An Electric Vehicle Onboard Microgrid with Solar Panel for Battery Module Balancing and Vehicle-to-Grid Applications

This article proposes an electric vehicle (EV) onboard microgrid for battery module balancing and vehicle-to-grid (V2G) applications. The proposed microgrid is formed by an onboard photovoltaic (PV) system, a bidirectional charger, an auxiliary power module (APM), and selection switches. The system is designed to use solar energy if available for battery balancing by supporting the battery modules with low state-of-charge (SOC) during driving or charging. During charging, when the battery pack is fully charged, the PV system is disconnected from the battery and delivers the solar power to the grid. When the number of these PV-assisted EVs is big enough, they can work together as an aggregated virtual solar farm with energy storage. When there is no solar energy available, the battery management system is able to use the APM for battery management. Simulation-based case studies with recorded solar irradiance data in Detroit, Michigan, show that the virtual solar farm with 10,000 EVs can generate 0.7 MW peak power and 2,953 kWh energy on a sunny winter day, and 1 MW peak power and 5,190 kWh energy on a sunny summer day. The actual experiments verify that the proposed system can perform the designed functions and automatically switch among the required operating modes.