Patent ID: 9030185
Filing Date: 2015-05-12
Classification: G05F

Abstract:
1. A power factor correction circuit comprising: a first series circuit that consists of a first rectifier element and a first switching element, a second series circuit that consists of a second rectifier element and a second switching element and is connected in parallel to the first series circuit, a smoothing capacitor that is connected in parallel to the first and second series circuits and a load circuit, and a reactor, one end of which is connected to a connecting point between the first rectifier element and the first switching element or a connecting point between the second rectifier element and the second switching element, and the other end of which is connected to one end of an AC power source, wherein the power factor correction circuit further comprises an input voltage detector that detects an input voltage of at least one end of the AC power source based on one end on a ground side of the smoothing capacitor, a current detector that detects a reactor current from the AC power source, the current detector having a transformer in which the reactor is a primary side, and a discriminating unit that discriminates between a positive half cycle and a negative half cycle of the AC power source, and the first and second switching elements are controlled based at least partially on a reactor current detection signal that is output in accordance with the reactor current from a secondary side of the transformer and on a time point at which the reactor current becomes zero as determined by the discriminating unit to supply a desired DC voltage to the load circuit.