Design and implementation of a grid-tied emergency back-up power supply for medium power applications

Dhiman Chowdhury, Mohammad Sharif Miah, Md. Feroz Hossain, Uzzal Sarker


This paper presents a design of a grid-tied emergency back-up power supply for medium power applications. There are a rectifier-link boost derived battery charging circuit and a 4-switch push-pull power inverter circuit, which are controlled by pulse width modulation (PWM) signals. A changeover relay based transfer switch controls the power flow towards the utility loads. During off-grid situations, loads are fed power by the proposed inverter circuit and during on-grid situations, battery is charged by an ac-link rectifier-fed boost converter. There is a relay switching circuit to control the charging phenomenon of the battery. However, a laboratory prototype of the design is developed and tested for different loads. Load voltage waveforms, back-up times, sending-end power factor, total harmonic distortion (THD) values of mains current and inverter output quantities are evaluated experimentally. In addition, a cost allocation affirms the economic feasibility of the proposed framework in case of reasonable consumer applications. The test-bed results corroborate the reliability of the system.


Back-up power supply; Boost converter; Changeover relay; IPS; Push-pull inverter; UPS

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ISSN 2088-8708, e-ISSN 2722-2578