The Calculation of Higher Harmonics of Periodically Switched A-C Voltages

摘要

The output waveform of switched semi-conductors and of magnetic amplifier circuits usually is not a pure fundamental waveform but contains harmonics which vary with the commutation. This paper analyzes three basic types of switched output waveforms; sinusoidal, rectified sinusoidal, and square wave. The results are summarized by sets of handbook-type curves from which the harmonics for various switching modes can be readily determined. Mathematical derivations are provided which make it possible to calculate the harmonics present for the most common switching modes. This information is useful in filter design as well as providing information for calculating losses in a load supplied with this waveform. In addition, the output waveform for the minimum harmonic content is indicated by the curves.