A wide constant power range vector-controlled AC motor drive using winding changeover technique

A high-performance vector-controlled induction motor drive with a very wide constant power range of 1:10 to 1:30 has been developed and widely accepted in the spindle drives of machine tools. The motor has two combinations of winding connections, and one of them is selected in accordance with the operating conditions. The versatility of the winding changeover technique has been introduced and demonstrated. A wide constant power range is achieved, and the gear box used in a conventional machine is eliminated. In addition, it was proved by actual operations that the machining operation can be continued during the changeover without sacrificing the quality of the final product. The basic idea, features, and test results of this technique are described