Polyphase Motor Stator with Segmented Teeth for Torque Control
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Solution Overview
Problem
Existing polyphase electric motors for automotive applications face challenges in balancing radial forces and minimizing residual torque while maintaining efficient copper volume and magnetic circuit length, which affects noise levels and production costs.
Innovation Solution
A polyphase motor design featuring a stator with wide and narrow teeth radially extending from an annular crown, where the wide teeth have a width twice that of narrow teeth, allowing separate coil winding and optimized copper volume, and a rotor with N pairs of radially magnetized poles to cancel residual torque, along with recesses for improved heat exchange and reduced part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If poles with the widest possible shape are used to control residual torque, then residual torque is minimized, but the winding becomes difficult due to narrow slots
Solution Approach 1:
The stator poles are segmented into two distinct types: wide poles and narrow poles. The wide poles carry the windings and provide sufficient slot width for economical winding, while the narrow poles contribute to the magnetic circuit and help balance radial forces. This segmentation allows each pole type to fulfill its specific function without compromising the other requirements.
2Ease of manufacture
If a multi-piece stator is used to facilitate winding, then winding simplicity is improved, but the stator circuit becomes complex and costly
Solution Approach 1:
Instead of dividing the stator into multiple pieces, the invention applies local quality by creating local variations in pole width within a single-piece stator. The wide poles are strategically positioned where windings are needed, providing adequate slot width for winding operations, while the overall stator remains structurally integrated, maintaining magnetic circuit integrity and avoiding the complexity of multi-piece assembly.
3Loss of energy
If copper volume is increased to limit Joule losses, then efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The invention optimizes the parameter of pole width to achieve efficient copper utilization. The wide poles provide sufficient width for economical winding with appropriate copper fill, while the alternating narrow poles create a compact magnetic circuit. This parameter variation allows achieving good efficiency with moderate copper volume, balancing performance and manufacturing cost.
4Loss of energy
If the magnetic circuit is shortened to minimize iron losses, then efficiency is improved, but the available space for windings is reduced
Solution Approach 1:
The alternating sequence of wide and narrow poles creates an optimized magnetic circuit path. The narrow poles shorten the magnetic circuit length, reducing iron losses, while the wide poles provide adequate space for windings. This segmented pole structure allows the magnetic flux to travel through efficient paths while maintaining sufficient winding space at the critical locations.
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 design achieves high efficiency, low noise, and cost-effectiveness by maximizing torque per ampere-turn, reducing residual torque, and simplifying winding production, while maintaining balanced radial forces and minimizing leakage flux and part count.
Implementation Method 1
a stator excited by electrical coils and a magnetized rotor with N pairs of radially alternating magnetized poles
Implementation Method 2
a sufficient volume of copper is necessary to limit Joule losses
Implementation Method 3
a short magnetic circuit is required to minimize iron losses
Implementation Method 4
the motor should have a good balance of radial forces and low residual torque
Data Source
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AI summary
The present invention relates to a polyphase motor, especially for applications for driving pumps or ventilators in the automobile industry, formed by a stator part (1) excited by electric coils (41 to 46) and by a rotor (2) exhibiting N pairs of poles that are magnetised radially in alternate senses, the stator part (1) exhibiting wide teeth (11 to 16) and narrow teeth (17 to 22) extending radially from an annular ring (10). The wide teeth carry the coil windings and the distance between a wide tooth and a narrow tooth is greater than the width of a narrow tooth.