A synthetic position decoding technology for rotary transformers based rotor position measurement system

Abstract

This article proposes a rotary transformer position decoding scheme for motor drive control. In this scheme, a simple analog circuit is used to design the excitation circuit and signal conditioning circuit. Demodulate the modulated sine/cosine signal through software and decode it through a phase locked loop (PLL) to obtain the implemented position signal. This scheme completely avoids the use of traditional, specialized decoding chips. At the same time, in order to make the position decoding scheme applicable to different motor drive control platforms, a single-cycle partition average based pulse signal estimation method is proposed for converting the angle position into pulse signals similar to the output of an encoder’s phases A, B, and Z, which are referred to as A/B/Z signals in the paper. In order to experimentally validate the proposed scheme, a software decoding platform based on the STM32F407 was built and compared with the decoding results of the chip. The effectiveness and accuracy of the proposed scheme were verified, and it can be effectively applied in the field of motor drive control.