A Practical Series-Shunt Hybrid Active Power Filter Based on Fundamental Magnetic Potential Self-Balance

In this paper, a novel series-shunt hybrid active power filter based on fundamental magnetic potential self-balance is reported. It consists of three parts: a passive power filter, a voltage-source pulsewidth-modulated (PWM) converter and a series zero magnetic flux current transformer. The zero magnetic flux current transformer locating in series between the power supply and nonlinear loads presents low reactance to fundamental and high impedance to the harmonics automatically. And the harmonic voltage dropped on the zero magnetic flux current transformer can be detected in real time. The voltage-source PWM converter is controlled as a harmonic voltage source. Wherein, it is connected to the passive filters in series through an isolated transformer. Therefore the flow-in harmonic current will be less than before. The configuration, working principle and performance analysis of the designed hybrid active power filter are determined. The validity of the theory and excellent compensation characteristics are proved by an experimental prototype. The current distortion factor is decreased from 20.46% to 2.67% by using this hybrid active power filter.