Analytical technique for calculating the output harmonics of an H-bridge inverter with dead time

An analytical technique for calculating the harmonic characteristics of the output voltage of an H-bridge inverter with dead time is presented. The analysis is based on a three-dimensional (3-D) model derived for generating the pulsewidth-modulated (PWM) pulse train. By applying double Fourier analysis, a generalized and elegant mathematical function for describing the harmonic components of the output voltage is formulated. The function can be divided into two parts: an ideal part representing the PWM signal without dead time and a correction part representing the dead-time effect. The function provides detailed composition of the fundamental component, signal harmonics, carrier harmonics, and cross-modulated harmonics. The proposed technique has been verified using examples and the theoretical predictions are confirmed with the results obtained from simulations using PSpice.