Optimal excitation of a high speed switched reluctance generator

This paper presents a new approach for controlling a switched-reluctance generator (SRG). The control objective is to produce the required power using the excitation that produces the highest efficiency. The SRG considered here operates above base speed. The turn-on and the conduction angles are the only control parameters that can be used to optimize the power conversion. The conventional control method that advances the turn-on angle as the speed increases is not enough to produce optimum performance. The turn-on and the conduction angles together are the key elements for optimal excitation. Optimization of the excitation angles is performed using a machine model based on finite element analysis. For all of the operating speeds, all possible turn-on and conduction angles are simulated to get the desired power output. The excitation angles using the minimum RMS phase currents are chosen among those that give the desired output power. The control strategy is experimentally tested using a 6 kW 5000 rpm SRG. The control algorithm is able to provide required power with very good generator efficiency.