Patent ID: 10523145

Abstract:
A motor control circuit (12) capable of performing a high-precision step-out determination under a wide range of conditions. The motor control circuit (12) includes an input voltage measuring unit (125), a temperature measuring unit (128), a back electromotive force measuring unit (126), a determination threshold value setting unit, and a determination unit. The input voltage measuring unit (125) measures an input voltage input to a motor control device (10). The temperature measuring unit (128) measures temperature. The back electromotive force measuring unit (126) measures back electromotive force induced in a coil for which energization is stopped out of the coils of plural phases. The determination threshold value setting unit sets a determination threshold value of back electromotive force based on a measurement result of the input voltage measuring unit (125) and a measurement result of the temperature measuring unit (128), and based on a determination reference value that is preset for each of plural partial areas sectioned in a matrix form with a threshold value relating to the input voltage and a threshold value relating to the temperature. The determination unit makes a determination on step-out of a stepping motor (20) based on a measurement result of the back electromotive force measuring unit (126) and the set determination threshold value of the back electromotive force.