A Novel Multilevel Controller

Active power filter is an important means to improve power quality, and power topology is an important part of active power filter. Therefore, the research on power topology has important practical value. This paper proposes a simple-structure topology that employs eight switching power devices, two capacitors, and eight diodes to realize nine-level voltage output. The proposed topology can effectively reduce the volume and weight of the device and achieve multilevel output. Simultaneously, a compound control strategy, consisting of integrated phase voltage control and cell capacitance voltage control, is proposed for unit voltage equalization control. Finally, taking the three-phase active power filter as the research object, simulation and experimental verification are carried out with the proposed topology. The results show that the proposed topology and control scheme are feasible, and in the case of sudden load change, the fluctuation of capacitor voltage V1 is less than 3 V, the fluctuation of capacitor voltage V2 is less than 1 V, and the THD (Total Harmonic Distortion) of the phase current is well suppressed to 3.84%.