| Electromagnetic flowmeter, which is based on Faraday's induction law, is a velocity-type flowmeter. Currently electromagnetic flowmeters generally adopt low-frequency square-waveform exciting mode, but sine- waveform exciting mode is also in consideration sometimes. However, intensive differential interference which is very difficult to be eliminated is produced when the author adopts sine-wave form exciting mode. How to eliminate the intensive differential interference in this mode is a big problem. Current anti-jam technique in sine-waveform exciting mode is complex and of fallibility, which is the reason for unpopularity of this exciting mode.For the advancement of anti-jam technique in low-frequency sine-waveform exciting mode, a new signal process method is used in which the exciting current signal in the loop is multiplied by the signal from the two electrodes. Then the product whose DC component is in proportion to the velocity of flow can be obtained. In this way the intensive differential interference will not influence the result. So zero-point stability and measurement accuracy can be improved.Based on the conceptions mentioned above, electromagnetic flowmeter prototype based on low-frequency sine waveform exciting mode was developed. In the thesis followed works are mentioned:(1) The basic theory, development and status of electromagnetic flowmeter were introduced in detail and a new signal process method is proposed.(2) The electromagnetic flowmeter prototype, based on MSP430 MCU, was developed and it adopts low-frequency sine waveform exciting mode.(3) Based on the flowmeter prototype, many experiments were done in different exciting frequency and sampling mode. Experiment results proved the advantage of the low-frequency sine waveform exciting mode.
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