A hot film wind sensor with four Constant Temperature Difference elements fabricated on ceramic substrate

This paper presents a novel hot film wind sensor operating in Thermal-Balanced (TB) mode for the meteorological applications. The sensor is composed of four Constant Temperature Difference (CTD) elements, and each of the elements includes one heater and one temperature detector. The four CTD elements have been designed and implemented to heat the chip and keep itself at a constant overheat temperature higher than the airflow. Meanwhile, the elements are used to balance the temperature difference between the up-stream and down-stream CTD elements by controlling the heating power of the four heaters. The difference of the heating power between the up-stream and down-stream is a measure for the wind. The testing results indicate that the accuracies of the wind sensor are in the range of 0.5m/s and ±2° at wind speed ranging from 0m/s to 40m/s and wind direction from 0° to 360°, respectively.