CED: a new method for high speed stepping motor driving

Stepper motors are indexing devices widely used today in microcomputer controlled machines because of their low cost, simplicity, accuracy and repeatability. Even though their speed is presently adequate for many purposes, there is still some room for improving this parameter. In this article, the authors propose a new electrical driving method especially designed for small stepper motors, fed with unidirectional currents. The method is called "controlled energy discharge" (CED) and is based on changing the time response constant of the current due to winding inductance by the addition of a charged capacitor. The theory of the method, its implementation and performance comparisons with traditional control schemes are presented. From these comparisons, the authors' proposal appears to be an excellent alternative for driving stepping motors.