Rectangular Stator Windings for Eddy Current Reduction
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Solution Overview
Problem
Electric machines with stators experience significant resistive losses due to eddy currents induced by alternating current in the windings, which increase the effective resistance and lead to heat generation and increased cooling requirements.
Innovation Solution
The stator design incorporates a plurality of windings with generally rectangular cross sections, where at least two windings are inserted into each slot, forming inner and outer groups that are electrically connected through clips, reducing resistive losses by minimizing the surface area for eddy currents to flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If AC current flows through the windings, then electrical energy is generated, but eddy currents are induced causing increased resistive losses
Solution Approach 1:
The winding conductor is divided into multiple parallel conductors arranged in inner and outer groups within each slot. This segmentation reduces the effective surface area exposed to cross slot flux, thereby reducing eddy current losses while maintaining the required electrical power generation capability
Solution Approach 2:
The patent introduces a radial dimension to the conductor arrangement by positioning conductors at different radial positions (inner group closer to rotor, outer group farther from rotor) within the same slot. This three-dimensional arrangement optimizes the conductor layout to minimize eddy current paths while maintaining electrical performance
2Loss of energy
If multiple windings are inserted into each slot, then resistive losses are reduced, but device complexity increases
Solution Approach 1:
Multiple conductors are merged into a single winding assembly with a unified insulation structure. The inner and outer groups of conductors are combined within the same slot and connected through end connections, simplifying the overall structure while maintaining the low-loss configuration
Solution Approach 2:
The insulation structure is differentiated locally with inner insulation surrounding the inner group of conductors and outer insulation surrounding the outer group. This localized differentiation provides necessary electrical isolation while maintaining a relatively simple overall structure
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 reduces resistive losses and heat generation, thereby minimizing cooling requirements and improving the efficiency of the electric machine.
Implementation Method 1
Electric machines, such as electric generators, are generally used to convert mechanical energy into electrical energy. Movement of the rotor relative to the stator causes an AC current to move through the windings.
Implementation Method 2
The eddy losses are caused by cross slot flux which is induced by the AC current in the winding. The cross slot flux flows through the winding and produces an eddy current on the winding conductor.
Data Source
AI summary
An electric machine includes a stator disposed about an axis in register with the rotor. The stator has a plurality of slots parallel to the axis. A plurality of windings with generally rectangular cross sections is provided with each winding having a first portion disposed radially inward of a second portion relative to the axis. At least two of the plurality of windings are at least partially inserted into each of the plurality of slots. The plurality of generally rectangular windings in each of the plurality of slots is configured to reduce resistive loss within the stator.