Switching power supply device and AC-DC power conversion system

摘要

In the present invention, a switching power source device has only one stage, is highly efficient, and has an output voltage maintenance function for responding to instantaneous power failure. In the positive half cycle of alternating-current input voltage, a first rectification/PFC circuit part is formed from a bidirectional switch element (Qbd) or a first switch element (Q1), a second switch element (Q2), and an energy storage capacitor (Cens1). In the negative half cycle of alternating-current input voltage, a second rectification/PFC circuit part is formed from the bidirectional switch element (Qbd) or second switch element (Q2), the first switch element (Q1), and the energy storage capacitor (Cens1). At the connection point of the first switch element (Q1) and second switch element (Q2), series resonance circuits are connected, configuring an insulation-type DC-DC converter having the energy storage capacitor (Cens1) as the input power source.