Numerical speed control of a current-fed asynchronous machine by measurement of supply voltages

Theoretical and experimental results are presented, concerning a control law for the speed regulation of a current-fed asynchronous machine. This law, which defines the stator frequency in terms of supply voltages, enables the machine to operate in the four quadrants of the speed/torque plane and particularly during regenerative braking. It also allows the rotor-current frequency to be controlled, and hence the speed to be estimated with no mechanical sensors. The implementation of control laws and the speed regulation loop, based on the aforementioned speed estimation, is carried out by means of a digital computer.