Design Of Multi-channel Digital DC Sensor Based On Finemet Material

As a key device of DC metering and monitoring,DC sensor has been developing rapidly and applied with the continuous development of microgrid,intelligent DC power distribution system and other technologies.It plays an important role in ensuring the safe and reliable operation of the DC system.First of all,aiming at the shortcomings of the existing DC leakage sensors in terms of accuracy,sensitivity and resolution,a high precision and high sensitivity DC leakage current sensor is proposed.The DC leakage sensor is based on Fe based nanocrystalline material.The core of the sensor is the magnetic modulated LR oscillator.The core idea is to measure the size and direction of the DC leakage current by detecting the change of the voltage pulse width at the two ends of the coil.By using the principle of differential detection,two coils around the opposite direction are wound on the same core to restrain the generation of zero drift and improve the stability of the system.Then based on PSPICE,a model of magnetic modulation DC leakage sensor is established.First,the single coil DC sensor is simulated,and then the three coil DC sensor is simulated with two coils winding to the opposite coil and a compensating coil.By comparing the simulation results of the two models,the linearity of the three coil DC sensor is obviously better than that of the single coil DC sensor.It shows that the three coil method can effectively suppress the generation of zero point drift,and the method proposed in the previous article is verified.Finally,on the basis of simulation,the hardware and software system of multi-channel digital DC sensor based on STM32 MCU is designed.And a suitable communication protocol is designed to realize the communication between the sensor and the host computer.In order to verify the rationality of the design,a system for detecting leakage current is set up.The test results show that the sensor has good linearity and accuracy in detecting the leakage current in the range of-200mA~+200mA.It is of practical significance to meet the requirements of the design.