| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that, when a bidirectional switch is shorted and failed, other semiconductor switch and capacitor are broken, in a multilevel conversion circuit that uses a flying capacitor and the bidirectional switch between an intermediate point of a DC power source and a conversion circuit using the semiconductor switch.SOLUTION: In a multilevel conversion circuit that uses a flying capacitor and a bidirectional switch between an intermediate point of a DC power source and a conversion circuit using a semiconductor switch, two bidirectional switches are connected in series, and further, a short circuit failure detection circuit is provided in a gate drive circuit which detects short circuit of a semiconductor switch element constituting the bidirectional switch at an off signal. When a short circuit failure is detected, all semiconductor switch elements are cut off to stop a system. |
