SiC Based Interleaved Voltage Source Converter for Active Power Filter Applications

An interleaved voltage source converter (VSC) based on commercially available SiC power devices is proposed and implemented for active power filter (APF) application to reach an effective switching frequency of 300 kHz. We developed a hybrid current controller combining multiple resonant (MR) and plug-in-repetitive (PIRC) compensators that enable enhanced transient and steady-state performance with a low computational burden. Leveraging a high performance FPGA based digital controller, a control update rate of 100 kHz is achieved. We analytically show that the high control update rate combined with enhanced ripple attenuation capability of the SiC-based interleaved topology facilitates natural damping of harmonic resonances: no passive or active damping measures are necessary to retain stable operation irrespective of variation in grid impedance over a very wide range. The need for load harmonics detection is eliminated by indirect harmonic compensation using only the grid current measurement. Active current balancing among the interleaved sub-phases is achieved by low-cost and low-bandwidth current sensors. Experimental results are presented to validate the performance of the proposed APF.