Analysis of on-state losses in PWM inverters

The authors present an analytical technique by which the on-state losses in the devices in a PWM inverter may be calculated. The authors take the regular type of symmetrical double-edge sinusoidal modulation, assume that the load current is sinusoidal, and show that the inherent Bessel Function solution can be reduced to a simple algebraic form when the frequency ratio is greater than about ten. It is assumed that the on-state voltage drop across an active device and a free-wheel diode is made up of a constant component plus a component that is linearly dependent upon current. The results are, therefore, applicable to most semiconductor devices. Experimental results are presented and are shown to be in good agreement with predictions