Development, Based On The Square Wave Excitation Capacitance Type Electromagnetic Flowmeter

As a major measuring instrument, electromagnetic flowmeter can be widely used in cement, chemical, steel, textile, pharmaceutical, aviation, water supply and drainage, food and beverage sectors. In addition to the advantages that the ordinary electrode electromagnetic flowmeter has, capacitive electromagnetic flowmeter has a unique feature that is the electrodes do not contact the measured liquid and thus saves many problems caused by the electrode-liquid contact like the electrodes surface cohesion, corrosion, friction and etc. It can also measure liquid that can hardly be measured by the electrode electromagnetic flowmeter Therefore, it expands the scope of application of electromagnetic flowmeter. Based on the fact that most domestic manufacturers import and assemble key parts and components and lag behind in R & D and key technologies are controlled by large foreign companies, the research and development of made-in-China capacitive electromagnetic flowmeter is of positively and practical significance in promoting the country's electromagnetic detection technology.This dissertation concerns the research and development of low-frequency excitation capacitive electromagnetic flowmeter, the main work is the design of sensor and research of flux signal detection and processing problem. It first introduces the historical development of electromagnetic flowmeter, and some basic principles. It discusses the implications of the research and development of made-in-China capacitive electromagnetic flowmeter. Then it introduces the components and their interrelations of the system. It analyzes the structure of the sensor, the composition of the excitation system and the design of capacitor electrode. It also carries out the calculation of magnetic circuit parameters and discusses the magnetic circuit. Next it explores various advantages and disadvantages of different modes of excitation theoretically, determines the low-frequency square wave excitation by experimental comparison. The fourth part of the dissertation analyses all kinds of noises encountered during the processing of flux signals. It designs the signal detection circuit, the amplifier circuit and the system of flow signal collection and processing. At last, it analyzes the effect to electromagnetic flowmeter from the distribution of flow velocity. It introduces the flow measurement devices, and the experimental results are analyzed.As a product of independent intellectual property rights, we believe it has a good prospect of the market.