Multilevel power conversion system and control device for the multilevel power conversion system

Abstract

The present invention provides a means for suppressing overvoltage breakdown of semiconductor elements in a power converter due to lightning surges in a multilevel power conversion system.　This multilevel power conversion system comprises a multilevel power converter (30) and a control device (40) including: an operation control unit (51) that, on the basis of a predetermined condition, transitions the operation mode of the multilevel power converter (30) to a standby mode in which power conversion is not performed between a DC input / output unit (31) and an AC input / output unit (32); and a gate signal generation unit (53) that, in the standby mode, generates and outputs a gate signal to put one and / or both of a third semiconductor switching element (3) and a second semiconductor switching element (2) into a state of continuity or a switching state.

Claims

1. A DC input / output section having a positive terminal and a negative terminal connected to a DC power supply or DC load, A plurality of DC capacitors are connected in series between the positive terminal and the negative terminal via a DC neutral point, An AC input / output unit having AC terminals connected to an AC power source or AC load, A first semiconductor switching element and a fourth semiconductor switching element are connected in series with the same polarity between the positive terminal and the negative terminal via the AC terminal, A first freewheeling diode and a fourth freewheeling diode are connected in antiparallel to the first semiconductor switching element and the fourth semiconductor switching element, respectively. A third semiconductor switching element and a second semiconductor switching element are connected in series with opposite polarity between the DC neutral point and the AC terminal. A third freewheeling diode and a second freewheeling diode are connected in antiparallel to the third semiconductor switching element and the second semiconductor switching element, respectively. A multilevel power converter having, An operation control unit that, based on predetermined conditions, transitions the operating mode of the multilevel power converter to a standby mode in which no power conversion is performed between the DC input / output unit and the AC input / output unit, In the standby mode, a gate signal generation unit generates and outputs a gate signal that causes at least one of the third semiconductor switching element and the second semiconductor switching element to be in a conductive state or a switched state, A control device having, An AC switch connected between the AC input / output section of the multilevel power converter and the AC power supply or the AC load, Equipped with, The gate signal generation unit generates and outputs a gate signal that causes at least one of the third semiconductor switching element and the second semiconductor switching element to enter a conductive state or a switched state when the AC switch is open and in standby mode. A multilevel power conversion system characterized by the following features.

2. In the multilevel power conversion system according to claim 1, The gate signal generation unit generates and outputs a gate signal that causes both the first semiconductor switching element and the fourth semiconductor switching element to become non-conductive when in standby mode. A multilevel power conversion system characterized by the following features.

3. A DC input / output unit having a positive terminal and a negative terminal connected to a DC power supply or DC load, A plurality of DC capacitors are connected in series between the positive terminal and the negative terminal via a DC neutral point, An AC input / output unit having AC terminals connected to an AC power source or AC load, A first semiconductor switching element and a fourth semiconductor switching element are connected in series with the same polarity between the positive terminal and the negative terminal via the AC terminal, A first freewheeling diode and a fourth freewheeling diode are connected in antiparallel to the first semiconductor switching element and the fourth semiconductor switching element, respectively. A third semiconductor switching element and a second semiconductor switching element are connected in series with opposite polarity between the DC neutral point and the AC terminal. A third freewheeling diode and a second freewheeling diode are connected in antiparallel to the third semiconductor switching element and the second semiconductor switching element, respectively. A multilevel power converter having, An operation control unit that, based on predetermined conditions, transitions the operating mode of the multilevel power converter to a standby mode in which no power conversion is performed between the DC input / output unit and the AC input / output unit, In the standby mode, a gate signal generation unit generates and outputs a gate signal that causes at least one of the third semiconductor switching element and the second semiconductor switching element to be in a conductive state or a switched state, A control device having, Equipped with, The gate signal generation unit, when in standby mode, generates and outputs a gate signal for operating the multilevel power converter based on a zero voltage command value that causes the AC input / output unit to output a voltage approximately equal to the DC neutral point. A multilevel power conversion system characterized by the following features.

4. A DC input / output unit having a positive terminal and a negative terminal connected to a DC power supply or DC load, A plurality of DC capacitors are connected in series between the positive terminal and the negative terminal via a DC neutral point, An AC input / output unit having AC terminals connected to an AC power source or AC load, A first semiconductor switching element and a fourth semiconductor switching element are connected in series with the same polarity between the positive terminal and the negative terminal via the AC terminal, A first freewheeling diode and a fourth freewheeling diode are connected in antiparallel to the first semiconductor switching element and the fourth semiconductor switching element, respectively. A third semiconductor switching element and a second semiconductor switching element are connected in series with opposite polarity between the DC neutral point and the AC terminal. A third freewheeling diode and a second freewheeling diode are connected in antiparallel to the third semiconductor switching element and the second semiconductor switching element, respectively. A multilevel power converter having, An operation control unit that, based on predetermined conditions, transitions the operating mode of the multilevel power converter to a standby mode in which no power conversion is performed between the DC input / output unit and the AC input / output unit, In the standby mode, a gate signal generation unit generates and outputs a gate signal that causes at least one of the third semiconductor switching element and the second semiconductor switching element to be in a conductive state or a switched state, A control device having, Equipped with, The control device is The multilevel power converter further includes a voltage command generation unit that generates a voltage command value based on a zero current command value to cause the AC input / output unit of the multilevel power converter to output a current of approximately zero when in the standby mode, The gate signal generation unit generates and outputs a gate signal for operating the multilevel power converter based on the voltage command value generated by the voltage command generation unit. A multilevel power conversion system characterized by the following features.

5. A DC input / output section having a positive terminal and a negative terminal connected to a DC power supply or DC load, A plurality of DC capacitors are connected in series between the positive terminal and the negative terminal via a DC neutral point, An AC input / output unit having AC terminals connected to an AC power source or AC load, A first semiconductor switching element and a fourth semiconductor switching element are connected in series with the same polarity between the positive terminal and the negative terminal via the AC terminal, A first freewheeling diode and a fourth freewheeling diode are connected in antiparallel to the first semiconductor switching element and the fourth semiconductor switching element, respectively. A third semiconductor switching element and a second semiconductor switching element are connected in series with opposite polarity between the DC neutral point and the AC terminal. A third freewheeling diode and a second freewheeling diode are connected in antiparallel to the third semiconductor switching element and the second semiconductor switching element, respectively. A multilevel power converter having, A control device for a multilevel power conversion system, characterized by comprising: The control device is An operation control unit that, based on predetermined conditions, transitions the operating mode of the multilevel power converter to a standby mode in which no power conversion is performed between the DC input / output unit and the AC input / output unit, In the standby mode, a gate signal generation unit generates and outputs a gate signal that causes at least one of the third semiconductor switching element and the second semiconductor switching element to be in a conductive state or a switched state, It has, The gate signal generation unit generates and outputs a gate signal that causes at least one of the third semiconductor switching element and the second semiconductor switching element to conduct or switch when the AC switch connected between the AC input / output unit of the multilevel power converter and the AC power supply or the AC load is open and in standby mode. A control device for a multilevel power conversion system, characterized by the following features.

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