Control of linear electrical generators for direct drive wave energy converters
This project aims to develop control strategies for optimising the energy absorbed from a wave energy device, such as heaving buoy, using a directly coupled linear electrical generator.
The energy captured by a wave energy device is a function of the frequency of the incoming waves and their amplitude. Maximum energy is captured when the incoming wave frequency matches the resonant frequency of the device, but this condition can never be guaranteed. Waves are random, and hence some form of control is required to optimise the energy captured. Phase control ensures the wave excitation force and the velocity are in phase, which is always the case at resonance. This is achieved at off resonant frequencies by applying an additional spring force by mechanical means. However, in a previous project it has been shown by simulation that a directly coupled linear electrical generator can be used to provide this additional spring force.
The aim of this project is to develop control strategies for direct phase and amplitude control using a linear electrical generator. An electromechanical test rig for emulating wave energy devices has been installed in the machines lab at Edinburgh so that the system can be demonstrated.
Power conversion and control for lightweight PM generators for wind turbines
In direct drive wind turbines the electrical generator is directly coupled to the slow moving prime mover, which rotates. It has been convention to use iron-cored machines, that is a machine have iron on both the stationary and moving parts, but the magnetic field between the two results in a large undesirable magnetic attraction force, which requires a significant mechanical structure to maintain the physical air gap between the two. Removal of the iron from one component eliminates the magnetic attraction force completely. Such machines are termed "air-cored".
In this project the main objective is to demonstrate a novel form of air-cored permanent magnet machine integrated in a commercially available small-scale wind turbine. A prototype machine will be designed and built to demonstrate the concept: a 15kW, 150rpm rotary machine. The prototype will initially be tested at the University of Edinburgh and subsequently transported to a wind turbine test site for field testing.
This project is funded by Scottish Enterprise PRP grant.
Fault tolerant control of power take-off systems for marine energy devices
For offshore marine energy converters, maintenance is regarded as a key issue which directly affects the overall performance of a device or a group of devices. It is well-known that component failure results in significant downtime and poses the risk of damage to other components. Hence minimising failure occurences is crucial for effective maintenance.
An initial study suggests that the time-to-failure of certain components within a marine energy conversion system can be extended by controlling the device to operate under different conditions. Previous work has shown that device control is possible through intelligent control of the power conversion stage.
This project looks at methodologies for component failure prevention and aims to develop control algorithms that will extend component time-to-failure.
The project will also analyse the effect that controlling for failure prevention has on the energy conversion system has a whole in order to optimise the overall performance.