BLDC Motor Magnet Segmentation to Reduce Eddy Current Loss
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Solution Overview
Problem
Brushless direct current (BLDC) motors in cleaners face challenges with high eddy current loss and efficiency, particularly when used in high-speed applications like vacuum cleaners, where existing designs do not effectively optimize magnetization patterns to minimize energy loss.
Innovation Solution
A cleaner with a BLDC motor featuring a rotor assembly of multiple magnets with different magnetization directions, arranged in a divided structure around a nonmagnetic shaft, optimizing the magnetization pattern to reduce eddy current loss and enhance field energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a BLDC motor is designed for high-speed rotation, then the impeller can rotate at high speed to suction and move air, but eddy current loss increases and efficiency decreases
Solution Approach 1:
The rotor is divided into multiple magnetic poles (N and S poles) arranged alternately around the shaft. This segmentation of the magnetic structure creates multiple flux paths that are more evenly distributed, reducing concentrated eddy currents in any single region of the stator core, thereby reducing eddy current loss while enabling high-speed operation.
Solution Approach 2:
The patent applies different magnetization directions to different regions of the magnets. Specifically, adjacent magnets are magnetized in opposite directions (alternating N and S poles), creating localized magnetic fields that optimize flux distribution. This local variation in magnetic quality smooths flux flow and reduces eddy current losses in specific areas of the stator core.
2Device complexity
If magnets are arranged in a conventional single-direction magnetization pattern, then the structure is simple, but flux flow is not smoothed and eddy current loss is high
Solution Approach 1:
The patent employs alternating magnetization directions for adjacent magnets around the rotor, creating an asymmetric magnetic pole arrangement (N-S-N-S pattern). This asymmetric distribution of magnetic polarity optimizes the flux path through the stator core, smoothing flux flow and reducing eddy current losses compared to uniform single-direction magnetization, 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
The solution significantly reduces eddy current loss and maximizes magnetic performance, improving the efficiency of the BLDC motor by smoothing flux flow and optimizing magnetization patterns, leading to enhanced operational performance in high-speed applications.
Implementation Method 1
a rotor shaft (14) and a plurality of magnets (M1 to M8) which surround the outer circumference of the shaft (14) in a divided state
Implementation Method 2
smoothing the flow of flux, thereby maximizing the performance of magnets
Implementation Method 3
minimizing eddy current loss using an assembly of a plurality of magnets having different directions of magnetization
Data Source
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AI summary
A brushless direct current (BLDC) motor is disclosed. The BLDC motor includes a shaft made of a nonmagnetic material, a plurality of magnets surrounding the outer circumference of the shaft, a stator surrounding the outer circumferences of the magnets, wherein each of the magnets has an arc-shaped outer circumferential surface, an arc-shaped inner circumferential surface facing the shaft, and opposite side surfaces facing other adjacent magnets, and the magnets include a first magnet magnetized in a direction directed from the outer circumferential surface to the inner circumferential surface, a second magnet magnetized in a direction directed from the inner circumferential surface to the outer circumferential surface, and a third magnet magnetized in a direction directed from one side surface to the other side surface. The efficiency of the motor is improved while eddy current loss is minimized.