Modulated Litz Wire Structure for Fill Factor and Current Sharing
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Solution Overview
Problem
Existing litz wire configurations improve current distribution but decrease the fill factor, leading to bulkier wires that reduce the effective conductor area in motor stator slots, creating a trade-off between current sharing and space efficiency.
Innovation Solution
A modulated litz wire design with varying sections of braided, twisted, and parallel stranded wire along its length, allowing for optimized fill factor and current redistribution by alternating between bulkier and less bulky braids or strands based on the specific application, manufactured using computer-controlled braiding machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex twisting constructions are used in litz wire to improve current distribution, then current sharing among strands is improved, but the overall volume of the wire increases and fill factor decreases
Solution Approach 1:
The litz wire is divided into multiple sections along its length, where each section has a different braid configuration (e.g., different braid angles, densities, or patterns). This segmentation allows different portions of the wire to have optimized properties for different functions: some sections prioritize current distribution while others prioritize compactness for fill factor
Solution Approach 2:
Different sections of the litz wire are given different local characteristics through varied braid configurations. Specifically, certain sections use tighter or looser braiding, different braid angles, or different strand arrangements to locally optimize either current distribution or volume efficiency depending on the specific application requirements at that location
2Reliability
If braided wire construction is used to improve current distribution, then current sharing is improved, but the fill factor decreases due to increased space between strands
Solution Approach 1:
The wire is segmented into multiple sections with different braid configurations along its length, allowing certain sections to have optimized current distribution while other sections have compact designs that maximize fill factor in space-constrained areas
Solution Approach 2:
Different sections of the wire are given different local braid characteristics (such as braid angle, density, or pattern) to locally optimize either current sharing or space efficiency depending on where the wire is positioned in the motor assembly
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
The modulated litz wire design enhances motor performance by improving current sharing and reducing ohmic losses while maintaining a higher fill factor, enabling more compact and efficient conductor arrangements in restricted spaces.
Implementation Method 1
Conductors carrying alternating currents are subject to eddy-current and proximity effects that increase the impedance of the conductor relative to its direct-current (DC) impedance.
Implementation Method 2
Conductors carrying alternating currents are subject to eddy-current and proximity effects that increase the impedance of the conductor relative to its direct-current (DC) impedance.
Implementation Method 3
uniform current sharing reduces ohmic losses, also known as Joule heating, in motors and other electromagnetic devices
Implementation Method 4
Litz wire is typically available in many different configurations, though all configurations are typically uniform along their length and commonly consist of individually insulated strands twisted or braided in such a way so as to improve the uniformity of current sharing among the strands
Data Source
AI summary
A modulated litz wire wherein the braid of a litz wire is varied along its length such that bulkier sections are located at the end-turns of a motor, while more compact parallel stranded sections are located in stator slots or magnetic gaps. Variations may include parallel stranded sections replaced with a longitudinal twist for improved handling or improved current sharing in strands.