Low Switching PWM Strategy Using a Carrier Wave Regulated by the Slope of a Trapezoidal Modulator Wave

A simple and novel pulsewidth modulation (PWM) technique is presented. It uses a trapezoidal modulator wave and a sinusoidal carrier signal with variable frequency. The instantaneous frequency of the carrier wave is proportional to the slope of the modulator signal, and only two parameters (the slope of the trapezoidal edges and the proportionality constant of the carrier wave frequency) allow one to control the output voltage level and the number of commutation per cycle in real time. The proposed technique generates high-quality voltages with very few commutations per cycle, and it is particularly appropriate for reducing commutation loss. Results are checked experimentally and compared to other PWM techniques, yielding better signal quality with an important reduction in the number of commutations.