Research On Absolute Magnetolectric Encoder And Its Anti-intference Algorithm

With the progress of science and technology and the development of national defense,large-diameter hollow shaft structure is more and more widely used in aerospace and other national defense industries.The large-diameter hollow shaft has large radial size and hollow shaft,which makes the commonly used magnetoelectric encoder unable to be used in the system.In order to solve this problem,through theoretical research,structural design,simulation verification and other research,a new absolute angle detection principle of magnetoelectric encoder for large hollow shaft is proposed.The research work of this paper can be divided into the following points:In order to solve the problem of the absolute angle measurement principle of the large hollow magnetoelectric encoder,the coding principle and decoding method of the double multipole encoder are proposed.The absolute angle detection process is mainly divided into two parts: single period angle decoding and pole position decoding.On the basis of fully understanding the existing encoder angle measurement principle,this paper determines the arctangent algorithm between partitions as a single period angle decoding algorithm.Based on the study of the coding principle of the double multipole encoder,the condition that the pole pairs of the permanent magnet need to meet the mutual quality is determined,and two pole position decoding methods based on switch Hall and linear Hall are proposed.Through the analysis of the mechanism of encoder error,the optimization algorithm of pole decoding method is proposed,which improves the anti-interference ability of decoding process.In this paper,the error model of single period angle decoding process is established with all kinds of errors considered.Due to the poor anti-interference ability of the two pole position decoding methods,this paper proposes two algorithms of interval judgment and region decoding to optimize the two pole position decoding methods respectively,and on the basis of the optimization algorithm,the anti-interference ability of the decoding method after optimization is quantified in order to determine the design index in the follow-up study.According to the anti-interference index of the encoder,relying on the permanent magnet synchronous motor for XX type turntable,the prototype design of the large hollow encoder is carried out.Firstly,according to the inner diameter of the encoder,the size of the inner and outer ring permanent magnet and the number of the outer ring poles are preliminarily selected.Then,according to the anti-interference ability index and the angle error model,the number of the magneticpoles,the size tolerance and the sine characteristic of the magnetic field are determined.On this basis,through the magnetic field finite element simulation analysis,the magnetic field detection position and the verticality and coaxiality error index of the magnetoelectric encoder are determined.Finally,on the basis of fully considering the absolute angle of the encoder,the circuit principle design of the encoder and the mathematical model of the circuit signal processing are completed through the circuit design.The digital simulation platform is established by using the magnetic field simulation model,circuit mathematical model and absolute angle calculation method of the prototype design.The correctness of the new absolute angle measurement scheme is verified,and the solution method of the characteristic parameters is designed.In the research process,the simulation process is suitable for the actual absolute angle measurement by reasonably considering the influence of magnetic field data source and circuit noise.Taking the middle data of the simulation process as the sample,the solution method of the characteristic parameters in the case of more pole pairs and misalignment of magnets is studied.