 may be any circuit as long as a plurality of switching elements are used. For example, the power conversion circuit 3 may be a converter that converts AC power into DC power, or an inverter that converts DC power into AC power. The power conversion circuit 3 is not limited to one that handles active power, but may be a reactive power compensation circuit that handles reactive power.

  Gate drive substrate 2 is provided corresponding to switching elements SW1 to SWN. The gate drive substrate 2 drives (switches) the corresponding switching elements SW <b> 1 to SWN according to the gate signal Sg received from the control device 1. Further, the gate drive substrate 2 determines the state of the corresponding switching elements SW1 to SWN, and outputs the determined state to the control device 1 as a feedback signal Sf.

  The gate drive substrate 2 includes a gate drive circuit 21 and a gate state determination unit 22.

  When the gate drive circuit 21 receives the gate signal Sg indicating the ON command, the gate drive circuit 21 applies a gate voltage that becomes a positive bias to the corresponding switching elements SW1 to SWN. Thereby, the corresponding switching elements SW1 to SWN are turned on. When the gate drive circuit 21 receives the gate signal Sg indicating the off command, the gate drive circuit 21 applies a negative gate voltage to the corresponding switching elements SW1 to SWN. Thereby, the corresponding switching elements SW1 to SWN are turned off. Here, switching elements SW1 to SWN will be described in which the gate trigger applied to the gate to be turned on is a voltage, but a switching element having a gate trigger as a current can be similarly configured.

  The gate state determination unit 22 detects the gate voltage of the corresponding switching elements SW1 to SWN and determines the state of the gate. There are three types of gate states: positive biased, negative biased, and no biased. The presence of positive bias indicates that the switching elements SW1 to SWN are on. The presence of negative bias indicates that the switching elements SW1 to SWN are in an off state. No bias indicates that the gate power supply of the switching elements SW1 to SWN has been lost.

  For example, when the detected gate voltage is higher than a preset positive threshold value, the gate state determination unit 22 determines that there is a positive bias, and the detected gate voltage is lower than the preset negative threshold value. Is determined to have a negative bias. If none of these applies, the gate state determination unit 22 determines that there is no bias. The gate state determination unit 22 generates a feedback signal Sf for detecting a failure based on the determination result of the gate state.

  The gate state determination unit 22 sets the feedback signal Sf to 1 when the positive bias is present, and sets the feedback signal Sf to 0 when it is not (with negative bias or without bias). The gate state determination unit 22 always determines the state of the gate and outputs the generated feedback signal Sf to the control device 1. Here, the feedback signal Sf is described as a binarized value, but is not limited thereto. For example, the feedback signal Sf may indicate three or more states so that it can be distinguished when the negative bias is present and when there is no bias.

  The control device 1 controls the power conversion device 10. For example, the control device 1 outputs a gate signal Sg to each of the switching elements SW <b> 1 to SWN configuring the power conversion circuit 3 to control the power conversion operation of the power conversion circuit 3. Moreover, the control apparatus 1 detects failure, such as a short circuit or a ground fault of the power converter device 10, and performs protection operation.

  The control device 1 includes N control units C1, C2,..., CN corresponding to the N gate drive substrates 2, respectively. Since all the control parts C1-CN are comprised similarly, the 1st control part C1 which performs control which drives 1st switching element SW1 as a representative is demonstrated.

  The first control unit C1 includes a switching control unit 11 and a failure detection unit 12.

  The switching control unit 11 generates a gate signal Sg for controlling the switching of the first switching element SW1. The switching control unit 11 outputs the generated gate signal Sg to the first gate drive substrate 2 for driving the first switching element SW1. The gate signal Sg indicates either an on command or an off command. When the gate signal Sg is 1, it indicates an on command. When the gate signal Sg is 0, it indicates an off command. The gate signal Sg is determined according to a command value for the output of the power conversion circuit 3 and the like.

  The failure detection unit 12 receives the gate signal Sg generated by the switching control unit 11 and the feedback signal Sf generated by the gate state determination unit 22. The failure detection unit 12 always compares the gate signal Sg and the feedback signal Sf to determine whether or not there is a failure. The failure detection unit 12 determines that the gate signal Sg and the feedback signal Sf match each other, and determines that the failure is normal. For example, the failure detection unit 12 may perform failure detection when the gate signal Sg and the feedback signal Sf are input and the calculation result of XOR (exclusive OR) is 1. When detecting a failure, the failure detection unit 12 outputs a trip signal TP for opening (tripping) the switch 5 as a protection operation.

  The failure detection unit 12 may output the trip signal TP after a predetermined time has elapsed since the failure was detected within a range in which the gate power supply system can withstand a failure current such as a short circuit. When the switch 5 is opened, a healthy gate power supply path is also opened. Further, it is desirable that the supply of gate power to each gate drive substrate 2 is stopped after the power conversion circuit 3 is stopped. Therefore, by outputting the trip signal TP after a certain time has elapsed since the failure was detected, it is possible to secure a time for stopping the power conversion circuit 3 before the switch 5 is opened.

  Further, the first control unit C1 may output a signal for stopping the first switching element SW1 to the gate block or the like to the gate drive substrate 2 before outputting the trip signal TP. A signal for stopping the other switching elements SW2 to SWN may also be output to the other control units C2 to CN or other gate drive substrates 2 to which healthy gate power is supplied.

  FIG. 3 is a waveform diagram showing a failure detection method by the failure detection unit 12 according to the present embodiment. FIG. 3 shows a case where a short circuit failure of the gate power source occurs between the transformer 4 and the gate drive substrate 2 at time t1. Actually, since the feedback signal Sf is generated later than the gate signal Sg, the gate signal Sg and the feedback signal Sf do not always match even in a normal state. Here, it is assumed that the gate signal Sg and the feedback signal Sf are adjusted so as to coincide with each other in consideration of a delay time from when the feedback signal Sf is generated until the feedback signal Sf is input to the failure detection unit 12.

  Prior to time t1, the gate signal Sg and the feedback signal Sf always match. Therefore, it is determined as normal.

  Due to the short-circuit failure that occurred at time t1, the gate power supply is not input to the gate drive substrate 2. Thus, regardless of whether the gate signal Sg is 1 (ON command) or 0 (OFF command), the gate state is biasless when the gate voltage applied to the switching element SW1 is measured. Therefore, after time t1, the gate state determination unit 22 sets the feedback signal Sf to 0 and outputs it. However, immediately after time t1, since the gate signal Sg is 0 and coincides with 0 of the feedback signal Sf, it is not determined that there is a failure.

  At time t2, the gate signal Sg and the feedback signal Sf become inconsistent at the moment when the gate signal Sg first becomes 1 after the occurrence of the short circuit failure. Thereby, the failure detection unit 12 determines that there is a failure and detects the failure.

  Similarly, when the gate signal Sg is 0 (off command) and the feedback signal Sf is 1 (the switching element SW1 is in the on state), it is similarly determined as a failure.

  According to the present embodiment, for each switching element SW1 to SWN, the gate signal Sg is compared with the feedback signal Sf indicating the state of the gate, so that the gate power supply supplied to each gate drive substrate 2 is short-circuited or grounded. Can be detected. Accordingly, it is possible to perform a protection operation against a failure occurring in each power supply path without providing an overcurrent detector or a disconnecting device or the like for each power supply path through which gate power is supplied to each gate drive substrate 2.

  Also, since the gate signal Sg and the feedback signal Sf reflecting the gate state are compared to detect a failure in the gate power supply system, the failure occurs earlier than when a failure signal detected by an overcurrent relay or the like is received from the outside. Can be detected.

(Second Embodiment)
FIG. 4 is a configuration diagram showing a configuration of a power conversion device 10A according to the second embodiment of the present invention.

  In the power conversion device 10 according to the first embodiment shown in FIG. 1, the power conversion device 10A replaces the control device 1 with the control device 1A, replaces the N transformers 4 with a plurality of transformers 4a and 4b, Two switches 5a and 5b are added. The other points are the same as in the first embodiment.

  The switches 5 a and 5 b are provided in each power supply path that branches into two in the lower system of the switch 5. The transformers 4a and 4b are provided with more windings than the number of windings of the transformer 4 according to the first embodiment. In the transformers 4a and 4b, the gate drive substrate 2 is connected to each load-side winding. As a result, gate power is supplied from the transformers 4 a and 4 b to the plurality of gate drive substrates 2. In FIG. 2, the number of windings of the transformer 4 according to the first embodiment is two, and in FIG. 4, the number of windings of the transformers 4a and 4b according to the present embodiment is four. The number of windings of the transformers 4a and 4b may be any number as long as it is three or more.

  In the control device 1 according to the first embodiment, the control device 1A is configured to open (trip) the two switches 5a and 5b with the trip signal TP in addition to the switch 5 when a failure is detected. . About another point, it is the same as that of the control apparatus 1 which concerns on 1st Embodiment.

  According to the present embodiment, in addition to the operational effects of the first embodiment, the switches 5a and 5b are also provided in the respective power supply paths that branch below the gate power supply system, and these switches 5a and 5b are detected when an accident is detected. Can also be removed more reliably. In addition, it is not necessary to provide the switch 5 instead of providing the switches 5a and 5b. Even in this case, since the two switches 5a and 5b play the same role as the switch 5, it is possible to obtain the same operational effects as those of the first embodiment.

  Moreover, the number of transformers 4a and 4b can be reduced by using the transformers 4a and 4b having a large number of windings.

(Third embodiment)
FIG. 5 is a configuration diagram showing a configuration of a power conversion device 10B according to the third embodiment of the present invention.

  The power converter 10B is obtained by replacing the plurality of transformers 4a and 4b with a plurality of transformers 4aB and 4bB in the power converter 10A according to the second embodiment shown in FIG. The other points are the same as in the second embodiment.

  The transformers 4aB and 4bB are obtained by connecting a plurality of gate drive substrates 2 to one load-side winding. Thereby, gate power is supplied to the plurality of gate drive substrates 2 from one winding of the transformers 4aB and 4bB. Any number of windings may be used for the transformers 4aB and 4bB.

  According to this embodiment, the same effect as that of the second embodiment can be obtained.

  In addition, the gate power supply system demonstrated in each embodiment is an example, and how many a transformer, a switch, and a gate power supply may be arrange | positioned, and a transformer may not be provided. Further, the system configuration may be branched in any way.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Control apparatus, 2 ... Gate drive board, 3 ... Power conversion circuit, 10 ... Power conversion apparatus, 11 ... Switching control part, 12 ... Failure detection part, C1-CN ... Control part, SW1 ... Switching element, TP ... Trip signal.

Claims (7)

A switching element;
A gate driving unit including a gate driving circuit that applies a gate trigger to the switching element, and a gate state detection unit that outputs a feedback signal corresponding to a gate state of the switching element;
And a controller for controlling switching of the switching element, and a controller including a switching control unit for supplying a gate signal to the gate drive circuit, and a failure detection unit determines the presence or absence of failure of the switching element,
With
The gate driving circuit applies a gate trigger to the switching element based on the gate signal supplied from the switching control unit ,
The gate state detection means outputs a feedback signal corresponding to the state of the gate of the switching element,
Said failure detection unit, the is synchronized with the gate signal and the feedback signal, by comparing the gate signal and the feedback signal and the power, wherein the benzalkonium detecting the presence or absence of a failure of the switching element Conversion device. The failure detection unit outputs an trip command indicating a failure of the switching element when the gate signal is an on command to turn on the switching element and a gate state of the switching element is not an on state. power converter according to claim 1 Symbol mounting to. A gate power supply system for supplying gate power to the gate drive circuit ;
The gate power supply system includes opening / closing means for controlling supply and stop of the gate power supply ,
The opened front Symbol closing means Ri by the outputted the trip signal from the fault detection unit, said to that請 Motomeko 2 Symbol mounting, wherein the benzalkonium to stop the supply of the gate power to the gate drive circuit Power converter. A plurality of the switching elements are provided,
A plurality of the gate driving units for driving each of the plurality of switching elements are arranged,
The controller receives the feedback signal output from the switching control unit that supplies a gate signal to each gate driving circuit of the plurality of gate driving units, and each gate state detection unit of the plurality of gate driving units. A plurality of failure detection units,
The power converter according to claim 3 , wherein the controller outputs the trip signal to the opening / closing means when a trip signal is output from any of the plurality of failure detection units. The power converter according to claim 4, wherein the controller outputs the trip signal with a predetermined time delay. The controller sends the switching element from the switching control unit to the gate drive unit including the gate state detection unit connected to the failure detection unit that does not output the trip signal among the plurality of failure detection units. The power converter according to claim 4, wherein the trip signal is output after the signal to be stopped is output. The gate power supply system includes a plurality of the opening / closing means, and the plurality of opening / closing means includes a first opening / closing means and a second opening / closing means,
The plurality of gate driving units include a first group including a gate driving unit to which the gate power is supplied through the first opening / closing unit, and a gate driving to which the gate power is supplied through the second opening / closing unit. A second group including a part,
The power converter according to any one of claims 3 to 6, wherein the controller outputs the trip signal to the first opening / closing means and the second opening / closing means.

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