| 摘要 |
PROBLEM TO BE SOLVED: To protect a switching element for constituting an electric power conversion system for an electric motor vehicle, by restraining surge voltage generated by cutting off a contactor, in a predetermined small current rate region, without using an additional component.SOLUTION: The electric power conversion system for the electric motor vehicle of the embodiment comprises an AC circuit breaker and a main transformer connected in series between a pantograph supplied with AC electric power from an overhead power line and a wheel grounded via a roadway and a converter-inverter part connected to a secondary side coil of the main transformer. Cutoff prohibiting means prohibits cutoff of an electric current flowing in the secondary side coil and the converter-inverter part in a cutoff state of the AC circuit breaker and also in a state where the electric current flowing in the secondary side coil and the converter-inverter part is in the predetermined small current rate region of becoming an occurrence factor of the surge voltage. |
