Computer-aided design of PWM power-electronic variable-speed drives

Abstract

Computer-aided design (CAD) techniques are presented which enable electrical machine models to be developed and included in circuit analysis CAD packages. The techniques are demonstrated using a 3-phase induction motor model as an example, based on the 2-axis machine equations. Simulation results produced from this motor model are shown to compare favourably with experimental results obtained from both a voltage-fed inverter drive and a current-fed inverter drive, confirming the validity and accuracy of the modelling techniques used.The modelling techniques can be used to represent other DC and AC electrical machines and electromechanical systems. Although the CAD techniques are developed and presented using a circuit analysis package called BTRAP (Bristol transient analysis package), they can equally be used in any other commercially available circuit analysis CAD package.The electrical machine model developed represents part of a larger ‘integrated-drive’ CAD package that includes facilities for simulating the complete PWM power-electronic drive system. Using this ‘integrated-drive’ CAD package allows all the interactions between the various components of the drive system to be simulated and investigated with relative ease, at a level of complexity previously unobtainable.