THE DESIGN AND IMPLEMENTATION OF A 3-PHASE ACTIVE POWER FILTER BASED ON SLIDING MODE CONTROL

This paper presents an active power filter for three-phase systems, Th e work is motivated by the need for active filtration in a current-sou rce excitation system for a variable-reluctance generator, The active filter is comprised of a six-switch three-phase inverter, a de bus cap acitor, and an isolation transformer. The isolation transformer is req uired by the application, The leakage inductance associated,vith each phase of the isolation transformer is used as the series impedance wit h each phase, by which the inverter is able to actively shape the phas e currents in order to compensate for the nonlinearities of all loads within the point of common coupling, The active filter is controlled t hrough two control loops, The inner current regulation loop uses slidi ng-mode control by virtue of its ease of implementation, The outer vol tage loop regulates the average voltage on the de bus capacitor, The o uter voltage loop is responsible for correctly setting the commanded m agnitude of the phase currents, This paper presents the analysis, desi gn, and operation of the active filter, Experimental results are provi ded for the active filter compensating a phase controlled rectifier wh ich is drawing 10.4 kW,