Three-Phase Current Sensor Layout Tolerant to Element Misalignment
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Solution Overview
Problem
Existing current detection apparatuses for three-phase motors suffer from reduced energy efficiency due to insufficient consideration of positional deviation of magnetic detection elements relative to phase current lines, which affects the accuracy of current measurements.
Innovation Solution
The apparatus includes α-axis and β-axis magnetic detection elements positioned such that their detection centers are orthogonal to specific virtual lines passing through the phase current lines, with the β-axis detection center arranged at equal distances from the phase current lines within a predetermined allowable setting error range, ensuring minimal sensitivity coefficient changes due to positional deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If magnetic detection elements are positioned at geometrically determined positions for spatial Clarke transformation, then the number of magnetic detection elements is reduced and calculation load is reduced, but the system becomes highly sensitive to positional deviation of the magnetic detection elements
Solution Approach 1:
The patent changes the geometric parameters of the magnetic detection element arrangement, specifically positioning the β-axis magnetic detection element on the second virtual line that passes through the midpoint of the first virtual line connecting the first and third phase current lines. This parameter optimization makes the spatial Clarke transformation less sensitive to positional deviations, thereby maintaining measurement precision while reducing the number of detection elements.
Solution Approach 2:
The patent performs preliminary positioning of the magnetic detection elements during the design and installation phase, ensuring that the detection centers are precisely located on the specified virtual lines before actual operation. This preliminary action prevents positional deviation issues from affecting measurement accuracy during motor operation.
2Measurement precision
If magnetic detection elements are positioned at ideal geometric positions, then measurement accuracy is maximized, but manufacturing and installation precision requirements become extremely high
Solution Approach 1:
The patent optimizes the geometric parameters of the detection element arrangement by defining specific virtual lines and midpoint relationships, which creates a configuration that is inherently more tolerant to positional deviations. This parameter optimization reduces the stringency of manufacturing and installation precision requirements while maintaining adequate measurement accuracy.
Solution Approach 2:
The patent employs an asymmetric arrangement where the β-axis magnetic detection element is positioned on the second virtual line passing through the midpoint of the first virtual line, rather than using a perfectly symmetric arrangement. This asymmetric configuration provides better robustness against positional deviations and reduces the impact of installation errors on measurement 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 enhances the robustness of the magnetic detection elements against positional deviations, improving energy efficiency and accuracy of current measurements in three-phase motors.
Implementation Method 1
an α-axis magnetic detection element provided around the first, second, and third phase current lines; and a β-axis magnetic detection element provided around the first and third phase current lines
Data Source
AI summary
A current detection apparatus includes an α-axis magnetic detection element 8α and a β-axis magnetic detection element 8β. A detection axis Oβ of the element 8β is arranged orthogonal to a first virtual line L1 connecting current lines 6u and 6w, on a surface Pβ that is orthogonal to the current lines 6u and 6w and includes a detection center of the element 8β; the detection center of the element 8β is arranged on a second virtual line L2 that is orthogonal to the line L1 and passes through a midpoint P0 of the line L1; and a second axial distance Dy between the detection center of the element 8β and the line 6u along the line L2 is within a range of an allowable setting error ±Δy with a first axial distance Dx between the current line 6u and the midpoint P0 along the line L1 as the center.