1.School of Automation, Northwestern Polytechnical University;2.School of Electrical Engineering, Xi'3.'4.an Jiaotong University
Project Supported by National Natural Science Foundation of China (51507142); Key Research and Development Program of Shaanxi Province, China (2020GY-116)
基于移相加占空比控制策略的三有源桥TAB（triple active bridge）DC-DC变换器具有效率高、软开关范围可扩展等优点，但其小信号建模过程复杂、闭环控制环路参数整定困难。针对上述问题，该文提出一种TAB工作在移相加占空比控制下的全阶连续广义状态平均建模和PI控制器设计方法。首先，分析TAB的运行原理和Y型等效结构；之后，结合移相加占空比控制控制的特点和交流方波源等效方法，推导出TAB的广义状态空间平均模型；然后，在推得模型的基础上求得输入到输出的传递函数，设计出PI控制器参数。最后，结合数字仿真及样机试验验证了所提方法的正确性及有效性。
The three active bridge (TAB) DC-DC converter based on phase shift plus duty cycle control strategy has the advantages of high efficiency and expandable soft switching range, but its small signal modeling process is complex and the parameter setting of closed-loop control loop is difficult. To solve the above problems, a full order continuous generalized state average modeling and PI controller design method for TAB converter under phase shift plus duty cycle control strategy is proposed in this paper. Firstly, the operation principle and Y-type equivalent structure of TAB are analyzed. Combined with the characteristics of phase shift plus duty cycle control and the equivalent method of AC square wave source, the generalized state space average model of TAB is derived. Then, based on the derived model, the transfer function from input to output is obtained, and the parameters of PI controller are designed. Finally, the correctness and effectiveness of the proposed method are verified by digital simulation and prototype tests.