A Novel Switched Reluctance Motor for Industrial and Commercial Applications

Switched reluctance motors offer many benefits such as simplicity of construction, low costs, fault-tolerance and a high torque to inertia ratio. They also have no reliance on rare earth metals and therefore have no demagnetisation temperature limitation. These benefits have made switched reluctance motors an attractive contender for use in a plethora of applications. These benefits however have been hindered by problems such as noise, torque ripple and lower torque density. It is only in recent times that reluctance machines can begin to compete with existing motor technologies through the use of new machine topologies. With advanced machine design and the holistic development of power electronics and microprocessor control methods, the advantages of these motors are brought to the fore. In recent years, field oriented control has been implemented on stepper motor drives in order to achieve servo-like performance. This performance can be achieved at a fraction of the cost of a traditional permanent magnet synchronous servo system. While this is suitable for small size motors, larger size stepper motors with a high output power, large speed range and low cogging torque do not exist. A class of motors with these characteristics is needed to provide a low cost alternative to costly torque motors and to allow machine designers to reap the benefits of direct drive systems. Direct drive motors offer many advantages and allow a gearbox or other speed reduction measures to be eliminated. Such advantages include the lowering of the system cost, design simplification, higher reliability and lower maintenance. In the development of the novel reluctance machine, techniques to alleviate these problems have been developed with minimal compromise of the machine performance while minimising the cost of the motor. An ideal application for the motor design, and one of the case studies in this thesis, is its use as the principle actuator for a delta robot lever arm. This has been published in the Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture titled Design for scalability of industrial processes using modular components