Harmonics in a.c. rotating machines

A general approach to harmonic phenomena in a.c. rotating machines is developed. A flux-density component, b = B sin (k¿t ± q¿s + ÿ), where k and q are integral constants, is taken as the central concept-This b-distribution is, in general, harmonic in time and space, and a series of such components can represent any cyclic flux distribution encountered. The effects of such a field in regard to voltage and torque production are analysed, with quite simple results when used with the concept that any machine winding may be treated as equivalent to a series connection of sinusoidal space-harmonic windings. Various common causes of harmonics are next analysed using these general results. Appendix 9.1 develops expressions for harmonic winding turns in terms of the actual winding distribution, while Appendix 9.2 examines some effects of saliency in synchronous machines.