IPM Rotor Auxiliary Magnet Phase Shift
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Solution Overview
Problem
Conventional brushless motors with interior permanent magnet (IPM) rotors experience flux leakage and varying magnetic flux density due to the mounting of auxiliary permanent magnets, affecting repulsive force and demagnetization resistance.
Innovation Solution
A rotor design featuring a circular rotor core with plate-like magnets and ring-shaped auxiliary magnets, where the same magnetic poles face each other circumferentially, with the auxiliary magnets' poles alternately formed and phase-shifted relative to the rotor core's poles to reduce repulsive force and enhance demagnetization resistance, thereby minimizing flux leakage and increasing average magnetic flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If auxiliary permanent magnets are mounted on the rotor core to reduce magnetic flux leakage, then flux leakage is reduced, but repulsive force between the rotor core and auxiliary magnets increases and demagnetization resistance decreases
Solution Approach 1:
The patent applies asymmetry by configuring the auxiliary magnets with an offset between their magnetic pole phases and the rotor core's magnetic pole phases. Specifically, the N-pole phase of the auxiliary magnet is positioned at a different angular position than the N-pole phase of the rotor core, creating an asymmetric magnetic field distribution that reduces repulsive force while maintaining flux leakage reduction benefits
Solution Approach 2:
The patent changes the phase parameter of the auxiliary magnets relative to the rotor core. By adjusting the angular position (phase shift) of the auxiliary magnet poles compared to the rotor core poles, the magnetic interaction is optimized to reduce both repulsive force and demagnetization effects while maintaining flux leakage reduction
2Object-generated harmful factors
If auxiliary permanent magnets are mounted on the rotor core to reduce magnetic flux leakage, then flux leakage is reduced, but demagnetization resistance decreases
Solution Approach 1:
The asymmetric phase configuration between auxiliary magnets and rotor core prevents direct opposition of like poles, reducing the demagnetizing field effect on the embedded magnets while maintaining the flux leakage reduction function
Solution Approach 2:
By changing the phase parameter (angular position) of the auxiliary magnets relative to the rotor core, the patent optimizes the magnetic field distribution to minimize demagnetization effects on the embedded magnets while preserving the flux leakage reduction benefit
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 effectively reduces flux leakage and enhances the average magnetic flux density in the outer circumferential part of the rotor, improving motor performance and torque by optimizing the number and thickness of magnetic poles and auxiliary magnets.
Implementation Method 1
an N-pole and an S-pole are alternately formed circularly on an opposed face of the auxiliary magnet facing an end face of the rotor core
Implementation Method 2
disk-like auxiliary permanent magnets are provided at both end faces of the rotor for the purpose of reducing the magnetic flux that may have leaked from the magnets embedded in the rotor yoke
Data Source
AI summary
A rotor includes a circular rotor core, a plurality of θ magnets, and ring-shaped Z magnets. The rotor core has a plurality of magnet holding sections formed radially with a rotating shaft as the center. The θ magnets are contained in and held by the magnet holding sections such that the same magnetic poles of adjacent magnets face each other in a circumferential direction of the rotor core. The rotor core is such that N-poles and S-poles are alternately formed in a circumferential direction of an outer circumferential surface of the rotor core. The Z magnets are such that N-poles and S-poles are alternately formed circularly on an opposed face of the auxiliary magnet facing an end face of the rotor core in a direction of the rotating shaft.