E-Bike PM Motor Rotor Structure for High Torque at Lower Magnet Cost
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Solution Overview
Problem
Existing drives for light electric vehicles are complex and expensive to manufacture, requiring costly components like rare earth magnets to achieve high torque.
Innovation Solution
A drive system for light electric vehicles featuring a PM electric motor with an inner rotor and outer stator, utilizing buried permanent magnets in a flux concentration arrangement, specifically in a spoke design, and connecting elements made of magnetically non-conductive material to enhance torque without increasing complexity or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If rare-earth magnets are used to generate high torque, then torque output is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the magnetic circuit parameters by introducing flux concentration arrangements and pole elements with specific geometries. This allows the use of less expensive permanent magnets while achieving the same torque output through optimized magnetic flux distribution and concentration in the air gap.
Solution Approach 2:
The rotor is segmented into multiple pole elements with embedded permanent magnets arranged in a flux concentration pattern. This segmentation allows each magnet to contribute more effectively to the overall torque, reducing the total amount of expensive rare-earth magnet material needed while maintaining high torque output.
2Force
If complex drive systems are designed to achieve high torque, then torque performance is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of torque generation and magnetic flux concentration into a single integrated rotor structure. The pole elements and embedded permanent magnets work together as a unified system, eliminating the need for separate complex transmission components and reducing overall structural complexity while maintaining high torque capability.
Solution Approach 2:
The patent introduces a flux concentration arrangement that utilizes the radial dimension of the magnetic circuit. By concentrating magnetic flux in the radial direction through specifically designed pole elements and magnet arrangements, the system achieves higher torque density without adding mechanical complexity in the tangential or axial dimensions.
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 design achieves high torque utilization with simple structural means, allowing for cost-effective production and efficient magnetic flux usage, even with lower energy density magnets, while minimizing magnetic short circuits and leakage flux.
Implementation Method 1
Applying an alternating current to the stator's electromagnets generates an alternating magnetic field that sets the rotor's permanent magnets in motion
Implementation Method 2
The permanent magnets are arranged perpendicular to the tangential magnetization direction, i.e., the permanent magnets run edgewise in the rotor. This so-called collector arrangement increases the torque of the electric motor
Data Source
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AI summary
A drive for a light electric vehicle, in particular an e-bike, comprising a PM electric motor (15) and a gearbox, wherein the PM electric motor (15) has an inner rotor (1) and an outer stator (16), preferably with a concentrated or distributed winding, wherein the inner rotor (1) has buried permanent magnets (3) arranged in a flux concentration arrangement, in particular in a spoke design, wherein pole elements (2) are arranged between the permanent magnets (3) and wherein the pole elements (2) are connected by connecting elements (4, 5, 9, 10, 11). A light electric vehicle is further specified.