Design Of Spin-valve Sensor Open Current Sensor Based On Shield Structure

With the rapid development of the Electric Vehicle industry,the demand for high reliability current sensors is becoming more and more urgent.Recently,in-vehicle current detection generally uses the open-loop Hall current sensor,which measures the magnitude and direction of the current by detecting the magnetic field generated by the current,combining a magnetic sensing element with a core.However,the Hall sensor has poor temperature stability,low resolution,and slow response speed.It is not suitable for high-precision,high-speed current detection,and cannot meet the demand for current sensors in the development of the Electric Vehicle.Compared with Hall sensors,spin-valve sensor has the advantages of high thermal stability,high resolution and fast response speed,making it suitable for high precision,high speed current detecting applications.For automotive high current detection,the required current sensor range is above 300A,and the magnetic field accumulated in the core air gap will reach several thousand Gauss.For giant magneto resistive sensors with a linear range of tens of gauss,it is difficult to apply for large current detection directly,and a closed-loop structure is usually required.However,the closed-loop current sensor is not suitable for in-vehicle current detection applications due to its complicated structure and high power consumption.This paper summarizes the common technical means and application requirements of current sensors,combined with the application status and development trend of giant magneto resistive sensors,focused on the principle and characteristics of spin-valve sensors,it proposes a design of spin-valve sensor open current sensor based on shield structure,which is to increase the measurement range of the spin-valve sensor in the open-loop current sensor.The whole design consists of a magnetic signal detection module based on a shield structure and a signal conditioning circuit module.The magnetic signal detection module comprises a poly magnetic core,a spin-valve sensor and a shield structure.Its function is to solve the problem match linear range of the spin valve sensor and the core magnetization size.The signal conditioning circuit module includes an instrumentation amplifier and the peripheral circuit components.Its function is to amplify the output voltage of the spin-valve sensor and correct the zero drift.This paper focuses on the magnetic signal detection module based on shield structure.Firstly,this paper uses Ansoft Maxwell software to simulate and analyze the magnetic performance of the spin-valve open-loop current sensor model based on the shield structure,derives the theoretical sensing structure and guides the design and assembly of the measured samples.Finally,this paper conducts experimental data collection and analysis,which through a data acquisition and instrument control system developed based on Labview.According to the measured results,the current sensor designed in this paper can detect the current range of-500?500A with a sensitivity of 0.85mV/V/A,linearity of 3.79%and hysteresis of 0.60%.