Evaluation and Improvement of Backup Capacity for Household Electric Vehicle Uninterruptible Power Supply (EV-UPS) Systems

Abstract

The use of electric vehicles (EVs) for household uninterruptible power supplies (UPSs), particularly in rural areas, can greatly improve household power reliability. However, because EVs are mobile, the evaluation of backup capacity for EV-UPS systems is completely different when compared to traditional UPSs. As a result, the focus of this paper is on the evaluation and improvement of backup capacity for EV-UPS systems. The architectures for EV-UPS systems are presented first. The methodology for calculating backup capacity for EV-UPS systems is then presented, followed by four detailed cases based on different grid failure times. Furthermore, the impact of system operating parameters on backup capacity, such as different load power, EV mobility pattern parameters, and grid outage durations, is investigated. The results of backup capacity in cases of different operating parameters are detailed using an EV mobility model. An improved strategy for increasing backup capacity is proposed, in which more backup energy can be released during a power outage. Meanwhile, the next trip requirement is unaffected. The backup capacity with the improved strategy is then calculated and compared to the results with the traditional strategy. Finally, a 5 kW EV-UPS experimental platform is constructed, and the experimental results are presented to validate the proposed method.