大功率牵引整流机组的高压直流母线存在较大电压波动，严重影响了系统的供电质量和稳定性。为满足系统电压波动抑制及负载宽范围调节的要求，针对中间级直流变换系统，以三有源桥变换器为研究对象，提出了一种基于信赖域狗腿法的模型预测控制策略。首先介绍了三有源桥变换器的工作原理及端口耦合机理，其次，建立了三有源桥变换器预测模型并构建了相应的代价函数；然后针对三有源桥变换器代价函数在线求解困难的问题，采用信赖域狗腿寻优算法实现代价函数的最小化；最后，在实验室样机上验证了所提策略的有效性。实验结果表明：与传统比例积分控制相比，所提方法有效抑制了三有源桥变换器的电压波动，提升了系统的动态性能及负载调节性能，同时实现了端口解耦。

Large voltage fluctuations are observed in the high-voltage DC bus of high-power traction rectifier units, which negatively impact the power supply quality and system stability. To address the requirements of voltage fluctuation suppression and wide-range load regulation in intermediate DC/DC converter systems, a model predictive control (MPC) strategy based on the trust-region dogleg method was proposed. The triple-active-bridge (TAB) converter was selected as the research object. Firstly, the working principle and port coupling mechanism of the TAB converter were introduced. Secondly, a prediction model was established, and a cost function was formulated. To address the difficulty of solving the cost function online, the trust-region dogleg method was employed to minimize the cost function. Finally, experimental validation was conducted on a laboratory prototype. The results indicate that compared with traditional proportional-integral control, the voltage fluctuations of the TAB converter are effectively suppressed, while the dynamic performance and load regulation capability of the system are significantly enhanced. Additionally, port decoupling is achieved.