This paper presents a new type metal detector measurement system based on linear Hall-effect elements. This system adopts a low voltage DC power supply, which drives a U type (or C type) core coil to generate a magnetic field space. Two linear Hall-effect elements are placed at the center of core coil measurement section. With the differential operational testing method, the sensing signal is collected and displayed with SCM system. In the paper, we analyze the feasibility of the measurement system in theory. Further a practical measurement device is designed and produced to verify the theoretical analysis. Experiments data shows that, within a sensing gap between 0.5mm and 3mm, this new Hall-effect element metal detection equipment could effectively resolute nondestructive metal and the damage metal with small cracks, especially sensitive to the longitudinal crack. As a conclusion, this metal detector has several advantages such as simple structure, small volume, low cost, no radiation, so that it would be convenient for production, carrying and application. The new type metal detector measurement system proposed in this paper has important significance for industrial and manufacturing production testing and maintenance of equipment.
Permanent magnet temperature estimation in PM synchronous motors using low cost hall effect sensors