A Single-Phase Five-Level Switched-Capacitor Boost Inverter With Improving Voltage Gain

In this paper, a new topology of single-phase five-level switched-capacitor boost inverter (5L-SCBI) is introduced to improve voltage gain in comparison with existing impedance-source inverters (ISIs). With switched-capacitor (SC) structure used in this topology, boost factor is increased to twice that in existing ISIs, and capacitor voltages are self-balanced. Unlike conventional SC-based inverters, charged/discharged currents of capacitors are limited by input current which significantly reduces current stresses of capacitors and switching devices. In this topology, the output of DC-DC stage has two voltage levels, which helps to create five levels at the output of H-bridge circuit. A new modified pulse-width modulation (PWM) technique is developed to control the proposed inverter. With the introduced control algorithm, modulation index utilization is improved compared to existing ISIs. Consequently, component voltage stresses are improved. Moreover, one switch of boost circuit can obtain zero-voltage switching (ZVS) on/off, which helps to reduce the switching loss of this switch. Experimental results are conducted by 1-kW laboratory prototype to verify the proposed inverter.