| 摘要 |
<P>PROBLEM TO BE SOLVED: To charge a smoothing capacitor connected with a switching circuit fully without requiring an LC relay. <P>SOLUTION: When a control means 28 turns a precharger contactor 18 on, an AC current from an AC power supply 22 is converted through a switching circuit 14 into a DC current for charging a smoothing capacitor 15. Since the smoothing capacitor 15 cannot be charged fully due to action of the capacitor 25 in an LC filter 16, the switching circuit 14 performs step-up operation to charge the smoothing capacitor 15 furthermore when the voltage of the smoothing capacitor 15 detected by a voltage detecting means 35 exceeds a predetermined level. Since the smoothing capacitor 15 can be charged fully even if an LC relay conventionally required for invalidating the capacitor 25 in the LC filter 16 is disused, reliability of a precharge circuit is enhanced by decreasing the number of components and performance of the LC filter 16 can be prevented from lowering due to loss of the LC relay. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
