【目的】无刷交流励磁机作为同步发电机励磁系统的核心部件，其等效电路建模的准确性直接决定输出性能分析的可靠性。传统等效电路模型在参数等效过程中，通常忽略交流励磁机的凸极效应，导致换相电抗参数的理论计算值与实际工况存在系统性偏差。这种偏差会进一步影响对交流电压畸变率、直流电压脉动等关键性能指标的评估精度。为解决此问题，本文提出了一种改进的等效电路建模方法，重点考虑了凸极效应对换相电抗的影响。【方法】首先，基于交流励磁机的磁链方程和电压方程，推导了无刷交流励磁机的等效电路模型；其次，结合三相桥式整流电路的工作模态，以半个周期为例，分析了无刷交流励磁机的工作过程，探讨了换相电抗对交流电压畸变率和直流电压脉动的影响规律；最后，研究了不同凸极效应强度下换相电抗的求解方法，并重新构建了考虑凸极效应的换相电抗计算模型。【结果】为验证模型的有效性，采用有限元法建立二维瞬态场-路耦合仿真模型。仿真结果表明:换相电抗的增大会导致交流电压畸变率和直流电压脉动的显著增加；考虑凸极效应的等效电路模型在换相电抗参数计算精度上具有明显优势，误差显著降低。【结论】本文提出的等效电路建模方法不仅为无刷交流励磁机的换相特性分析提供了高精度工具，还可拓展至永磁同步电机、电励磁双馈电机等含整流电路的发电机系统。对复杂电磁装置的动态性能预测与多物理场协同优化具有重要指导意义。

[Objective] As a core component of the synchronous generator excitation system, the accuracy of the equivalent circuit modeling for brushless AC exciters directly determines the reliability of output performance analysis. Traditional equivalent circuit models often overlook the magnetic circuit asymmetry caused by the salient pole effect of AC exciters during parameter equivalence, resulting in systematic deviations between theoretical calculations of commutation reactance parameters and actual operating conditions. These deviations further compromise the evaluation accuracy of key performance indicators, such as AC voltage distortion rate and DC voltage ripple. To address this issue, an improved equivalent circuit modeling method is proposed, with a focus on the influence of the salient pole effect on commutation reactance. [Methods] First, the equivalent circuit model of the brushless AC exciter was derived based on its flux linkage and voltage equations. Second, by analyzing the operational process of the brushless AC exciter over half a cycle in conjunction with the working modes of a three-phase bridge rectifier circuit, the effect of commutation reactance on AC voltage distortion rate and DC voltage ripple was systematically investigated. Finally, a solution for determining commutation reactance under varying salient-pole effect intensities was developed, and a refined commutation reactance calculation model incorporating the salient-pole effect was re-established. [Results] To validate the effectiveness of the model, a two-dimensional transient field-circuit coupling simulation model was established using finite element analysis. Simulation results showed that an increase in commutation reactance significantly increased both the AC voltage distortion rate and DC voltage ripple. The proposed equivalent circuit model, which incorporated the salient-pole effect, exhibited higher accuracy in calculating commutation reactance parameters, with significantly reduced errors compared to conventional methods. [Conclusion] The proposed equivalent circuit modeling method not only offers a high-precision tool for analyzing the commutation characteristics of brushless AC exciters, but also extends to generator systems with rectifier circuits, such as permanent magnet synchronous motors and electrically excited doubly-fed generators. This approach has significant implications for dynamic performance prediction and multi-physics co-optimization of complex electromagnetic devices.

国家自然科学基金(51977055);安徽省重大科技专项项目(201903a05020042)