A Novel Five‐Level Neutral‐Point‐Clamped Inverter for Wireless Power Transfer Systems With Voltage Boosting and Self‐Balancing

ABSTRACT In response to the low harmonic requirement of wireless power transfer (WPT) systems and the problems in existing five‐level inverters, this paper proposes a novel five‐level neutral‐point‐clamped (NPC) inverter for WPT systems by replacing the low side DC capacitor in the traditional NPC inverter with a DC power source and connecting an inductor between the neutral point and one of the AC output ports. Compared with traditional NPC inverter, the proposed inverter can perform symmetrical alternating charging and discharging of the inductor between the DC power source and the high side DC capacitor without increasing the number of power switches, so that the DC capacitor voltage is always maintained at the DC power source voltage, thereby generating an AC output with an amplitude twice that of the DC power source. Therefore, it has the advantages of being able to boost voltage, achieve capacitor voltage self‐balance, and suppress capacitor current spikes. This paper analyzed the operating principle and calculated the theoretical model of the proposed inverter, and conducted comparative analysis with other five‐level inverters in literature. Then, the parameters and power loss were calculated. Meanwhile, a segmented modulation strategy was designed to optimize its operating efficiency. Finally, experiments were conducted, which verified the enhanced performance of the proposed inverter over other five‐level inverters. Moreover, its maximum efficiency can reach 93% and the dynamic response time of the WPT system is basically no more than 10 ms, which is suitable for various WPT applications.