Line interharmonic currents in frequency changers

Harmonic studies of power rectifiers usually ignore the noninteger harmonics because there is no agreed method of either calculating them or measuring them. This paper shows one way of estimating the DC side current harmonics of a frequency changer and converting them to the AC line current harmonics with the aid of the current switching function. This method is extended to characteristic and noncharacteristic DC harmonics to enable the AC line current to be reconstructed including the integer and noninteger modulation harmonics.