大容量电力电子装置母排网络结构矩阵分析方法

Matrix Analysis for Busbar Network in Large-capacity Power Electronic Equipment

为了抑制杂散电感对器件开关过程造成的应力,大容量电力电子装置换流回路需采用低感层叠母排。然而大尺寸公共汇流结构中的层叠母排方案加工难度大,成本显著上升。与之相对的铜条母排方案既保证通流能力,同时设计安装简便,工程应用价值高。但与层叠母排相比,铜条母排电感参数成倍增大,母排电感与支撑电容、交流模块谐振造成的电应力会产生绝缘与热击穿等危害,而针对该问题定量分析与精确设计理论尚未见报道。文中提出大尺寸汇流母排网络结构的矩阵分析方法。首先构建汇流环节各部件子网络导纳参数矩阵并研究其组合特性,推导出全网络通用化矩阵表达式以及解释了子网络相互影响造成的多峰值谐振现象。然后,针对非正弦母线电流分析的困难,将传递函数矩阵与正负序分解法组合,推导出各序电流传递函数与准确的子网络电流。最后,得出母排结构设计方面的改进措施,315kW光伏系统仿真与实验均证明了所提理论的有效性,改进后谐振电流降低30%以上。

Laminated busbar is utilized for the commutation circuits in large capacity power electronic devices to reduce the device stress by stray inductance during the switching process. For large-size structure in the DC-link of a high-capacity converter, the laminated busbar is not applicable due to the machining difficulty and significantly increased cost. The copper bar busbar features high current conducting capability, simple design and convenient installation, which is valuable in application. Compared with the laminated busbar, the copper bar busbar has larger parasitic inductance. The stress caused by the interaction among busbar inductance, supporting capacitors and AC power modules would lead to insulation breakdown and thermal damage. Related analysis and design theory have not been reported. In this paper, a matrix analysis method was presented for the network structure of large size busbar. Firstly, the admittance parameter matrices for the sub networks of components in current confluence link were constructed and the characteristics of their combination were studied. The generalized matrix expression for the whole network was derived and the multi-peak resonance caused by the interaction of the sub networks was explained. Then, aiming at the difficulty of analysis for the non-sinusoidal DC-link currents, the transfer function matrix and the positive and negative sequence decomposition method were combined to derive the current transfer functions of different sequences and the accurate sub network currents. Finally, the improvement for busbar design was obtained. The effectiveness of the proposed theory was validated by simulations and experiments on the 315 kW photovoltaic system and the resonant current gets reduced by more than 30%.