Research Of Four-terminal-pair Bifilar Helix Calculable Resistor And Its Quantity Value Transfer System

Metrology is the activity for keeping the unity of the unit and ensuring the accuracy and reliablitiy of the quantity value. Metrology is a national basic technology and become an important mark of technology, economy and society. Resistance standard is one of the most important standards in field of electromagnetic metrology. In China, since the DC Quantum Hall Resistance(QHR) standard had already been set up, the establishment of AC resistance standard becomes the major interests at present. One feasible solution is to apply the Calculable Resistor as the standard component and make the AC resistance quantity values indirectly traced to QHR. This thesis aims at solving key problems of establishing national AC resistance standard based on four-terminal-pair BHCR, including the develpoment of resistor and precision quantity value dissemination system.In this thesis, Bifilar Helix Calculable Resistor(BHCR) is extended to four-terminal-pair component which has perfect definition and shielding structure. The definition of four-terminal-pair component includes the impedance of the coaxial cable, once the parameters of coaxial cables have been changed, the impedance of the component will be changed as well. The additional error caused by coaxial cable is calculated through establishing the equivalent circuit model of four-terminal-pair BHCR in consideration of coaxial cable. The AC/DC resistance difference of BHCR induced by parasitic parameter, dielectric loss and skin effect are analyzed and calculated.The material resistor and corresponding AC resistance box are designed to meet the definition requirements of four-terminal-pair BHCR. Two dimensional steady heat conduction equations of temperature field are set up and solved by the method of separating variables to obtain the best thickness ratio between heat dissipation layer and heat insulating layer.Temperature control system is implemented based on low power microcontroller and high resolution digital thermal sensor, and the controller parameters are optimized by particle swarm algorithm. Automatic test system based on virtual instrument is built to test the four-terminal-pair BHCR. Measurement results show that the temperature stability inside AC resistance box is 0.0156℃ and the resistance stability of four-terminal-pair BHCR is about 3.5×10-7.A digital error compensator is presented whose output can be regulated in four-quadrant in a wide frequency range. The kernel component of the compensator is 16-bit multiplying digital-to-analog converters and the in-phase and quadrature component of the output can be independently adjusted according to the controlling code with high linearity and low frequency dependency.A computer-controlled current-comparator bridge for scaling four-terminal-pair BHR is proposed. The induced electromotive force of detection wind is measured by a lock-in amplifier, and the controlling code for the compensator is calculated by Newton iterative method. The error current in the bridge is tracking compensated and the current comparator will be auto-balanced.The AC/DC relative difference of four-terminal-pair BHCR is measured by the proposed bridge. Measurement results show that four-terminal-pair BHCR has good consistency, because the AC/DC resistance relative difference between three four-terminal-pair BHCRs is below 1×10-7. At last, the AC/DC difference of four-terminal-pair BHCR is transferred to commercial AC standard resistor, and the combined standard uncertainty of measurement is 1.7×10-7 which can meet the requirement of AC resistance quantity value transfer.