Magnetoelectric Current Sensor Orientation for Leakage Field Rejection
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Solution Overview
Problem
Conventional electric power converting apparatuses face increased measurement errors in electric current sensors due to magnetic leakage fields from electric reactors, especially when magnetoelectric transducers and magnetic flux concentrating cores are used together, leading to higher sensitivity to external disturbances and increased costs for shielding.
Innovation Solution
The electric power converting apparatus includes a magnetic flux concentrating core with a measuring space and a magnetoelectric transducer positioned such that the core opening direction is perpendicular to the magnetic leakage field from the electric reactor, reducing the influence of external magnetic fields on the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetoelectric transducer is disposed in a vicinity of the electric reactor, then the electric current can be measured, but measurement errors increase due to magnetic leakage field from the electric reactor
Solution Approach 1:
The patent extracts the harmful magnetic leakage field from the measurement path by positioning the magnetoelectric transducer such that the magnetic leakage field from the electric reactor passes through in a direction perpendicular to the magnetic sensitivity direction of the transducer. This separation of the harmful field component from the measurement path reduces measurement errors while maintaining the ability to measure electric current through the busbar.
Solution Approach 2:
The patent introduces asymmetric orientation between the magnetoelectric transducer and the electric reactor. By aligning the magnetic sensitivity direction of the transducer perpendicular to the magnetic leakage field direction, the measurement system becomes asymmetric with respect to the interference field, allowing the transducer to be sensitive to the busbar's magnetic field while being insensitive to the reactor's leakage field.
2Measurement precision
If the sensitivity of the magnetoelectric transducer to magnetic fields is increased, then measurement capability is improved, but external disturbances are detected more, requiring additional shielding and increasing costs
Solution Approach 1:
The patent applies local quality by creating a specific spatial configuration where the magnetoelectric transducer has high sensitivity to magnetic fields in one direction (perpendicular to the leakage field) while being inherently insensitive to disturbances in another direction (parallel to the leakage field). This directional selectivity allows high sensitivity without requiring additional shielding against external disturbances.
3Measurement precision
If a magnetic flux concentrating core is added to the electric current sensor, then measurement capability is improved, but the magnetic leakage field from the electric reactor is more likely to reach the magnetoelectric transducer, increasing measurement errors
Solution Approach 1:
The patent resolves the contradiction by introducing a spatial dimension solution - positioning the magnetoelectric transducer in a specific orientation relative to both the busbar and the electric reactor. The core opening direction is set perpendicular to the magnetic leakage field direction, creating a three-dimensional spatial relationship where the magnetic flux concentrating core can concentrate the busbar's magnetic field while the transducer's sensitivity direction remains perpendicular to the reactor's leakage field, preventing the leakage field from reaching the transducer through the core.
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 effectively suppresses measurement errors in electric current sensors by minimizing the impact of magnetic leakage fields, reducing the need for additional shielding and lowering costs while maintaining sensor accuracy.
Implementation Method 1
a magnetoelectric transducer that has a magnetically sensitive portion disposed in the measuring space, the magnetoelectric transducer generating a signal in response to a magnitude of a magnetic field that is sensed by the magnetically sensitive portion
Implementation Method 2
a magnetic flux concentrating core that has a first end portion and a second end portion that face each other so as to have a measuring space interposed
Data Source
AI summary
In the electric power converting apparatus, an electric current sensor that measures an electric current that flows through a busbar includes: a magnetic flux concentrating core that has a first end portion and a second end portion that face each other so as to have a measuring space interposed; and a magnetoelectric transducer that has a magnetically sensitive portion that is disposed in the measuring space. The magnetoelectric transducer generates a signal in response to a magnitude of a magnetic field that is sensed by the magnetically sensitive portion. Where a core opening direction of the magnetic flux concentrating core is a direction that is directed from the busbar, through the measuring space, and outward from the magnetic flux concentrating core, a direction of the magnetic leakage field at the electric reactor is a direction that is different than the core opening direction.