Research on Double Closed-Loop Control Strategy of Contactors Based on Flux Linkage Observers

In this article, a double closed-loop control structure of a contactor is proposed for the first time, in which the outer flux linkage loop controls the inner current loop to retain the merits of current closed-loop control while avoiding its defects. A voltage integral flux linkage observer is designed in the making process of the contactor. In the closing process of the contactor, the state space expression of the contactor is given, and the closed-loop flux linkage observer is formed by reconstructing the flux linkage variable. The observed flux linkage is used as the closed-loop return signal to realize flux linkage closed-loop control of the contactor in the making and closing processes. This control scheme can realize self-adjustment of the coil current; thus, contact bounces are inhibited. Meanwhile, whether the movable core is closed in place is judged according to the proportional relationship between the flux linkage and the coil current in the closing process. Finally, the feasibility of the proposed scheme is verified by simulation and experiment.