| 摘要 |
The present invention includes: a main switch Tr1 connected to two ends of a DC power supply Vi via a first primary winding 1a and a second primary winding 1b, connected to the first primary winding in series, of a transformer T1; a series circuit connected to the two ends of the main switch, and including a reactor L1, a diode D1, a smoothing capacitor Co and a hoist winding 1c connected to the second primary winding in series; a series circuit connected to the two ends of the main switch, and including a diode D2, a diode D3 and the smoothing capacitor; a control circuit 10 to turn on and off the main switch; a soft-switching circuit Da1,Tral,Lal,Cal to cause the main switch to perform a soft-switching operation each time the main switch turns on; and a switching control circuit 20 to switch the soft-switching circuit between operating and non-operating modes in accordance with the state of a load. |
