IPM Rotor Magnet Layout for D-Axis Flux Concentration
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Solution Overview
Problem
Conventional rotors for interior permanent magnet (IPM) motors face challenges in maximizing output torque due to voids at the ends of magnet holes, which divert magnetic fluxes away from the d-axis, leading to inefficiencies.
Innovation Solution
Incorporating an auxiliary magnet in the voids of the outermost magnet holes to redirect magnetic fluxes back towards the d-axis, enhancing torque production without increasing the size of the main magnets and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If auxiliary magnets are disposed in the distal end voids of outermost magnet holes, then magnetic fluxes are concentrated near the d-axis and output torque increases, but the device complexity and manufacturing cost increase due to additional magnets and assembly steps
Solution Approach 1:
The patent applies local quality by placing auxiliary magnets specifically in the distal end voids of outermost magnet holes, where magnetic flux concentration is needed most. This localized modification targets the specific region where flux diversion occurs, rather than uniformly modifying the entire rotor structure. The auxiliary magnets are positioned to specifically address the flux path issue in the outermost holes while leaving other regions unchanged.
Solution Approach 2:
The auxiliary magnets are nested within the existing magnet hole structure, specifically occupying the distal end voids that already exist in the rotor design. This nesting approach utilizes the existing spatial framework without requiring complete structural redesign, thereby limiting the increase in device complexity while achieving the desired flux concentration effect.
2Power
If auxiliary magnets are added to redirect magnetic fluxes, then output torque increases, but manufacturing cost increases due to additional materials and assembly processes
Solution Approach 1:
The patent implements partial action by placing auxiliary magnets only in the distal end voids of outermost magnet holes, rather than filling all voids throughout the rotor structure. This selective approach provides sufficient flux redirection to achieve torque improvement while minimizing the number of auxiliary magnets required, thereby controlling material costs and assembly complexity.
Solution Approach 2:
The invention changes the magnetic properties parameter by introducing auxiliary magnets with specific magnetic characteristics in strategic locations. This parameter modification allows for optimized flux distribution without requiring a complete redesign of the magnet system, enabling cost-effective torque enhancement through targeted material property adjustments.
3Ease of manufacture
If the number of magnets is reduced to maintain cost-effectiveness, then manufacturing cost decreases, but magnetic flux concentration and torque output may be compromised
Solution Approach 1:
The patent segments the magnet system into main magnets in regular magnet holes and auxiliary magnets in distal end voids of outermost holes. This segmentation allows for an optimized distribution where fewer total magnets are used compared to a uniform dense arrangement, while the strategically placed auxiliary magnets ensure adequate flux concentration. The segmentation enables cost-effective design by reducing overall magnet count while maintaining performance through intelligent spatial distribution.
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 auxiliary magnet configuration concentrates magnetic fluxes near the d-axis, increasing the output torque of the motor while reducing the number of required magnets and maintaining cost-effectiveness.
Implementation Method 1
Some of magnetic fluxes emitted from a middle main magnet are drawn to the auxiliary magnet and come closer to the d-axis. The rotor disclosed in the present specification allows magnetic fluxes of the magnetic pole to concentrate near the d-axis.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A rotor for an electric motor includes: a rotor core (11, 111, 211, 311); a plurality of magnet holes provided to the rotor core (11, 111, 211, 311); and a plurality of permanent magnets disposed in the respective magnet holes. The magnet holes extend along the axis of the rotor core (11, 111, 211, 311) and are disposed to have line symmetry with respect to the d-axis as viewed along the axis. The magnet holes include an outermost hole (12, 12L, 12R) located the farthest from the axis and a middle hole (13L, 13R) located next to the outermost hole (12, 12L, 12R) in the radial direction of the rotor core (11, 111, 211, 311). The permanent magnets include an outermost main magnet (14L,14R) and an auxiliary magnet (16L, 16R) disposed in the outermost hole (12, 12L, 12R), and a middle main magnet (15L, 15R) disposed in the middle hole (13L, 13R). Here, the auxiliary magnet (16L, 16R) is adjacent to the outermost main magnet (14L,14R) on the side farther from the d-axis and faces the middle main magnet (15L, 15R).