Asymmetric IPM Rotor Structure for Higher Torque Utilization
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Solution Overview
Problem
Motors with interior permanent magnets suffer from low utilization rates of reluctance and permanent magnet torque due to large differences in current advancing angles and magnetic flux leakage, leading to reduced torque density and increased material usage.
Innovation Solution
A rotor design with asymmetric groove groups and magnetic isolation structures, including air grooves, first, and second grooves, and magnetic bridges, which reduces the angular difference between peak torque components and enhances torque utilization without increasing permanent magnet material, thereby improving torque density and reducing magnetic flux leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional rotor design with interior permanent magnets is used, then the motor can generate torque, but the current advancing angle difference between permanent magnet torque peak and reluctance torque peak is large, resulting in low utilization rate of torque components
Solution Approach 1:
The patent applies asymmetry by designing the rotor with asymmetric groove structures including air grooves, first grooves, and second grooves with different configurations. This asymmetric design optimizes the magnetic flux distribution to reduce the current advancing angle difference between permanent magnet torque and reluctance torque, enabling both torque components to reach their peaks simultaneously and improving torque utilization rate
Solution Approach 2:
The rotor structure is segmented into multiple functional grooves: air grooves for magnetic isolation, first grooves for permanent magnet placement, and second grooves for additional magnetic flux control. This segmentation allows independent optimization of different torque components while maintaining overall rotor functionality
2Reliability
If conventional rotor design is used, then permanent magnets can be mounted, but magnetic flux leakage is large and material utilization is low
Solution Approach 1:
The patent converts the potentially harmful magnetic flux leakage into beneficial flux paths by strategically designing air grooves and magnetic isolation structures. These structures guide the magnetic flux through controlled paths, reducing unwanted leakage while improving overall flux utilization efficiency
Solution Approach 2:
Different regions of the rotor are given different local qualities through the groove design: air grooves provide magnetic isolation in specific regions, while first and second grooves create localized flux concentration zones. This local quality differentiation optimizes flux distribution and reduces overall leakage
3Power
If conventional rotor design is used, then the motor can operate, but iron core saturation occurs and power density is limited
Solution Approach 1:
The patent introduces additional spatial dimensions through the multi-groove structure (air grooves, first grooves, second grooves) to provide alternative flux paths. This dimensional expansion of the magnetic circuit allows flux to distribute more evenly, avoiding concentration that leads to iron core saturation and enabling higher power 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
The asymmetric rotor design significantly increases maximum torque, improves torque utilization rates, and reduces permanent magnetic flux leakage, leading to enhanced power density and lower production costs while maintaining the same amount of permanent magnets.
Implementation Method 1
A first magnetic isolation structure is arranged between the first end of the air groove and the first end of the first groove that are close to each other. A second magnetic isolation structure is arranged between the first end of the first groove and the first end of the second groove that are close to each other.
Implementation Method 2
a plurality of first permanent magnets mounted in the first groove; and a plurality of second permanent magnets mounted in the second groove
Implementation Method 3
the asymmetric structure of the rotor significantly reduces a difference between a current advancing angle corresponding to a peak point of a permanent magnet torque and a current advancing angle corresponding to a peak point of a reluctance torque
Data Source
AI summary
A rotor for a motor is provided. The rotor has a rotor core, first permanent magnets mounted in first grooves of the rotor core, and second permanent magnets mounted in second grooves of the rotor core. The rotor core is provided with groove groups distributed in a peripheral direction of the rotor core. Each groove group has an air groove, a first groove and a second groove. The ends of the air groove, the first groove and the second groove, which are close to a center point of the rotor core, are close to one another. The end of the air groove, the first groove and the second groove, which are away from the center point of the rotor core, are away from one another. Multiple magnetic isolation structures are provided in the rotor core.