The development and implementation of an advanced power electronics converter and electric machine control technology for flywheel energy storage system applications

The development and use of flywheels as mechanical energy storage devices date back several hundred years and the associated technology was developed throughout the Industrial Revolution. Modern flywheel energy storage devices or Electromechanical Batteries are gaining extensive development attention because of their promising perspective applications in power conditioning, transportation, space exploration, etc. Microelectronics, magnetic bearing suspension and high power density, highly reliable electronics power conversion are among the enabling technologies for the recent development of modern flywheel energy storage systems. Significant challenges exist in high-speed electric machine control and reliable electronics power conversion.; This research dissertation focuses on such aspects of electric machine control and electronics power conversion technology as applied to flywheel energy storage systems. Specifically, this dissertation deals with the following two important issues:; 1. Optimal DC bus utilization for fast response peak power delivering. An investigation of the minimum-time current transition problem reveals that, with the inverters under the hexagonal voltage constraint, the time-optimal current transition is achieved by an inverter switching scheme patch, which takes the minimum number of power device switchings, to the regular PWM modulation operation in the dynamic process. Simulations are performed to investigate the details of its applications and practical implementations.; 2. Fault tolerant capability development for the electronics power converters. A fault tolerant modulation of three-level neutral point clamped inverters is proposed in this research to enhance system reliability and fulfill the critical safety requirement to the electronics power converters. A three-level inverter rated at 150kW has been constructed in the Power Electronics and Electric Machine Laboratory (PEEM) at The Ohio State University. A DSP based microcontroller which incorporates the proposed fault tolerant technology has been prototyped. Experimental investigation of the fault tolerant modulation is successfully conducted via a low voltage laboratory test setup.