A Novel Step-Up Multilevel Inverter Based On Switched-Capacitor Technique For Renewable Energy Conversion System

Abstract

In this paper, a novel step-up multilevel inverter structure has been proposed. The structure uses switched-capacitor technique to boost the output voltage at the desired voltage level from small power supplies such as solar PV arrays. The structure can produce 13 output voltage level by using 10 unidirectional switches, 1 bidirectional switch, 2 capacitors, 2 diodes and 2 symmetric non-isolated power supplies $(V_{dc},~V_{dc})$. The capacitors utilized in the structure can be charged to $V_{dc}$ and $3V_{dc}$ voltage levels by using simple switching strategy. The structure does not require any balancing circuit or complex control algorithm to balance the capacitor voltages. Hence, the structure has self-voltage boosting capability and self-capacitor voltage balancing ability. The detailed operating principle of the structure is discussed in this paper. Further, two modulation strategies namely low switching frequency and high switching frequency modulation strategies have been used for switching the proposed structure. An extensive comparison study between the proposed structure and the recently developed switched capacitor multilevel inverter structures shows that the proposed structure requires lower components to achieve the specified output voltage level. Further, the cost per voltage level for all the topologies has been compared using a cost function. It has been observed that the proposed structure is more cost effective as compared to other structures. The effectiveness and merits of the proposed 13-level inverter have been verified by an extensive simulation study of the proposed structure in MATLAB/Simulink platform.