Regenerative Braking for EVs Using a Brushless DC Motor and Multi-Level Bidirectional Traction Converter

Brushless DC (BLDC) motors stand out as a preferred choice for electric vehicles (EVs) due to their high efficiency, precise speed control, and impressive torque-to-weight ratio. Regenerative braking, which recovers kinetic energy during deceleration, is crucial for enhancing EVs’ driving range. This paper explores the development of a regenerative braking strategy for BLDC motors in EV applications. To establish the foundation for this strategy, a thorough examination of the dynamic model governing BLDC motors is conducted. The proposed regenerative braking strategy relies on accurately estimating the torque on the drive shaft by assessing various forces acting on an EV along an inclined road. A modular multilevel converter (MMC) equipped with two-stage isolated bidirectional SEPIC-full-bridge submodules (SMs) is used to manage power flow efficiently. Moreover, three-level space vector pulse width modulation (SVPWM) is implemented to increase the modulation index and reduce output total harmonic distortion (THD). The efficacy of the proposed regenerative braking strategy is validated by simulations across acceleration, constant speed, and deceleration modes.