Improvement of Power Factor by Input Filter and Ripple Reduction using Cuk Converter in Continuous Conduction Mode

The basic Converters like buck, boost and buckboost provide pulsed ripple currents either on input or output sides. A Cuk Converter has inductors on both input and output sides, thus produces continuous currents with reduced ripple. By extending the Cuk Converter to AC side with the support of additional rectifier circuit the power factor can be assessed. The significant concerns when utilizing DC-DC converters with AC source is large Total Harmonic Distortion (THD) and low power factor. A properly designed filter circuit on AC side reduces THD and improves the power factor. In this paper a Cuk Converter (CC) topology with rectifier and inductive. capacitive. inductive (LCL) filter is proposed to reduce THD and improve the power factor. The CC circuit is designed and analyzed to reduce ripple content of currents. The reduction in ripple on DC side in turn improves the sinusoidal shape of current on AC source side. The closed loop simulation of the proposed circuit is carried out using a systematically derived type III compensator. The proposed circuit is practically validated in closed loop using FPGA controller to confirm the simulated waveforms. The results substantiate the fact that the proposed circuit shrinks ripple on DC source side and reduces harmonics of AC source current. The reduction in harmonics decreases THD to a large extent and improves distortion factor, which enhances the power factor. Also the reduction in ripple trims down losses in the circuit and improves the output power, thus suitable for DC to DC conversions in power supplies for viz. electric vehicles, computers, battery chargers and televisions. The improvement in power factor reduces the power drawn from the source and hence the efficiency of the system is improved.