应用于两级式逆变的双有源串联谐振变换器二倍频波动抑制及控制参数设计

在两级式逆变器中，后级逆变器在带有单相或三相不平衡负载时会产生二倍频的瞬时功率波动，此二倍频波动会耦合进入前级直流变换器，造成前级双有源串联谐振变换器(dual active bridge series resonant converter, DBSRC)的交流谐振电流幅值出现较大的二倍频波动。考虑到DBSRC高阶模型较为复杂，提出简化的降阶一阶小信号模型。基于此简化模型，通过在电压闭环回路中串入二倍频陷波器，大范围地增加二倍频处的闭环输出阻抗，从而实现抑制前级的DBSRC的谐振电流波动。进一步，提出保证两级式逆变系统稳定的二倍频波动抑制的控制参数设计方法。最后，通过仿真和实验验证了所提出的简化降阶模型和控制系统参数设计的有效性和可行性。

Second harmonic suppression and design of control parameters for a dual-active-bridge series resonant converter applied to a two-stage inverter

In a two-stage inverter, the downstream inverter with single-phase or three-phase unbalanced load will generate an instantaneous power fluctuation of the second harmonic frequency. This will be coupled into the front-end DC converter and result in a large second harmonic fluctuation of the AC resonant current amplitude in the front-end dual-active-bridge series resonant converter (DBSRC). Taking into account the complexity of the high-order model of DBSRC, the simplified model of a reduced first-order small signal model is proposed. Based on the simplified model, the output impedance at the second harmonic is greatly increased by inserting a double frequency notch in the voltage closed-loop, so that the resonant current fluctuation of the front-end DBSRC can be suppressed. Further, a parameter design method of the control system to suppress the second harmonic fluctuation is proposed, and the control strategy to ensure the stability of the two-stage inverter is realized. Finally, the feasibility and effectiveness of the proposed simplified reduced-order model and the design approach of control parameters are verified by simulation and experiment.