热温差型微流量传感器热敏电阻自热的补偿方法

Thermistor Self Heating Compensation Method for Micro Flow Sensor with Thermal Temperature Difference

摘要:

分析了热温差型微流量传感器的热敏电阻自热对测量的影响和惠斯通电桥作为前端信号采集电路的不足，提出了相应的解决方法。利用ANSYS软件对热敏电阻自热的各种情况进行了仿真，发现当上下游热敏电阻的功率越接近且值越小时，传感器的输出信号越稳定。从仿真的结论和惠斯通电桥的不足出发，提出了以恒流电路作为信号检测前端电路的方法，不但可以基本消除传感器热敏电阻自热所造成的测量误差，而且改善了由于电源不稳定给传感器测量造成的影响。分析表明，当流速为1m/s、流道高度为150μｍ时，传感器的测量误差降低了1％左右。

Abstract:

The effects of thermistor self heating of the micro flow sensor with thermal temperature difference and the shortages of using Wheatstone bridge as the front end of signal collecting circuit were analyzed, and the corresponding solutions were proposed. Simulations were performed by using the ANSYS software to make the finite element analysis for the thermistors’self heating under various conditions. It is found that more adjacent and smaller power value of the upstream and downstream thermistors brings more stable output signal. According to the simulation result and the shortage of Wheatstone bridge, the scheme of using constant-current circuit as the front-end signal detection circuit was put forward, which not only eliminates the measurement error brought by self heating, but also controls the effects brought by astable power. The analysis shows that the measurement error of the sensor decreased by about 1% when the flow rate is 1m/s and the channel height is 150μm.