Research On Ultra-precision Temperature Regulation Of Circulating Cooling Water Based On Dynamic Thermal Capacity Filtering

In the 1960 s and 1970 s,the Lawrence Laboratory in the United States concluded,after counting a large number of precision measurement/machining-related projects,that thermal contamination was the largest single source of error in the field of precision measurement and machining.Relevant domestic research also shows that: in the ultraprecision machining process,the error caused by thermal contamination accounts for 40%to 70% of the total machining error.Therefore,thermal pollution control technology has become the core key technology for ultra-precision measuring instruments and manufacturing equipment to guarantee accuracy.Circulation cooling technology is widely used in the field of ultra-precision manufacturing such as advanced lithography because it can efficiently "transport" the heat inside the equipment to the outside of the equipment,and can combine high temperature control accuracy,large power and dynamic performance.At present,there are two key problems in this field that need to be studied:(1)the existing methods can hardly balance the high temperature stability of circulating cooling water and the dynamic performance of temperature regulation to meet the needs of the new generation of lithography equipment;(2)the existing analytical models of circulating cooling water systems use simplified aggregate parameter models,which ignore the dynamic circulation process of cooling water between the system and the equipment to be cooled,and cannot accurately describe(2)The existing analytical models of circulating cooling water system adopt simplified aggregate parameter models,which ignore the dynamic circulation process of cooling water between the system and the cooled equipment,and cannot accurately describe the spatial distribution characteristics of circulating cooling water,as well as the characteristics and laws generated by the circulation.The main innovative work done in this thesis,“Research on Ultra-precision Temperature Regulation of Circulating Cooling Water Based on Dynamic Thermal Capacity Filtering”,addresses the above issues as follows.Firstly,a circulating cooling water temperature control scheme that can take into account high temperature stability and dynamic performance of temperature regulation is proposed,and a fully closed cooling water circulation structure and two closed-loop feedback control loops for temperature and flow are designed.With the principle of minimal thermal inertia and thermal resistance,a sandwich structure semiconductor refrigeration actuator and a long-tube electric heating actuator are designed to realize bidirectional high precision temperature regulation and control by using the characteristics of electric heating actuator with minimal thermal inertia and thermal resistance.A fuzzy PID-based circulating cooling water temperature control algorithm is designed to finalize the system integration of the circulating cooling water temperature regulating system.Secondly,a circulating cooling water temperature fluctuation attenuation method based on dynamic thermal capacity filtering is proposed.The main point of the principle is to intercept and close a part of circulating cooling water as thermal capacity filtering medium by shunting,and the thermal capacity filtering medium and circulating cooling water form a highly efficient heat exchange structure,and use the thermal capacity filtering medium to absorb/release heat to realize the smoothing and attenuation of circulating cooling water temperature fluctuation and effectively improve its temperature stability;when the temperature setting value of circulating cooling water changes,through the real-time monitoring and feedback control of temperature observation points,the temperature fluctuation of circulating cooling water is attenuated.This method can effectively improve the temperature stability of circulating cooling water without affecting the dynamic performance of temperature regulation,and solves the problem that it is difficult to balance the two in the existing technology.Thirdly,a circulating cooling water system model and analysis method based on the principle of polar coordinate mapping is proposed.The circulating water circuit of the system is mapped to the unit circle in polar coordinates,and the circulating motion of cooling water is mapped to the circumferential motion of temperature observation points on the unit circle in polar coordinates,so as to obtain a unit circle model that can describe the temperature control topology of the system and the circulating motion of cooling water;at the same time,the equivalent circuit models of heating and cooling units are derived from the heat transfer/circuit analogy equivalence principle,and the heat flow is used as the characteristic parameter to couple the equivalent circuit model is coupled with the unit circle model to establish a polar coordinate mapping model that can simultaneously describe the cooling water circulation motion and the system temperature control law;this method can accurately characterize the spatial temperature field distribution of circulating cooling water,as well as the characteristics and laws of temperature changes with space and time introduced by the cooling water circulation.Finally,the main research content of this paper is experimentally verified,and the key performance indicators of the developed circulating cooling water temperature control system are tested.The experimental results show that the dynamic heat capacity filtering temperature fluctuation suppression method proposed in this paper can suppress the temperature fluctuation ratio up to-15 d B or more;the temperature stability of the developed circulating cooling water temperature control system can reach ±3m?,and the regulation time at 1? step is 128 s,which can meet the demand of new generation lithography equipment for m? level temperature stability and 100 seconds level regulation time.