The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields ...The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields under extreme sea states. The model, integrating the ST6 source term, is validated against observed data, demonstrating its credibility. The spatial distribution of the occurrence probability of strong nonlinear waves during typhoons is shown, and the waves in the straits and the northeastern part of the South China Sea show strong nonlinear characteristics. The high-order spectral model HOS-ocean is employed to simulate the random wave surface series beneath five different platform areas. The waves during the typhoon exhibit strong nonlinear characteristics, and freak waves exist. The space-varying probability model is established to describe the short-term probability distribution of nonlinear wave series. The exceedance probability distributions of the wave surface beneath different platform areas are compared and analyzed. The results show that with an increase in the platform area, the probability of a strong nonlinear wave beneath the platform increases.展开更多
针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbe...针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbench and Optislong联合仿真软件建立8极48槽TMPS-HESM模型,运用遗传算法进行全局多目标优化,得到pareto最优解集后使用优劣解距离法(TOPSIS)客观选取最优解。最后对比分析优化前后电机的各项其他性能,结果表明:采用遗传算法和TOPSIS法对电机参数进行优化,能提升电机多目标优化效率,不仅可解决混合励磁电机励磁电流增加导致齿槽转矩剧增的问题,还能有效削弱电机转矩脉动,提升电机平均转矩,在减少电机的振动噪声和提高电机输出转矩方面均取得改善。展开更多
以一台2.5 k W切向聚磁型并联结构混合励磁电机为研究对象,研究切向聚磁型并联结构混合励磁电机磁极偏心对电机振动噪声的影响。根据电机电磁振动噪声相关理论,建立磁极偏心切向聚磁型并联结构混合励磁电机模型,采用磁极偏心优化其气隙...以一台2.5 k W切向聚磁型并联结构混合励磁电机为研究对象,研究切向聚磁型并联结构混合励磁电机磁极偏心对电机振动噪声的影响。根据电机电磁振动噪声相关理论,建立磁极偏心切向聚磁型并联结构混合励磁电机模型,采用磁极偏心优化其气隙磁密畸变率和电磁噪声,分析该电机在优化前后径向电磁力的阶次、频率特征,并对该电机的定子进行模态分析,利用ANSYS Workbench仿真平台搭建电机振动噪声耦合模型,计算优化前后电机的振动响应与噪声变化。结果表明:采用磁极偏心能有效优化电机气隙磁密和电磁力密度,气隙磁密谐波畸变率显著下降,电磁力(16,4 f1)分量幅值减小74%,从而可达到抑制电机振动噪声的目的。展开更多
基金financially supported by the National Key R&D Program of China(No.2022YFC3104205)the National Natural Science Foundation of China(No.42377457).
文摘The generation and propagation mechanism of strong nonlinear waves in the South China Sea is an essential research area. In this study, the third-generation wave model WAVEWATCH Ⅲ is employed to simulate wave fields under extreme sea states. The model, integrating the ST6 source term, is validated against observed data, demonstrating its credibility. The spatial distribution of the occurrence probability of strong nonlinear waves during typhoons is shown, and the waves in the straits and the northeastern part of the South China Sea show strong nonlinear characteristics. The high-order spectral model HOS-ocean is employed to simulate the random wave surface series beneath five different platform areas. The waves during the typhoon exhibit strong nonlinear characteristics, and freak waves exist. The space-varying probability model is established to describe the short-term probability distribution of nonlinear wave series. The exceedance probability distributions of the wave surface beneath different platform areas are compared and analyzed. The results show that with an increase in the platform area, the probability of a strong nonlinear wave beneath the platform increases.
文摘针对切向聚磁型并联结构混合励磁电机(TMPS-HESM)随着励磁电流增加导致齿槽转矩剧增容易引发电机振动噪声的问题,根据齿槽转矩的产生原理,探讨改变转子极靴宽度、磁极偏心距和气隙长度削弱电机齿槽转矩的可行性。借助Maxwell and Workbench and Optislong联合仿真软件建立8极48槽TMPS-HESM模型,运用遗传算法进行全局多目标优化,得到pareto最优解集后使用优劣解距离法(TOPSIS)客观选取最优解。最后对比分析优化前后电机的各项其他性能,结果表明:采用遗传算法和TOPSIS法对电机参数进行优化,能提升电机多目标优化效率,不仅可解决混合励磁电机励磁电流增加导致齿槽转矩剧增的问题,还能有效削弱电机转矩脉动,提升电机平均转矩,在减少电机的振动噪声和提高电机输出转矩方面均取得改善。
文摘以一台2.5 k W切向聚磁型并联结构混合励磁电机为研究对象,研究切向聚磁型并联结构混合励磁电机磁极偏心对电机振动噪声的影响。根据电机电磁振动噪声相关理论,建立磁极偏心切向聚磁型并联结构混合励磁电机模型,采用磁极偏心优化其气隙磁密畸变率和电磁噪声,分析该电机在优化前后径向电磁力的阶次、频率特征,并对该电机的定子进行模态分析,利用ANSYS Workbench仿真平台搭建电机振动噪声耦合模型,计算优化前后电机的振动响应与噪声变化。结果表明:采用磁极偏心能有效优化电机气隙磁密和电磁力密度,气隙磁密谐波畸变率显著下降,电磁力(16,4 f1)分量幅值减小74%,从而可达到抑制电机振动噪声的目的。
