Patent ID: 8773879

Claim:
A bridgeless power factor correction (PFC) circuit system, comprising: a bridgeless PFC circuit, comprising: a first switch and a second switch coupled to the first switch at a first middle point; a third switch and a fourth switch coupled to the third switch at a second middle point; and a bidirectional switch coupled between the first middle point and the second middle point; an inductor coupled between the first middle point and an AC power source, wherein the AC power source is coupled to the second middle point; and a current sensing circuit comprising: a first current transformer (CT) for sensing a first current flowing through the bidirectional switch coupled to the bidirectional switch in series, which having only one primary side winding coupled to the bidirectional switch between the first middle point and the second middle point, and a first and a second secondary side windings; and a switching device coupled to the first and the second secondary side windings.