Research On The Characteristics Of Self-powered Variable Thermal Resistance And Temperature Control Application Based On Thermoelectric Effect

The resistance of the heat transfer process is called thermal resistance.When the thermal resistance of an object can be changed according to actual needs,it is a variable thermal resistance.Variable thermal resistance has important applications in building energy conservation and testing.However,there is currently no application in temperature control.At present,temperature control technology has achieved good results in temperature control accuracy.However,in the process of applying control methods such as fuzzy control and neural network control,the user needs to have a high theoretical basis,which brings inconvenience to the majority of users.In this paper,a temperature control method is proposed.The variable thermal resistance is applied in the temperature control device.By applying the variable thermal resistance in an appropriate way,the accuracy of the basic temperature control is improved and the complexity of the user's use is reduced.Firstly,due to the lack of experimental data of self-energy and variable thermal resistance,this paper designs a thermal resistance measurement device using constant heat flow and auxiliary heating plate.This paper measures the self-energizing thermal resistance characteristics of semiconductor refrigeration components including TEC1-12704(40),TEC1-12704(30),TEC1-12705(40),TEC1-12706(40),TES1-3105(15),TES1-3105(20)by setting the main heating plate power and cold junction temperature,and experiments show that : the thermal resistance of semiconductor refrigeration components decreases with the increase of the overall temperature,and the absolute value of the range of thermal resistance changes is less than 0.4;the relationship between the thermal resistance of different types of components is inversely proportional to the logarithm of the semiconductor pair inside the component,and inversely proportional to the ratio of the length of the internal semiconductor to the cross-sectional area,which is consistent with the conclusions obtained by simulation in other literatures and provide a basis for the practical application of self-powered variable thermal resistance;Increasing the number of series stacking of semiconductor refrigerating components can effectively increase the resistance and variation range of the variable thermal resistance,and the multiple of the increase is less than 2;the experimental data in this paper has a deviation of less than 0.4 compared to the theoretical value.Secondly,in order to realize automatic control of self-energizing variable thermal resistance,a variable resistance based on analog circuit and a variable resistor based on digital potentiometer are designed and studied.The variable resistor based on the analog circuit is composed of a base resistor,a single-chip STC89C52,a digital-to-analog converter AD7521,and an operational amplifier circuit.The variable resistor based on the digital potentiometer is controlled by the single-chip STC89C52 to control the digital potentiometer X9C102 and the solid state relay KS1-60 DD.Parallel circuit configuration.Through experimental research and analysis,the latter has achieved good experimental results,can achieve the same variable resistance function as the sliding varistor,and applied it to subsequent experiments.In order to facilitate the application of PID control in subsequent experiments to achieve good control effects,a PID self-tuning temperature control system based on LabVIEW was developed in this paper,which can achieve a control accuracy of 0.1 °C,and can be applied to variable Thermal resistance in PID control experiments.The microcontroller controls the actuator using PWM control.Finally,in order to observe the effect of variable thermal resistance on temperature control accuracy,experimental devices were designed for working conditions above room temperature and below room temperature,and the heating plates,semiconductor refrigeration components and cooling fan supply voltage were set.The two-position control is performed separately with the semiconductor refrigeration component.After the two-position control and the PID control are respectively applied to the variable thermal resistance applied to the experimental device,the temperature control accuracy higher than the room temperature condition is based on the basic temperature control accuracy-0.25 °C~+0.13°C has been increased to 0.06°C,and the temperature control accuracy under room temperature conditions has been increased from-0.1°C to +0.17°C to-0.06°C to +0.09°C.Therefore,the addition of variable thermal resistance has a good effect on the improvement of temperature control accuracy.