An electro-mechanical braking energy recovery system based on coil springs for energy saving applications in electric vehicles

Regenerative braking system is a promising energy recovery mechanism to achieve energy saving in EVs (electric vehicles). This paper focuses on a novel mechanical and electrical dual-pathway braking energy recovery system (BERS) based on coil springs for energy saving applications in EVs. With the aims of maximizing energy recovery efficiency, mechanical and electrical recovery strategies are respectively employed under two different brake situations of inching braking and emergency braking. This system mainly consists of three parts, including the mechanical module, electrical module and control module. The mechanical module utilizes coil springs to store the kinetic energy in the form of elastic potential energy which can be utilized to provide a part of the starting torque for EVs. The electrical module enables recovery of the braking energy into the vehicle battery. The control module controls the mechanical module and the electrical module to work coordinately to select an appropriate energy recovery pathway under different braking modes. A full-size prototype, manufactured and based on this design, is introduced. Simulations and experiments of the proposed regenerative braking system are conducted to verify the system. Auxiliary starting torque of 12.7 N m, maximum voltage of 3.5 V and total energy recovery efficiencies of 0.53 can be obtained, verifying that the proposed braking energy recovery system is effective and beneficial for vehicle energy savings.