Energy saving algorithm on induction motors controlled by a 68HC11 microcontroller system using fuzzy logic approaching

The potential of energy saving in induction motors is in light loads. This research has overcome the situation, by sensing the load and controlling the motor terminal voltages to meet the load requirement using a microcontroller system. The program in this microcontroller system can detect the motor load indirectly using /spl beta/ angle. Based on this angle we predict a notch angle (/spl gamma/) using a fuzzy logic algorithm. The experiment results on a squirrel cage three phase induction motor, 1.5 kW, 380/220 V, Y connected, shows that the biggest energy saved when the motor is in no load condition, is about 58%. Energy saving started at about 60% of rated load. There is no saved energy at full load condition. The fuzzy logic algorithm does work well on slow changing of loads.