A hybrid fuzzy current regulator for three-phase voltage source PWM-inverter

This paper presents a fuzzy logic strategy for the current control of a three-phase voltage source power PWM-inverter. The base of this regulator is a direct digital predictive loop which has a very good dynamic performance, but the steady state performance will heavily depend on the accuracy of the model structure and plant´s parameters. To reduce the steady errors and compensate the system uncertainties, a feedforward control loop and a fuzzy logic algorithm are introduced. The direct digital predictive loop with the feedforward loop, which can be seen as a hybrid current regulator, generates the command voltage based on the nominal system conditions, guarantees the system with a very fast dynamic response and a smaller system error. The fuzzy logic algorithm, by measuring the amplitude and phase angle of the system error, generates a modifying signal to correct the gains of the direct digital predictive loop and the feedforward loop. When the difference between the reference and actual signals is larger than a given threshold, therefore it minimizes the effects of system uncertainties. Simulation results are presented to verify the effectiveness of the current regulation algorithm.