Research On Low Power Consumption And Temperature Drift Compensation Of Micro MEMS Wind Sensor

In recent years,with the rapid development of science and technology and people’s demand for higher quality of life,the importance of meteorological monitoring in people’s production and life has gradually increased.Wind sensor,as an important sensing instrument for wind speed and direction measurement,has also attracted more attention.However,traditional wind sensors have the disadvantages of large size and high power consumption.In recent years,with the rapid development of micro-electromechanical system(MEMS)technology,it is possible to develop wind sensors with small size and low power consumption.Among them,MEMS thermal wind sensors have the advantages of low cost,high sensitivity and fast response,which have high market application value.The laboratory has been conducting research on MEMS thermal wind sensor since 2000.We have a relatively mature scheme for the design,preparation,packaging,circuit and assembly of the sensor system,and have formed commercial products.However,the volume and power consumption of the sensor system currently used is still large,which cannot give full play to the advantages of MEMS technology,and is not suitable for portable applications.In order to solve the above problems,this paper proposes a miniaturized low-power MEMS wind speed and direction sensor design scheme,in order to reduce the size and power consumption of the sensor system,the hardware circuit,software function and assembly scheme have been improved to make the sensor more suitable for portable use.Based on this,the problem of the temperature drift effect has been solved.The main contents and innovations of this paper are as follows:(1)In order to meet the needs of miniaturization of MEMS sensors,a miniaturized PCB circuit and assembly shell are designed,and a miniaturized assembly scheme is proposed.In this paper,the assembled shell is manufactured using 3D printing technology,and the assembly of the sensor and circuit is completed.The assembled sensing system is a cylinder with a diameter of 4.5 cm and a height of 13.4 cm,which is about 73% smaller than the traditional sensor system.(2)In order to meet the needs of low power consumption of MEMS wind sensor,the sensor driving circuit and software function are improved.In this paper,the constant temperature difference(CTD)circuit is improved to achieve low power consumption,and a CTD circuit using DC-DC switching power supply instead of triode is innovatively proposed.In addition,the power supply system is optimized,and the lowpower MCU MSP430G2553 is used;The software has been reprogrammed for the new MCU.Some redundant functions was removed.The new MCU has the functions of sampling and calculating wind speed and wind direction information,Bluetooth communication and online debugging.The comparative experiment shows that without affecting the performance,at 0m/s,the power consumption of the sensing system is reduced from 324 mw to 96.3 mw,a decrease of 227.7 mw,70.3%;At 40 m/s,the power consumption of the sensing system is reduced from 372 mw to 132 mw,a decrease of240 mw,70.2%.(3)In order to ensure the working stability of the sensor in practical application,the problem of temperature drift of the sensor is analyzed and solved.Firstly,the causes of sensor temperature drift are analyzed theoretically,and on this basis,the corresponding solutions are put forward.First,by connecting resistors in series and parallel with the ambient temperature measuring resistor or the heating resistor,the temperature coefficients of the two are compensated and made equal,so as to ensure the temperature difference between the surface temperature of the sensor and the ambient temperature does not change with ambient temperature;Second,an adaptive temperature drift compensation algorithm which uses the output value of the thermal temperature difference circuit to compensate the output voltage of the CTD circuit is proposed,so as to solve the problem that the output zero of the CTD circuit changes with the ambient temperature.Finally,the effect of software and hardware compensation is verified through four groups of comparative experiments.The results show that the temperature drift problem is serious before compensation,the average measurement error is 7.84 m/s,and the maximum error is as high as 30 m/s within the ambient temperature range of 10-40 ℃ and wind speed range of 0 – 30 m/s;After software and hardware compensation,the average measurement error is only 0.21 m/s,and the maximum error is reduced to 0.96 m/s.