Induction Motor Drive System With Novel Mechanical Winding Changeover Device

This report presents a mechanical winding-changeover system to improve energy consumption of traction motors for automobiles. Conventional mechanical winding changeover devices have two drawbacks: large volume for large current, and short lifetime due to contact arc. We have adopted multi contacts to downsize the winding changeover device, which results in half size compared with the conventional relay structure of 5 L, with rated current of 440 Arms. We also established the operation principle which does not occur any contact arc, where the switching timing is controlled so that the motor internal voltage is constantly below the inverter DC voltage. Our developed winding changeover device can be provided with the longer lifetime of the switching contact. The actual test of 1.5 kW induction motor (IM) system demonstrated that the contact arc did not occur at the winding changeover operation during motor acceleration. Measurement results also demonstrated that the proposed winding changeover devices would endure the switching more than 200,000 reciprocation. Furthermore, energy loss was estimated to be reduced by 4% at WLTC mode because of the improvement of system efficiency due to winding changeover.