A Hybrid Synergetic Control for 3-φ VSC & 3L-ANPC DC-DC Stage for Off-board/Portable EV Charger

Wide adjustable EV battery voltage adaptability is a major concern, which directly affects the system power density. This is because several series/parallel DC-DC converters cascaded with PFC stage. Since, power factor correction (PFC) stage, facilitate only voltage boost capability. This is due to control the grid current total harmonics distortion with all three phases conducting under PWM mode. To enable wide variation in intermediate DC link over switch voltage stress constraints, this paper proposes hybrid synergetic control to facilitate buck-boost operation of PFC stage. This is done by utilization of 1/3, 2/3 and 3/3 pulse width modulation (PWM) control. A concept is on account to modulation of minimum 3 phases to provide excellent grid current THD, as in 3/3 PWM. In each PWM, numerator figure of phase legs of PFC stage is controlled in PWM whereas other phase legs are clamped. At similar instant, remaining phases of DC-DC stage are in PWM mode. In addition to this, each leg of active neutral point clamped (ANPC) stage is gated with dual phase shift (DPS) modulation. It is configured to operate ANPC with equally half voltage stress and limited current stress. This is done by optimized selection of phase shift and conduction angles of both 3L-H-bridges. With this, 200-575V range of intermediate DC link voltage and 42-425V battery charging voltage range are achieved. Proposed concept facilitates portable EV charger designed for a wide category of EVs. A 3.3kW prototype is designed to validate designed control.