Stator PM-Based Variable Reluctance Resolver with Advantage of Motional back-EMF

The stator-PM motor has an advantage with its simple and firm rotor, which is suitable when being applied to automotive applications. This paper proposes a novel structure for a variable reluctance (VR) resolver by using the concept of the stator-PM. This novel VR resolver shares a similar operation principle with the conventional VR resolver by injecting a 10 kHz excitation signal at low-speeds. Alternatively, at higher speeds, the stator-PM can produce motional back-EMF to support position measurement without the need for electrical excitation. The motional back-EMF can also reduce decoding computation. In addition, higher frequency signal excitation is not required for position measurement at higher speeds. This feature is beneficial for extremely high-speed motor applications. As a sensor, an inexpensive and low-amount ferrite magnet is used in the prototype to satisfy the low-cost requirements of the automotive industry.