| 摘要 |
PURPOSE: To reduce in size a power converter by reducing the capacity of a filter capacitor in a main converter using an IGBT. CONSTITUTION: When a short-circuit damage occurs in the IGBT 11a of either a two-phase bridge circuit 10 or a three-phase bridge circuit 30, the damage is detected by a current detector 22a, the thyristor 28 of a quick discharging circuit is fired, and a vacuum breaker 2 is operated. Then, a power converter is stopped before a filter capacitor 21b is charged by a shorter quick discharging circuit having a time constant shorter than the discharging circuit without resistor 25. Accordingly, even if the short-circuit damage occurs in the either of the IGBTs and either upper or lower filter capacitor 21a is short-circuited, the other filter capacitor 21b can be so protected as not to be raised to the DC link voltage, and hence the capacitors 21a, 21b can be used in such a manner that they can use a capacitor of low withstand voltage of about 1/2 of the DC link voltage. |
