Steady-state analysis of dead-time effect on bidirectional buck converters

Half-bridge inverters, full-bridge inverters and bidirectional buck converters share a common topological structure, in which two switches and two diodes are present. In such a topology, a dead time between the two signals controlling the switches is inserted. This influences the relationship between output voltage, input voltage and duty cycle as a function of the output current. In the literature, the dead-time effect has been studied in relation with inverters, active filters, voltage regulated modules and high-precision power amplifiers, and dead-time compensation techniques have been proposed. However, the measurement of the current is normally required for all dead-time compensation strategies, which can be a problem when the current approaches or crosses zero. In this paper, the operation of a bidirectional buck converter in the region around zero current has been analytically analyzed. It has been shown that in a region around zero there is no dead-time effect. The analytical expression of the borders between the areas where the dead-time effect is positive, zero or negative has been given. Moreover it has been shown that between these three areas, there are four other transitional areas. The analytical analysis has been confirmed by simulation and experimental results.