Patent ID: 8625319

Claim:
A bridgeless circuit, comprising: an AC power source having a first and a second terminals; a first and a second bridge arms, each of which has a first and a second terminals and a middle point, wherein the first terminal of the first bridge arm connects to the first terminal of the second bridge arm, the second terminal of the first bridge arm connects to the second terminal of the second bridge arm, and the middle point of the second bridge arm connects to the second terminal of the AC power source; a bidirectional switch module including a bidirectional switch having a first terminal connected to the middle point of the first bridge arm, and a second terminal connected to the middle point of the second bridge arm; an inductor having a first terminal connected to the first terminal of the AC power source and a second terminal connected to the middle point of the first bridge arm; and a first auxiliary winding magnetically coupled to the inductor for generating a sensing voltage so as to sense a zero crossing current of the inductor when the input voltage has a value being one selected from a group consisting of a positive value, a zero and a negative value.