Design Of A Low Wind Speed High Accuracy Thermal Wind Speed Sensor

The measurement of the wind speed has a wide range of applications in meteorological monitoring,industrial and agricultural production and many other fields.At present,the anemometer is mainly divided into mechanical,ultrasonic and thermal according to different measurement principles.The mechanical anemometer has limitations such as large starting wind speed and difficulty in accurately measuring wind speed below 0.5m/s.The ultrasonic wind speed sensor can achieve the resolution of 0.01m/s,but it is not only susceptible to noise,shadow effects,but also expensive.The thermal anemometer has great application potential in low wind speed measurement due to its small size,high sensitivity to medium and low wind speed measurement and fast response speed,but it is susceptible to temperature drift.Therefore,it is of great significance to design a thermal wind speed measurement system with high precision,good temperature drift suppression effect,simple structure and reasonable price.This paper proposes a thermal wind speed sensor based on the principle of heat loss.The sensor system is mainly composed of ambient temperature probe,heating probe,ARM processor,high precision measuring circuit and constant power heating circuit.The sensor probes were designed and verified by heat transfer theory research and computational fluid dynamics simulation.A STM32 microprocessor was selected as the main control chip,and a high-precision analog-to-digital converter AD7794 was used to perform analog-to-digital conversion on the voltages of the platinum resistances and the reference resistances of the heating circuit to achieve accurate measurement of the temperature of two probes and heating power.At the same time,the heating power was closed-loop controlled by combining the fuzzy PID control algorithm and pulse width modulation(PWM)technology to achieve the constant heating power.Finally,the influence of temperature drift of the sensor was corrected by L-M algorithm.In addition,the data collected by the system was sent to the host computer software which was programmed by C# language for display and storage through the serial port.The experimental results show that the measurement errors of the system are ±0.08m/s and ±0.19m/s when the ambient temperature is-10~50°C and the wind speed is in the range of 0~1m/s and 1~5m/s,respectively.This system has high precision for low wind speed measurement and good suppression of temperature drift,and has certain application potential in the field of low wind speed measurement...