Multi-phase motor drives, including induction motors and permanent magnet motors, are used in a wide variety of applications and offer fault-tolerant operation under faults in motor windings and converter switches. Symmetrical multi-fed drives based on three-phase modules are of special interest in safety critical applications. They offer simple control under a fault condition. However, even a single open-circuit fault of one switch or winding will cause complete interruption of a faulty module.

Rensselaer researchers have designed a convenient and inexpensive linear permanent magnet machine solution for transportation, conveyance, and other applications. When designed for short-strokes, the machine is very robust and rugged, and exhibits excellent performance characteristics such as very high thrust density, low ripples, and normal forces. Traditionally, linear PM machines had the armature windings in the translator and the PMs in the stator or vice-versa. This novel design allows both the field and armature excitations in the same part of the machine.

This invention is directed to a method to improve the performance of stepper motor driven systems.Stepper motors are ubiquitous in modern office equipment and other machinery, yet little is published regarding their optimal use in open loop systems.Accurate control of a stepper motor is limited by the ability of the control system to approximate the actual motor and subsequently provide the correct instructions for achieving the actual desired movement with little or no error.Moving the motor to a specific position within a specified time period is difficult due to variations between motors