DISCRETE TIME DC MOTOR MODEL FOR LOAD TORQUE ESTIMATION FOR PID-IMC SPEED CONTROL

This study explores the direct current (DC) motor load torque calculation using an effective discretization of the motor dynamics and the proper choice of sample time. The Euler backward differences and the bilinear transform methods are compared considering an adequate sampling time that is not usually specified in discretization methods. The Euler backward differences discretization of a reduced order motor model was solved and computed for the load torque. The real-time estimation of the motor load can be used in an internal model control-based proportional integral derivative control strategy. Results show that the proposed control scheme has robust performance for variable load and variable speed for motor control applications.