Exploring the Boundaries and Effects of the Discontinuous Conduction Mode in H-Bridge Inverter with Dead-time

Dead-time of an H-bridge inverter can cause nonlinear error on the inverter output. In different switching cycles during a fundamental period, the effect of dead-time might be different. The H-bridge inverter in different switching cycles can operate in three kinds of modes, including soft-switching continuous conduction mode, discontinuous conduction mode and hard-switching continuous conduction mode. In addition, the discontinuous conduction mode can be further classified into four different types, which have not been fully studied in previous research. In this paper, four different kinds of switching cycle in the discontinuous conduction mode are investigated. The effect of the dead-time on the voltage error is elaborated and the boundaries of each kind of switching cycle are determined by a series of constraint functions. Based on the analysis, a complete mathematical expression of the voltage error in a fundamental period is given and it yields a better accuracy compared to previous publications.