Triaxial Magnetic Sensor Array for Interference-Resistant Current Measurement
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Solution Overview
Problem
Current current measuring devices face challenges in accurately measuring direct and alternating currents of low frequency in hybrid and electric vehicles due to limited flexibility, interference from magnetic fields, and poor measurement accuracy, especially in confined spaces and with small pitch between power semiconductor pins.
Innovation Solution
A current measuring device utilizing three triaxial magnetic sensors arranged with a prescribed positional relationship to exclude the influence of magnetic fields from opposing current paths, allowing for noncontact measurement of currents flowing in measurement-object conductors, including power semiconductor pins and bus bars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic core with a certain size is provided in the vicinity of a measurement-object conductor (zero-flux type), then a current can be measured by detecting a current flowing to cancel out a magnetic flux, but it is difficult to install in a small place
Solution Approach 1:
The patent divides the measurement system into multiple small magnetic sensors (three or more sensors) distributed at different positions around the conductor, replacing a single large magnetic core. Each sensor measures the magnetic field at its specific location, and the controller synthesizes these measurements to calculate the current, enabling measurement in confined spaces while maintaining accuracy.
Solution Approach 2:
The patent transitions from a single-point measurement approach (using one large sensor) to a multi-dimensional spatial distribution approach. By placing multiple sensors at different positions and orientations around the conductor, the system captures magnetic field information from multiple spatial dimensions, enabling accurate current measurement without requiring a large installation space.
2Adaptability or versatility
If a Rogowski coil is used to measure alternating current by detecting voltage caused by magnetic field linkage, then alternating current can be measured, but direct current and low-frequency alternating current cannot be measured accurately
Solution Approach 1:
The patent creates a measurement system that can universally measure both direct current and alternating current (including low-frequency AC) using the same hardware configuration. The combination of multiple magnetic sensors with the controller's calculation algorithm provides multi-functional capability, eliminating the need for different measurement devices for different current types and frequencies.
Solution Approach 2:
The patent replaces the voltage-detection-based Rogowski coil mechanism with a direct magnetic field detection mechanism using magnetic sensors. This substitution allows the system to detect the static magnetic field produced by direct current and the time-varying magnetic field produced by alternating current, including low-frequency AC, through direct magnetic coupling rather than induced voltage, thereby expanding measurement capability across all current types and frequencies.
3Loss of information
If magnetic sensors are disposed at different distances from a measurement-object conductor, then distances can be calculated from sensor outputs, but the magnetic-sensing direction must be aligned with the circumferential direction of the conductor
Solution Approach 1:
The patent creates a dynamic and adaptable sensor arrangement system where sensors can be positioned at various distances and orientations around the conductor without requiring precise alignment with the circumferential direction. The controller dynamically calculates the conductor's position and dimensions by processing measurements from sensors at different locations, allowing flexible installation while still extracting accurate distance and geometric information.
Solution Approach 2:
The patent introduces the controller as an intermediary that processes and synthesizes measurements from multiple sensors positioned at different locations. The controller calculates the conductor's position, dimensions, and current by integrating data from sensors with varying orientations and distances, serving as a mediator that transforms diverse sensor inputs into accurate measurement results without requiring strict sensor alignment.
4Measurement precision
If currents flow in a pair of measurement-object conductors in opposite directions, then current paths are formed, but magnetic field influence from one conductor interferes with measuring current in the other conductor
Solution Approach 1:
The patent extracts and separates the magnetic field contributions from different current paths by using multiple sensors positioned at different locations. The controller processes the sensor measurements to distinguish and extract the magnetic field component originating from each specific conductor, effectively isolating the measurement of interest from interfering magnetic fields produced by adjacent conductors carrying opposite currents.
Solution Approach 2:
The patent implements a feedback mechanism where the controller uses measurements from multiple sensors to calculate and identify the magnetic field contributions from each conductor. By continuously processing sensor data and comparing measurements from different positions, the system can identify and compensate for magnetic field interference from adjacent conductors, improving measurement accuracy through iterative feedback processing.
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 flexible and accurate measurement of direct and alternating currents of low frequency in a noncontact manner, improving measurement accuracy and adaptability in confined spaces.
Implementation Method 1
three triaxial magnetic sensors (31, 32, 33) that are arranged with a prescribed positional relationship such that magnetic-sensing directions of the three triaxial magnetic sensors are parallel to each other
Data Source
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AI summary
A current measuring device (2) that measures a current flowing in one of a pair of measurement-object conductors (MC1, MC2) in which currents flow in opposite directions, includes three triaxial magnetic sensors (31, 32,33) that are arranged with a prescribed positional relationship such that magnetic-sensing directions of the three triaxial magnetic sensors (31, 32,33) are parallel to each other; and a calculator configured to exclude an influence of a magnetic field which is generated due to a current flowing in another measurement-object conductor based on detection results from the three triaxial magnetic sensors (31, 32, 33) and the positional relationship between the three triaxial magnetic sensors (31, 32, 33) and to calculate the current flowing in the one of the measurement-object conductors (MC1, MC2).