Magnetoresistor Current Sensing With Galvanic Isolation and Offset Control
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Solution Overview
Problem
Existing current measurement technologies lack a single magnetoresistor-based solution that provides non-dissipative galvanic isolation, offset adjustment, and current biasing using a triple voltage-to-current converter, leading to issues such as self-heating, limited DC response, and complex compensation mechanisms.
Innovation Solution
An electronic device utilizing a single magnetoresistor with a triple voltage-to-current converter, comprising a sensing subsystem, a resistor with gain, an offset adjustment resistor, and a processor to provide galvanic isolation, compensate for imbalances, and generate a voltage signal proportional to the current, without dissipating the measured current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shunt technology is used to measure current, then the measurement is simple and direct, but galvanic isolation is not provided and self-heating occurs
Solution Approach 1:
The patent introduces a magnetoresistor as an intermediary element that couples the current-carrying conductor to the measurement circuit through magnetic field interaction rather than direct electrical contact. This mediator provides galvanic isolation while enabling accurate current measurement without self-heating of the measurement circuit components.
Solution Approach 2:
The patent replaces the direct electrical connection (shunt resistor) with a magnetic field-based measurement system. The magnetoresistor detects the magnetic field generated by the current through non-contact means, eliminating the need for direct electrical contact and thereby preventing self-heating and providing galvanic isolation.
2Object-affected harmful factors
If current transformer is used, then galvanic isolation is provided, but the device volume is large and DC measurement is not possible
Solution Approach 1:
The patent extracts the magnetic core from the traditional current transformer design, using only the magnetic field interaction principle without requiring a bulky closed magnetic core. This allows galvanic isolation to be maintained while dramatically reducing the device volume to accommodate magnetoresistor-based current sensing.
3Object-affected harmful factors
If Hall effect sensor is used, then galvanic isolation is provided, but the device is bulky and requires high current consumption
Solution Approach 1:
The patent employs magnetoresistors that can be implemented as simple resistive elements without requiring complex Hall effect sensor structures, ferrite cores, or high-current consumption circuitry. This provides a more compact, lower-power solution while maintaining galvanic isolation through magnetic field coupling.
4Device complexity
If magnetoresistor is used without triple voltage-to-current converter, then the structure is simpler, but offset compensation and thermal drift compensation are not achieved
Solution Approach 1:
The patent implements feedback mechanisms through the triple voltage-to-current converter that continuously monitor and compensate for offset errors and thermal drift in the magnetoresistor. The converter adjusts the excitation current based on detected variations, maintaining measurement accuracy despite environmental changes or component imperfections.
Solution Approach 2:
The patent dynamically changes the excitation parameters (voltage and current) through the triple voltage-to-current converter to compensate for thermal drift and offset variations. By adjusting the operating parameters of the magnetoresistor based on temperature and offset detection, the system maintains measurement precision across varying conditions.
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
The device offers non-dissipative galvanic isolation, eliminates self-heating, simplifies manufacturing, and compensates for offset and thermal drift, providing accurate current measurement across a wide range of applications.
Implementation Method 1
a magnetoresistor which changes its value as a function of the current to be measured
Data Source
Figure 1~2
AI summary
A device for measuring electric current by means of non-dissipative galvanic isolation, with offset adjustment and current biasing using a triple voltage-to-current converter, comprising: a first sensing subsystem comprising at least one magnetoresistor configured as a sensing element configured to provide galvanic isolation from an electric current to be measured; a second subsystem comprising a resistor through which a current flows according to the value having a gain and a control voltage; a third subsystem comprising an offset adjustment resistor through which the current determined in the second subsystem flows, which makes it possible to compensate for any eventual imbalance existing in the sensing element at zero measured current; and a fourth subsystem consisting of a processor providing a voltage signal proportional to the electric current to be measured.