The Design Of Precision Electromagnetic Force Balance Sensor

Electromagnetic force balance sensor is widely used in a wide range of precisionweighing instruments. As precision weighing industry booming, the demand is increasingyear by year. Currently, domestic productions of precision electromagnetic force balancesensor are mainly based on imitating foreign sensors. However, the lack of a complete set ofstructural design, material selection, and magnetic circuit analysis theory methods, bring theissues of measuring and processing errors, as a result, these sensors can not meet the desiredtechnical requirements, which has severely restricted the development of precisionelectromagnetic force balance sensor, and failed to meet the demand of the domestic market.In order to improve the precision performance of the electromagnetic force balancesensor further, this thesis proposes an optimized design theory based on the mechanicalstructure and magnetic circuit. A mechanical and magnetic system with high accuracy andstability is also established. In addition, high performance aluminum alloy and other sensitivematerials are selected to design the precision electromagnetic force balance sensor.This thesis consists of six chapters: Firstly, the domestic and overseas development ofelectromagnetic force balance sensor and its structure are described, the mechanism of drift isdiscussed, and the focus of the research work is highlighted. Secondly, the structure andworking principle of precision electromagnetic force balance sensor are introduced, and thestatic and dynamic characteristics and mechanical model are also analyzed. The precisionelectromagnetic force balance sensor is designed according to the technical specifications. Asone of the key points of this thesis, structural design consists of spring leaf and beammechanics model building and parameter tuning, power coil and skeleton designing. Itconverts the quality signals to electrical signals. Another key point is the magnetic circuitdesign, which consists of magnetic steel structure design, theory analysis, finite elementsimulation and optimization of magnetic circuit. Thirdly, several kinds of common spring leafand permanent magnet materials are selected. And the properties of these materials and theirprocessing methods are analysis further. Finally, the precision electromagnetic force balancesensor designed in this paper is applied in the electronic analytical balance. According to theverification regulation JJG1036-2008for electronic balance, the technical specifications ofelectronic balance are given. The experiment is carried out to analysis the partial load error,repeatability error and indication error using F1grade standard weight at room temperature.The experimental results show that the design of electromagnetic force balance sensor in this thesis well meets the desired requirements of the scale range of220g, and the accuracy of0.1mg, as well as excellent stability, and rapid response features.