Research On Control System And Control Method Of Intelligent Synchronous Contactor With Double Coils

AC contactor is mainly used in frequent switching and breaking AC load circuit. Due to its frequent operating characteristics, AC contactor must have high electrical property to guarantee a certain service life. The arc and the contact bounce generated in the opening and closing movement are the main factors which influencing its electrical life of the AC contactor. The intelligent control technology and methods are the most effective ways to improve the electrical life of the AC contactor, which can realize the AC contactor in the closing course with no bounce and the breaking course with no arc, and remarkablly improve the electrical life of the AC contactor. In this paper, the intelligent control technologies and methods of AC contactor is deeply studied. The main works of this paper including the following aspects.A new structure of asynchronous combination type AC contactor with double coils electromagnetic system is presented. The traditional large size contactor and single coil electromagnetic system are replaced by the three small size contactors and the double coils electromagnetic system respectively, which is favorable to realize the closed-loop control of the contactor. The structure parameters of the contactor and the related electrical parameters are designed, and the dynamic simulation model based on Simulink and the finite element method are established in this paper. Simulation analysis of dynamic characteristics of the contactor during movement process is carried out, and the correctness of the model and the feasibility of the closed loop control method are verified.A speed detection method and device are proposed. The simulation system is built by magnetic circuit analytic method and the effect of magnetic pressure drop and magnetic flux leakage on flux calculation is calculated piecewise by using finite element method. The corresponding linear air gap compensation method is proposed to keep the air gap magnetic field to maintain a constant value, which greatly improves the detection accuracy. Simulation and experiments show that the model can be well applied to the speed detection of contactor.In view of the traditional current transformer structure cannot achieve a good application in the AC contactor, the application of the fast saturation current transformer to detect the AC zero and the corresponding detection method is proposed. The electrical parameters and the measurement range of the current transformer are analyzed and designed, and the related simulation models are established. The simulation and experiment show that the current transformer can realize the accurate detection of the AC zero on the contactor.The corresponding control system is designed based on the closed loop movement process of AC contactor. The overall design scheme of the control system is put forward, and the feasibility and rationality of the control system are demonstrated and analyzed. The microcontroller and related peripheral circuit, power circuit, control circuit, drive circuit, signal detection circuit and other core hardware circuit of the control system are designed and the simulation analysis of the hardware circuit of each part is carried out.