Rotor Magnet Layout With Cavity Control for Lower Iron Loss
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Solution Overview
Problem
Existing rotor structures in rotary electric machines suffer from increased iron loss and magnetic flux short-circuiting when variable magnetic-force magnets change their magnetization state, particularly in the demagnetizing state, leading to inefficiencies.
Innovation Solution
A rotor structure with a specific arrangement of fixed and variable magnetic-force magnets, including auxiliary magnets and cavities, forms a closed magnetic path by aligning magnetizing directions oppositely between adjacent poles and narrowing the cavity width, preventing magnetic flux leakage to the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cavity is formed in the rotor core longitudinally outward of the first fixed magnetic-force magnet to suppress magnetic flux short-circuiting, then the magnetic flux from the first fixed magnetic-force magnet is suppressed from short-circuiting, but the magnetic flux may leak to the stator side while avoiding the cavity in the demagnetizing state, causing increased iron loss
Solution Approach 1:
The invention transitions from a single cavity design to a multi-dimensional cavity system with varying widths. The first cavity has a first width and the second cavity has a second width different from the first, creating a stepped or tapered cavity structure that controls magnetic flux paths in multiple spatial dimensions, preventing flux leakage to the stator while maintaining suppression of magnetic flux short-circuiting
Solution Approach 2:
The invention changes the geometric parameter of the cavity by introducing two different cavity widths. The first width and second width are specifically designed to control the magnetic flux paths differently in various regions, allowing the cavity to serve dual functions of suppressing short-circuiting and preventing flux leakage to the stator
2Loss of energy
If the width of the cavity part in the circumferential direction is narrower than the minimum width of the gap between the rotor core and the stator core, then magnetic flux leakage to the stator is prevented, but the cavity must be precisely positioned and dimensioned, increasing manufacturing complexity
Solution Approach 1:
The invention incorporates the auxiliary fixed magnetic-force magnet radially outward of the fixed magnetic-force magnet as a preliminary structural feature that guides the cavity positioning. The magnet and cavity are designed together as an integrated unit, where the magnet's position pre-determines the optimal cavity location and dimensions, reducing the need for high-precision independent cavity positioning
Solution Approach 2:
The auxiliary fixed magnetic-force magnet acts as an intermediary element between the fixed magnetic-force magnet and the cavity structure. It helps establish the magnetic flux paths and provides a reference framework for cavity design, making the overall structure more tolerant to manufacturing variations
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 suppresses magnetic flux short-circuiting and reduces iron loss, optimizing the power factor and output of the rotary electric machine across a wide operating range.
Implementation Method 1
a fixed magnetic-force magnet configured to be magnetized in a radial direction of the rotor core, an auxiliary fixed magnetic-force magnet disposed radially outward of the fixed magnetic-force magnet, and magnetized in the radial direction so that a magnetizing direction thereof becomes the same direction as that of the fixed magnetic-force magnet
Implementation Method 2
first variable magnetic-force magnets disposed at both sides of the fixed magnetic-force magnet in the circumferential direction, a magnetization state of the first variable magnetic-force magnets being changeable in the circumferential direction by a given magnetic flux
Implementation Method 3
A cavity part is formed in the rotor core, between the auxiliary fixed magnetic-force magnet and the first variable magnetic-force magnets in the circumferential direction, the cavity part extending from the auxiliary fixed magnetic-force magnet to the fixed magnetic-force magnet in the radial direction
Data Source
AI summary
A rotor structure includes a rotor, a stator, and magnetic pole parts provided to a rotor core. Each magnetic pole part includes a radially-magnetized fixed magnetic-force magnet, an auxiliary fixed magnetic-force magnet disposed radially outward of the fixed magnetic-force magnet and radially magnetized in the same direction as the fixed magnetic-force magnet, and first variable magnetic-force magnets disposed at both sides of the fixed magnetic-force magnet in the circumferential direction. A magnetization state of the first variable magnetic-force magnets is changeable in the circumferential direction by a given magnetic flux. A cavity part is formed between the auxiliary fixed magnetic-force magnet and the first variable magnetic-force magnets in the circumferential direction to have a circumferential width at a position of the auxiliary fixed magnetic-force magnet in the radial direction narrower than a minimum width of a gap between the rotor core and a stator core.