Hybrid stepper motors

Stepping motors are characterised by their ability to translate switched excitation changes into precisely defined increments in rotor position. This makes them an inherently digital device ideally suited to numerically controlled servo systems, with applications ranging from multi-kilowatt drives for steering radio antenna to numerous low power applications in the computer peripheral markets. The author reviews the principles of operation of both hybrid and permanent magnet stepping motors. The relative merits of different motor topologies are outlined and methods of analysis and design discussed. Finally design examples based on rare earth and Alnico magnets are compared