Lower electric stress ZCS-PWM superbuck converter for electric vehicle DC charging spot

To promote the wide acceptance of electric vehicles (EVs), the charging facilities should satisfy with some basic requirements, such as high efficiency, low harmonic pollution, long lifetime, low cost, and ease of bulk construction. Therefore, a novel EV charging facility - dc charging spot and a lower stress zero current switch-pulse width modulation (ZCS-PWM) Superbuck converter suitable for output stage of the former are proposed in this paper. The proposed converter features ZCS of all power switches at entire input voltage and load range, lower voltage stress benefiting from passive clamping circuit. Furthermore, this converter has no additional current stress in the main switch in comparison to hard-switching converter counterpart. In the paper, operation principles, constraint to achieve the ZCS soft communication and electric stress of all power switches have been analyzed in detail. Then, the state-space averaging approach is used to estimate steady-state character of the ZCS-PWM Superbuck converter in continuous current mode (CCM). Finally, a charger prototype rated l.8 kW, operating at 80kHz is constructed for a 320V/50Ah Lithium-iron-phosphate propulsion battery. The validity of the proposed novel EV charging facility and the ZCS technique are verified by the experimental results.