Stator-PM-Based Variable Reluctance Resolver With Advantage of Motional Back-EMF

The stator-permanent magnet (PM) motor has an advantage with its simple and firm rotor, which is suitable when being applied to automotive applications. This article 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 to 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 electromotive force (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.