| This thesis presents the design, construction, and test of a high-speed integrated flywheel energy storage system. This flywheel system integrates a homopolar inductor motor/alternator and a steel energy storage rotor to achieve high power density energy storage using low-cost materials. A six-step inverter drive strategy that minimizes inverter VA-rating and enables high frequency operation is also implemented.; Lumped parameter design equations are developed, and used to optimize the flywheel system. Analytical expressions for rotor and stator losses from harmonics in the six-step drive are also developed.; A prototype flywheel energy storage was built. A novel method for constructing the slotless stator was developed and implemented. The prototype flywheel was designed for 30kW of power, 140W · hr of energy storage, and an operating speed range of 50,000 rpm--100,000rpm.; Experiments were conducted for speeds up to 60,000rpm and power levels up to 10kW. System efficiencies of 83%, which includes losses in the power electronics and the motor, were achieved. Most experimental results were in line with designed values. Experimental measurements of the harmonic losses showed very good agreement with the analytical calculations, and demonstrated that low rotor losses had been achieved. |
