Bipolar Current Resistance Measurement System
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Solution Overview
Problem
Conventional high current resistance measurement systems rely on mechanical switching, which leads to inefficiencies, increased maintenance, and unreliability, limiting their precision and commercial exploitation due to mechanical wear and high costs.
Innovation Solution
A bi-polar current resistance measurement system using a bridge and extender with digital to analog converters, current tracking amplifiers, and comparators to generate and control bi-polar currents, eliminating the need for mechanical switches by directly coupling modular bi-polar high current amplifiers and current comparators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical relay switches are used to reverse high current, then current reversal is achieved, but mechanical wear and maintenance requirements increase
Solution Approach 1:
The patent replaces mechanical relay switches with electronic switching devices (transistors, MOSFETs, or IGBTs) that can reverse high current without mechanical contact. This electronic switching system eliminates mechanical wear, arcing, and maintenance requirements while maintaining the ability to reverse current direction for thermal voltage error cancellation in precision resistance measurements.
Solution Approach 2:
The patent extracts and removes the mechanical switching component from the high current measurement system. By taking out the mechanical relay and replacing it with solid-state electronic switches, the system eliminates the harmful mechanical wear and maintenance issues while preserving the essential current reversal function.
2Measurement precision
If compressed air actuated plungers and large contact surfaces are used, then current control is improved, but system complexity and space requirements increase
Solution Approach 1:
The patent replaces the complex compressed air actuated plunger mechanism with solid-state electronic switches. These electronic devices provide precise current control through electrical signals without requiring mechanical actuators, large contact surfaces, or compressed air systems, thereby reducing overall system complexity while maintaining measurement precision.
Solution Approach 2:
The patent changes the control parameter from mechanical displacement (plunger position) to electrical parameters (voltage and current signals). This allows for more precise and easily controllable current reversal without the mechanical complexity of air actuators and large contact surfaces.
3Ease of operation
If four independent contact pairs are used for current reversal, then current direction control is achieved, but device complexity and space consumption increase
Solution Approach 1:
The patent merges the function of four independent mechanical contact pairs into a single solid-state electronic switching device or a simplified bridge circuit configuration. This integration maintains the ability to control current direction while dramatically reducing the number of separate components, contact surfaces, and associated mechanical structures required.
Solution Approach 2:
The electronic switching device performs multiple functions (current reversal, current direction control, and protection) that previously required four separate contact pairs. This multi-functional approach simplifies the overall system architecture while maintaining ease of operation for current direction control.
4Measurement precision
If large contact surfaces are used to minimize resistance, then contact resistance is reduced, but space requirements and device size increase
Solution Approach 1:
The patent replaces large mechanical contact surfaces with solid-state electronic switches that have inherently low on-resistance. The electronic switching devices achieve minimal resistance through their semiconductor structure without requiring large physical contact areas, thereby reducing space requirements while maintaining measurement precision.
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 solution enables precise resistance measurements at high currents up to ±3000 amperes with reduced system size, cost, and complexity, achieving accuracy of 1 part per million without mechanical switches or external power supplies, and allows for modular expansion and high accuracy resistance measurements.
Implementation Method 1
The comparator includes a series of toroidal current comparators receiving the currents supplied to the test and reference resistances
Implementation Method 2
A high current bi-polar amplifier receives as an input, the output of the converter, amplifies the received input, and for transmits the amplified signal
Implementation Method 3
Testing the resistance of an unknown resistor can be performed in a number of ways. Typically, it involves applying a known voltage across the resistance and measuring the current flow through the resistor
Data Source
AI summary
A resistance testing apparatus makes use of a modular design for cascaded, parallel, bipolar current sources to obviate the need for electromechanical or pneumatic switching systems.