270V直流开断特性研究与耗散功率变化的Mayr模型仿真分析

Research on DC Breaking Characteristics of 270V DC System and Simulation Analysis of the Mayr Model With Variable Dissipation Power

为了优化航空270V直流接触器结构设计以及预期接触器的开断容量,采用一种以栅片和磁吹系统相结合的直流接触器,进行典型负载类型下的开断性能实验,得到了感性负载情况下开断难度最大,且随着回路电感值的增大,燃弧时间和电弧熄灭时过电压峰值增加。主触点间并联RC支路虽然会增加整个燃弧时间,但能有效限制过电压的数值,且过电压峰值随并联支路电容C的增加而减小。假设燃弧过程中电弧具有对称性,并对电弧进行受力分析,提出横向磁场中电弧运动速度和消散功率的计算方法,得到一种Mayr电弧修正模型。在不同等级的阻性负载情况下,分别对燃弧过程进行数值仿真,经仿真与实验结果对比,所提Mayr电弧修正模型能够准确描述电极分断过程中电弧电压及运动速度的变化情况,为航空直流接触器的设计提供有效的参考。

In order to optimize the structure design of an aero 270 V DC contactor and expect it breaking capacity. In this paper, a DC contactor combined with splitter plate and magnetic blow out system was adopted to test the breaking performance under typical load conditions. The experimental results show that inductive load is the most difficult condition to break and with the increase of the inductance of the circuit,the arcing time and the over-voltage value increase. Although the RC branch will increase the entire arcing time, it can effectively limit the over-voltage value and the over-voltage peak decreases as the capacitance of the parallel branch capacitor C increases. Then, assuming that the arc has symmetry during the arcing process, a calculation method of the arc motion speed and the dissipated power in the transverse magnetic field was proposed and obtained a modified Mayr arc model. Finally, the numerical simulation of the arcing process was carried out under different levels of resistive loads.Comparing the simulation with the experimental results, the modified Mayr arc model proposed in this paper can accurately describe the changes of arc voltage and moving speed during electrode breaking process, which can provide an effective reference for the design of aero DC contactor.