Design And Experimental Study Of Flexible Transparent Electric Heating Film System

To meet the low-energy and lightweight demand of the electrical equipment for new energy vehicles,this dissertation studies a flexible transparent electric heating film system to replace the defrosting and defogging role of automobile air conditioners.It has a higher power utilization rate and can effectively increase the battery life of pure electric vehicles.Three aspects will be discussed and designed as follows.First of all,the stability of the conductive network of silver nanowires on the heating film has been improved.By collecting the voltage,current,and temperature of the heating film during operation,a simple model of the silver nanowire conductive network was established,and the reason for the collapse of the conductive network was analyzed.In view of the collapse of the silver nanowire conductive network,a composite of silver nanowire and zinc oxide was proposed to improve the stability of the transparent conductive film.Due to the high thermal conductivity of transparent zinc oxide,it transfers the local high temperature on the surface of the heating film to a relatively low temperature area,ensuring that the silver nanowire network is not fused by the high temperature.Secondly,the temperature control algorithm of the flexible transparent electric heating film is optimized.Considering the stability of the silver nanowire network,the overshoot and oscillation in power supply should be strictly limited.However,they are easy to occur during the traditional PID temperature control process.This kind of environment with unstable voltage and continuous varied temperature will increase the probability of silver nanowire network collapse.Therefore,a fuzzy PID control algorithm is proposed in this dissertation to adjust the temperature of the heating film.This algorithm can adjust three parameters of PID control in real time,which can reduce the amount of overshoot and oscillation in the control process.These two control methods are simulated by MATLAB.The results show that the fuzzy PID control has smaller overshoot,shorter adjustment time and smaller steady-state error.Finally,an embedded control system is designed for the flexible transparent electric heating film system.The microcontroller STM32F103C8T6 with ARM Cortex-M3 core is used as the main control unit,and the corresponding hardware circuit and software system are designed.The system includes functions of temperature acquisition,temperature display,temperature control,key input and fault detection.Human-computer interaction with the user is realized through the liquid crystal display(LCD).The experimental results show that the flexible transparent heating film controlled by fuzzy PID algorithm can adjust the temperature from 19.5 °C to 65 °C in about 20 s.There is no obvious overshoot,and the steady-state error is ± 1%.The system can maintain good control performance in a large range to meet its temperature control requirements for defrosting and defogging.