Patent ID: 9742272
Date: 2017-08-22
CPC Classifications: H02M

Claim:
1. An AC to DC converter, comprising: a plurality of rectifier circuits connected in series to an AC voltage source at an input side to collectively receive an output voltage of the AC voltage source; a plurality of switching units respectively connected to the plurality of rectifier circuits, each of the switching units having a semiconductor switching device, a diode, and a capacitor, and performing ON/OFF switching of the semiconductor switching device provided therein to step up a voltage received from the corresponding rectifier circuit, each of the switching units supplying the stepped-up voltage to said capacitor through said diode so that a resulting DC across said capacitor can be provided, as a DC output voltage of the switching unit, to a respective load to be connected to terminals of said capacitor; and a control device that performs pulse width modulation control on said semiconductor switching device to control said DC output voltage in each of the switching units, and that controls a waveform of an AC current flowing into the corresponding rectifier circuit from the AC voltage source so as to be a sinusoidal waveform, wherein said control device comprises: a pulse width correction unit that performs pulse width modulation control on the respective switching units such that, when the DC output voltage of one switching unit is lower than the DC output voltage of another switching unit, a conducting period of the diode in said one switching unit is caused to be longer than in said another switching unit, and such that when the direct current output voltage of said one switching unit is higher than the direct current output voltage of said another switching unit, the conducting period of the diode in said one switching unit is caused to be shorter than in said another switching unit.