Rotor Recesses for Electrical Machine Magnet Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost of permanent magnets in electrical machines due to their significant contribution to the overall cost, while also requiring a large number of magnets to achieve efficient operation with multiple magnetic field configurations.
Innovation Solution
The design of a rotor with strategically placed recesses and permanent magnets, where the number of magnets is reduced by utilizing recesses without core material and optimizing the arrangement of magnets to create a four-pole magnetic field with fewer magnets, allowing for the use of higher harmonic components of the magnetomotive force for torque generation, thereby reducing the number and size of required magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a large number of permanent magnets are used to create multiple magnetic field configurations for efficient operation, then the efficiency of the electrical machine is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The rotor is segmented into multiple independent recesses (first recesses and second recesses) that can be selectively filled with permanent magnets. This allows the magnetic field to be divided into different configurations (two-pole, four-pole, six-pole) by activating specific segments, rather than requiring all magnets to be present simultaneously. The segmentation enables efficient operation across multiple magnetic field configurations while using fewer total magnets.
Solution Approach 2:
The electrical machine employs dynamic reconfiguration of the magnetic field by selectively energizing different combinations of permanent magnets in the first and second recesses. The system can switch between two-pole, four-pole, and six-pole configurations during operation, allowing the same physical rotor structure to adapt to different operational requirements and load conditions, thereby maintaining high efficiency across varying operating points without requiring a separate rotor for each configuration.
2Adaptability or versatility
If multiple permanent magnets are arranged to create different magnetic field configurations, then the versatility of the electrical machine is improved, but the device complexity increases
Solution Approach 1:
The rotor is divided into multiple independent recesses (first recesses and second recesses) that can be selectively filled with permanent magnets. This segmentation allows different magnetic field configurations to be created by activating specific segments, reducing the need for complex mechanical reconfiguration mechanisms. Each recess acts as an independent module that can be individually controlled.
Solution Approach 2:
The rotor is pre-configured with multiple recesses at specific angular positions during manufacturing, allowing for selective population with permanent magnets. This preliminary structural preparation enables flexible magnetic field configuration changes without requiring complex assembly or disassembly operations during operation. The recesses are positioned in advance to facilitate easy magnet insertion and removal for different pole configurations.
3Quantity of substance
If the number of permanent magnets is reduced to lower costs, then the manufacturing cost decreases, but the ability to generate sufficient magnetic field strength for efficient operation is compromised
Solution Approach 1:
The patent applies different types of recesses (first recesses extending from the air gap toward the shaft, and second recesses arranged differently) with specific local characteristics to optimize magnetic field generation. Each recess type is strategically positioned and dimensioned to maximize its contribution to the overall magnetic field strength. The local quality of each recess configuration is optimized to ensure sufficient magnetic field generation even with fewer total magnets.
Solution Approach 2:
The rotor employs a composite structure combining ferromagnetic rotor core material with strategically placed permanent magnets in specific recesses. This composite arrangement allows the ferromagnetic material to channel and concentrate the magnetic flux generated by the fewer permanent magnets, thereby maintaining sufficient magnetic field strength. The composite structure of rotor material and selective magnet placement works synergistically to compensate for the reduced number of magnets.
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 design reduces the number and size of permanent magnets needed, lowering manufacturing costs and enhancing the efficiency of the electrical machine by optimizing the magnetic field configuration and using higher harmonic components for torque generation.
Implementation Method 1
The stator winding can be connected to power electronics and be designed to generate a rotating field. The rotor magnetic field interacts with a magnetic field of the stator.
Implementation Method 2
To generate a rotor magnetic field, the rotor may have permanent magnets. In operation, a rotor magnetic field interacts with a magnetic field of the stator.
Data Source
AI summary
An electrical machine (20) comprising a stator (21) and a rotor (22) rotatably supported relative to the stator (21) is disclosed. The rotor (22) comprises two first recesses (23) and at least one second recess (24), wherein an air gap (25) is arranged between the stator (21) and the rotor (22), the two first recesses (23) are arranged in the rotor (22) and extend completely through the rotor (22) from the air gap (25) to a shaft (26) on which the rotor (22) is arranged, the two first recesses (23) are arranged in a manner displaced relative to one another by less than 180° along the circumference of the rotor (22), the at least one second recess (24) is arranged in a manner displaced relative to the first recesses (23) by at least 90° along the circumference of the rotor (22), the at least one second recess (24) does not extend through the rotor (22) to the shaft (26), and a first permanent magnet (27) is arranged each in the first recesses (23) and/or a second permanent magnet (28) is arranged each in the at least one second recess (24). In addition, a method of operating the electrical machine (20) is provided.