	US 7,453,710 B2
	Transformerless safety isolation in a power supply using safety capacitors for galvanic isolation
Stefan Bäurle, San Jose, Calif. (US); David Michael Hugh Matthews, Sunnyvale, Calif. (US); and Roland S. Saint-Pierre, San Jose, Calif. (US)
Assigned to Power Integrations, Inc., San Jose, Calif. (US)
Filed on Apr. 26, 2006, as Appl. No. 11/412,630.
Prior Publication US 2007/0253225 A1, Nov. 01, 2007
Int. Cl. H02H 7/125 (2006.01)

U.S. Cl. 363—52 [323/222; 323/364]

11 Claims

1. A power converter, comprising:

input terminals included in a primary circuit of the power converter;

output terminals included in a secondary circuit of the power converter;

a plurality of safety capacitors including first and second safety capacitors, wherein each of the plurality of safety capacitors includes a respective first terminal coupled to the primary circuit and a respective second terminal coupled to the secondary circuit such that the plurality of safety capacitors galvanically isolates the primary circuit from the secondary circuit;

a first inductor included in the primary circuit and coupled to the first terminal of the first safety capacitor;

a second inductor included in the secondary circuit and coupled to the second terminal of the first safety capacitor, wherein the first inductor and the second inductor are non-coupled inductors that are substantially non-mutually inductive;

a third inductor included in the primary circuit and coupled between the first terminal of the first safety capacitor and the first terminal of the second safety capacitor: and

a power switch included in the primary circuit, wherein the power switch is coupled such that switching of the power switch causes energy to transfer between the primary and secondary circuits through the plurality of safety capacitors such that substantially all of the energy that is transferred between the primary and secondary circuits is through the plurality of safety capacitors.