Control of Non-conventional Synchronous Motors

Chapter 9

Control of the Stepping Motor ¹

9.1. Introduction

This chapter deals with control of the stepping motor, or rather controls of stepping motors. There are, in fact, different stepping motor technologies possessing particular properties that need adapted supply converters. These different types of motors are represented by specific models. The technology used in these motors and their converters as well as the development of their models are not covered in the framework of this chapter which is devoted to control. This is why, after having briefly indicated the particularities of the different types of stepping motors, the principles of control will be presented and illustrated on the basis of the most common models: those of the permanent magnet motor and the hybrid motor.

9.2. Modeling

9.2.1. Main technologies

We usually distinguish three families of stepping motors:

– The motor with variable reluctance exploits the principle of natural evolution towards the minimum magnetic potential energy or maximum flux rule. The torque being a function of the square of the supply current intensity, a unipolar converter that is simple and economical is sufficient. On the other hand, to increase the number of stable positions, we need to increase the number of teeth, which requires precise and costly machining. For this reason, it is not often used.

– The permanent magnet motor implements the interaction force between the magnetic field generated by the stator windings and the magnetic ...