Calculating and controlling harmonics caused by power converters

Simple, practical methods for calculation of voltage distortion caused by converter harmonic currents are presented for both controlled (thyristor) and uncontrolled (diode) converters. The methods are especially directed towards converters used with adjustable frequency controllers. The classical assumption of smooth DC current used in earlier methods is shown to give lower harmonics than actual results. The method presented addresses the practicality of nonideal operation and only requires knowledge of equipment type, full load current, and system short-circuit current. Finally, results are given for a 12-pulse converter scheme which provides the expected harmonic reduction and eliminates concern over meeting most distortion specifications.<>