Synchronous Reluctance Rotor Core Bridge Width Optimization
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Solution Overview
Problem
Synchronous reluctance rotary electric machines experience torque ripple due to interactions between magnetic irregularities in the stator and rotor cores, which can be exacerbated by resonance, leading to inefficiencies in torque transmission.
Innovation Solution
The machine's rotor core is designed with four layers of hollow parts and bridges, where the circumferential widths between bridges are strategically set to reduce torque ripple by minimizing areas where magnetic flux does not readily pass, thereby reducing the rapid changes in magnetic flux density that contribute to torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hollow parts are formed in the rotor core to generate reluctance torque, then torque generation is improved, but torque ripple increases due to interaction with stator magnetic irregularities
Solution Approach 1:
The patent applies local quality by making the hollow parts asymmetric in shape, with different curvature radii at different locations. Specifically, the hollow part has a first curvature radius at its pole center side and a second curvature radius at its other side, where these radii differ. This asymmetric local configuration modifies the magnetic flux distribution locally to reduce torque ripple while maintaining overall torque generation capability.
Solution Approach 2:
The patent changes the geometric parameters of the hollow parts by specifying different curvature radii for different portions of the hollow part. The first curvature radius and second curvature radius are set to different values, which changes the magnetic flux density distribution pattern and reduces the resonance interaction between rotor and stator magnetic irregularities, thereby reducing torque ripple.
2Manufacturing precision
If hollow parts are curved to follow magnetic flux flow, then magnetic flux directionality is improved, but magnetic irregularities in the rotor increase
Solution Approach 1:
The patent applies local quality by creating non-uniform curvature in the hollow parts. The curvature radius varies along the circumference of the hollow part, with the first curvature radius at the pole center side being different from the second curvature radius at the other side. This local variation in curvature allows the hollow part to follow the magnetic flux flow pattern more accurately in critical regions while reducing magnetic irregularities in other regions.
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 torque ripple while maintaining torque performance, enhancing the overall efficiency and stability of the rotary electric machine by minimizing areas where magnetic flux does not pass through, thus improving the machine's operational performance.
Implementation Method 1
the synchronous reluctance type rotary electric machine rotates the shaft using a reluctance torque generated by the hollow parts
Implementation Method 2
Each of the hollow parts is formed to be curved toward the radially inner side such that a pole center thereof is positioned furthest inward in the radial direction to follow a flow of magnetic flux
Data Source
AI summary
A synchronous reluctance rotary electric machine of an embodiment includes a shaft and a rotor core. The shaft rotates around a rotation axis. The rotor core is fixed to the shaft, includes four layers of hollow parts having a convex shape toward a radially inner side formed for each pole in cross section, and includes bridges between the respective hollow parts and an outer circumferential surface thereof. Then, in each pole, when a center in a circumferential direction is a pole center, both ends in the circumferential direction are pole ends, and the plurality of bridges are a first layer bridge, a second layer bridge, a third layer bridge, and a fourth layer bridge in order from the pole center toward each of the pole ends, a circumferential width between the second layer bridge and the third layer bridge is set to be greater than a circumferential width between the first layer bridge and the second layer bridge and a circumferential width between the third layer bridge and the fourth layer bridge.