Improvement in control system for the medium frequency direct current resistance spot welding system

The paper deals with a medium frequency direct current resistance spot welding system. The system consists of special electromagnetic structure and works in a particular pattern. After studying the structure, working principle and possible operating modes of the system, a new mathematic model is developed to precisely describe the dynamic behavior of the whole system. A phenomenon that the operation of the system can be in dead zone is observed. And the performance of the system would be deteriorated if the phenomenon is not handled properly. And then a control algorithm is proposed to improve the performance of the system. The effectiveness of the proposed algorithm is verified through a numerical simulation.