The transputer control of induction motor drives

Abstract

The inherent advantages of the induction motor in variable speed drive applications can now be realised in a cost-effective manner as a result of recent advances in power electronics and microelectronics. This thesis is devoted to the advancement of the use of induction motors in variable speed applications, and describes the analysis, simulation and implementation of a variable speed induction motor drive.The state-space method lends itself as an ideal approach both for digital computer modelling and design of modem controller and was therefore adopted for the analysis and simulation of the drive system. The simulation was developed by means of a low cost personal computer package called MATLAB that has been designed to facilitate matrix operations. The use of such a specialized software package provided a 'user-friendly' operating environment with error messages identifying problem areas during program development. The resulted computer model of the drive system offers high flexibility and modularity and can be readily incorporated into further analysis and real-time controller design. Experimental results of the drive demonstrated good correlation with the model at both steady and transient states and the validity of the model is therefore confirmed.The experimental drive system was developed by means of transputers and its associated programming language occam. It was a flexible and comprehensive drive system comprising: (i) an on-line user interactive environment facilitated by the Transputer Development System; (ii) a 3-phase inverter bridge as the power conditioning unit; and (iii) a signal processing unit by means of a multi-transputer network system. The adoption of the transputer and occam enabled parallel processing to be achieved cost effectively in the drive system. The specifications of the drive system developed included on-line speed change, dynamic braking and programmable soft-start. Vector-control was also incorporated for good dynamic response. Experimental results of the specified functions of the drive are provided to confirm the proposed specifications of the drive. Further research areas on the present system are proposed, so that a viable industrial implementation may be contemplated.<br/