A Modular Structured Multilevel Inverter Active Power Filter with Unified Constant-Frequency Integration Control for Nonlinear AC Loads

Active power filter (APF) has a vital role for compensating the reactive power and harmonics from a group of nonlinear loads connected at the common point of coupling to ensure that the resulting total current drawn from the main incoming supply is sinusoidal. This paper is to present the performance of a modular structured multilevel inverter (MSMI) APF with unified constant frequency integration (UCI) control technique for compensating the distorted current caused by various nonlinear AC loads. MSMI is well known for its capability in reducing the voltage and current stresses on the semiconductors switches and providing the convenience for future expansion in order to achieve higher power ratings for the APF system. Whereas, the UCI control technique is adopted due to its constant switching frequency operation and simple analog circuitry. To demonstrate the capability of the single phase MSMI APF with UCI control technique for compensation of harmonics caused by various AC nonlinear loads, simulation results are presented and discussed.