Self-Excited, Electromagnetic Braking and Heating System for Electric Buses

New energy vehicles usually recover the braking energy and store it back into the battery using the electric motor. Such a regenerative braking system improves the vehicle mileage. In the process of regenerative braking, all components of the system dissipate a great amount of energy, especially in winter. On the other hand, heating the vehicle's cabin consumes electric energy, further reducing its autonomy. Based on this, we propose a novel Self-excited, electromagnetic Braking and Heating System (SBHS), to solve problem of the driving range dramatic decline of electric bus when heating the bus cabin in winter. The system converts the kinetic energy of the electric bus into heat, via electromagnetic braking, and uses it to warm the vehicle's cabin in winter. Our system improves the conversion efficiency of regenerative braking. We present the structure of the system and calculate the air gap magnetic density using the magnetic circuit method. We develop the braking heat generation model and obtain the heat generation performance at different speeds using J-MAG. To improve the braking energy utilization efficiency, we design a braking force distribution strategy based on a fuzzy control system. We also characterize the braking and built-in generator performances in a test bench, and obtain the braking and heating characteristic at different speeds. We implemented our EBHS and installed on a test electric bus. The test records include SOC, temperature inside the vehicle and distance. The results show that the SBHS can provide both sufficient braking torque for the vehicle and heat energy for the cabin.