Digital Weak Magnetic Field Sensor Design

In recent 30 years, measurement technology for magnetic field has developed greatly. In many field, such as accelerators, electronic microscope, grant physic machines, artificial satellites, space navigation and so on, measurement technology for magnetic is used. And many instruments for magnetic field measurement are required. In recent, there are more than ten methods for magnetic field measurement, such as nuclear magnetic resonance,Hall effect, electromagnetic effect, magnetic-optic effect, etc. However, the resolution of fluxgate can reach to 10-11T of range 10-3T. Fluxgate magnetic sensors play an important role in this field, for its credibility, easy fabrication, lower power etc. Fluxgate technology has made great progress in recent years because new technology and methods are used.In this dissert, the principle and technology of traditional fluxgate magnetic sensor was discussed. Then one-axis PCB fluxgate magnetic sensor was made using a new printed circuit board (PCB) technology. This sensor is low power and fabricated easily and is one direction of development in the future. The configuration of this sensor was presented. The behavior of the fluxgate sensor was analyzed with software tools Flux3D based on the finite element method. The output wave based on different extra magnetic field was recorded, which also was analyzed.In order to improve the stable and limit the disturbance, the fluxgate magnetic system is made up of magnetic sensor DSP, CPLD and other devices. The system sufficiently exerts the ability of high rapidness, powerful signal processing, and utilizes the flexible logical control character. Comparing to traditional magnetic measure instrument, there are many strongpoint.1. It is more stable than analog magnetic instrument and is less affected by environment. The system also has ability of limiting disturbance.2. Little volume and high integration. In the system, signal processing is completed by a very little DSP chip. And the logic control in the system is implemented by the CPLD chip, These chips used in the system enhance system integration, and also improve its stability. 3. Flexible usage, and scalability. Both signal processing and system logic control are programmable, so to upgrade the system is very easy. To upgrade the system, hardware redesigning is unnecessary, and the only work to do is to rebuild the software.