| 摘要 |
PURPOSE:To reduce the size and cost of an equipment by making the withhold voltage of such devices as an ac contactor and a charging resistor of an initial charging circuit of an electric car which has a PWM converter and a PWM converter small. CONSTITUTION:In an electric car which has a PWM converter 4 and a PWM converter 6, an initial charging circuit is installed which passes the output of an ac supply 1 through a tertiary winding 15 of a transformer whose voltage is lower than that of a secondary winding 3 of a transformer, an ac contactor 17, and a charging resistor 18 and then rectifies it by a diode bridge circuit 19 and charges a smoothing capacitor 5 with the rectified current. When this initial charging circuit intially charges the smoothing capacitor 5, it opens an ac contactor 8 and closes the ac contactor 17 and preliminarily charges the capacitor 5 using the tertiary winding 15 of the transformer as a power supply and after that, it opens the ac contactor 17 and closes the ac contactor 8 and further charges the capacitor through the diode bridge circuit of the PWM converter 4. Even if the ac contactor 8 is closed directly, rush current and overvoltage are small since the smoothing capacitor 5 is preliminarily charged and thereby charging can be done safely. |
