Patent ID: 9571021
Date: 2017-02-14
CPC Classifications: H02P

Claim:
1. A motor control device for controlling a stepping motor having at least two coils, through which coil currents having different phases flow respectively, and a rotor configured to rotate by periodically switching a phase of the coil currents flowing through each of the coils, the motor control device comprising: a controller configured to apply a pulse voltage being subjected to pulse width modulation to each of the coils and to provide a stop period to a target coil being subjected to switching of a direction of the coil current, during which the application of the pulse voltage to the target coil is temporarily stopped; a back electromotive voltage measuring unit configured to measure a back electromotive voltage induced in the target coil during the stop period; and a detecting unit configured to detect an out-of-step of the stepping motor when the back electromotive voltage measured by the back electromotive voltage measuring unit satisfies a predetermined out-of-step determination criterion, wherein the controller performs a control to set on-duty of the pulse voltage applied to all of the coils except the target coil to be either 100% or 0% during the stop period, by changing a target current of all of the coils except the target coil during the stop period, or by performing a feed-back control while changing a measured value of the coil current flowing through the all of the coils except the target coil during the stop period.