Development of a hybrid flywheel/battery drive system for electric vehicle applications

Today's electric vehicles are severely limited in multistop and go driving range and accelerating capability by the lead acid battery's inability to handle high power peaks while maintaining maximum energy storage capability. A hybrid flywheel/battery system can be used to isolate the battery from the accelerating power peaks, and should recover a substantial part of the braking energy. This paper describes the development of a small, high speed, lightweight flywheel/ ac synchronous motor alternator sealed energy storage package coupled into the battery and dc drive motor system through a simple rectifier/inverter power circuit. This system stores just enough energy in the rotor of the machine for one start-stop cycle. Provision is made to add a flywheel to store energy for several cycles, or enough energy for climbing or descending long grades. The fields of the two machines are electronically controlled to achieve optimum performance and effective energy utilization.