Analysis and control of active power filter with optimized injection

An active filter that removes harmonics from the AC line by the injection of pulse-width-modulated (PWM) controlled currents is described. These compensating currents are optimized for the removal of all harmonic components up to a specified order using a filter that requires no supply other than the line to which it is connected. The required bidirectional power flow in the filter is achieved by establishing an internal inductor current within upper and lower limits by a purely fundamental current flow into the filter from the line. The performance characteristics of the proposed method are investigated by analysis and simulation. Experimental results from a microcomputer-controlled model establish the validity of the approach