热温差型微流量传感器的温度补偿方法研究

Study on the Temperature Compensation Technique for Micro Thermal Flow Sensors

热温差型微流量传感器的性能受多个因素的影响,如环境温度的变化、供电电源的波动、加热电阻的冷却和导线电阻的引入等。通过ANSYS软件对环境温度及加热电阻温度的改变进行了有限元仿真,发现当两者的温度差值为恒定值时,传感器的输出信号偏差较小。从环境温度与加热电阻温度差值恒定的思路出发,结合目前补偿方法存在的不足——导线引入误差、环境温度检测电阻的自热效应使其检测出错误的环境温度、加热电阻受被测流体冷却后使测量发生偏差以及供电电源波动的影响等,提出了一种可行的补偿方案,包括对前端信号采集电路的优化和后续单片机电路的设计,使影响流量传感器测量性能的诸多因素被削弱,且控制也更灵活。通过分析验证,在相同测试条件下,所提出的方法比常用补偿方法的测试精度高出约1.2%,误差为0.2%。

The performances of micro thermal flow sensors are affected by many factors,such as the environment temperature variation,power fluctuation,cooling of heating resistors and introduction of the conductor resistance,etc.The finite element simulations were carried out for the changes of the environment temperature and heating resistor temperature with ANSYS software.It is found that the output signal deviation of the sensor is smaller when the temperature diffe-rence of the environment temperature and heating resistor temperature is constant.Based on the idea that the difference of the environment temperature and heating resistor temperature is constant,combining with the shortages of the current compensation method,such as the error caused by wire,the wrong environment temperature detected due to the self-heating effects of the environmental temperature measuring resistance,the measured deviation because of the heating resistor cooled by fluid,and the power fluctuation and so on,a feasible method was presented, including the optimization of the front signal acquisition circuit and design of MCU processing circuit.This method weakens many effect factors of the sensor performance measurement and makes the control more flexible.Under the same testing conditions,the analysis and test show that the measuring accuracy of the method is about 1.2% higher than that of the common compensation method,and the error is 0.2%.