Patent ID: 6703794
Filing Date: 2004-03-09
Classification: H05B,Y02B

Abstract:
A power factor correction device including electronic ballast function, comprising:a lamp for illumination; a rectifier, to provide a DC operating voltage; a storage capacitor, to receive the DC voltage and output a desired voltage for lighting the lamp; an ignitor, to light the lamp based on the desired voltage; a plurality of sensing resistors, to measure the voltage across the lamp when lighting; a voltage and current controller, to produce a feedback control signal according to the measured voltage; and a power factor correction controller, to adjust the desired voltage according to the feedback control signal, wherein the power factor correction circuit further comprises: a transformer including a first inductor and a grounding second inductor, wherein an end of the first inductor is connected to the positive end of the storage capacitor; a start resistor including an end connected to the output of the rectifier, the first inductor and the storage capacitor; an integral filter capacitor, connected to another end of the start resistor; a block diode, coupled between the grounding second inductor and the connection point of the integral filter capacitor and the start resistor; a power sensing resistor, with an end connected to the connection point of the block diode and the grounding second inductor; an MOSFET switch including a source, a gate and a drain, the source connected to another end of the first inductor and a forward-biased diode connected to an output of the power factor correction circuit, the drain connected to a grounding resistor for detecting a feedback voltage from the voltage and current controller; and a controller, having an output connected to the gate of the MOSFET switch through an impedance-matched resistor, inputs connected to the output of the voltage and current controller, the connection point of the MOSFET switch and the grounding resistor, another end of the power sensing resistor and the connection point of the start resistor, the block diode and the integral filter capacitor, respectively.