Improving the performance of an active power filter as part of a multifunctional high power electrical vehicle charging station

This paper first analyzes low switching frequency discrete-time control techniques of an active power filter (APF) of a multifunctional high power electrical vehicle charging station. Based on the analysis, two major factors which greatly degrade the performance of the APF under this control technique, are identified. The first one is that there is always a delay caused by performing digital control algorithm. The second one is that the voltage at the point of common coupling (PCC) is changing during one sampling period. Then, techniques to deal with these problems and improve the performance of the cascaded multilevel inverter based APF are given. These techniques use data collected in previous line cycle to generate reference current and voltage for the APF. Finally, simulation results in Matlab/Simulink are provided to validate these techniques.