Mohamed Osama

Segmented permanent magnet synchronous machines for wind energy conversion system

Direct-drive generators are appealing candidates for some wind energy conversion systems (WECS) since they provide a means of eliminating the gearbox from the drivetrain. However, a fundamental problem associated with these machines is their large size that makes them difficult to manufacture, transport, and assemble. This paper introduces the concept of segmented permanent magnet (PM) synchronous machines with both single and dual stator/rotor layers that feature a modular structure which makes them appealing candidates for use in direct-drive wind generators. To form a multi-phase machine, a spatial phase-shifting iron piece is inserted between adjacent segments to maintain the appropriate spatial positioning between phases. The segmentation strategy for this type of machine is discussed, considering the trade-offs between average torque production and torque ripple. A nine-phase segmented PM synchronous machine configuration is proposed for reducing torque ripple and improving fault-tolerance capabilities. The performance characteristics of this segmented machine configuration are evaluated using finite element (FE) analysis.

High specific power electrical machines: A system perspective

There has been a growing need for high specific power electrical machines for a wide range of applications. These include hybrid/electric traction applications, aerospace applications and Oil and Gas applications. A lot of work has been done to accomplish significantly higher specific power electrical machines especially for aerospace applications. Several machine topologies as well as thermal management schemes have been proposed. Even though there has been a few publications that provided an overview of high-speed and high specific power electrical machines [1-3], the goal of this paper is to provide a more comprehensive review of high specific power electrical machines with special focus on machines that have been built and tested and are considered the leading candidates defining the state-of-the art. Another key objective of this paper is to highlight the key “system-level” tradeoffs involved in pushing electrical machines to higher specific power. Focusing solely on the machine specific power can lead to a sub-optimal solution at the system-level.

Motor/generator controller design for the COMET flywheel

This work describes the process of designing and implementing a controller for a permanent magnet synchronous motor/generator to be used to demonstrate the momentum and energy transfer capabilities of a new flywheel system. Selection of the motor/generator controller algorithm and architecture is discussed. Typical real-time system, hardware, and software design considerations are also presented.