Modelling and implementation of a sinusoidal-pulse-width-modulated DC drive system

The increasing availability of controlled on-and-off power switching devices enables self-commutated AC-to-DC pulse width modulated converters to be efficiently and economically employed in DC drive systems. In this paper, a mathematical model for a sinusoidally pulse width modulated DC drive system is developed. The model is presented in a generalized analytical form that is applicable for any number of pulses per output period of symmetry. The limitation of the input voltage to match the requirements of the sinusoidal pulse width modulated control strategy is pointed out. The developed model and its solution procedure are verified using a transistorized self-commutated testing model, implemented for this purpose. The effects of the chopping-to-supply frequency ratio and the armature inductance-to-resistance ratio on the nature of the armature current are investigated. The general performance characteristics are also presented and investigated.