Patent ID: 6700801
Filing Date: 2004-03-02
Classification: H02M,Y02B,Y02P

Abstract:
A switching power supply capable of translating a.c. voltage of sinusoidal waveform into d.c. voltage, comprising:(a) a pair of a.c. input terminals for inputting a.c. voltage having a known frequency; (b) a rectifier circuit connected to the pair of input terminals for rectifying the input a.c. voltage, the rectifier circuit having a first and a second output for providing a rectifier output voltage; (c) a main inductor connected to the first output of the rectifier circuit; (d) a main switch connected to the first output of the rectifier circuit via the main inductor on one hand and, on the other hand, to the second output of the rectifier circuit; (e) soft-switching capacitance means associated with the first main switch; (f) a rectifying diode; (g) a smoothing capacitor connected in parallel with the main switch via the rectifying diode; (h) an ancillary inductor connected to the main inductor and electromagnetically coupled thereto; (i) an ancillary switch connected to the main inductor via the ancillary inductor on one hand and, on the other hand, to the second output of the rectifier circuit; a first reverse-blocking diode connected in series with the ancillary inductor; and (k) a switch control circuit connected to the main switch for on-off control thereof at a repetition frequency higher than the frequency of the input a.c. voltage, and to the ancillary switch for on-off control thereof at such a repetition frequency, and with such conducting periods, as to assure soft turn-on of the main switch.