Electric Machine Winding Bundle Interchange for Current Displacement Reduction
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Solution Overview
Problem
Electrical machines with windings in slots experience significant additional losses due to current displacement phenomena, particularly at high frequencies, leading to increased ohmic resistance and energy losses.
Innovation Solution
The bundles of the strands are interchanged between coils such that each bundle is arranged at least n times and at most n' times at each possible bundle position relative to the lowest possible bundle position, where n is the integer quotient of the number of series-connected coils and possible bundle positions, effectively distributing bundles evenly within the slots to minimize current displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional bundle arrangement is used in slots, then manufacturing is simple, but current displacement losses are high at high frequencies
Solution Approach 1:
The patent divides the bundles into multiple groups and assigns them to different slot positions systematically. Each bundle is segmented and placed in specific slot positions according to the calculated distribution, reducing current displacement losses by ensuring more uniform current distribution across the conductor cross-section.
Solution Approach 2:
The patent changes the arrangement parameters of bundles in slots by calculating optimal distribution based on the number of series-connected coils and possible bundle positions. This parameter optimization ensures that each bundle position is occupied evenly, minimizing skin effect and current displacement losses.
2Reliability
If bundles are evenly distributed across all positions, then ohmic resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent calculates and determines the optimal bundle arrangement in advance during the design phase. The distribution pattern is pre-planned based on the number of series-connected coils and possible bundle positions, allowing manufacturers to follow a clear guideline rather than making complex real-time decisions during assembly.
Solution Approach 2:
The patent implements a periodic distribution pattern where bundles are arranged in a repeating sequence across slot positions. This periodic arrangement ensures even distribution and minimizes ohmic resistance while providing a simple, rule-based manufacturing process that can be easily replicated.
3Power
If high feed frequency is used, then power transmission capability is improved, but current displacement losses increase significantly
Solution Approach 1:
The patent addresses the frequency-related current displacement problem by introducing a spatial dimension solution. Instead of changing the electrical parameters, it optimizes the physical arrangement of bundles across multiple slot positions, creating a multi-dimensional current distribution path that reduces skin effect and allows higher frequency operation with lower losses.
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 arrangement significantly reduces ohmic resistance, resulting in lower energy losses and improved efficiency by compensating current displacement effects across the windings, outperforming existing methods like bundle swapping and sub-conductor transposition.
Implementation Method 1
With alternating current flowing through electrical conductors, the current density inside a conductor is lower than on the surface. This effect, known as current displacement or skin effect, can also be observed in an electrical machine that has windings and turns arranged in slots.
Data Source
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AI summary
An electric machine has grooves and windings, divided into strands, of electrical conductors. At least one strand has a number s of coils connected in series and arranged in the grooves. Each coil has sub-conductors connected in parallel and arranged in bundles. Each bundle is arranged in a groove at a bundle position relative to a deepest possible bundle position in the groove. The positions of all bundles in all coils define a number b of possible bundle positions of the strand. The bundles are interchanged between the coils such that each bundle is arranged in the grooves at least n times and at most n′ times at each possible bundle position, wherein n is the integer quotient in regard to the quotient of the number s and the number b, wherein n′=n if s is divisible by b and n′=n+1 if s is not divisible by b.