Electric Machine Rotor Magnet Pocket Segmentation
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Solution Overview
Problem
Existing electric machines with high rotor flux levels suffer from high torque ripple and increased losses, particularly in the field-weakening range, leading to noise and inefficiency.
Innovation Solution
The electric machine design features a rotor with two pairs of magnet pockets arranged at specific angles and distances, optimizing the rotor flux while minimizing torque ripple and losses, and incorporating a unique air gap and pole segment configuration to enhance performance and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high rotor flux is achieved through conventional magnet arrangements, then torque and performance are improved, but torque ripple and losses increase
Solution Approach 1:
The rotor magnet arrangement is segmented into two distinct pairs of magnet pockets: a first pair at a first radial level and a second pair at a second radial level. This segmentation allows independent optimization of each pair's angular positioning to simultaneously achieve high torque and reduce losses, resolving the contradiction between power output and energy efficiency.
Solution Approach 2:
The invention introduces a radial dimension differentiation by positioning magnet pockets at two different radial levels within the rotor. The first pair is positioned at a first radial distance from the rotor axis, while the second pair is positioned at a second radial distance. This dimensional arrangement enables optimized magnetic flux distribution that achieves high torque while minimizing losses through reduced magnetic interference and improved field utilization.
2Power
If high rotor flux is achieved through conventional magnet arrangements, then torque is improved, but torque ripple increases
Solution Approach 1:
The magnet arrangement is divided into two pairs positioned at different radial levels, each pair contributing to torque generation in a complementary manner. This segmentation smooths the overall torque output by distributing the magnetic contribution across multiple spatially separated sources, reducing torque ripple while maintaining high average torque.
Solution Approach 2:
By positioning magnet pockets at two different radial distances from the rotor axis, the invention creates a multi-layered magnetic field structure. The first pair at the outer radial level and the second pair at the inner radial level work synergistically to produce a more stable torque output, reducing ripple effects through improved magnetic flux distribution across the air gap.
3Power
If high rotor flux is achieved, then performance is improved, but noise increases due to torque ripple
Solution Approach 1:
The segmented magnet arrangement with two pairs at different radial levels reduces torque ripple through distributed magnetic contribution, which directly lowers mechanical vibrations and associated noise. The first pair and second pair work in coordination to smooth torque delivery, eliminating the sharp torque variations that generate noise in conventional single-level arrangements.
Solution Approach 2:
The radial dimension differentiation creates a more balanced magnetic field distribution that reduces fluctuating forces on the rotor-stator interface. By spacing magnet pockets at two radial levels with optimized angular positions, the invention minimizes magnetic attraction variations that cause vibrations and noise, while maintaining high performance through improved flux utilization.
4Speed
If field-weakening operation is used to achieve high speed, then speed performance is improved, but losses increase significantly
Solution Approach 1:
The dual-radial-level magnet arrangement optimizes the magnetic field distribution across the air gap, improving flux utilization efficiency. During field-weakening operation, the spatially distributed magnet pockets at different radial levels maintain more stable magnetic coupling with the stator, reducing eddy current losses and hysteresis losses that typically increase during high-speed operation. This dimensional arrangement enables efficient field control across the speed range.
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 rotor flux and torque with low torque ripple, noise, and losses, while maintaining high speed performance and cost-effectiveness, and providing improved demagnetization stability.
Implementation Method 1
the rotor has magnet pockets for accommodating permanent magnets
Implementation Method 2
A large number of electric machines having a rotor and a stator are known. It is in particular the magnetic rotor flux which is to be taken into account in electric machines.
Data Source
AI summary
The invention relates to an electric machine comprising a rotor (10) and a stator (20). The rotor (10) has magnet pockets for receiving permanent magnets (55, 56, 85, 86), and the magnet pockets comprise at least one first pair of magnet pockets (50, 51) and a second pair of magnet pockets (80, 11). The second pair (80, 81) is arranged further inwards than the first pair (50, 51) when viewed in a radial direction with respect to a rotational axis, and the magnet pockets of each pair of magnet pockets (50, 51, 80, 81) are arranged symmetrically to one another with respect to an axis of symmetry (45), wherein the axis of symmetry (45) runs in the radial direction and through the center of the rotor (10). The magnet pockets of each pair of magnet pockets (50, 51, 80, 81) are arranged such that the distance of each magnet pocket to the axis of symmetry (45) increases as the distance to the circumferential edge (110) of the rotor (10) decreases. The magnet pockets of the first pair (50, 51) are arranged at a first mechanical angle to one another, and the magnet pockets of the second pair (80, 81) are arranged at a second mechanical angle to one another. The invention is characterized in that the first angle ranges from ca. 100° to ca. 140°, in particular from ca. 120° to ca. 140°, and the second angle ranges from ca. 65° to ca. 112°, in particular from ca. 88° to ca. 112°.