A Quasi-3-Level Active Neutral Point Clamped Converter for Onboard Chargers in Electric Vehicles

A Quasi-3-Level (Q3L) Active Neutral Point Clamped (ANPC) converter is introduced that allows for higher-efficiencies and power-densities for high-voltage bidirectional AC-DC converters, which are especially relevant in the On-board Chargers (OBC) design in an Electric Vehicle (EV). The use of Quasi-2-level (Q2L) cells to allow the use of lower-voltage rated semiconductor devices is explored and the balancing schemes of the flying-capacitor are discussed. Carrier-based modulation schemes and subsequent semiconductor duty-cycles and RMS current are derived, along with the filter sizing which provides the design expressions of the converter. The effect of switching frequency (and consequently, the power density) on the efficiency is analysed. The operation of the converter is verified in simulations and the analytically calculated design parameters are verified.