An Integrated High Speed Flywheel Energy Storage System for Peak Power Transfer in Electrical Vehicles

Abstract

<p>An investigation is conducted into the practical electric vehicle implementation of a high speed flywheel energy storage system that can supply and accept peak acceleration and braking power. Electric vehicle battery life cycle can be extended considerably by supplying peak energy requirements from a secondary source. Simulations are performed to determine the peak power and energy requirements over the SAE recommended electric vehicle test procedure. A scaled prototype secondary energy storage unit is built using flywheel energy storage. Tests are conducted to determine the energy transfer capabilities of a flywheel couples high speed permanent magnet synchronous machine through the proposed system's energy storage tank. Results are presented that indicate the necessity of the energy storage tank. A system evaluation is also included which indicates its near-term practically when compared to conventional regenerative control applications. Construction techniques are discussed for the development of high speed drive circuits used in electrically noisy environments. Shielding and electromagnetic interference reduction methods are proposed for application to an actual high efficiency sinusoidal phase current, microprocessor interfaced, vector controlled, high speed permanent magnet synchronous machine drive. A discussion on the theory and construction of such a drive is provided to demonstrate the implementation of a laboratory prototype high speed flywheel energy storage system. An experimental investigation is conducted using the developed high speed drive to determine permanent magnet synchronous machine parameter behaviour in the high speed flux weakening operating range. Special computer assisted measuring techniques are used to determine the realtime operating characteristics for two commercially available machines. The repeatable experimental results show a significant variation in the machine parameters as a function of the speed and torque angle. Implications of the newly identified dynamic parameters are discussed regarding their application to, and effect on, high performance permanent magnet synchronous machine torque control.</p>