The synthetic loading of three-phase induction motors using microprocessor controlled power electronics

The paper describes methods of loading three-phase induction motors, without the need to connect a load to the machine´s drive shaft. Three methods are described and compared. One method uses microprocessor controlled power electronics to replace the electrical machines of the existing dual frequency equivalent load technique. The second method uses microprocessor controlled power electronics to rapidly modulate the machine´s supply frequency. The third method uses microprocessor controlled power electronics to produce a rotating magnetic field which rotates at constant speed but with sinusoidally varying magnitude. The third method is shown to be superior in that the oscillating torque during the test is substantially reduced without affecting the accuracy of the temperature rise results