The multi-modular shunt APF based on direct current control and frequency doubling carrier phase-shifted SPWM

Multi-modular shunt active power filter (APF) is widely used in high voltage and high power fields to promote the power quality. However, the traditional multi-modular shunt APF needs to handle harmonic and reactive current, so the algorithm is complex, and the harmonic compensation performance is deteriorated. A multi-modular shunt APF based on direct current control (DCC) and frequency doubling carrier phase-shifted (FDCPS-SPWM) control scheme is proposed in the paper. There is no need to sense load current, and can realize higher equivalent switch frequency with lower real switch frequency devices. Thus it has better harmonic compensation performance. Double closed loop control scheme for the DC voltage and in-grid current is constructed, and then the small-signal model and stability conditions are studied. The design guidelines for the multi-modular shunt APF system are also deduced. A 1kVA prototype based on two APF modules in parallel connection operating at 10kHz is developed to verify the theoretical analysis. Experiment results show that multi-modular shunt APF with the proposed control strategy has better harmonic compensation performance, and is easier to be controlled. So it has a broad application in high voltage and high power fields.