Current Sensor Using Test Current Injection for Shunt-Free Measurement
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Solution Overview
Problem
Current current sensors employing dedicated shunts face complexities in design due to the need to interrupt the primary current path, result in increased space and cost, and suffer from high insertion losses and thermo offsets, especially when used on substrates like PCBs.
Innovation Solution
A system and method that allows for the determination of primary current without a dedicated shunt by injecting a test current into the conductor, measuring the voltage drop, and using a microelectronic device to calculate the primary current based on a predefined reference resistance, which can be calibrated to account for temperature drift and material differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated shunt is employed to measure current, then measurement accuracy is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent extracts the current measurement function from a separate dedicated shunt component and integrates it directly into the power conductor traces. By removing the need for a separate shunt assembly and its associated routing, vias, and solder interfaces, the system achieves simpler design while maintaining measurement capability through direct voltage sensing across segments of the power conductor itself.
Solution Approach 2:
The power conductor traces serve dual functions: they carry the primary current and simultaneously provide the sensing path for current measurement. The same conductor structure that performs power transmission also enables voltage-based current measurement, eliminating the need for separate measurement components and reducing overall system complexity.
2Measurement precision
If a dedicated shunt is used, then current measurement is enabled, but power dissipation increases
Solution Approach 1:
The patent changes the measurement approach from current-based (using a shunt resistor that dissipates power) to voltage-based measurement. By measuring the voltage drop across known segments of the power conductor and using Ohm's law to calculate current, the system eliminates the need for a dedicated power-dissipating shunt resistor, thereby reducing energy loss while maintaining measurement accuracy.
3Measurement precision
If the primary current path is interrupted for shunt measurement, then measurement accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the current-carrying function and the voltage-sensing function into a single integrated conductor structure. Instead of interrupting the power path to insert a separate shunt, the design uses continuous power conductor traces with embedded voltage sensing capability, eliminating the need for additional vias, solder interfaces, and complex routing arrangements.
4Measurement precision
If solder interfaces are used to connect shunt, then current measurement is achieved, but reliability decreases due to electromigration
Solution Approach 1:
The patent removes the solder interface connection step entirely by integrating the voltage sensing function directly into the power conductor traces. This eliminates the reliability issues associated with solder joints subjected to high current density and electromigration, as there are no separate connection interfaces where such degradation could occur.
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
Enables accurate measurement of primary current with reduced complexity and cost, minimizing power dissipation and thermo offsets, while eliminating the need for a dedicated shunt, thus simplifying the design and improving measurement accuracy.
Implementation Method 1
The at least one processor is configured to determine a primary current through the conductor based on the input signal and the predefined reference resistance
Implementation Method 2
a pair of force terminals configured to inject, via the at least one first electrical contact and the at least one second electrical contact, a test current into the conductor
Data Source
AI summary
Current sensors, systems and methods are provided. A test current is injected via a pair of force terminals into a conductor and a pair of sense terminals are configured to provide an input signal that corresponds to a voltage drop across the conductor. Based on the test current in the conductor and based on the input signal, a contribution to the voltage drop due to the test current and a contribution to the voltage drop due to a primary current through the conductor may be determined. In addition, at least one of a reference resistance of the conductor and the primary current in the conductor may be further determined.