Resonance type one-converter equipped with a new power-factor correction circuit

As a countermeasure against harmonic waveforms of switching power supplies, some methods are available which insert an inductor or an active filter circuit between the commercial power supply input and the inverter. In the method of the inductor insertion, a large inductor is required because the operation frequency is the commercial power supply frequency. On the other hand, insertion of an active filter requires many component parts for its control circuit. Therefore a power converter with high power factor and a reduced component count has been studied extensively. This paper reports on a single-converter method which enables high power factor with few additional components. High power factor (98%) was obtained in this circuit using a current resonant-type power converter (ZVS and ZCS) and switching diodes instead of AC rectifier diodes, and also providing a capacitor circuit which feeds resonant current back to the input side rectifier. This paper reports the circuit operation, input current waveforms under several conditions and experimental results.