The pulsed power supply based on air-core pulsed alternators, with advantages in terms of miniaturization and lightweight, has been a preferred power source for electromagnetic launch (EML) systems in all-electric vehicles or ships. However, when an air-core pulsed alternator is used to drive the electromagnetic railgun, the bulk of the inertial energy storage converts into energy losses. These losses not only reduce the efficiency of the system but also cause temperature rising of the alternator, leading to a limit on its repetitive output performance, affecting the performance of the electromagnetic railgun, and ultimately, the alternator’s volume and weight will also increase. Therefore, it is necessary to develop research relating to those losses. In this article, the operation principle of the EML system is explained first, and four typical operating stages are described. Then, the influence of the rotor eddy current on the performance of the alternator is analyzed. After that, the various losses generated in the pulsed power supply system are analyzed in detail. The eddy current losses are obtained from simulation. The copper losses and switch losses are calculated by formulas derived in different stages and different members. The formulas of windage and mechanical losses are obtained too. Based on these analyses, losses can be calculated by the parameters of the EML system or derived from a cosimulation model. Also, the influence of alternator parameters and structures on losses is studied. Finally, a seven-phase six-pole air-core prototype is introduced, and the windage and mechanical losses are tested on the prototype. Moreover, the cosimulation model of the EML system is built, its losses are evaluated, and the efficiency of the EML system is derived.

中文翻译：

---

空心脉冲发电机驱动理想电磁轨道炮的损耗分析

基于空芯脉冲交流发电机的脉冲电源具有小型化、轻量化等优点，已成为全电动汽车或船舶电磁发射（EML）系统的首选电源。然而，当使用空心脉冲交流发电机驱动电磁轨道炮时，大部分惯性能量存储会转化为能量损失。这些损耗不仅会降低系统的效率，还会引起交流发电机的温升，导致其重复输出性能受到限制，影响电磁轨道炮的性能，最终还会增加交流发电机的体积和重量。因此，有必要开展与这些损失相关的研究。在本文中，首先解释EML系统的运行原理，并描述了四个典型的操作阶段。然后，分析了转子涡流对交流发电机性能的影响。之后，详细分析了脉冲电源系统中产生的各种损耗。涡流损耗是从模拟中获得的。铜耗和开关损耗按不同阶段、不同成员推导出的公式计算。也得到了风阻和机械损耗的公式。基于这些分析，可以通过 EML 系统的参数或从协同仿真模型中得出损失。此外，还研究了交流发电机参数和结构对损耗的影响。最后介绍了一个七相六极空芯样机，并在样机上测试了风阻和机械损耗。此外，