A direct optimum symmetry (DOS) spectral calculation method for cycloconverter synchronous motor drive systems

A technique is presented that can be used to evaluate the harmonic performance of cycloconverters. It uses conventional Fourier analysis techniques complemented by special algorithms. A description of the program, the theoretical basis for it, and results are presented. The major advantages of this technique are that nonsinusoidal output command voltages and output currents can be accounted for and commutation effects can be modeled quite effectively. This obviates the need for developing closed-form expressions that describe the cycloconverter harmonic performance under these nonideal conditions. This technique can also be used to analyze unbalanced systems and circulating current cycloconverters.<>