A Study of Inverter Loss Reduction Using Discontinuous Pulse Width Modulation Techniques

In this paper, the reduction in inverter losses by using various forms of Discontinuous Pulse Width Modulation (DPWM) scheme is investigated. Models for various forms of DPWM excitation have been implemented using Pspice and these have been combined with an existing model for a three-phase voltage source inverter. The models were then used to predict inverter losses and these have been verified by direct measurements in a calorimeter. Both simulated and measured results confirm the expectation that DPWM can reduce losses, and that optimum variant depends on load conditions. Reductions in losses in the range 5 to 10% can be expected by appropriate choice of variant. Measurements of inverter losses have been made for an induction motor load operating under a range of conditions and these again show how the optimum choice of scheme depends on load conditions.