Active Power Factor Correction for LED Lamp Driver

Traditionally conversion of ac to de voltages has been dominated by phase controlled or diode rectifiers. The non-ideal character of the input current drawn by these rectifiers creates number of problems like increase in reactive power, high input current harmonics and low input power factor, lower rectifier efficiency, large input voltage distortion etc. To compensate for the higher reactive power demand by the converters at high power transfer levels, power factor correction becomes mandatory. Phase controlled converters are widely used because these converters are simple, less expensive, reliable, and do not require any commutation circuit. However, the SPF in phase-controlled converters is low when the output voltage is less than the maximum, that is, when the firing angle is large. As the firing angle increases, the displacement angle between the supply voltage and current increases and the converter draws more lagging reactive power, thereby decreasing the PF. Semi-converter systems provide better PF than full-converter systems, although the improvement is not remarkable. This poor PF operation is a major concern in variable speed drives and in high power applications. Better electrical utilization and efficiency can be achieved with the use of PF improvement system. This is the area we have identified to work. Our efforts will be in the direction towards increasing the active power and to reduce reactive power. Thus in turn PF will be improved. A novel digital and analog power factor correction techniques for single phase boost converter using pulse width modulation. It attempts to bring the input voltage waveform and input current waveform in phase with each other. In digital technique, switching is carried out using digital signal processor TMS320F2812. In analog technique, it is implemented using IC UC3854.