Prototype production and comparative analysis of high-speed flywheel energy storage systems during regenerative braking in hybrid and electric vehicles

In conventional EVs and HEVs, only a small part of the vehicle's kinetic energy can be usefully stored during deceleration. Generally, this storage process can be done by providing energy flow to the main battery of the vehicle. Since batteries work with a chemical reaction, they are not suitable for fast charging and discharging required for regenerative braking. In this case, a fast storage system is needed to store the regenerative braking energy in a short time. As a solution, the flywheel energy storage system (FESS) can be offered. In the literature, power transmission of vehicles with integrated FESS is provided by mechanical systems (CVT FESS). These systems are heavy, high cost, large volume, and occupy the rear axle of the vehicle. In the proposed system, a purely electrical power transmission is proposed to store the kinetic energy of the vehicle in FESS. In developed topology, the traction machine of the vehicle is also used as a generator, and the recuperation energy is stored in the electrically driven (M/G) FESS. As a result of the experimental studies, a minimum of 56% energy recovery efficiency was obtained. In addition, it has been shown that the developed system is 30% lighter, occupies 60% less space in volume, is at least 50% more cost-effective, maintenance-free, and has fewer moving parts compared to the CVT FESS. As a result, the addition of a fast-response secondary energy storage system to the electric vehicle battery contributes to the increase in efficiency.