Abstract
This paper discusses the voltage error caused by the dead time in voltage-source PWM converters. The theoretical analysis in this paper derives the nonlinear voltage error paying attention to the parasitic output capacitance in each switching device. The analytical result reveals that the turn-off current or the switching current ripple strongly affects the voltage error. In addition, it is also clarified that the conventional compensation methods based on linear and three-level approximations are suitable for small and large current ripple conditions, respectively. A simple calculation method of current ripples is also developed to estimate the turn-off currents in three-phase PWM converters. A compensation method based on the analysis is developed and compared with three different conventional methods in experiments using a 200-V, 5-kW three-phase grid-connection converter. The analysis-based method exhibits a good compensation performance, having a lower voltage THD than the conventional methods over a wide operating range.
