Hybrid battery-supercapacitor energy storage system for micromobile electric vehicles

Abstract

The study proves the importance of hybridising the power supply system of micromobile electric vehicles, taking into account the strict limitations on the final size and weight of the storage device, using the example of an electric bicycle. The authors offer a brief overview of the main hybridization topologies and analyze the advantages and disadvantages of each of them. The paper describes the possibilities of using supercapacitors as an additional source of energy for a hybrid system and proposes a way to deal with the disadvantages of using standard batteries by combining them with an additional energy source. A mathematical basis is given to such a solution being able to unload the main power source by drawing excessive current at peak consumption times, thereby providing a wider range of operating voltages compared to using only a standard power source. To ensure optimal weight and size parameters of the drive, an active system with a controlled auxiliary power source is chosen. In this topology, the second converter is installed between the additional energy source, the supercapacitor storage device, and the battery. It is proposed to implement the schematic of this converter using a Chuck converter with an automated control system containing a feedback loop and based on a microcontroller, which ensures a relatively quick change of the control algorithm depending on the configuration and requirements for the system. The paper also presents the algorithm of the storage system operation for possible modes of electric bicycle operation. The transfer characteristic is calculated using the averaged state method. To confirm the operability of the auxiliary power source, a converter circuit is developed and simulation modelling is carried out in MATLAB Simulink. The system simulation allowed assessing the nature of the transient processes of the open-loop system and the accuracy of the transfer characteristic calculation.