Application of a locally infinitesimal nonlinear observer to the speed sensorless control of series connected direct current machines

Abstract

The paper introduces an application of a local observer based on the infinitesimal observability to the sensorless speed control of series connected direct current (DC) machines. The model of the machine is first analyzed and written in an appropriate form of controlled system. Afterwards, an infinitesimally nonlinear observer is designed on the basis of the measurement of armature current of DC machines in order to estimate the machine speed under the variation of mechanical torque. Finally, computer simulation of the speed control of DC machines with the feedback of estimated speed is implemented. The simulated result confirms the performance of the proposed observer as well as the feasibility of the application to the sensorless control of series connected DC machines.