PWM Dead Time Optimization Method for Automotive Multiphase DC/DC-Converters

This paper introduces a PWM dead time optimization method for multiphase DC/DC-converters with synchronous rectifiers. The aim of the method is to reduce power losses. After a perturbation of the dead times in one converter phase, the phase-currents starts to deviate, whereby the most efficient phase has the higher current. A current balancing controller compensates for this deviation by adjusting duty cycles. Consequently, optimal dead times can be detected by duty cycle differences of the phases. The proposed optimization approach was implemented in a two-phase boost-/buck converter prototype for automotive dual-voltage power-nets. No additional components or circuit modifications were necessary. The detection of optimal dead times, increasing efficiency and reduction of voltage transients are discussed and investigated experimentally.