Energy Reports (Nov 2022)
Design and application of electromechanical flywheel hybrid device for electric vehicle
Abstract
The electromechanical flywheel hybrid power device has the dual attributes of energy supply and power output, which can provide more design space for the optimization of vehicle energy utilization efficiency. It involves two key problems of device parameters design and energy management. Therefore, the optimization design of electromechanical flywheel device’s parameters and the energy management strategy are the main research objects in this paper. Firstly, based on the working principle of planetary gear mechanism, the dynamic characteristics of electromechanical flywheel device under different topological structure schemes are analyzed, and the design schemes of speed regulating motor connecting to the sun gear, flywheel connecting to the ring gear and output end connecting to the planet carrier are determined. Then, according to the dynamic characteristics of the vehicle, the parameters of flywheel, speed regulating motor and planetary gear mechanism were designed. Furthermore, considering the state of energy (SOE) of the electromechanical flywheel device, 15 working modes of the vehicle were designed, and the corresponding energy management strategies were proposed. Finally, a vehicle test platform was constructed to analyze the dynamic and economic performances of the electromechanical flywheel hybrid electric vehicle. Results show that, compared with the original vehicle driven by a single motor of the front axle, owing to the power intervention of the electromechanical flywheel hybrid device, the average acceleration from 0 km/h to 100 km/h is increased by 22.32% and the acceleration time is reduced by 18.25%, which effectively improves the vehicle dynamic performance. Moreover, the new hybrid system designed is conducive to the miniaturization design of the drive motor, increasing the load rate of the motor and improving the efficiency of powertrain system. With the advantage of short-term energy supply of electromechanical flywheel, the average discharge current of lithium battery can be reduced to improve its efficiency. Under J1015, NEDC and HWFET cycles, the average operating efficiencies of the powertrain system are increased by 8.2%, 5.6% and 4.3% respectively; the efficiency improvements of lithium battery also reach 6.7%, 4.2% and 4.1% respectively. The research of this paper is devoted to applying electromechanical flywheel to electric vehicles to help improve the performance of vehicles and promoting the development of hybrid electric vehicles in the future.
