| 摘要 |
PROBLEM TO BE SOLVED: To enable a power converter to protect a semiconductor element from excess surge voltages by suppressing surge voltages, by only using a power supply collecting snubber. SOLUTION: A power converter is constituted of smoothing capacitors 1 which are provided as DC power sources, first to fourth switching elements 6-9, each of which is composed of an IEGT(injection enhanced gate transistor) and a diode which is connected antiparallel with the IEGT, and first and second coupling diodes 10 and 11. The converter is also constituted of snubber circuits, each of which is composed of a capacitor (snubber capacitor) 12a, a diode (snubber diode) 12b, and a discharging resistor 12c. The three groups of capacitors 1, switching elements 6-9, diodes 10 and 11, snubber circuits 12 constitute three-level NPC main circuits of U-, V- and W phases, with each group constituting one phase of three-level NPC main circuit. |
