TPS-based resultant force-balanced sensorless control for dynamic making of PM contactors

To address the high control cost and poor dynamic performance of permanent magnet (PM) contactor making, this paper proposes a time pulse sequences (TPS)–based resultant force-balanced sensorless (RFBS) control strategy. First, by coupling mechanical motion equations with voltage balance equations using the finite element method (FEM) for electromagnetic fields, a collaborative state monitor–resultant force balancer model is constructed. This model dynamically matches electromagnetic attraction with mechanical reaction forces, mitigating abrupt force variations at the overstroke point of the movable iron core, thereby suppressing speed surge and contact bounce. Second, predefined TPS replace laser displacement sensors, establishing an equivalent mapping between TPS and the displacement and force of the movable iron core, which enables low–cost sensorless control. Furthermore, the differential evolution algorithm (DEA) optimizes the TPS parameters with objectives of making smoothness and rapidity, automatically refining the timing of pulse sequences and the flux–weakening trigger to derive the optimal TPS. A MATLAB/Simulink simulation model verifies the feasibility of the proposed control strategy. Finally, 30 repetitive making experiments demonstrate that the algorithm reduces contact bounce time by 92.5%, bounce count by 93.0%, terminal velocity of the movable iron core by 76.4%, making time by 48.6%, and arc splashing height from 43 mm to 1 mm. This study accomplishes the triple objectives of sensorless operation, low cost, and superior performance, significantly enhancing making smoothness and reliability while extending the mechanical and electrical lifespan of the PM contactor.