Novel PWM Technique for Quasi Switched Boost Converter for the Nano-grid Applications

Abstract

Scaled down version of the Micro grid is nanogrid, where each residential home, commercial building etc. are optimized and power is shared between the Battery Energy Storage (BES) and the utility grid. The recently proposed impedance source converters (ISC) are attractive solution for the nanogrid applications. Among them Conventional Simple Boost Converter (SBC) is a good choice. Here, a novel quasi Switched Boost converter (qSBC) is proposed. With the proposed structure, high gain from the DC-AC for multiple input (Photovoltaic (PV) and BES) and multiple output (BES and AC gird) is obtained. This paper proposes new Pulse Width Modulation (PWM) control strategy to increase the gain and the modulation index. The benefits of the proposed circuit include: 1) High modulation index during DC - AC conversion, 2) Significantly reduced voltage stresses across the components 3) Continuous input current from PV panel 4) Reduced inductor current ripple 5) Low shoot-through current and 6) high efficiency. All the operating modes and circuit analysis for the proposed converter are investigated in detail. Mathematical modeling of the proposed circuit is carried out in MATLAB/Simulink® and obtained results are discussed. Experimental prototype for 500W, 240V/50Hz output voltage is developed to validate the proposed converter with the developed PWM control algorithm. Hardware results obtained validates the performance and advantages of the proposed circuit and associated modulation method.