Research on Reducing Assembly Errors in Inductive Encoders With Observer Phase Detector Phase-Locked Loop

Inductive encoders, as a rising noncontact rotary encoder, are widely used in multiple fields, but assembly errors in the manufacturing process can affect the accuracy of their angular output. In this article, we investigate the impact of assembly error on the decoding signal of inductive encoder and establish a model that reveals the influence of assembly error on the angle signal. Specifically, we adopt the observer phase detector phase-locked loop (OPD-PLL) method, which depends on a model and can mitigate the impact of nonideal factors resulting from assembly error. The experiment applies STM32F407ZG as the algorithm processing chip to verify the model at different poles and speeds by fast Fourier transform (FFT) and achieve an accuracy of ± 0.004 rad in angle output.