A DSP based power factor correction converter to reduce total harmonic distortion of input current for improvement of power quality

Abstract

This paper proposes a controlled approach to be used in power factor correction (PFC) circuits to decrease total harmonic distortion (THD) of input current by eliminating the input current harmonics. This method removes the problems of the conventional PFC converters. Since in conventional PFC circuits the input current is controlled to follow the ac input voltage, it will have the same harmonics of the input voltage. This is an important disadvantage of the conventional method especially when the input voltage is distorted. In this approach, a sinusoidal signal is generated by the DSP microprocessor and is used as reference in controlling the converter switch to obtain a sinusoidal input current based on zero crossing points of distorted input voltage. Due to the reflection of input voltage distortions to the output voltage, an adaptive digital FIR filter is designed and embedded into the voltage control loop. The feed forward is also used into the control algorithm. The implementation of feed forward and adaptive digital FIR filter improves the converter performance to obtain a near unity power factor correction with lower input current THD. Average current control mode is implemented and operated in continuous conduction mode. The experiments performed in the laboratory for different cases of operation verify the theoretical and simulation studies performed in MATLAB/Simulink. The control approach is programmed by the TMS320F2812 DSP microprocessor. The experimental results are good in accordance with IEC 61000-3-2 Current Harmonic Standard.