A three-phase active power filter operating with fixed switching frequency for reactive power and current harmonic compensation

The performance and dynamic characteristics of a three-phase active power filter operating with fixed switching frequency are presented and analysed. The proposed scheme employs a pulse width modulation voltage source inverter and has two important characteristics. First, it operates with fixed switching frequency, and, second, it can compensate the reactive power and the current harmonic components of nonlinear loads. Reactive power compensation is achieved without sensing the computing the reactive component of the load current, thus simplifying the control system. Current harmonic compensation is done in the time domain. The principles of operation of the proposed active power filter along with the design criteria of the power and control circuit components are discussed in detail. Experimental results obtained from a 5 kVA prototype confirm the feasibility and the features of the proposed system