Bosch Limited
Control Unit and Method to Detect Stall or Step-Loss in a Stepper Motor

Abstract:

A control unit is configured to determine a first parameter from a back EMF signal, and to determine at least one second parameter from the back EMF signal corresponding to the first parameter. The control unit verifies, based on the first parameter, at least one condition containing the at least one second parameter, and detects stall or step-loss in the stepper motor based on the verification. The control unit uses a pattern detection by identifying characteristic features of peaks of the back EMF signal, which are order, magnitude and polarity. These characteristic features are independent of RPM, backlash, load and do not require complex calculations and are very robust even at lower RPMs.