Minebea Company, Limited

Nadthawut Chalermboon

Kohei Nishibori

Yoshihiro Nakamura

A power factor correction circuit includes: the first series circuit consisting of the first rectifier element and the first switching element; the second series circuit consisting of the second rectifier element and the second switching element; the first/second reactors; and the first/second current detectors. The first/second current detectors have each the first/second transformers, both primary parts of which consist of the first/second reactors. The first and the second switching elements are controllable based on the first output signal according to the reactor current from the secondary side of the first transformer and the second output signal according to the reactor current from the secondary side of the second transformer so as to apply a desired DC voltage to the load circuit.

Bridgeless power factor correction circuit with improved critical mode (CRM) operation

A power factor correction circuit includes a first series circuit, a second series circuit, a smoothing capacitor, and a reactor. The power factor correction circuit further includes an input voltage detector that detects an input voltage of at least one end of an AC power source based on one end on a ground side of the smoothing capacitor, and 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 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 to supply a desired DC voltage to a load circuit.

Power factor correction circuit

A power source apparatus includes: a first series circuit that has a first rectifier element, a first switching element, and a third rectifier element; a second series circuit that has a second rectifier element, a second switching element, and a fourth rectifier element; a reactor connected between a connecting point of the first rectifier element and the first switching element and a connecting point of the second rectifier element and the second switching element; and a current detection unit having a first resistor element. The first and second switching elements are controllable based on a first zero current detection signal in accordance with a first current detected in the current detection unit, and a desired direct current voltage is fed to a load circuit.

Power source apparatus

The present invention relates to a PFC switching power supply which can perform polarity determination and voltage detection of AC voltage without using a DC isolator such as a transformer. Included are: a power factor correction section which rectifies AC voltage inputted, outputs DC voltage to a load and corrects a power factor; an input voltage detecting section which outputs L pole detected voltage and N pole detected voltage; and a switching controller which controls the operation of the power factor correction section. An AC waveform generating section of the switching controller generates an AC waveform. The switching controller generates a drive pulse having a frequency and a duty ratio varying depending on AC waveform, whereby a predetermined level of the DC output of the power factor correction section is maintained and in addition, the power factor is corrected.

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Fukuroi, Japan

Nadthawut Chalermboon