Improvement on single "Y" current of the variable speed system with cycloconverter-fed 12-phase synchronous motor

The analytic equations of d, q current harmonics of the variable speed system with cycloconverter-fed 3-phase synchronous motor and those of single "Y" d, q current harmonics of the variable speed system with cycloconverter-fed 12-phase synchronous motor are derived. By an actual example, the d, q current harmonics of the two systems are calculated and the simulating current curves and experimental ones are also provided. The simulating and experimental results proves the validity of analytic equations and also denotes the single "Y" current of 12-phase synchronous motor variable speed system has much more harmonics than the current of related 3-phase system. This character is analyzed in theory and the main factor affecting the single "Y" current harmonic of the 12-phase system is obtained. The method of improving the single "Y" current harmonics of 12-phase system is pointed out and the simulation results testify its correctness