Current Detection Device Shielding Eddy Current Compensation
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Solution Overview
Problem
Conventional current detection devices with shield layers suffer from eddy currents generated by high-frequency AC currents, which cancel out the magnetic fields detected by Hall elements, leading to insufficient output voltage and reduced detection accuracy.
Innovation Solution
The current detection device incorporates an additional coil pattern and operation circuit to generate a counter-eddy current in the shield layer, adjusting the current supplied to this coil to optimize the cancellation of eddy currents and enhance the magnetic field detected by the Hall element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shield layer is disposed between the coil and the Hall element to ensure high-performance and stable operation, then shielding effectiveness is improved, but eddy currents are generated on the shield layer when high frequency AC current flows through the coil, causing the magnetic field to be canceled and detection accuracy to deteriorate
Solution Approach 1:
The patent applies the principle of converting harm into benefit by utilizing the eddy current phenomenon. Instead of merely suppressing eddy currents as harmful effects, the invention introduces a compensation coil that generates a compensating magnetic field to counteract the adverse effects of eddy currents. This transforms the problem of eddy current interference into a solvable issue through active compensation, thereby maintaining both shielding effectiveness and detection accuracy.
Solution Approach 2:
The patent employs an intermediary approach by introducing a compensation coil as a mediating element between the shield layer and the Hall element. This compensation coil generates a magnetic field that acts as an intermediary force to counterbalance the harmful magnetic field produced by eddy currents, thereby protecting the detection accuracy without compromising the shielding function.
2Reliability
If a shield layer is disposed between the coil and the Hall element, then electromagnetic shielding is improved, but the output voltage from the Hall element is lowered due to magnetic field cancellation, requiring amplification circuits that increase device complexity
Solution Approach 1:
The patent converts the harmful effect of eddy currents into a beneficial solution by using the compensation coil to generate a counteracting magnetic field. This active compensation approach reduces the need for complex amplification circuits, as the magnetic field cancellation is addressed at its source rather than requiring post-detection signal processing.
Solution Approach 2:
The patent applies preliminary action by proactively compensating for eddy current effects before they significantly degrade the detection signal. The compensation coil continuously generates a counteracting magnetic field that prevents magnetic field cancellation, thereby maintaining sufficient output voltage from the Hall element without requiring excessive amplification.
3Speed
If high frequency AC current is supplied to the coil for detection, then detection speed is improved, but eddy currents are generated on the shield layer that cancel the magnetic field and reduce output voltage
Solution Approach 1:
The patent converts the harmful energy loss from eddy currents into a manageable issue by introducing active compensation. The compensation coil generates a magnetic field that counteracts the eddy current effects, thereby preserving the output voltage and enabling high-frequency AC current detection without significant energy loss.
Solution Approach 2:
The patent implements a feedback mechanism where the compensation coil's operation is based on the detected eddy current effects. By continuously monitoring the magnetic field conditions and adjusting the compensation accordingly, the system maintains optimal detection performance at high frequencies while minimizing energy loss.
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 increases the magnetic field detected by the Hall element, improving the accuracy and performance of current detection by effectively canceling out the opposing eddy currents and enhancing the output voltage.
Implementation Method 1
The generated magnetic field is detected by a Hall element, for example
Implementation Method 2
when a current which flows through the coil is an AC current, particularly, a high frequency AC current, an eddy current is generated on the shield layer, so that a magnetic field is generted by the eddy current
Implementation Method 3
a current to be detected is supplied to a coil, and the current is detected by detecting a magnetic field generated from the coil
Data Source
AI summary
A current detection device includes a first coil, a magnetic field detection element, a shield layer, a second coil, and an operation circuit. The first coil has a planar shape. The magnetic field detection element is disposed in a spaced apart manner from the first coil in a direction orthogonal to a plane of the first coil, and is disposed so as to receive a magnetic field which the first coil generates. The shield layer is disposed between the first coil and the magnetic field detection element. The second coil is disposed in a spaced apart manner from the first coil with respect to an axis perpendicular to the shield layer. The operation circuit operates the second coil.