New modified carrier-based level-shifted PWM control for NPC rectifiers considered for implementation in EV fast chargers

Abstract

In this study, the aim is to evaluate three-phase (3ϕ) AC/DC neutral point-clamped (NPC) power factor-corrected (PFC) multilevel converter performance for electric vehicle (EV) fast chargers. Power factor correction for EV fast chargers is very important in terms of efficient power usage and charger compatibility with the grid. Multilevel converters improve charging efficiency, reduce voltage stresses on components, minimize electromagnetic interference, and support high power capabilities. For this reason, multilevel converters with the PFC feature contribute to the reliable and effective operation of the fast-charging infrastructure. Rectifier analysis is tested with extensive simulations using a new modified carrier-based level-shifted pulse-width modulation (PWM) technique. The results obtained are in accordance with international standards. The proposed PWM technique provides low voltage regulation, low total harmonic distortion input current, unit input power factor, and a well-regulated DC bus voltage for the NPC rectifier in fast charging systems, and the system has high efficiency. In addition, the modulation method eliminates the need for an additional PFC circuit. The system demonstrates remarkable success in addressing critical parameters such as capacitor voltage balance. This modified carrier-based PWM is highly successful for NPC rectifiers designed for DC fast chargers, rated for power up to 300 kW. The simulation results of the DC fast charger system demonstrate the validity and flexibility of the proposed carrier-based level-shifted PWM method.