The optimization analysis of the hybrid DC circuit breaker based on electromagnetic coupled coils

Aiming at the problems of long current transfer time and low efficiency caused by too low arc voltage in the opening process of the hybrid DC breaker, we propose to increase the DC arc voltage and shorten the current transfer time by adding the highfrequency transformation magnetic field outside the vacuum interrupter. In the end, the working principle and switching process of the hybrid DC circuit breaker are briefly described. Based on the finite element analysis method, we establish a transient mathematical model of field-circuit coupling of vacuum interrupter with external high-frequency transformation magnetic field, and build a drive circuit with external magnetic field in the MATLAB/simulink. The magnetic fields produced by different forms of coils and the key parameters affecting the magnetic field are analyzed by joint simulations of MATLAB and Ansoft Maxwell, Including coil turn spacing, coil cross-sectional area, and coil excitation; According to the simulation results, we found the two-coil symmetric model has high magnetic field uniformity, large magnetic field strength and small space occupation. When the turn spacing is 2mm, the cross-sectional area is 1mm×15mm, the magnetic field strength at 70mm matches the design; Finally, we set up a principle test platform, calibrate the parameters of the coil and the drive circuit, obtain the open arc voltage of the DC circuit breaker by experiments, which is compared with the results without magnetic field. The result shows that the coil designed in accordance with the simulation results can significantly increase the arc voltage, shorten the current transfer time, and contribute to the opening of the DC circuit breaker.