A DPWM-Based Hybrid Variable Switching Frequency Control for Parallel Interleaved Three-Level T-type Inverter

This paper proposes a discontinuous pulse width modulation (DPWM)-based hybrid variable switching frequency control for a 20 kVA two parallel interleaved three-level T-type inverter. Inductor current ripple prediction is adopted to minimize the unnecessary conduction loss, and the variable switching frequency can be calculated easily. DPWM is used to simplify the zero voltage switching (ZVS) realization because only two phases are high-frequency switching. Full-range ZVS can be achieved, and the switching frequency variation range in a line cycle is narrow under any load, power factor, or modulation index, without additional sensors, auxiliary circuits, or current zero-crossing detection (ZCD) circuits. The power density and dynamic response can be significantly improved due to the high switching frequency and extremely low inductance. In addition, the utilization of coupled inductors enhances the power density further. Simulation results have been presented to verify the strategy and performance.