Design Method of the Heating System for Controllable Heating Humidity Sensor

Abstract

Humidity sensors are prone to condensation in high humidity and low temperature environments, reducing the sensor's measurement performance. Aiming at the current humidity sensor heating system that may not reach the target temperature due to open-loop control and high power consumption, a closed-loop control heating system for the humidity sensor is designed to perform real-time heating and temperature detection of the humidity-sensitive structure. The finite element analysis method is used to conduct thermal analysis on the heating structure, which obtains the temperature distribution of the sensor heating area, guides the heater structure design and gains the location distribution of temperature sensors. A variable parameter fuzzy PID (Proportion Integration Differentiation) control method with variable target temperature is proposed to perform closed-loop control on the temperature of the sensor’s sensitive structure. The heating target temperature is set as a function of the ambient temperature. Also the coefficient of PID changes with error. Thus, the power consumption of the system has been effectively reduced and the heating speed is apparently increased. Simulation experiments show that the heating system designed for controllable heating humidity sensor has uniform temperature distribution. When the ambient temperature is −70°C, the difference between upper and lower temperatures is only 0. 0878°C, with a low power consumption (5 × 106W/m3). At the same time, the overregulation of the temperature control system is low, which is 7. 227%. The system has high environmental adaptability and temperature stability.