Stator and Rotor Core Thermal Conductivity for Motor Heat Control
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Solution Overview
Problem
Existing rotating electrical machines face inefficiencies due to temperature rises from iron and copper losses, leading to issues like dielectric breakdown and demagnetization, with no effective management of thermal conductivity and diffusivity between the stator core and casing.
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 thermal conductivity is higher than the rotor's, and the stator's diffusivity is higher than the rotor's, ensuring efficient heat dissipation and reduced iron loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator core and rotor core use conventional electrical steel sheets with uniform thermal properties, then the manufacturing process is simple, but the temperature rise from iron and copper losses cannot be effectively managed, leading to reduced motor efficiency and potential dielectric breakdown or demagnetization
Solution Approach 1:
The patent applies local quality by using electrical steel sheets with different thermal conductivities for the stator core and rotor core. The stator core uses steel sheets with higher thermal conductivity (15-25 W/mK) to efficiently dissipate heat from copper losses, while the rotor core uses steel sheets with lower thermal conductivity (10-20 W/mK) to reduce iron losses. This localized differentiation of thermal properties optimizes temperature management in each component without requiring complex overall system changes.
Solution Approach 2:
The patent implements parameter changes by selecting electrical steel sheets with specific thermal conductivity ranges for different components. By changing the thermal conductivity parameter of the steel sheets used in the stator and rotor cores, the patent achieves effective heat dissipation in the stator while minimizing heat generation in the rotor, thereby improving overall temperature management and motor reliability.
2Loss of energy
If the rotor core uses steel sheets with low thermal conductivity to reduce iron loss, then heat generation is minimized, but the overall heat dissipation capability of the motor is reduced
Solution Approach 1:
The patent applies local quality by assigning different thermal conductivity characteristics to the stator core and rotor core steel sheets. The stator core uses higher thermal conductivity steel (15-25 W/mK) to efficiently dissipate heat and reduce copper loss temperature rise, while the rotor core uses lower thermal conductivity steel (10-20 W/mK) to minimize iron loss. This localized differentiation allows each component to optimize its energy loss characteristics.
Solution Approach 2:
The patent implements parameter changes by selecting electrical steel sheets with specific thermal conductivity ranges for different components. By changing the thermal conductivity parameter of the steel sheets used in the stator and rotor cores, the patent achieves effective heat dissipation in the stator while minimizing heat generation in the rotor, thereby improving overall temperature management and motor reliability.
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 enhances motor efficiency by effectively managing heat conduction and diffusion, suppressing temperature rises and reducing copper and iron losses, thereby improving overall performance.
Implementation Method 1
the heat generated due to a copper loss of a coil wound around a teeth portion of a stator core is radiated from a casing disposed along the outer periphery of the stator core to the atmosphere or cooling water that flows through a cooling jacket via the stator core
Implementation Method 2
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 W/(m·K)
Data Source
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 W/(m·K), and both the thermal conductivities have a relationship of an expression (1) of A>BCondition 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.