A new microcomputer-based direct torque control system for three-phase induction motor

A microcomputer-based direct primary flux and torque control system for three-phase induction motors is presented, showing that the instantaneous primary flux of the induction motor can be calculated by means of computer software. It is shown that, by selecting a space nonzero voltage vector and its time width, the amplitude of primary flux can be controlled, and that, by selecting a space zero voltage vector and its time width, the amplitude of electromagnetic torque also can be controlled. Therefore, flux and torque control can be achieved separately. The control algorithm can be implemented online with a 1 kB ROM memory. The controller, therefore, can be quite compact, and the hardware and software implementations are easy to achieve. A fully digital controller with a 16 b microcomputer is developed. The experimental results are presented and agree with the theory