Research Of Water Turbine Flowmeter Based On MSP430

As a common water flow measuring instrument,water turbine flowmeter has a strong anti-jamming capability,and the advantages of good signal resolution.But current water turbine flow measurement system has some disadvantages of only two wire system and non real-time display.In this paper,a method for designing four line turbine flowmeter is proposed and a new water turbine flowmeter is designed by the method,which can reduce the power consumption and display the flow results in site.Firstly,the development history of flow meter is elaborated in this paper,the current common water flowmeters and the working principle and characteristics of the turbine flowmeter are introduced.Secondly,the general design scheme of new type water turbine flow measurement system.The coil sensor is chosed as the sensor,its output signal is sine wave(pp value is 15mV)whose frequency proportional to flow rate.In order to amplify the signal of the sensor,a single power supply amplification circuit is employed,while the power consumption and noise of the system is reduced.While the midpoint voltage method is used to ensure the normal negative signal amplification,the final output signal's value is 6.2V.A high-pass filter is used to filter out the DC bias of the signal output from the amplifying circuit.High precision chip is used to generate standard square wave with the amplitude of 0-12 V.MSP430F149 is used as the core controller of the system whose on-chip capture module is used to count the number of the pulse.The liquid crystal module is used to display the measurement results.At the same time,the frequency-voltage conversion circuit is designed based on the f/V chip.In order to keep its output stable,a new power supply is designed with the superimposed power.Experimental results show that compared to the traditional power supply,the stability of output voltage signal has been greatly improved.And then design the 4~20mA current loop circuit based on V/I chip to achieve the long-distance signal transmission.Finally,the static volumetric method is used for water flow measurement system calibration,and the experimental results show that the measuring accuracy of the system can reach 0.5%.