A Resilient Temperature Suppressed Optimal Charging Strategy for Ultracapacitors to Attain Desired State of Charge

Ultracapacitors used for energy storage in energy management applications like electric vehicles undergo numerous charge-discharge cycles. This demands an optimal charging profile for proper SOC regulation in accordance with to drive profile. An optimal charging mechanism aiming at the attainment of desired SOC only may suffer from serious thermal effects, and hence reduced ultracapacitor life. Increased longetivity, efficient utilization of the storage capacity and reduced thermal distress demand simultaneous SOC attainment and temperature regulation. In this regard, a temperature suppressed optimal charging profile has been proposed for attaining the twin objectives of SOC attainment within a pre-specific period and avoiding thermal distress. A thermal model developed for temperature estimation ensures online monitoring and avoiding any possibility of thermal runaway by correlating the ultracapacitor core temperature with the charging current. The temperature suppressed charging current profile derived using the proposed scheme has been extensively validated using experimental and simulation results in terms of maintaining temperature-suppressed charging for SOC attainment.