【目的】针对传统热网络法(LPTN)难以表征绕组绝缘层与浸渍漆之间温度梯度的问题,本文提出一种耦合保角映射法与LPTN解析绕组等效导热系数的瞬态温升计算方法。【方法】首先,以一台10 kW表贴式永磁同步电机为研究对象,利用保角映射法将铜导体的圆弧形等温边界变换为直线边界,从而将绕组内部复杂的非均匀热场映射为平板热场,解析求解绕组的等效导热系数。然后,基于得到的绕组等效传导热阻构建等效热网络模型,并考虑绕组电阻率随温度变化的影响迭代更新铜耗。最后,通过有限元分析(FEA)与温升试验对比,验证了解析模型的可靠性。【结果】仿真和试验结果表明,绕组温升的LPTN与FEA的误差为1.94%,证明了热网络模型在预测绕组热特性方面具有较高的计算精度。机壳温升的LPTN与FEA及试验的误差分别为3.20%和6.56%,进一步验证了所提模型的有效性。【结论】本文提出的基于保角映射法的绕组均匀化等效建模方法,在保证计算效率的同时能有效反映绕组的热特性,可推广至其他电机的热分析。此外,针对定子内外径比影响电机瞬态温升的分析表明,通过合理调配铜耗与铁耗的占比,可有效抑制电机的瞬态温升。

[Objective] To address the challenge that the traditional lumped-parameter thermal network (LPTN) struggles to characterize the temperature gradient between the winding insulation layer and impregnating varnish, this paper proposes a transient temperature rise calculation method. This method couples conformal mapping with an LPTN to analytically derive the equivalent thermal conductivity of the windings. [Methods] Firstly, a 10 kW surface-mounted permanent magnet synchronous motor was taken as the research object. The conformal mapping method was utilized to transform the arc-shaped isothermal boundary of the copper conductors into a straight-line boundary, thereby mapping the complex non-uniform thermal field inside the winding into a flat-plate thermal field, and the equivalent thermal conductivity of the winding was solved analytically. Then, an equivalent thermal network model was constructed based on the obtained equivalent conduction thermal resistance of the winding, and the copper loss was iteratively updated by considering the influence of the winding resistivity changing with temperature. Finally, the reliability of the analytical model was verified by comparing with finite element analysis (FEA) and temperature rise experiments. [Results] The simulation and experimental results showed that the error between the LPTN and FEA for the winding temperature rise was 1.94%, which proved the high calculation accuracy of the thermal network model in predicting the winding thermal characteristics. The errors between the LPTN model and FEA/experimental results for housing temperature rise were found to be 3.20% and 6.56% respectively, which further validated the effectiveness of the proposed model.[Conclusion] The winding homogenization modeling method based on the conformal mapping method proposed in this paper can effectively reflect the thermal characteristics of the winding while ensuring the calculation efficiency, and can be extended to the thermal analysis of other motors. In addition, the analysis of the influence of the stator inner and outer diameter ratio on the transient temperature rise of the motor shows that the transient temperature rise of the motor can be effectively suppressed by reasonably allocating the proportion of copper consumption and iron consumption.

辽宁省优秀人才基金(LJQ2015082)