Novel clamp switching method for a single phase three-level inverter with high efficiency and low harmonics

This paper proposes a modulation method to reduce power losses and achieve high efficiency for a single-phase NPC three-level inverter. In conventional switching methods, the bipolar and unipolar pulse width modulation methods are commonly used in a single phase inverter. However, these switching methods have the disadvantages in aspects of the power loss. The several clamp switching methods aggravating the Total Harmonic Distortion (THD) are introduced to solve the loss problem. To overcome these weaknesses in these switching methods, this paper proposes a novel clamp switching method that combines two switching method, unipolar PWM method and clamp switching method. Since the proposed method has all the advantages of both methods, the optimal performance in the power losses and THD can be obtained. The analysis of the power loss reduction and THD is showed through the simulation.