Department of Engineering

Centre for Advanced Electronically Controlled Drives

MOTOR DRIVES

This centre and these projects have mostly moved to the Company Technelec Ltd, that was set up
by Professor Pollock to exploit this technology

Switched Reluctance Drives

The switched reluctance drive is a brushless motor with no windings or permanent magnets on the rotor.  When current flows in one of the stator phase windings a salient pole rotor is pulled into a position of minimum reluctance. Rotation continues by increasing the current in another phase winding.

Professor Charles Pollock has worked on the switched reluctance drive for fifteen years and in that time has earned a reputation for innovative design configurations of motor and power electronic converter.  The key to this success has been the ability to maintain active research in both power electronics and motor design.

Projects on Switched Reluctance Drives

This covers the below topics in the order shown : -

High Efficiency Switched Reluctance Drives

Low Cost Power Converter Topologies

Very Low Cost Switched Reluctance Drives

Novel Designs of Single and Two Phase Switched Reluctance Drives With High Torque Starting and Reversing

Low Cost Control Implementation for the Switched Reluctance Drive

A Novel Electronically Controlled Propulsion Motor

Analysis and Reduction of Acoustic Noise in the Switched Reluctance Motor

Robust, Variable Structure Controllers for the Switched Reluctance Drive

Switched Reluctance Drives Tutorial

Refer to our Tutorial about Switched Reluctance Drives.

Flux Switching Motors and Drives

Refer to our Tutorial about Flux Switching Motors and Drives.

Permanent Magnet Hybrid Stepping Motor Drives

A recently completed collaborative research project with Stebon Ltd. developed a sensorless closed loop control system for a hybrid stepping motor. This was achieved by a new design of power electronic controller, in which the calculation of the back-emf in the motor windings made it possible to improve the performance of the drive, particularly under lightly loaded conditions.  The new power electronic controller operated with unity power factor and allowed full four quadrant motoring and generating operation. These drives are now reaching commercial reality through a Teaching Company Programme.

An advanced computer aided design environment for the hybrid permanent magnet stepping motor has also been developed.  This new CAD environment allows Stebon Ltd. to design the motors quickly and easily. Three dimensional finite element analysis can then be used to verify the final design.

Induction Motors

The group has been developing a range of controllers for induction motors for the HVAC market where it is vital to simultaneously satisfy the requirement of low noise and low cost.  The inverter controlled induction motor is too expensive for some applications where voltage control can be used as an alternative.  However voltage control employing a triac subjects the induction motor to non-sinusoidal voltages and creates unwanted motor vibrations.  The circuits which have been developed employ high frequency PWM schemes to create a variable voltage, fixed frequency sinusoidal output.  The improvements in acoustic noise are dramatic.

Return to Research Topics Page

Go to Power Electronics Page

Author: Ewan Goodier, last updated 17/10/2000.
This document has been approved by the Head of Department.