Current Sensor Design Using Differential Magnetic Detection
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Solution Overview
Problem
Current sensors face challenges in measuring high currents accurately while minimizing size and thickness, as magnetic sensors become magnetically saturated by induction magnetic fields, especially when positioned near high-current conductors, leading to difficulties in noise reduction and sensitivity enhancement.
Innovation Solution
A current sensor design featuring first and second magnetic sensors disposed on opposite surfaces of a substrate parallel to a conductive member, with sensing axes forming a predetermined angle to the induction magnetic field, reducing magnetic saturation and noise interference by applying induction magnetic fields in reverse directions, and using a differential unit to process output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If magnetic sensors are disposed in the vicinity of the current line to reduce sensor size and thickness, then the sensor dimensions are reduced, but the magnetic sensors become magnetically saturated by the induction magnetic field from high current
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional configuration by disposing magnetic sensors on both the front and back surfaces of a substrate. This spatial arrangement allows the sensors to be positioned closer to the current line (reducing size) while maintaining measurement capability through differential detection of magnetic fields from opposite sides, thus resolving the contradiction between miniaturization and measurement reliability.
Solution Approach 2:
The substrate acts as an intermediary structure that holds the magnetic sensors at optimized positions relative to the current line. By placing sensors on both surfaces of the substrate, the system mediates between the need for close proximity (for compactness) and the need to avoid magnetic saturation (for reliability), enabling high-current measurement capability while maintaining small form factor.
2Measurement precision
If magnetic sensors are disposed on the substrate at positions opposing each other with current line interposed to enhance output sensitivity, then detection sensitivity is improved, but the sensor thickness increases
Solution Approach 1:
Instead of increasing thickness to place sensors on opposite sides, the patent utilizes the third dimension by disposing sensors on both the front and back surfaces of a thin substrate. This approach achieves differential measurement capability (improving sensitivity) while maintaining minimal thickness, as the substrate itself serves as the separation medium rather than requiring additional spacing.
3Volume of moving object
If the pair of magnetic sensors are disposed in the vicinity of the current line to reduce size, then compactness is achieved, but magnetic saturation occurs during high current measurement
Solution Approach 1:
The patent divides the sensing function into multiple segments by using both front and back surfaces of the substrate for sensor placement. This segmentation allows each sensor to operate within its linear range even during high current measurement, as the differential configuration distributes the magnetic field exposure, thereby expanding the measurable current range while maintaining compact dimensions.
Solution Approach 2:
The patent changes the operational parameters of the magnetic sensors by applying differential measurement techniques. This parameter change allows the sensors to operate in a regime where they remain linear even when exposed to high induction magnetic fields, thus expanding the measurable current range from minute currents to high currents without increasing sensor size.
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
This configuration allows for accurate measurement of high currents, reduces sensor size and thickness, and enhances detection sensitivity by minimizing noise from disturbance magnetism, thereby improving measurement accuracy and dynamic range.
Implementation Method 1
a first magnetic sensor and a second magnetic sensor which output signals having reversed phases to each other due to an induction magnetic field from the current to be measured
Implementation Method 2
a differential unit which performs differential operation on the output signal of the first magnetic sensor and the output signal of the second magnetic sensor, wherein since the output signals having reversed phases to each other are output from the pair of magnetic sensors, the output signals are processed to be added to each other by differential operation and thus output sensitivity is enhanced. In addition, noise components other than the output signals of the pair of magnetic sensors have the same phase and thus are removed by the differential operation.
Implementation Method 3
a sensor including a magnetic sensor that detects a current to be measured, which flows through a conductor, using a change in magnetic field in the periphery of the conductor
Data Source
AI summary
A current sensor includes: a conductive member through which a current to be measured flows; first and second magnetic sensors which output signals having reversed phases to each other due to an induction magnetic field from the current to be measured; and a control unit which performs differential operation on the output signal of the first magnetic sensor and the output signal of the second magnetic sensor, wherein sensing axis directions of the first magnetic sensor and the second magnetic sensor are fixed in the same direction, form a predetermined angle with respect to an application direction of the induction magnetic field from the current to be measured applied to the first magnetic sensor and the second magnetic sensor, and are fixed so that the induction magnetic fields are applied to the first magnetic sensor and the second magnetic sensor in reverse directions to each other.