Method for Estimating the Efficiency of Energy Recycling for Electric Transport Equipped with Mobile Supercapacitor Storage System

This paper describes a method for estimating the efficiency of traction drive braking energy recycling. The recycling process of public electric transport braking or regenerated energy includes its storage in supercapacitors during braking mode and its discharge from supercapacitors during acceleration mode. Although the charge current of the supercapacitor circuit is variable, the proposed method shows how the average value of current throughout the entire process of charging can be used to simplify energy efficiency calculation. The paper shows that a similar approach can be used for discharging. The calculation considers losses in the traction inverter and DC/DC converter and also losses due to the internal resistance of supercapacitors. The method provides comparable results for a wide range of cases without performing time-consuming simulations.