Twisted Wire Stator Coils for Switched Reluctance Motor Efficiency
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Solution Overview
Problem
Switched reluctance motors face inefficiencies at both low and high speeds due to coil designs that either fail to carry significant current without excessive heating or perform poorly as operating frequencies increase, limiting their ability to power work machines effectively.
Innovation Solution
A rotary electric machine with a stator having an open slot configuration and coils made of electrically conductive wires that are twisted between approximately one and five times per turn, allowing lateral movement and efficient packing within stator slots to reduce air gaps and increase current carrying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wires with square cross-section are used to increase conductor density in stator slots, then current carrying capacity is improved, but electrical characteristics deteriorate at high operating frequencies
Solution Approach 1:
The patent changes the cross-sectional shape parameter from square to circular, and introduces a twisting parameter (one to three twists per turn) to the wire configuration. This parameter change allows the conductor to achieve both high packing density and good electrical characteristics at high frequencies by reducing skin effect and improving current distribution.
Solution Approach 2:
The patent introduces dynamic twisting of the wires within the coil, where the wires are twisted one to three times per turn around the coil axis. This dynamic configuration optimizes both the packing density in the stator slot and the electrical performance at high operating frequencies by creating a more uniform current distribution.
2Quantity of substance
If coils are designed to carry significant current, then current carrying capacity is improved, but coil heating increases excessively
Solution Approach 1:
The patent changes the wire configuration from straight or简单地 bundled to twisted (one to three twists per turn), which improves heat dissipation by increasing surface area exposure and improving thermal contact with the stator slot, thereby reducing coil heating while maintaining current carrying capacity.
3Speed
If coils are designed for high speed operation, then operating frequency performance is improved, but current carrying capacity is reduced
Solution Approach 1:
The patent applies twisting (one to three twists per turn) to the wires, which simultaneously improves high-frequency electrical characteristics by reducing skin effect and maintains high conductor density for current carrying capacity. The circular cross-section and twisting configuration optimize both speed performance and current capacity.
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 solution enhances electrical efficiency and reduces copper losses by minimizing skin and eddy currents, improving thermal conductivity, and averaging voltage induction across wires, resulting in improved performance over a range of operating conditions.
Implementation Method 1
minimizing skin and eddy currents
Implementation Method 2
minimizing skin and eddy currents
Implementation Method 3
improving thermal conductivity
Implementation Method 4
averaging voltage induction across wires
Data Source
AI summary
A rotary electric machine includes a stator having an open slot configuration and a plurality of stator poles with a coil positioned about each stator pole. Each coil has a plurality of electrically conductive wires defining a group of wires and the group of wires is wrapped generally around a stator pole to define a plurality of turns. At least a portion of the group of wires is twisted, and the portion of the group of wires has between approximately 1 and 5 twists per turn. A method of fabricating a stator assembly is also disclosed.