Pulse Increment Modulation of Three-Level Inverter-Based Wireless Power Transfer

Multilevel inverters have attracted more and more attention in high-power WPT systems, but their switching loss is a worrying issue. To solve this problem, this article proposes and implements a sigma-delta pulse increment modulation (PIM) of a full-bridge three-level flying-capacitor inverter for wireless power systems. The proposed method outperforms the segmented vector pulse frequency modulation of the three-level full-bridge inverter-based WPT system for lower harmonics and an easier realization. A commutative flying-capacitor voltage balancing and switch-state selecting method of the three-level full-bridge inverter for the WPT is also proposed. It can balance the capacitor voltage with dynamic perturbations and eliminate the voltage spike caused by current commutation. Finally, theoretical analysis, simulations, and hardware experimentation are given further to verify the effectiveness of the proposed Σ-Δ PIM WPT system.