Novel electromagnetic rotor position sensor for aerospace brushless DC machine

In order to implement aerospace brushless DC machine servo control system in a high-temperature hostile environment, a novel electromagnetic rotor position sensing device was put forward. Concentrated excitation windings and detection ones were alternately mounted on the stator teeth. The rotor cylinder outer surface was notched at the corresponding positions of the magnetic S poles on the machine rotor. With the magnetic field excited by a high frequency sinusoidal current, the detected signals were modulated by machine rotor position, as the total mutual inductance between one detection winding and all the excitation ones varied as a function of the sensor rotor position. With all magnetic iron cores laminated from new soft magnetic alloy ultra-thin sheet, the excitation current frequency may be increase to 100 KHz. Moreover a linear model and a magnetic-equivalent-circuit model were set up and the sensor geometry parameters were optimized based on the later. A finite element analysis was done in ANSYS software program and an experiment system was also built up. Both the simulation and the experiment results revealed the validity and reliability of the whole scheme.