Synchronous Reluctance Rotor Barriers for Lower Torque Ripple
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Solution Overview
Problem
The use of arc-shaped magnets in permanent magnet-assisted synchronous reluctance motors increases manufacturing costs and assembly difficulty, limits the expansion angle between magnetic barriers and magnetic conduction segments, and sacrifices output torque.
Innovation Solution
A rotor design with magnetic barrier groups featuring symmetrical magnetic barriers protruding radially inward, comprising perpendicular and outward extending portions, allows for the use of rectangular magnets, simplifying assembly and enhancing output torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If arc-shaped magnets are used in the magnetic barrier, then torque ripple is reduced, but manufacturing cost increases and assembly difficulty increases
Solution Approach 1:
The magnetic barrier is designed with an asymmetric cross-sectional shape where the first portion (adjacent to magnetic conduction segment) has a different width than the second portion (adjacent to q-axis). This asymmetric design allows the use of simple rectangular magnets while achieving the same torque ripple reduction effect that would otherwise require complex arc-shaped magnets, thereby simplifying manufacturing and assembly.
Solution Approach 2:
The magnetic barrier is divided into two distinct portions with different dimensions: the first portion adjacent to the magnetic conduction segment and the second portion adjacent to the q-axis. By optimizing the local geometry of each portion independently, the design achieves effective torque ripple reduction while accommodating simple rectangular magnets, thus resolving the contradiction between performance and manufacturability.
2Object-generated harmful factors
If arc-shaped magnets are used in the magnetic barrier, then torque ripple is reduced, but assembly difficulty increases
Solution Approach 1:
The asymmetric cross-sectional shape of the magnetic barrier with its two distinct portions allows rectangular magnets to be easily assembled while achieving torque ripple reduction. The specific geometric configuration guides the assembly process and simplifies magnet placement compared to arc-shaped designs.
3Object-generated harmful factors
If the expansion angle between magnetic barrier and magnetic conduction segment is limited, then torque ripple is reduced, but output torque is sacrificed
Solution Approach 1:
The magnetic barrier's first portion adjacent to the magnetic conduction segment is designed with an optimized width that balances torque ripple reduction and output torque maintenance. The second portion adjacent to the q-axis has a different width to maintain proper magnetic flux paths. This local optimization of each portion's dimensions achieves both goals simultaneously.
Solution Approach 2:
The design optimizes specific geometric parameters including the width of the first portion (adjacent to magnetic conduction segment) and the width of the second portion (adjacent to q-axis), as well as the expansion angle. By carefully selecting these parameters within specific ranges, the design achieves torque ripple reduction while maintaining or improving output torque through enhanced magnetic flux 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 design reduces torque ripple and improves output torque by using symmetrical magnetic barriers with specific angular relationships, facilitating easier magnet assembly and increasing total reluctance torque.
Implementation Method 1
A rotor portion of each pole consists of a plurality of magnetic conduction segments and a magnetic barrier, and each pole in the rotor has a position with minimum reluctance (d-axis) and a position with maximum reluctance (q-axis). When a stator winding is energized, the magnetic flux will attempt to pass in a direction where the reluctance in the rotor is minimum, causing the rotor to rotate at a synchronous speed.
Implementation Method 2
In the synchronous reluctance motor, magnets are sometimes disposed in the magnetic barrier, forming a permanent magnet-assisted synchronous reluctance motor (usually referred to as PMA-SynRM), in order to improve the efficiency, etc.
Data Source
AI summary
A synchronous reluctance motor includes magnetic barriers in each magnetic barrier group of a rotor core, each having a shape which protrudes toward a radial inner side and is symmetrical about a q-axis. A portion closer to a circumferential side than the q-axis includes a first portion extending perpendicular to the q-axis and a second portion extending farther toward the circumferential side from a circumferential side of the first portion and radially outward, and the first portions of the magnetic barriers in each magnetic barrier group have the same radial dimension. The first portions of the magnetic barriers other than the radial outermost magnetic barrier have the same circumferential dimension, which is the same as or twice a circumferential dimension of the first portion of the radial outermost magnetic barrier.