For the application of the motor driving mechanism in the 126 k V vacuum circuit breaker

theoretical modeling is carried out

and kinematic and dynamic constraint equations of the transmission chain of the rotary motor driving mechanism are constructed. MATLAB is employed to solve the constraint equations

and the load torque of the servo motor is decomposed and analyzed. In order to reduce the load torque of the servo motor

optimization is performed on the starting angle of the crank

the self-closing force of the arc extinguishing chamber

and the mass of the contact moving end. The rigid body dynamics analysis software Adams is used to simulate the load torque under different servo control strategies. In the position servo control mode

the fluctuation range of servo motor load torque is large

and the torque utilization rate during switching-off process is low. To improve the motor torque utilization rate

a closed-loop rotation angle control method is proposed. Comparison of the results between simulation calculation and test show that the motor current is in the higher amplitude range of 400 A in the over-travel section and the acceleration section

and descends rapidly during the deceleration phase. The torque utilization rate reaches 49.4%

which indirectly reflects that the output torque of the servo motor is in good agreement with the trend of the simulation results.