Matthew Senesky

An integrated flywheel energy storage system with homopolar inductor motor/generator and high-frequency drive

The design, construction, and test of an integrated flywheel energy storage system with a homopolar inductor motor/generator and high-frequency drive is presented in this paper. The work is presented as an integrated design of flywheel system, motor, drive, and controller. The motor design features low rotor losses, a slotless stator, construction from robust and low cost materials, and a rotor that also serves as the energy storage rotor for the flywheel system. A high-frequency six-step drive scheme is used in place of pulsewidth modulation because of the high electrical frequencies. A speed-sensorless controller that works without state estimation is also described. A prototype of the flywheel system has been demonstrated at a power level of 9.4 kW, with an average system efficiency of 83% over a 30000-60000 r/min speed range.

Hybrid modelling and control of power electronics

Switched circuits in power electronics by their nature present hybrid behavior. Such circuits can be described by a set of discrete states with associated continuous dynamics. A control objective, usually regulation of the output in the face of disturbances in the continuous system, is accomplished by choosing among discrete states. We describe a hybrid systems perspective of several common tasks in the design and analysis of power electronics. A DC-DC boost converter circuit is presented as an illustrative example, and the extension of this circuit to a multiple output configuration is provided to show the favorable scaling properties and broad utility of the hybrid approach.

A synchronous homopolar machine for high-speed applications

The design, construction, and test of a high-speed synchronous homopolar motor/alternator, and its associated high efficiency six-step inverter drive for a flywheel energy storage system are presented in this paper. The work is presented as an integrated design of motor, drive, and controller. The performance goal is for power output of 30 kW at speeds from 50 kRPM to 100 kRPM. The machine features low rotor losses, high efficiency, construction from robust and low cost materials, and a rotor that also serves as the energy storage rotor for the flywheel system. The six-step inverter drive strategy maximizes inverter efficiency, and the sensorless controller works without position or flux estimation. A prototype of the flywheel system has been constructed, and experimental results for the system are presented.

Simplified modelling and control of a synchronous machine with variable-speed six-step drive

We report on simple and intuitive techniques for the modelling of synchronous machines and their associated control systems. A scheme for control of electrical power flow is proposed for machines with variable-speed six-step drive. The scheme is developed with an eye toward efficient system operation, simple implementation, low latency in the control path and minimized cost of power electronics. Experimental results are presented for application of the control scheme to a homopolar inductor motor, as used in a flywheel energy storage system.

A millimeter-scale electric generator

The research presented in this paper concerns the design, construction and testing of an electrical generator intended for interface with a MEMS internal combustion (IC) Wankel engine. The engine and generator are integrated into a single unit by utilizing the engine rotor as the generator rotor. The design allows for thermal insulation between the stator and combustion chamber, simple assembly of the engine and generator and excellent utilization of copper in the generator winding. The majority of the generator structure is built from discrete millimeter-scale components, with only the rotor being microfabricated. Prototype construction and testing are described; a peak open-circuit voltage of 2.63 V and a maximum power output of 375 /spl mu/W at 133 kRPM are reported.