Analysis of single-phase rectified thyristor-controlled load with integral-cycle triggering

A rectified-voltage waveform caused by integral-cycle triggering of thyristors is found to contain most subharmonics and harmonics, odd and even, from zero to infinity. For a control period (on-plus-off time) of T supply cycles, the lowest subharmonic has a frequency of 1/T of the supply frequency. Subharmonics and higher harmonics can have amplitudes exceeding that of the average load voltage, dependent on T and the number of conducting cycles N. The ripple factor is a function of N/T and exceeds unity for N/T < 1/9. Average load voltage and load power both vary in proportion to N/T. In connection with electromagnetic interference, a method is developed for estimating the amplitude of high-order harmonic components.