Magnetoresistor Sensor Galvanic Isolation Automotive
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Solution Overview
Problem
Existing systems for measuring voltage or current in on-board power generators, such as fuel cells, face challenges with galvanic isolation, size constraints, heat dissipation, accuracy, and reliability, particularly in automotive applications where multiple cells require complex and bulky setups with intrusive devices and limited compatibility with CAN networks.
Innovation Solution
A magnetoresistor integrated sensor with elongated parallel sections and a galvanic isolation layer, utilizing giant or tunnel magnetoresistors, provides significant galvanic isolation and an integrated fuse function, enabling compact and reliable voltage or current measurements by arranging the metal measuring line directly on the galvanic isolation layer, with magnetoresistors sensitive to the magnetic field created by the current flow, and incorporating a resistor bridge for voltage range extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage measurement systems with DC-to-DC converters and optoelectronic converters are used, then galvanic isolation can be achieved, but the device size and complexity increase significantly
Solution Approach 1:
The patent extracts the measurement function from the high-voltage side by using a current loop that carries a current proportional to the voltage being measured. This current loop is placed on the low-voltage side of the galvanic isolation barrier, eliminating the need for complex DC-to-DC converters and optoelectronic converters on the high-voltage side. Only simple resistors and a differential amplifier are needed on the low-voltage side to process the current signal.
Solution Approach 2:
The patent introduces a current loop as an intermediary carrier that transfers measurement information across the galvanic isolation barrier. Instead of directly converting high voltage to isolated digital signals, the system uses a current-proportional signal that can be easily transmitted through the isolation barrier and then converted to voltage signals on the low-voltage side using simple resistors.
2Adaptability or versatility
If multiple cells are measured using conventional systems with multiplexers and resistor bridges, then voltage range can be covered, but measurement accuracy decreases due to crosstalk and potential channeling
Solution Approach 1:
The patent assigns a dedicated current loop to each cell being measured, eliminating the need for multiplexers and resistor bridges that cause crosstalk. Each cell's voltage is converted to a proportional current in its own isolated loop, which is then converted back to voltage by a dedicated amplifier stage. This segmentation ensures that measurements from different cells are electrically independent and free from mutual interference.
3Ease of manufacture
If intrusive measurement devices are used during adjustment phase, then no on-board feed is needed, but permanent diagnosis and control interaction are not permitted
Solution Approach 1:
The patent designs a measurement system that serves multiple functions: it provides accurate voltage measurement for diagnosis, enables control interactions by providing precise voltage information to the control unit, and maintains permanent operation capability. The system uses a current loop that can continuously monitor cell voltages without being intrusive, allowing both adjustment phase measurements and permanent operation monitoring.
4Productivity
If large number of cells are measured with conventional systems, then complete coverage is achieved, but constraining cables and intermediate boxes are required
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated current loop system. Instead of using separate cables and intermediate boxes for each cell, the system uses a common current loop that carries a current proportional to the voltage being measured. This current loop is processed by a single differential amplifier stage that can handle multiple cells, eliminating the need for complex cabling arrangements and intermediate measurement boxes.
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 solution achieves high galvanic isolation, compactness, and reliability, allowing for accurate voltage or current measurements across multiple cells with reduced noise and power consumption, while the integrated fuse function protects against overvoltage, enhancing the system's robustness and compatibility with automotive environments.
Implementation Method 1
at least two magnetoresistors for measuring the magnetic field created remotely by said current flowing through said measuring line
Implementation Method 2
said current flowing through this line creating a magnetic field measured remotely by the magnetoresistors
Data Source
AI summary
The invention relates to an integrated sensor, including terminals (1, 2) for connection to an electric generator, said terminals being connected to a metal measuring line (4, 5) in which a current proportional to the voltage or current of the generator to be measured flows, and magnetoresistors (31, 32, 33, 34). The metal measuring line includes elongate and parallel sections (4, 5) in which the current flows in opposite directions, said sections being connected to a portion (3) for closing the metal measuring line (3, 4, 5), which is arranged on a galvanic isolation layer (8) that is in turn arranged on an integrated circuit portion including the magnetoresistors (31, 32, 33, 34), each of which have a sensitive portion that is vertically adjacent to one of the elongate sections (4, 5). The sensor can be integrated into a diagnostic system.