为了满足高压直流断路器对其操动机构快速性驱动的要求，针对40.5 kV真空断路器设计了一种具有较高分合闸速度并适用于快速开断的新型电磁斥力机构，其由线盘式和双线圈式机构串联而成。首先，运用有限元方法进行电磁场仿真模拟，通过对机构的电磁斥力、位移／时间特性和速度／时间特性分析，初步验证了其可行性；然后，采用单一变量法对其运动特性进行仿真分析，得到了各参数对运动特性影响的规律，确定了优化参数；最后，为了减小快速电磁斥力机构的分闸弹跳，设计了电磁缓冲器，分析了缓冲电流投入时间和缓冲驱动电路参数对缓冲特性的影响。研究表明：新型电磁斥力机构结合了线盘式机构的快速响应和双线圈式机构的较高驱动效率的优点，其响应时间短、运动速度大、全行程时间短，满足快速开断的需求，在驱动电路电容3 500 μF、电压1 200 V，缓冲电路电容3 500 μF、电压1 300 V的参数条件下，设计的电磁斥力机构全行程时间仅有2.18 ms。

In order to meet the requirements of high-voltage DC circuit breakers for rapidity actuation of their actuating mechanisms, a new electromagnetic repulsion mechanism was designed for 40.5 kV vacuum circuit breaker, which had high breaking and closing speeds and was suitable for quick disconnection. It consisted of a coil-plate and a double-coil mechanism connected in series. Firstly, the electromagnetic field simulation was carried out by the finite element method, the feasibility of the mechanism was initially verified by analyzing the electromagnetic repulsion, displacement/time characteristics and velocity/time characteristics. Then, the single-variable method was used to simulate and analyze its motion characteristics. the law of the influence of each parameter on the motion characteristics was obtained, and the optimization parameters were determined. Finally, in order to reduce the tripping bounce of the long-stroke fast electromagnetic repulsion mechanism, an electromagnetic buffer was designed. the effects of buffer current input time and buffer driving circuit parameters on buffer characteristics were analyzed. The results show that the new electromagnetic repulsion mechanism combines the advantages of the fast response of the coil-plate mechanism and the high drive efficiency of the double-coil mechanism, with its short response time, large motion speed and short full stroke time, and meet the need of quick disconnection. Under the parameter conditions of 3 500 μF capacitance and 1 200 V for the driving circuit and buffer circuit capacitance 3 500 μF capacitance and 1 300 V for the buffer circuit, the full travel time of the designedelectromagnetic repulsion mechanism is only 2.18 ms.