AC Quantum Resistance Bridge With Isolated Winding for Fast Balance
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Solution Overview
Problem
The existing four-terminal-pair AC impedance bridges face challenges in achieving high-accuracy resistance dissemination due to complex structures and mutual interference between balance networks, leading to slow convergence and difficulty in achieving 10−8 order of magnitude uncertainty, which is essential for traceability and quantum impedance standardization.
Innovation Solution
An isolated inductive winding with a small number of turns is wound on the ratio transformer to supply excitation current to the injection inductive voltage divider, reducing mutual interference and allowing for rapid balance convergence by minimizing the load impact on the supply transformer, thus enabling high-accuracy four-terminal-pair AC resistance dissemination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the primary winding of the injection inductive voltage divider is directly connected to the supply transformer, then the excitation current is supplied, but the mutual interference between balance networks increases and balance convergence becomes slow
Solution Approach 1:
An isolated inductive winding is introduced as an intermediary component between the supply transformer and the injection inductive voltage divider. This isolated winding provides magnetic coupling to supply excitation current to the voltage divider while electrically isolating it from the supply transformer, thereby reducing mutual interference between balance networks and improving balance convergence speed without sacrificing measurement precision
2Measurement precision
If the injection inductive voltage divider is adjusted to achieve error balance, then the load of power supply changes, but the Wagner branch balance is broken and cyclic adjustment is required
Solution Approach 1:
The isolated inductive winding acts as a buffer that decouples the load changes in the injection inductive voltage divider from the supply transformer. When the voltage divider is adjusted for error balance, the isolated winding prevents these load changes from significantly affecting the Wagner branch balance, thereby reducing the need for repeated cyclic adjustments and saving time
3Measurement precision
If a four-terminal-pair AC impedance bridge is used to achieve 10−8 order of magnitude uncertainty, then the traceability is improved, but the structure becomes very complicated and the balancing process becomes tedious
Solution Approach 1:
The isolated inductive winding simplifies the overall bridge structure by providing a clean excitation path that reduces interactions between different balance networks. This intermediary component enables the bridge to achieve 10−8 order of magnitude uncertainty while reducing structural complexity and making the balancing process less tedious
4Measurement precision
If multiple balance networks are used to eliminate various interferences, then the measurement accuracy is improved, but the balance convergence becomes slow due to mutual influence
Solution Approach 1:
The isolated inductive winding serves as a mediator that allows multiple balance networks to operate more independently. By providing magnetic coupling with electrical isolation, it enables the injection inductive voltage divider to function without significantly interfering with other balance networks, thereby maintaining high measurement accuracy while improving balance convergence speed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces mutual interference between balance networks, allowing for quick convergence and achieving the required 10−8 order of magnitude uncertainty, simplifying the measurement process and reducing the workload of measurement personnel.
Implementation Method 1
an isolated inductive winding L0 of a small number of turns is independently and additionally wound on the winding of the ratio transformer IVD2 to supply an excitation current to a primary winding of the injection inductive voltage divider A4
Data Source
AI summary
A four-terminal-pair AC quantum resistance dissemination bridge and related methods are provided. The bridge includes: a supply transformer IVD1, a Kelvin branch A1, a Wagner branch A0, the first and second current sources A2, A3, an injection inductive voltage divider A4, a ratio transformer IVD2, the first and second four-terminal AC resistor connection points Z1, Z2, chokes H, and null indicators D. An isolated inductive winding LO is wound along the ratio transformer IVD2 and supplies excitation current to primary winding of injection inductive voltage divider A4 to avoid the mutual influence among various balance networks and rapid balance of the bridge can be realized. By changing turn ratio of primary winding L3 and secondary winding L4 of the second inductive voltage divider T2, the phase shift can be realized through only one set of capacitors for imaginary part error compensation, the bridge with multiple frequency points can be obtained.