Hard dead zone and friction modeling and identification of a permanent magnet dc motor non-linear model

Abstract

The identification of a permanent magnet DC motor model including non-linearities dead zone, Coulomb friction, and viscous friction, is presented. The dead zone considered here is the so call "hard" dead zone, whereas the friction force is modeled in two different ways: first, considering the value of viscous coefficient friction as a constant and second, approximating viscous coefficient by a polynomial depending on motors rotor velocity. The polynomial representation of the viscous friction value allows it to be adjusted automatically as a function of the speed of the system, as occurs in real systems. Therefore, a model capable of better representing the real motor behavior along a wide range of operation is obtained. The non-linear model is validated and compared using real-time data obtained from Quanser's direct current motor control trainer system, using the numerical tool Matlab®/Simulink™.