模态分析是研究电机振动噪声问题不可或缺的一环，以一台额定功率为1.98 kW的压缩机用永磁电机为例，分析了热应力和过盈应力对电机结构径向各阶模态固有频率的影响。首先分析了绕组以及建模对电机结构模态分析的影响；然后从理论上解析了电机过盈配合量的选取范围，通过热-结构耦合的有限元仿真对压缩机电机温升最高工况时铁心与机壳的热变形大小进行了分析，结合过盈量的选择范围从振动噪声抑制角度选取最佳过盈配合量；最后建立了压缩机预应力模态仿真模型，分析了热应力和过盈应力对压缩机模态固有频率的影响。考虑热应力和过盈应力效应，能够有效地精确计算整机模态，提高空调压缩机NVH性能评估的准确性。

Modal analysis is an indispensable part of the research on motor vibration and noise issues. Taking a permanent magnet motor for compressor with a rated power of 1.98 kW as an example, the effects of thermal and interference stresses on the radial natural frequencies of various modes of the motor structure are analyzed. Firstly, the influence of winding and modeling on the modal analysis of motor structure is analyzed. Then, the selection range of motor interference fit is analyzed theoretically, the thermal deformation size of the iron core and casing during the highest temperature rise of the compressor motor is analyzed through finite element simulation of thermal-structural coupling. Based on the selection range of interference fit, the optimal interference fit is selected from the perspective of vibration and noise suppression. Finally, a compressor pre-stressed modal simulation model is established, and the effects of thermal stress and interference stress on the modal natural frequency of the compressor are analyzed. Considering the effects of thermal stresses and interference stresses, the modal of the entire machine can be calculated effectively and accurately, which improves the accuracy of the NVH performance assessment of air-conditioning compressors.