Busbar Current Sensing Layout for Positional Deviation Tolerance
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Solution Overview
Problem
Existing current detection apparatuses for three-phase motors face challenges in maintaining accuracy and efficiency due to positional deviations of magnetic detection elements relative to phase current lines, which affect the conversion of currents from three-phase to two-phase systems, particularly in vector control applications.
Innovation Solution
A current detection apparatus with α-axis and β-axis magnetic detection elements arranged orthogonally to the busbars, featuring a slit on one busbar and offset detection centers, ensures robustness against positional deviations, allowing proportional output values for current detection without significant sensitivity coefficient variations.
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 influence of positional deviation becomes large
Solution Approach 1:
The patent changes the geometric parameters of the busbar (introducing a slit) to modify the magnetic field distribution pattern. This parameter change makes the magnetic field distribution more tolerant to positional deviations of the detection elements, thereby maintaining measurement precision while using fewer detection elements
Solution Approach 2:
The patent预先 compensates for potential positional deviations by designing a slit structure on the busbar that creates a magnetic field distribution inherently more robust to positioning errors. This beforehand cushioning approach ensures that even if detection elements are not perfectly positioned, the measurement accuracy remains acceptable
2Adaptability or versatility
If three phase currents are converted to two phase currents through Clarke transformation and Park transformation, then vector control is enabled, but calculation load on computer increases
Solution Approach 1:
The patent extracts the Clarke transformation calculation from the computer processing by using a physical spatial arrangement of detection elements that directly outputs two-phase current components. This removes the computational burden of Clarke transformation while maintaining vector control capability through the remaining Park transformation
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
Enhances the toughness of magnetic detection elements, improving energy efficiency by maintaining accurate current detection despite positional deviations and ensuring proportional output values for improved vector control performance.
Implementation Method 1
an α-axis magnetic detection element (8α) and a β-axis magnetic detection element (8β) provided around a first phase busbar (6u), a second phase busbar (6v), and a third phase busbar (6w) and detecting currents (Iu, Iv, and Iw) flowing through the busbars (6u, 6v, and 6w)
Data Source
AI summary
A current detection apparatus includes an α-axis magnetic detection element 8α and a β-axis magnetic detection element 8β provided around the three busbars. A slit S extending in a width direction is formed on a V-phase busbar; a detection axis Oβ of the β-axis magnetic detection element 8β is arranged orthogonal to the width direction of the V-phase busbar 6v, on a β-axis element arrangement surface Pβ that is orthogonal to the V-phase busbar 6v and includes a detection center of the β-axis magnetic detection element 8β; and the detection center of the β-axis magnetic detection element 8β is arranged at a position that is in the center of the V-phase busbar 6v in the width direction and is offset from the slit S by a predetermined distance a along an extension direction of the V-phase busbar 6v when seen along the detection axis Oβ.