| 摘要 |
An electric power conversion system characterized by a direct current power supply (1), a plurality of main circuit switching devices (4u, 4v, ...) bridge-connected to convert direct current of the direct current power supply to alternating current, having free wheeling diodes (5u, 5v, ...) connected in reverse parallel thereto, respectively, and a reverse voltage application circuit (7) for applying a reverse voltage smaller than the direct current power supply to each free wheeling diode, upon a cutoff of back-flow current of the free wheeling diode, the reverse voltage application circuit being composed of a series connection of a low-voltage direct current power supply (8) having a voltage lower than a voltage of the direct current power supply, a reverse voltage application switching device (11) having a lower withstand voltage than the main circuit switching devices and adapted to turn on upon a reverse recovery of the free wheeling diode, and an auxiliary diode (12) having a shorter reverse recovery time than the free wheeling diode, the reverse voltage application switching device being a device having holes as a majority carrier. |
