A Common‐Ground Structure Switched‐Capacitor Multilevel Inverter With Low–DC Bias Characteristics

ABSTRACT Common‐ground switched‐capacitor (CGSC) inverters show unique advantages in voltage boosting and eliminating leakage current due to the combination of switched‐capacitor and common‐ground structure. However, the existing CGSC inverters have a drawback in that the unbalanced AC output voltage waveform will lead to DC bias. To address this problem, a CGSC five‐level inverter with low–DC bias characteristics is proposed in this article. The topology consists of a single–DC input voltage, 11 switches, two diodes, and three capacitors. The inherent circuit feature enables the hybrid modulation strategy to repeatedly charge the capacitors using the DC source, optimizing the voltage ripples. By further designing the capacitance to compensate for the asymmetry of the voltage ripple, the output DC bias can be effectively suppressed. This article details how the topology works and the hybrid modulation strategies, as well as capacitance analysis. In addition, a performance comparison analysis with other similar topologies highlights the advantages of the proposed topology to suppress DC bias and improve capacitor utilization. The simulation results show the suppression effect with the hybrid modulation strategy and ripple compensation. Finally, a 500‐W experimental prototype was built to verify the feasibility of the proposed topology.