Investigation of Novel Doubly Salient PM Variable Reluctance Resolvers

Abstract

As rotor position sensors, the variable reluctance (VR) resolvers are playing critical roles in the industrial electric machine drivers. The VR resolvers have a simple structure, therefore, they are reliable and durable under rough operation scenarios. However, the dedicated decoding system requires the voltage signal injection with high-frequency (HF), which must be much higher than the machine operation frequency. The HF injection increases the decoding computation and system cost, especially for the high-speed applications. To avoid applying the HF injection, this paper proposes a new category of VR resolvers by adopting the concept of the doubly salient permanent magnet (PM) motor. The doubly salient PM machines have the magnets and windings on the stator side, thus, they can keep simple and reliable rotors as the VR resolvers. A significant benefit is that the stator-PM can produce back-EMF, which provides the rotor position information. By this way, the HF injection-based VR resolver solution is only serving for low-speeds and can be shut down as long as the PM back-EMF can be detected by the analog circuit. Besides, the proposed linear counterpart is also a novel option for the mover position sensor in the high speed and long distance linear drive system. The modeled examples are analyzed by finite-element analysis (FEA).

Keywords

• Doubly salient PM motor
• linear drive system
• rotor position sensors
• variable reluctance resolvers