Patent ID: 8247922
Filing Date: 2012-08-21
Classification: H02M,Y02B

Abstract:
1. A power device, comprising: an input unit comprising a first rectifying circuit to rectify input power; a power factor unit comprising a power factor correction circuit to receive and correct the rectified power from the first rectifying circuit; an output unit comprising an output transformer comprising a primary winding and at least one secondary winding, a power switch, a pulse width modulation (PWM) circuit and at least one second rectifying circuit, wherein the primary winding couples to the power factor unit to receive the corrected power, and the at least one secondary winding is connected to the at least one second rectifying circuit, wherein the power switch is connected to the primary winding and is under control of the PWM circuit; a power saving unit comprising a first electronic switch, a first diode and a single-direction switch, wherein the first electronic switch is connected between the first rectifying circuit and the power factor unit, an anode of the first diode is connected to the first rectifying circuit and a cathode of the first diode is connected to the output unit, and the single-direction switch is connected to the power factor unit and the output unit to block current from the output unit to the power factor unit; and a control signal port to control an on/off state of the first electronic switch; wherein the power factor unit further comprises a coil, a second diode, a third diode, and a filtering capacitor, wherein the coil receives the rectified power from the first rectifying circuit, and outputs power to the output unit through the second diode, wherein an anode of the third diode is connected to an output end of the coil and a cathode of the third diode is connected to the power factor correction circuit through a resistor, wherein one end of the filtering capacitor is connected to the cathode of the third diode, and the other end of the filtering capacitor is grounded, and wherein the single-direction switch is connected between a cathode of the second diode and the cathode of the third diode.