Voltage Control of Stepper Motors Using Position and Velocity Measurements

Abstract

In this chapter, voltage level controllers utilizing position and velocity measurements are presented for the PM and Sawyer stepper motors. Our controller design follows [114] for PM stepper motors (Sect. 9.1) and [113] for Sawyer motors (Sect. 9.2) . Stator current measurements are not required for feedback. For the PM stepper, the analysis is carried out with the detailed model including nonsinusoidal flux distribution phenomena. Simplifications under the assumption of sinusoidal flux distribution are indicated. For simplicity of presentation, only the sinusoidal flux distribution case is examined in the case of Sawyer stepper motors. The more general treatment with nonsinusoidal flux distribution can, of course, be carried out using the same approach as with PM stepper motors. The controllers presented are adaptive and do not require any knowledge of the electromechanical system parameters, except for lower and upper bounds on the time constant of the electrical subsystem. Furthermore, under the assumption of sinusoidal flux distribution, it is shown that these bounds on the time constant are not necessary. The controllers designed are robust to load torques, cogging, and disturbances which can be bounded by a function of the rotor position and the rotor velocity.