Pole-changing motor winding - has two layers with three strands of coil groups maintaining constant torque

摘要

The three-strand twin layer winding of motors for speed changing by altering the number of poles ensures maintenance of the torque. The design results in a high winding factor so that the generated flux can provide an increased power per unit of weight of the motor. Each group of coils is subdivided in both strands to form symmetrical combinations to decrease the circulation currents which are determined by the equivalent e.m.f. derived from phase vectors of voltages.