US Patent 7724556 Power converter

There are provided: sets of pairs of main circuit switching elements (4u), (4x) that supply power to a load, connected in series with a DC power source; free-wheel diodes (5u), (5x) connected in anti-parallel with these main circuit switching elements; and a reverse voltage application circuit (8) that applies reverse voltage smaller than the DC voltage source to the free-wheel diodes when these free-wheel diodes cut off. The reverse voltage application circuit includes a current suppression circuit (10) that suppresses the main circuit current flowing in the low-voltage DC voltage power source on reverse recovery of the free-wheel diodes.