Investigation of a Low-Power Consumption Decoding Method in an Axial Field Variable Reluctance Resolver

The axial field slotless resolver with a leaf-style rotor has been proposed with the advantages of its small size and simple manufacturing, which are extremely welcome in the industrial powertrain system. It is attractive to adopt the printed circuit board (PCB) windings instead of the traditional enameled wires. However, the field excitation (EXC) is too weak to generate a significant electromagnetic force for the axial field slotless resolvers. This is because the slotless coupling makes a high path reluctance; besides, the PCB windings have a limited number of coils. To satisfy the decoding requirement, a square wave injection was applied to generate high-level electromotive force (EMF) signals. Even though, this interesting injection scheme needs a high-power excitation to make a strong magnetic field so to induce the SIN/COS coils EMFs. This article proposes an asymmetric narrow pulse injection (ANPI) scheme, which can excite a good tracking envelope but requiring only a low power consumption. Furthermore, the feedback error suppression by rotor contour designing is discussed. The proposed low-power consumption decoding method is realized with an axial field slotless resolver.