Magnetic Current Sensor Self-Test Using a Parallel Test Conductor
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Solution Overview
Problem
Existing current sensor detection methods either require redundant sensors, interrupt the current flow, or incur energy losses, making them inefficient for early detection of failure phenomena in safety-critical applications like power electronics.
Innovation Solution
A device with a test conductor loop arranged parallel to the main current path, using a test current generator to introduce a modulated test current, allowing for error-free operation detection without interrupting the current flow, utilizing magnetic-field-sensitive effects like AMR, GMR, or Hall effects for timely failure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shunt resistors are used for current measurement, then current can be measured, but additional energy losses occur in the form of heat
Solution Approach 1:
The patent replaces the mechanical/electrical shunt resistor system with a magnetic field-based measurement system. A magnetic field sensor detects the magnetic field generated by the current in the conductor, eliminating the need for physical contact through a shunt resistor. This substitution transforms the measurement from direct electrical contact to indirect magnetic field detection, thereby eliminating energy losses in the shunt resistor while maintaining measurement capability.
2Reliability
If a test current is introduced into the main current path for detection, then failure detection is enabled, but the current flow is influenced or temporarily interrupted
Solution Approach 1:
The patent segments the current path into two separate loops: the main current path for normal operation and a separate test current path for detection. The test current flows through a dedicated test conductor that is spatially separated from the main current path, allowing independent testing without affecting the main current flow. This segmentation enables continuous monitoring while maintaining uninterrupted power delivery.
Solution Approach 2:
The patent introduces a magnetic field sensor as an intermediary element that detects magnetic fields from both the main current path and the test current path. This intermediary enables the detection system to monitor both currents simultaneously without direct electrical connection or interference between the test and main current paths, allowing failure detection without interrupting the main current flow.
3Measurement precision
If ferromagnetic cores with auxiliary windings are used, then current measurement is achieved, but the system becomes bulky and requires mechanical guidance of the main current conductor
Solution Approach 1:
The patent replaces the bulky ferromagnetic core structure with planar conductors arranged in loops on a circuit board. The magnetic field detection is achieved through integrated magnetic field sensors positioned near the conductor loops, eliminating the need for large ferromagnetic cores and mechanical guidance structures. This planar integration significantly reduces the physical size and complexity of the measurement system.
Solution Approach 2:
The patent transitions from a three-dimensional ferromagnetic core structure to a two-dimensional planar conductor layout. The current paths are formed as planar loops on a circuit board plane, with magnetic field sensors positioned in the same plane or slightly offset. This dimensional reduction simplifies the overall system architecture and eliminates the need for complex mechanical assembly of the main current conductor through the core.
4Device complexity
If simple shunt measuring systems are used, then galvanic isolation is lacking, but the system design must accommodate any possible voltages and currents
Solution Approach 1:
The patent uses magnetic field sensors as intermediaries to achieve galvanic isolation between the high-voltage current path and the low-voltage measurement circuitry. The magnetic field sensor converts the magnetic field generated by the current into an electrical signal without requiring direct electrical contact. This intermediary transformation provides inherent galvanic isolation, protecting the measurement system from high voltages and currents while maintaining design simplicity.
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 continuous, non-invasive monitoring of current sensors, ensuring timely detection of failures without influencing the main current flow, suitable for demanding safety applications like electric vehicles and power electronics.
Implementation Method 1
a magnetic field sensor and an ammeter. Structures are formed on a substrate as diagonal or perpendicular walls relative to a main substrate plane which are preferably formed as channels or ridges for generating variously oriented magnetic-field-sensitive layers at different angles. A magnetic field sensor outfitted in this manner is then used in a current sensor such that the magnetic effect of the current flow in a conductor at the location of the magnetic field sensor is utilized for determining the current strength.
Implementation Method 2
a test current generator for introducing a modulated test current into the test conductor loop. The test conductor loop is adapted to a main current path predetermined by the busbar or conductor loop such that a modulated test current introduced into the test conductor loop can be sensed in a magnetic-field-sensitive manner in the measuring region of the current sensor
Implementation Method 3
detecting an error-free operation of a current sensor based on a magnetic-field-sensitive sensing element which is preferably formed as a gradient sensor
Data Source
AI summary
A device for detecting an error-free operation with a magnetic-field-monitored busbar or conductor loop for current measurement based on a magnetic-field-sensitive sensor element. The busbar or conductor loop is formed in a measurement plane of the current sensor and can be sensed at least in a measurement region by the current sensor based on a magnetic-field-sensitive effect. The test conductor loop is arranged in spatial proximity to the conductor loop sensed by the current sensor, the test conductor loop being arranged in a plane which is parallel to the measurement plane of the sensed conductor loop and is adapted to a main current path predetermined by the conductor loop such that a modulated test current introduced into the test conductor loop can be sensed in a magnetic-field-sensitive manner in the measuring region of the current sensor together with a current in the main current path.