Fuzzy Logic Controller Implementation for the Compensating Capacitor Voltage of an Indirect Current Controlled Active Filter

The voltage regulating system of an active power filter dc-link capacitor was experimentally validated in this paper, after previous validation of the method, by simulation. The active filter adopted control method is the indirect current control. The control section of the active filter consists of a dSpace DS1103 prototyping board. The control algorithm was implemented in the Matlab Simulink programming environment and the DS1103 board program was obtained by compiling the Simulink model. The controller performance is dependent on the proper definition of the membership functions yet proper voltage regulation can be obtained with the cost of higher controller output ripple. A compromise can be achieved, having some voltage regulation with low controller ripple, further reduced by a low pass filter. For this configuration the active filtering system performance is good, but dependent on the load current RMS value. An optimum operating point was achieved, for which the compensated current distortion is the lowest and the power factor is the highest. The system performance is affected by the relatively high time step of the DS1103 control board, imposed by the complexity of the fuzzy inference system. The experimental active filtering system efficiency at the optimum operating point is 93%.