单相两级联H桥整流器负载不平衡度范围研究

Load Imbalance Degree Range of Single-phase Two-stage Cascaded H-bridge Rectifier

级联H桥整流器在实际运行中会因负载不平衡产生直流母线电容电压不平衡问题。针对负载不平衡下直流母线电压平衡问题,提出了直流母线参考电压范围内的负载不平衡限制范围。为减小锁相环给系统控制带来的复杂性,采用无锁相环控制结构。通过深入研究二维调制控制算法,推导出两桥调制波电压波形。然后根据功率平衡原则推导出系统稳定运行在单位功率因数下的负载不平衡限制范围,同时给出了直流母线参考电压选取范围。仿真和实验结果验证了所提出的直流侧电压选取范围与负载不平衡限制范围的有效性与可行性,对级联H桥整流器系统参数设计提供了有重要依据。

Due to load imbalance, the dc-link capacitor voltage imbalance problem will occur in the actual operation of cascaded H-bridge rectifier. To solve the problem of dc-link voltage balance under unbalanced load, we put forward the range of load imbalance within the dc-link reference voltage. In order to reduce the complexity of the phase-locked loop to the system control, the lockless loop control structure is adopted. Through in-depth study of the two-dimensional control algorithm, the voltage waveform of two-bridge modulation wave is deduced. Then, according to the principle of power balance, the load unbalance limit range is deduced when the system is under unit power factor. Meanwhile, the reference range of dc-link voltage is given. The simulation and experiment results have verified the validity and effectiveness of dc-link reference voltage selection range and the load imbalance limit range, which provides an important basis for the design of cascaded H-bridge rectifier system parameters.