Steady-state modelling of a uniform pulse-width modulated single-phase AC-to-DC converter-fed DC motor drive

With the increasing availability of power transistor switches, PWM controlled rectifiers can efficiently and economically be employed in low and medium power applications of DC drive systems. In this paper, steady-state modelling and solution of a uniform pulse-width modulated single-phase AC-to-DC converter-fed DC motor drive is accomplished. The developed model is presented in a generalized form that is applicable irrespective of the number of pulses per supply half-cycle. Measured and predicted parameters are shown to be very close and the model is proved to be efficient and accurate. Both continuous and discontinuous modes of operation are covered, and critical operating conditions at which the system moves from one mode to the other are thoroughly investigated. The effects of the armature inductance-to-resistance ratio and the chopping frequency on these critical conditions, load and line harmonics, and on the ripple contents of the armature current are also thoroughly investigated.