Single-phase two-speed pole-change motors using phase-mixing techniques

The paper describes how the phase-mixing techniques which have previously been applied to 3phase operation may be extended for use in single-phase machines. A description is given of the operation of the previous 3phase versions when single-phase connected, and a subsequent analysis shows how windings which are harmonic-free at both speeds may be formed. The material is supported by some practical tests in which an example of the new two-speed windings is compared with a single-speed winding in a similar frame.