Hall Effect Current Sensor with Opposing Detectors and Shielding
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Solution Overview
Problem
Current detection apparatuses are bulky due to the requirement of a ring-shaped core for Hall elements, restricting downsizing and making precise failure determination of Hall elements challenging, especially when affected by external magnetic fields.
Innovation Solution
A current detection apparatus with two magnetic detectors arranged oppositely on a board above a current path, enclosed within an electromagnetic shielding frame, allowing for precise failure determination without a core and minimizing external magnetic field interference, with sensitivities adjusted to ensure identical current outputs in normal states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two Hall elements are provided in the magnetic gap of a ring-shaped core to detect current in sufficient levels, then current detection performance is improved, but the size of the whole device becomes large and mounting structure is restricted
Solution Approach 1:
The patent transitions from a planar arrangement of Hall elements on the same plane to a three-dimensional arrangement where Hall elements are positioned at different heights above and below the current path. This vertical dimensionality change allows compact positioning of multiple sensors without increasing planar footprint, resolving the contradiction between detection performance and device size.
Solution Approach 2:
Instead of placing Hall elements on the same plane as in conventional designs, the patent inverts the arrangement by positioning them at different heights in the vertical direction. This inverted spatial configuration enables better current detection while reducing overall device dimensions.
2Device complexity
If two magnetic detectors are arranged on the same plane without a core, then device complexity is reduced, but failure determination of Hall elements becomes difficult when affected by external magnetic fields
Solution Approach 1:
The patent positions Hall elements at different vertical heights above and below the current path rather than on the same plane. This three-dimensional arrangement creates symmetric detection conditions that enable reliable failure determination through comparison, while maintaining simple device structure without requiring a ring-shaped core.
Solution Approach 2:
The patent employs asymmetric positioning of Hall elements at different heights relative to the current path, with one element above and one below. This asymmetric yet symmetric-magnitude arrangement allows differentiation between external magnetic field effects and sensor failures, improving reliability while keeping the structure simple.
3Object-affected harmful factors
If Hall elements are arranged at different heights in the electromagnetic shielding frame, then external magnetic field interference is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by positioning Hall elements at specific heights above and below the current path where magnetic field strength is comparable. This localized strategic positioning reduces external magnetic field interference while maintaining manufacturability, as the specific height positions can be optimized during manufacturing without requiring extreme precision.
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 simplifies and downsizes the apparatus, enabling precise current measurement and failure determination of Hall elements without external magnetic field interference, allowing for efficient detection of current values.
Implementation Method 1
the Hall element in the magnetic gap generates a voltage (Hall voltage) due to Hall Effect in accordance with the magnetic field
Implementation Method 2
an electromagnetic shielding frame member is mounted on the current path so that the two magnetic detectors and a part of the current path where the two magnetic detectors are arranged are accommodated inside the electromagnetic shielding frame member
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
There is provided a current detection apparatus which enables the downsizing in structure, and which can perform failure determination of Hall elements with high precision without being affected by an external magnetic field. It includes two magnetic detectors (15, 16) that are arranged oppositely on a front surface and a back surface (23a, 23b) of a board (23) which is located above a current path in order to detect a strength of a magnetic field which is generated by a current which flows in the current path (11), an electromagnetic shielding frame member (14) that is mounted on the current path (11) so that the two magnetic detectors (15, 16) and a part of the current path (11) where the two magnetic detectors are arranged are accommodated inside the electromagnetic shielding frame member, and a control circuit that determines whether a failure which occurs in either of the two magnetic detectors (15, 16) from a difference between magnetic fields detected by the two magnetic detectors, respectively. Sensitivities of the two magnetic detectors (15, 16) are made adjusted so that current values outputted from the two magnetic detectors depending on detected magnetic fields are identical to each other in a normal state.