Overview of supercapacitor voltage equalisation circuits for an electric vehicle charging application

The ability to rapidly charge an electric vehicle is limited by the power available at the charging location. In a domestic charging application the power available is limited by the utility supply to the household. One method of increasing the available power without substantial alteration of the domestic wiring scheme is to use a bank of supercapacitors - ‘trickle charged’ whilst the vehicle is not charging - to provide a power boost at the time of charging. Boosting the available power reduces the charge time for the vehicle. Supercapacitor technology requires that series connected banks of supercapacitors be coupled with a voltage equalisation scheme to avoid cell over-voltage and increase storage efficiency. Presented is an evaluation of relevant existing cell voltage balancing solutions from literature with analytical and simulation analysis. This work is the first time these converters have been evaluated against each other using cell models derived from actual supercapacitor cells.