Reducing the Contact Erosion of AC Contactors Based on Novel Control Circuits

During the switch-off process, the contact erosion generated by the AC contactor will seriously affect its performance, thereby directly influencing the normal operation of the power equipment. Therefore, aiming at the problem of contact erosion caused by contact bounce during the switch-on and switch-off period of AC contactors, this paper designed the driving circuits during the switch-on, holding, and switch-off processes. During the switch-on process, DC excitation was used instead of AC excitation to eliminate or reduce the contact bounce. During the holding process, low-voltage DC was used instead of high-voltage AC to save energy and reduce coil losses. During the switch-off process, the contact current was used as the control factor, and the scheme of shunting control was employed to achieve the goal of few or even no arcs. In addition, in order to detect the high voltage and large current signals in the main circuit, the three-phase voltage acquisition circuit and three-phase current acquisition circuit were designed. Therefore, a whole process dynamic control which included the switch-on, holding, and switch-off was formed. Through simulation testing and relevant experimental testing, the results demonstrated the correctness and effectiveness of the designed circuit.