Loss-Based Design for Natural Balancing in Multicell Converters using Vectorized Models
Résumé
Due to the inherent features of the multilevel Flying Capacitor (FC) converter, the voltages in the capacitors are naturally balanced under phase-shifted pulse width modulation (PS-PWM) techniques. Nevertheless, under certain operation conditions the voltages in the capacitors vary between the commutation cells and an external balancer booster is required. This paper provides a methodology to properly design the balance booster for a FC converter with n-cells based on vectorized models. However, due to the trade-off between balancing speed and power losses, it is difficult to design a balance booster based on speed requirements, and checking loss constraints afterwards may result in a very long iterative process. Designing for losses and checking for speed is a much simpler process and this illustrated here for different types of balance boosters. Some simulations results obtained in PLECS R , are provided to enhance the benefits of the vectorized model for power electronic circuits, and the application to the design of balance boosters is presented.