Reluctance resolver is an electromagnetic sensor, which is composed of stator and rotor. When the AC magnetic field generated by the excitation winding is periodically stable, the rotor rotation leads to the change of the air gap magnetic field between the stator and rotor, and the inductance fed back to the secondary winding changes, so that the induced electromotive force changes and forms a voltage signal, which is converted into a digital signal (i.e. angle signal) through a / d. This product is suitable for various harsh environments and is widely used in military equipment fields such as aviation, aerospace and radar, as well as industrial fields such as automobile, robot, metallurgical machinery and textile machinery.