Linear motor with integral position sensor

摘要

Systems and methods for a linear motor having an integrated position sensing of the anchor of the motor are disclosed. An integrated position sensing of the anchor is achieved by sensing the inductance of one or more coils driving the anchor. The anchor comprises at least one permanent magnet. The inductance is dependent on a current position of the anchor. The anchor is driven by PWM pulses. A control unit controls the duration of driving the anchor and the duration of sensing the inductance. In normal operation during about 80% of a motor control period the anchor is driven and during a remaining time the inductance is sensed. In a preferred embodiment of the invention the linear motors invented are used in a camera module driving a lens barrel and a shutter.