Torque sensor using power measurement

摘要

A torque sensor attached to a shaft for detecting torque applied on the shaft is disclosed. The torque sensor of the present invention includes a magnetic portion attached on the shaft and a retainer arranged to surround the magnetic portion and supported to rotate with respect to the magnetic portion. A first coil supported in the retainer to surround the magnetic portion forms a first magnetic circuit passing through the magnetic portion. A power source applies an alternating current to the first coil. A measuring circuit measures torque applied on the shaft based on an alternating current and an alternating current. The alternating current flows in the first coil when the alternating voltage is applied.