Research On High-precision Thermostat System Based On Standard Resistance Comparison

Beginning on January 1,1990,the International Metrology Commission announced the opening of the quantized Hall resistance reference worldwide.The traceability of the DC resistance is no longer based on the physical resistance,and is subject to the harsh conditions of the quantum Hall resistance.The magnitude of the resistance reproduced by it is still to be passed down by the physical resistance as a transmission standard.In order to keep the resistance of the transmission resistance highly stable,not only the materials and manufacturing processes with excellent electrical resistance are required,but also a highly stable temperature environment is provided for the resistance during transportation.In the process of benchmarking the quantized Hall resistance in the Hepingli District of China Institute of Metrology and Changping Campus,the standard resistance is inevitably moving back and forth between the two courtyards.Due to changes in ambient temperature,standard resistance is inevitable.Based on the current situation,this paper designs a high-precision movable incubator system based on standard resistance comparison by understanding the characteristics of the bridge circuit sensitive to the resistance change of weak resistors.Including the design and implementation of the main body structure of the incubator,the design and implementation of the temperature control circuit,the design and implementation of the data acquisition,and the experimental verification of the parameters of the incubator,and finally applied to the verification experiment of the standard resistance comparison,the main contents are as follows:Firstly,in this design,the temperature stability of the incubator should meet the requirements of standard resistance storage.The structure design of the incubator adopts double-layer aluminum shell structure design and insulation treatment on the surface.Firstly,the overall structure of the box body is through SolidWorks software.The sealing insulation details are designed,and in order to ensure the uniformity of the temperature of the cabinet,the box body is designed as a square body structure,and the position of the power resistor is uniformly designed on the six faces of the box body.Secondly,the key to the design of the thermostat hardware in this paper is to realize the precise control of the thermostat.The temperature measurement platinum resistance and the laboratory high-precision resistance are used to form the AC bridge circuit,the power amplifier circuit,the phase sensitive detection circuit,and the aluminum shell box power resistor in series.The closed-loop feedback loop composed of the circuit controls the temperature,and the oscillator circuit is used to provide a stable input signal.At the same time,a power supply module is provided to provide a stable DC voltage for the uninterrupted design of the entire system power supply.Finally,in this paper,the visualization and real-time storage of the incubator data is realized by LabVIEW software.At the same time,the short-term stability and long-term stability of the incubator,temperature gradient experiment,power resistance analog standard resistance heat dissipation experiment and standard resistance comparison experiment are designed.The performance of the system is analyzed.The experimental results show that in the laboratory environment,the temperature control process of the oven is less than 5h,the short-term peak-to-peak fluctuation is less than 2mK,and the temperature gradient is less than 5mK.When the applied power is less than 400 mW,the incubator has no obvious change within 1mK.When it is greater than 1.06 W,the temperature control point is obviously shifted,and the stability is deteriorated.The experiment proves that the incubator developed in this paper has reached the standard resistance ratio of 10-9 in the standard resistance ratio under certain conditions.And achieve a moveable goal.