Current sense method for bridgeless boost (BLB) PFC circuit using single current transformer

摘要

A circuit and method for improving current sensing in a bridgeless PFC boost converter. Such a converter comprises a current transformer having first and second primaries; a boost inductor having a first end connected to a first AC input terminal and a second end connected to a first junction defined between the anode of a first diode and a first end of the first primary, the second end of the first primary being connected to a first terminal of the first switch; a second terminal of the first switch being connected to a common line; a parallel circuit of a capacitance and a load connected between the cathode of the first diode and the common line; a series circuit of a second diode, the second primary and a second switch connected between the cathode of the first diode and the common line; and a second AC input terminal connected to a second junction defined between the second primary and the second switch. A second boost inductor may be connected between the second AC input terminal and the second junction. The first and second switches may be MOSFETs. The circuit also includes a rectification circuit on first and second secondaries of the current transformer, comprising a MOSFET and additional diodes.