Analysis And Experimental Study Of Position Detection Precision Of Linear Motor Based On Magnetic Field Coupling

The advanced CNC machine tools mostly used high-power,large-thrust,fastresponse permanent magnet synchronous linear motors as the source of power for linear motion.The linear motor directly converted electrical energy into mechanical motion.In the transmission system of machine tool,it implemented closed-loop control with high-precision displacement sensors such as gratings to ensure the accuracy of processing feed and motion.Traditional external displacement sensors would make the system structure complicated and bloated,and the manufacture of motors and sensors was not relevant.The emerging sensorless detection technologies had some shortcomings such as low position detection accuracy and complicated implementation.Based on the idea of "time measurement space" of time-grating position sensing technology with independent intellectual property rights,and with the key science and technology project of Chongqing municipal education commission,this subject studied a new technology of linear motor position detection based on magnetic field coupling.The experimental results verify the correctness and feasibility of the method.The main research work of this article is as follows:1.According to the regular arrangement of permanent magnets of permanent magnet synchronous linear motors,the distribution of magnetic field was regular.It studied that using multi-field sensor combined with time grating sensing technology to detected the magnetic field of a permanent magnet containing mover position information.The relationship between the position sensing of the permanent magnet synchronous linear motor and the mechanical structure was constructed by the method of synthesizing traveling waves with multiple standing wave signals.2.Identify the key components of the measurement system and simulated the permanent magnetic field,it used single excitation signal and two excitation signals to drive multi-sensor to establish measurement model,the correctness of the principle was verified through theoretical formula derivation,and the magnetic field coupling parameters are analyzed according to the simulation results.3.The research analyzed that the measurement error transfer mechanism caused by the non-orthogonality between amplitude and spatial location,analyzed the factors that errors occurred from signal generation to signal processing in the detection system;In order to improve the detection accuracy,proposed a multi-sensor error method through space translation.The Fourier series harmonic correction algorithm was used to correct the error of long-period data.4.The software and hardware of the measurement system were designed according to the principle of magnetic field coupling linear motor position detection.It had designed the mechanical structure to fix the sensor PCB,excitation circuit and FPGA minimum system circuit,sensor peripheral circuit and traveling wave signal preprocessing circuit,the excitation chip driver,Signal processing system program and Fourier series harmonic correction algorithm program.5.After building an experimental platform and testing the excitation circuit and pre-processing circuit including the phase shift circuit,according to the accuracy experiment results,it proved that the stability of the double excitation detection scheme was the best;the opposite pole of the single excitation detection scheme The maximum error was about 158?m,the translational W / 6 detection scheme had a minimum intrapolar error of 133?m,and the single excitation detection scheme and the double excitation detection scheme were measured for long periods.According to the longperiod error data,after correction,the error of the single excitation detection scheme was about 84 ?m,and the accuracy was improved by about 50%.The error of the double excitation detection scheme was 93 ?m after modification,and the accuracy was improved about 40%.