Design and Implementation of a Fuzzy Control System Applied to a 6 × 4 SRG

Abstract

This article presents an experimental methodology to control the voltage generated from a switched reluctance generator (SRG) using fuzzy logic control. The generated voltage is controlled by varying the demagnetization angle ( θ off), maintaining the magnetization angle ( θ on) fixed. The developed strategy operates on the upper switches of the asymmetric half-bridge converter. The converter topology is used in conjunction with an intermediate freewheeling stage between the steps of magnetization and demagnetization of the phases. The control algorithm was developed in a DSP/FPGA with high processing capacity using LabVIEW graphical platform. Results in open loop and closed loop are presented, subjecting the SRG to variable speeds and load application. For the purpose of performance comparison, a PI compensator has been implemented and tuned for this specific application and the results for both controllers are presented and discussed. For the open-loop tests, the SRG was subjected to variations in the rotor speed, namely, shaft speed varying sinusoidally and triangularly. In these tests, it was observed that the bus voltage suffered great variations. Load variations were also implemented in open loop and, once again, the bus voltage varied significantly. In laboratory tests in closed loop, the SRG was again subjected to variations in sinusoidal and triangular speed and still under load step. In all these experiments, comparisons of results were made between PI controllers and using fuzzy logic control. At the end, it was observed that the imposition of a control loop allowed the bus voltage to be maintained at the preestablished value.