Axial Gap Motor Segmented Rotor Core Design
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Solution Overview
Problem
Existing axial gap motors suffer from demagnetization of magnet pieces due to a large demagnetizing field, leading to a decrease in output torque, as the distance between N-pole and S-pole of each magnet is limited by the rotor pedestal thickness, and magnet pieces are demagnetized when facing two stator cores at the same magnetic pole.
Innovation Solution
The axial gap motor design includes a rotor and stator with rotor and stator cores made of soft magnetic material, curved to face the same direction, with magnets positioned such that their N-pole and S-pole are in the thickness direction, forming a U-shaped magnet configuration that increases the distance between poles, reducing demagnetization, and using directional electromagnetic steel sheets for higher saturation magnetic flux density to enhance torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If magnet pieces are fixed along the circumferential direction of the rotor pedestal with N-pole and S-pole arranged in the thickness direction, then the motor structure is simplified and manufacturing is easier, but the distance between N-pole and S-pole is limited to only the rotor pedestal thickness, causing a large demagnetizing field that demagnetizes the magnet pieces and decreases output torque
Solution Approach 1:
The rotor is divided into multiple rotor cores (first rotor core, second rotor core, etc.) arranged along the circumferential direction. Each rotor core has independent N-pole and S-pole regions, allowing the magnetic circuit to be segmented into multiple paths. This segmentation enables each magnet piece to have extended N-pole and S-pole distances through the rotor core thickness without increasing the overall rotor pedestal thickness, thereby reducing the demagnetizing field while maintaining manufacturing simplicity.
Solution Approach 2:
The patent transitions from a two-dimensional arrangement (magnets fixed only on the surface of the rotor pedestal) to a three-dimensional structure by inserting rotor cores with N-pole and S-pole regions extending through the thickness direction. This dimensional change allows the magnetic flux path to extend axially through the rotor core, effectively increasing the N-pole to S-pole distance without increasing the circumferential or radial dimensions, thus reducing demagnetization while maintaining compact structure.
2Power
If two stator cores face a magnet piece at the same magnetic pole, then the motor can achieve higher torque density, but the magnet piece is demagnetized by the repulsive force from both stator cores simultaneously
Solution Approach 1:
The rotor is segmented into multiple rotor cores (first rotor core, second rotor core, third rotor core, etc.) arranged along the circumferential direction, with each rotor core having independent N-pole and S-pole regions. When stator cores face the rotor, the magnetic interaction is distributed across multiple segmented rotor cores rather than concentrating the demagnetizing stress on a single magnet piece. This segmentation allows the rotor to withstand higher torque density while protecting individual magnet pieces from simultaneous demagnetization by multiple stator cores.
Solution Approach 2:
The rotor core acts as an intermediary magnetic structure between the stator cores and the magnet pieces. The rotor core with its soft magnetic material provides a controlled magnetic flux path that mediates the interaction between stator cores and magnets. This intermediary structure allows the magnetic flux to be guided and distributed, preventing direct and simultaneous repulsive forces from multiple stator cores from acting on the same magnet piece, thereby protecting against demagnetization while maintaining high torque density.
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 configuration effectively reduces demagnetization and maintains output torque by increasing the distance between magnetic poles and using directional electromagnetic steel sheets to enhance magnetic flux density, improving motor efficiency and torque output.
Implementation Method 1
magnetic flux emitted from the N-pole of a first magnet enters the S-pole of a second magnet through the rotor core
Implementation Method 2
a large demagnetizing field occurs in the magnet pieces. This demagnetizes the magnet pieces
Implementation Method 3
using directional electromagnetic steel sheets for higher saturation magnetic flux density to enhance torque
Implementation Method 4
The rotor cores and the stator cores are cores each made of a soft magnetic material
Implementation Method 5
coils wound around the stator cores
Implementation Method 6
an axial gap motor including a rotor and a stator... coils wound around the stator cores
Data Source
AI summary
An axial gap motor is configured such that: a rotor includes a plurality of rotor cores fixed along the circumferential direction of a rotor pedestal, and a plurality of magnets; and a stator includes a plurality of stator cores fixed along the circumferential direction of a stator pedestal, and coils wound around the stator cores. A first divided surface of each rotor core faces an N-pole of a corresponding magnet, and a second divided surface of the each rotor core faces an S-pole of a corresponding magnet. Respective divided surfaces of the rotor cores are placed to face respective divided surfaces of the stator cores across the magnets.