Low-Switching-Loss Model Predictive Control Methods With Constant Switching Frequency for Single-Phase 5L-ANPC Converters

This article presents a series of low-switching-loss (LSL) model predictive control (MPC) methods with constant switching frequency for a single-phase five-level active neutral-point-clamped (1P-5L-ANPC) topology. In this MPC strategy, a cost function without any weighting factors and a three-segment sequence consisting of two vectors are employed to obtain the duty ratios and track the current, respectively. For the purpose of reducing the switching loss, two schemes (Schemes A and B) are proposed. They have the self-balancing ability of neutral-point (NP) voltage. For Scheme A, in each fundamental period, one of the two phases is always clamped, which reduces the switching loss significantly. Without increasing the switching loss, Scheme B can enhance the performance of balancing NP voltages. Both schemes can maintain a constant switching frequency and increase the efficiency. Besides, a new single topology with less power devices based on Scheme A and its corresponding MPC strategy (Scheme C) are also proposed. Finally, simulations and experiments have been carried out to validate the effectiveness of the three proposed schemes.