Performance Evaluation of a 17-Level Octuple Boost Inverter for a Grid-Connected PV System

This paper presents a novel single-phase, 17-level octuple boost switched-capacitor multilevel inverter (OBSC-MLI) for a grid-connected photovoltaic (PV) system. The proposed inverter can boost the low voltage obtained from a small PV source up to eight times at the output to reach the grid voltage level. Thus, the proposed inverter is most suitable for a PV system, as it can eliminate the need for any boost converter or step-up transformer for its grid integration application, resulting in an overall compact system. The inverter consists of a lower number of power electronic components and capacitors. The cost of each switch and diode is lower as the devices' standing voltages (SV) are only half of the output voltage. Due to its voltage-boosting capabilities, this inverter is a strong contender for transformer-less grid-connected PV systems. A closed-loop dq current control and DC-link voltage control are adopted to manage the active power supplied to the grid and balance the DC-link voltage. A near-sinusoidal output voltage with higher voltage levels is obtained owing to increased efficiency and lower harmonics. Furthermore, the filter size becomes smaller even at a much lower switching frequency. Experimental results for both RL-load and grid-connected modes are presented and analyzed.