Complex-Vector Flux-Linkage Envelope Demodulation for High-Speed Resolver-to-Digital Conversion System

With the rising demand on power density of the propulsion systems, the operation speed of electric machines increases significantly, which is challenging for the position sensors to maintain high accuracy. In the conventional resolver-to-digital conversion (RDC) systems, the excitation frequency error increases distinctively in envelope and angle with the rise of speed, which is adverse to the output power and efficiency of electric machines. Therefore, to eliminate the limitation of excitation, a complex-vector flux-linkage envelope demodulation method is proposed in this article. The complex-vector demodulation principle is innovatively implemented based on the high-speed resolver model to entirely remove the excitation component. The high-speed resolver output error can be reused in flux-linkage envelope demodulation. In the simulation and experiment verification, the absolute angle error of the proposed method is less than 2<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${}^{\circ}$</tex-math></inline-formula> under 2 kHz electric speed, in which the excitation frequency error is suppressed to only 0.04<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${}^{\circ}$</tex-math></inline-formula>.