低压塑壳断路器中电动斥力的三维有限元非线性分析与实验研究

3-D FINITE ELEMENT NONLINEAR ANALYSIS AND EXPERIMENTAL INVESTIGATION OF ELECTRO-DYNAMIC REPULSION FORCE IN MOLDED CASE CIRCUIT BREAKERS

电动斥力的计算对低压塑壳断路器(MCCB)的设计有重要意义。基于电流一磁场一电动斥力之间的方程,并考虑铁磁物质的影响,应用三维有限元非线性分析,引入圆柱导电桥模型作为接触点模拟触头问的电流收缩,统一计算触头间的Holm力和动导电杆上的Lorentz力。耦合电路方程,并以动触头上的预压力为约束通过迭代运算,从而确定动触头的打开时间。分析了五种不同结构的MCCB,并对电动斥力和触头打开时间进行了实验研究,结果表明,该方法是有效的,可用于MCCB新产品触头系统的设计。

For the optimization design of molded case circuit breakers (MCCBs), it is necessary and important to calculate the electro-dynamic repulsion force acting on the movable conductor. With 3-D finite element nonlinear analysis, according to the equations among current-magnetic field-repulsion force and taking into account the ferromagnet, we introduce contact bridge model to simulate the current constriction between contacts, so Lorentz and Holm force acting on the movable conductor and contact, respectively, can be integrated to calculate. Coupled with circuit equations, the opening time of movable contact also can be obtained using iteration with the restriction of contact force. Simulation and experiment for repulsion force and opening time of five different configuration models have been investigated. The results indicate that the proposed method is effective and is capable of evaluating new design of contact systems in MCCBs.