| 摘要 |
PURPOSE:To improve power factor of input power to an air-conditioner and to suppress higher harmonics by obtaining first and second electric angles corresponding to AC input current to the air-conditioner and then turning switching elements ON/OFF based on thus obtained electric angles. CONSTITUTION:A controller 18 operates an inner timer while employing a zero-cross point, detected through a zero-cross detection circuit 15, in the interruption and detects a predetermined electric angle from an AC zero-cross point. When the inner timer detects a first electric angle, ON/OFF operation of switching elements 10, 11 constituting an input current control circuit is interrupted. Upon subsequent detection of second electric angle, ON/OFF operation of the switching elements 10, 11 is started. Since the ON/OFF operation of the switching elements 10, 11 is interrupted or resumed at a predetermined timing, it causes no hunting nor the waveform of input power is disturbed significantly by an AC power supply 6. |
