Single Phase Power Factor Correction Based on Averaged Current Mode Controlled Boost Converter

The conventional full-wave diode bridge rectifier with an output capacitor filter produces current spikes in the supply, thus lowering the power factor and distorting the waveform. An ideal rectifier presents an effective resistive load (Emulated resistance) to the AC power line; hence, if the supplied AC voltage is sinusoidal, then the current drawn by the rectifier is also sinusoidal and is in phase with the voltage. Converters that approximate the properties of the ideal rectifier are sometimes called power factor corrected, because their input power factor is nearly unity. The boost converter, as well as a variety of other converters, can be controlled such that a near ideal rectifier system is obtained. This is accomplished by control of a high-frequency switching converter, such that the ac line current waveform follows the applied ac line voltage. The boost converter is operated in Continuous Conduction Mode (CCM), and controlled by Average Current Mode Control (ACMC). The system contains multi-loop control strategy and a feed-forward loop in order to get power factor near unity with constant output power. There are a variety of Power Factor Correction (PFC) chips available in the market, one being the UC3854, can be operated in Average Current Mode Control. The simulation of a 250W, AC – DC rectified system with Unity Power Factor at the input using UC3854 was done in PSIM Power Electronics simulation software and results were obtained.