Self-balanced Quadruple-Boost Nine-Level Switched-Capacitor Inverter for Solar PV System

Switched capacitor-based multi-level topologies have recently gained attention due to their inherent technical superiority suitable for renewable-based applications. In this work, a single-phase boosting nine-level inverter is proposed, which employs a DC-source (V_dc) and three capacitors. It uses 14 switches that require nine independent control signals from the controller, conducts a maximum of 8 switches at any instant and provides a 9-level quadruple-boosted output voltage. The proposed topology is verified for an experimental setup’s steady and transient load conditions. A detailed discussion on the balanced charging of the capacitors is also presented. A novel harmonic elimination-based-nearest level modulation scheme is proposed, wherein the simplified control scheme of the nearest level control is extended to eliminate the undesired low-order harmonics from the output voltage waveform of the 9-level inverter. Moreover, its merits of a simplified control, lower power loss, reduced total voltage stress and enhanced voltage gain are discussed in comparison with various 9-level inverters in detail.