A simplified digital control method for active power filters

This paper presents a novel simplified digital control method for active power filters. By forcing the mains current to be linear with the mains voltage, the functions of harmonics elimination, reactive power compensation and unbalance correction are realized. In the proposed control method, only the mains currents and the dc bus voltage of the inverter are required to be detected. And with simple calculation, the duty ratios of switches in each switching cycle are got. So the fully digital control is easy to realize, the complex calculation in the conventional instantaneous reactive power theory is avoided and the difficulty in realizing digital control caused by the hysteresis is overcome. The viability and effectiveness of the proposed control method is demonstrated by simulation and experimental results.