Study On Eddy Current Turbine Flowmeter Based On GPRS Wireless Communication

Turbine flowmeter is a kind of velocity type flowmeter, it has many advantages,such as high precision, easy to use, good adaptability and digital signal output. However, the traditional turbine flowmeter, with reluctance rotor speed detector, has some drawbacks, namely when it works below the low limit flow rate, the rotating speed of the rotor slows down because of the the suction force of the coil core, resulting in a bad repeatability in low limit or even the rotor stops rotating.So, the flow rate below the low limit can not be measured accurately.In this thesis,eddy current technology was used for improving the performance of the turbine flowmeter. And an eddy current type turbine flowmeter was successfully developed, its flow range is wide, repeatability, reliable and stable characteristics at low flow rate are good.The GPRS wireless communication technology which was combined in the eddy current type turbine flowmeter.First, the causes and the effect of the suction force were pointed out by the analysis of the structure, the working principle and the performance of the turbine flowmeter.Second, the principle and the application of eddy current technology was introduced.The circuit of the eddy current turbine flowmeter was designed, including excitation, detection, amplifier and pulse output and compared with the traditional turbine flowmeter with reluctance rotor speed detector by real flow test. It was verified that the eddy current turbine type flow meter improved the performance at low flow rate.Then, the meter factor below the low flow limit was corrected to improve the linearity and the flow range was broadened. MSP430 microcontroller was used as the core of the non-linear correction circuit, and the non-linear correction programme was made.The variation of the meter factor according with the change of frequency was shown by the data and the curve graph in the cases of before and after the non-linear correction.At last, the application of GPRS wireless communication technology was introduced.The GPRS wireless communication systems was designed, including network establishment, gateway software and so on. The data transmission through the GPRS network was realized,and combined with the eddy current type turbine flowmeter, instantaneous flow rate, total flow rate, meter factor,repeatability and so on can be sent to the superior PC.