Dhiman Chowdhury
University of South Carolina

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Implementation of a grid-tied emergency back-up power supply for medium and low power application Dhiman Chowdhury; Mohammad Sharif Miah; Md. Feroz Hossain; Uzzal Sarker
International Journal of Electrical and Computer Engineering (IJECE) Vol 10, No 6: December 2020
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v10i6.pp6233-6243

Abstract

Emergency back-up power supply units are necessary in case of grid power shortage, considerably poor regulation and costly establishment of a power system facility. In this regard, power electronic converters based systems emerge as consistent, = properly controlled and inexpensive electrical energy providers. This paper presents an implemented design of a grid-tied emergency back-up power supply for medium and low power applications. There are a rectifier-link boost derived DC-DC battery charging circuit and a 4-switch push-pull power inverter (DC-AC) 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 system and during on-grid situations, battery is charged by an AC-link rectifier-fed boost converter. Charging phenomenon of the battery is controlled by a relay switched protection circuit. Laboratory experiments are carried out extensively for different loads. Power quality assessments along with back-up durations are recorded and analyzed. 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 research work.
Inverse sinusoidal pulse width modulation switched electric vehicles’ battery charger Saurav Das; Khosru M. Salim; Dhiman Chowdhury; Mohammed Mahedi Hasan
International Journal of Electrical and Computer Engineering (IJECE) Vol 9, No 5: October 2019
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (490.002 KB) | DOI: 10.11591/ijece.v9i5.pp3344-3358

Abstract

This paper documents an efficient, cost-effective and sustainable grid-connected electric vehicles (EVs) battery charger based on a buck converter to reduce the harmonics injected into the mains power line. To utilize the switching converter as an effective power factor controller (PFC), inverse sinusoidal pulse width modulation (ISPWM) signals have been applied. A mathematical relationship between the sending-end power factor and the duty ratio of the switching converter has been presented. To ensure the sustenance of the proposed method, a simulation model of the proposed battery charging system has been tested on PSIM simulation platform. The simulation results yield to a lossless charging system with a sending-end power factor close to unity. An experimental testbed comprising a 60 V battery bank of 100 A-h capacity with a charging current of 7 A has been generated. The laboratory assessments present an 88.1% efficient charging prototype with a resultant sending-end power factor of 0.89. The laboratory framework concerns with the comparative analysis of the power efficiency, sending-end power factor and lines current total harmonic distortion (THD) values obtained for different charging methods and the evaluations corroborate the reliability of the proposed work.