Stator and Rotor Core Steel Selection for Motor Heat Dissipation
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Solution Overview
Problem
Existing motors face inefficiencies due to temperature rises from iron and copper losses, leading to issues like dielectric breakdown and demagnetization, with no effective solution addressing the thermal conductivity and diffusivity characteristics of stator and rotor cores.
Innovation Solution
The solution involves using non-oriented electrical steel sheets for the stator and rotor cores with specific thermal conductivity and diffusivity ranges, where the stator's conductivity is higher than the rotor's, and controlling chemical compositions and annealing temperatures to achieve A > B and A1 > B1, enhancing heat conduction and diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-oriented electrical steel sheets are used for both stator and rotor, then manufacturing cost is reduced and inventory is simplified, but performance optimization is limited due to different magnetic flux conditions
Solution Approach 1:
The patent applies different tooth width designs to different parts of the machine: the stator has a first tooth width optimized for stator magnetic flux density, while the rotor has a second tooth width optimized for rotor magnetic flux density. This local differentiation allows each component to be optimized for its specific operating conditions while using the same non-oriented electrical steel sheet material, thus maintaining manufacturing simplicity while improving overall performance.
2Reliability
If oriented electrical steel sheets are used, then magnetic performance is improved, but manufacturing cost increases and inventory management becomes more complex
Solution Approach 1:
The patent changes the geometric parameters (tooth widths) of the stator and rotor to optimize magnetic flux density distribution. By adjusting the first tooth width and second tooth width to specific ranges, the design achieves effective utilization of non-oriented electrical steel sheets, obtaining magnetic performance comparable to oriented steel sheets while avoiding their higher cost and inventory complexity.
3Reliability
If different types of electrical steel sheets are used for stator and rotor, then magnetic flux density is optimized, but manufacturing complexity and inventory requirements increase
Solution Approach 1:
The patent implements local quality differentiation through asymmetric tooth width design: the stator teeth have a first width optimized for stator winding magnetic flux, while the rotor teeth have a second width optimized for rotor magnetic flux. This geometric optimization allows single-use non-oriented electrical steel sheets to achieve differentiated performance in different locations, eliminating the need for different steel sheet types while maintaining optimal magnetic flux density in both stator and rotor.
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 approach improves motor efficiency by effectively dissipating heat from the stator to the casing while reducing iron loss in the rotor, thereby suppressing temperature rises and enhancing overall performance.
Implementation Method 1
A stator and a rotor of a rotating electric machine, each having a three-phase armature winding, are separately assembled and then fixed to each other
Implementation Method 2
a first tooth width of the stator is different from a second tooth width of the rotor... it has been found that, when a rotating electric machine is designed on the basis of the above findings, effective use of non-oriented electrical steel sheets can be achieved
Data Source
Figure 1
AI summary
The rotating electrical machine includes a stator, a rotor, and a casing that accommodates the stator and the rotor, in which at least one of the following conditions 1 and 2 is satisfied. Condition 1: a thermal conductivity A of a non-oriented electrical steel sheet that is used for a core of the stator is in a range of 12 to 35 W/(m- K), a thermal conductivity B of a non-oriented electrical steel sheet that is used for a core of the rotor is in a range of 10 to 33 Wf(m-K), and both the thermal conductivities have a relationship of an expression (1) of A > B Condition 2: a thermal diffusivity A1 of the non-oriented electrical steel sheet that is used for the core of the stator is in a range of 3.0 × 10-6 to 9.0 × 10-6 m2/sW/(m·K), a thermal diffusivity B1 of the non-oriented electrical steel sheet that is used for the core of the rotor is in a range of 2.5 × 10-6 to 8.5 × 10-6 m2/sW/(m·K), and both the thermal diffusivities have a relationship of an expression (3) of A1 > B1