Design and Simulation of a Regenerative Braking System for Small Electric Vehicles;

Abstract

Small electric vehicles (SEVs), such as e-scooters and e-bikes, are becoming increasingly important for sustainable urban transport. However, their limited battery capacity significantly constrains range and usability, particularly in cities like Ulaanbaatar, where cold weather and limited charging infrastructure further exacerbate these issues. This thesis investigates the design, simulation, and prototype testing of a regenerative braking system (RBS) specifically tailored for lightweight SEVs, with the goal of improving energy efficiency through kinetic energy recovery during deceleration. The research begins with an exploration of the historical development and theoretical principles behind regenerative braking, including electromagnetic induction, Lenz’s Law, and energy conservation. A simulation model was developed in MATLAB/Simulink to replicate a realistic SEV drivetrain using a 12V brushed DC motor, an H-bridge inverter, a lithium-ion battery, and a control logic system for modulating torque. Simulations were performed under both regenerative and non-regenerative scenarios. The results showed that when braking was applied, the system recovered approximately 4.48 joules of energy from 38.87 joules consumed, achieving an energy recovery efficiency of 11.52%. In contrast, the coasting scenario confirmed zero energy recovery, highlighting the effectiveness of controlled regenerative braking. To validate the simulation, a hardware prototype was built using an Arduino Uno, L298N motor driver, ACS712 (1) current sensor, and a 14.8V 2800mAh battery pack. The prototype ran a similar 10-second drive-brake cycle, with real-time current and power readings collected to calculate energy use and recovery. While the simulation demonstrated ideal regenerative behavior, the physical system was limited by the L298N’s unidirectional current flow allows only dynamic braking but not true regeneration. Nevertheless, the prototype showed measurable reverse current during braking and achieved a recovery efficiency of 8.76%, confirming the system’s potential with improved hardware. This work concludes that regenerative braking can offer tangible energy savings in SEVs and provides a foundational model for implementing RBS in low-cost, micro-mobility systems. Future improvements, such as upgrading the motor driver to a bidirectional one regenerative controller and integrating supercapacitor storage, are recommended to maximize energy recovery and system performance.