适用于直流断路器的大电流快速开关分闸特性

快速开关分闸稳定性是影响直流断路器开断性能的关键要素。文中对大电流快速开关的双弹簧永磁操动和电磁斥力双动机构的分闸过程，用有限元方法进行电磁、热和位移等多物理场耦合计算，分析了永磁操动机构驱动线圈是否有必要投入以及不同驱动线圈电流对双动机构分闸特性的影响。结果表明：在永磁操动机构驱动线圈投入的情况下，可提前将永磁吸力抵消，进而避免电磁斥力因做功时间较短而引起分闸回弹现象；由于分闸初期电磁斥力非常大，永磁操动机构驱动线圈的投入对分闸初期的速度影响较小；在电磁斥力消失后，永磁操动机构驱动线圈电流在一定范围内越大，到达额定开距的速度越大，为避免其造成分闸反弹，应合理选择驱动线圈电流值。将仿真结果与实际样机分闸特性曲线进行对比，二者具有较好的一致性，验证了仿真方法的正确性。

Opening characteristics of high current fast switch for DC circuit breaker

The stability of opening process of fast mechanical switch is the key factor affecting the breaking performance of DC circuit breaker. Based on the finite element method,the multi-field coupling calculation of electromagnetic,thermal and momentum is carried out for the opening process of high current fast switch with permanent magnet operating mechanism and electromagnetic repulsion mechanism. The influence of the driving coil input for the permanent magnet operating mechanism and different driving coil currents on the opening process of double-action mechanism are analyzed. The calculation results show that the permanent magnet suction force can be cancelled in advance when the driving coil of the permanent magnet operating mechanism is put in,thereby avoiding the opening spring back phenomenon caused by the electromagnetic repulsion force due to the short working time. Because the electromagnetic repulsion force is very large at the initial stage of opening,the driving coil input of the permanent magnet operating mechanism has little influence on the initial speed of opening. After the electromagnetic repulsion disappears,the greater the driving coil current of the permanent magnet operating mechanism is,the greater the speed to reach the rated opening distance after the electromagnetic repulsion force disappearing. In order to avoid opening rebound phenomenon,the current value of the driving coil should be selected reasonably. The comparison between the simulation results and the opening process characteristic curves of the actual prototype shows that two curves are in good agreement, which verifies the correctness of the simulation method.