A sensorless electric motor drive is the popular term for drives which do not use shaft mounted speed or position sensors. Sensorless operation is highly desirable for reasons of cost, simplicity and system integrity. However, it is well known that there are serious problems with sensorless motor drive control at zero and low speeds and this has been one of the main research topics in this field for many years. The conventional method for sensorless control, used in commercial products, is to estimate the machine flux and speed using a mathematical model of the motor. Below 1 to 2% base speed however, position and speed estimation using such a model deteriorates and speed and torque control is lost. There has been a recent impetus for zero speed sensorless drives for more-electric aircraft and vehicular applications. For the former, there is a requirement for direct electromechanical (EM) actuation of critical actuators in which locking of the mechanical transmission is not permissible. In the vehicular field direct EM drives will be required for the main drive train, and for power steering, active suspension and braking actuation. One approach to the solution of the zero speed problem, which does not require a machine model, has been to exploit the natural asymmetries or saliencies in AC machines. These saliencies are cause by magnetic flux saturation and the geometry of the construction of the motor itself. Flux or rotor position can then be tracked by processing the current response to a test voltage signal injection overlaid on the supplied motor voltage. These signal injection methods are now quite well understood, but do contribute to increased accoustic noise, reduced efficiency, the requirement for additional sensors, and an increase in bearing wear and electrical stress within the machine windings.The current proposal aims to overcome the above disadvantages by developing methodologies by which:1) No signal injection is required, the method being integrated with the fundamental voltage applied to the drive via the power converter. This eliminates the problems of extra noise, losses, bearing wear and electrical stresses.2) The requirements for sensors is substantially reduced (depending on the application). For bespoke applications (e.g. aerospace, automotive), the aim will be for one current sensor and one low cost di/dt sensor. For industrial standard drives the target aim is to use only the existing line current sensors. These aims are quite challenging. Mathematical feasibility of a non-signal injection method has been shown at Nottingham and the technique is currently subject to patent at the University. Practical investigation is now possible owing to advances in high-accuracy timing and sampling available in low-cost digital control systems.

Tribology is an essential technology for nearly all UK Industry, including defence, and impacts on energy efficiency, carbon and other emissions, machine life, engine design, maintenance schedules and machine downtime, and the recovery and processing of oil reserves. It is also critical to the long term mobility, health and quality of life of patients with damaged or replacement joints. The Centre for Advanced Tribology at Southampton (CATS) will use the 3.05M S & I grant plus 6.2M gearing from the University and Industry to recruit young staff from a variety of strategic disciplines to create an internationally leading research centre. This will conduct research into areas of major national importance such as future machines of all scales, energy efficiency, emissions and human health. The key role of the new staff will be to link with 18 academics in the School of Engineering Sciences and to 18 academics in six other Schools/Centres within the University of Southampton. The other Schools participating will be those of Electronics and Computer Science, Biological Sciences, Medicine, Mathematics, Statistics and Chemistry, thus creating a truly multidisciplinary Centre. This will be the first large interdisciplinary centre specifically focused on Tribology in the UK. CATS will uniquely address the combination of multiscale modelling, analytical and experimental techniques to develop a better understanding of tribological processes at the molecular, nano and micro scales. This understanding will be used in the development of micro-systems as well as predictive models concerned with macro contact performance. It will also address the interactions of biology and tribology, critically, by coupled modelling-experimental approaches to the nature of solid/liquid and cell-surface interfaces in biotribological and biological processes. CATS will have a distinctive platform by accessing the world class facilities and expertise at Southampton in high performance computing (Microsoft Institute of High Performance Computing), microfabrication and MEMS (new 60M clean room complex), advanced surface science, Developmental Sciences incorporating the Centre for Human Development, Stem Cells and Regeneration in the School of Medicine as well as researchers in electrochemistry and biological sciences. CATS would use these resources for innovative modelling, applying novel solutions to MEMS, developing MEMS as sensors and novel probes for tribological processes, surface film characterisation by scanning probes. It would also deploy advanced electrochemical techniques to understand the human biological reactions to metal ion release and the surface-biotribology performance of joint implants. CATS will also aim to use collaborations with over twenty industrial partners with major tribological activities (such as Airbus, DePuy, Shell, Lloyd's Register, Dstl, NPL and Schlumberger) to ensure that the research footprint of the centre is aligned with industrial need, research can be exploited efficiently and to ensure effective national technology transfer of the knowledge generated by the centre.