Differential-geometric methods for control of electric motors

The differential-geometric techniques of nonlinear control developed over the last 20 years or so include static and dynamic feedback linearization, input-output linearization, nonlinear state observers and disturbance decoupling. The theory has now reached a level of maturity where control practicioners are making effective use of the techniques for electric motors. Indeed, DC and AC motors have well-defined nonlinear mathematical models which often satisfy the structural conditions required of the differential-geometric theory. In this paper, the application of various differential-geometric methods of nonlinear control is shown by way of examples including DC motors (series, shunt and separately excited), induction motors, synchronous motors and DC-DC converters. A number of contributions are surveyed which show the benefits of the methods for the design of global control laws by systematic means.