A simple and low cost of delta modulator for static PWM inverter

The problem of switching frequency over the fundamental period of the modulation signal in fixed band delta modulation is improved by adding a triangular carrier wave to the sinusoidal reference and forcing the integrator output to follow the sum of these two signals is proposed in this paper. The proposed method is applied to the voltage source inverters for variable-speed three-phase induction motor drives applications (VSD).