| Electrode roll forming is to roll the battery electrode into a preset thickness through the hydraulic roll seam thickness automatic control system(hydraulic AGC for short).The traditional hydraulic AGC adopts electro-hydraulic servo valve control technology,which has some inherent defects such as low energy efficiency,large footprint and poor antipollution ability.In this paper,electro-hydraulic servo pump-controlled AGC technology replaces electro-hydraulic servo valve-controlled AGC technology.While solving the inherent defects of valve-controlled AGC,the system has technical advantages such as high integration,high power/weight ratio,high energy efficiency and strong anti-pollution ability.However,pump-controlled AGC is a highly nonlinear hydraulic system,which integrates mechanical,hydraulic and electronic control disciplines.Therefore,as a new technology,it still faces many challenges in the field of pole plate rolling.In this paper,the high precision thickness control of pump-controlled AGC is taken as the research objective.Based on the nonlinear stiffness characteristics and nonlinear transmission characteristics of pumpcontrolled AGC,the rolling forming mechanism of pole thickness is revealed and the thickness control strategy with high performance is proposed.Specific research contents include the following aspects:Firstly,the nonlinear deformation stiffness of the pole plate and the nonlinear spring stiffness of the hydraulic cylinder were analyzed in view of the nonlinear excitation disturbance inside and outside the pole plate rolling,and the comprehensive stiffness characteristics of the pump-controlled AGC hydraulic system and the pole plate were obtained.At the same time,the dynamics main line of pump-controlled AGC system is discussed,and the speed characteristics of servo motor,the stiffness characteristics of transmission shafting,the flow dead zone characteristics of hydraulic pump and the transmission characteristics of pump-controlled cylinder are analyzed,thus the nonlinear transmission mechanism of pump-controlled AGC hydraulic system is obtained.Secondly,according to the nonlinear stiffness characteristics and nonlinear transmission characteristics of the system,a characteristic compensation control strategy is proposed.At the same time,considering the intermittent coating rolling condition of lithium battery and the load fluctuation caused by the uneven thickness of the incoming electrode,a fuzzy internal model control strategy was proposed.Combining the control advantages of the two controllers,a fuzzy internal model compensation controller is designed,and the system simulation analysis platform is used to verify that the control strategy has higher control performance.Finally,the fuzzy internal model compensation control algorithm proposed in this paper is applied to the pump-controlled electrode mill equipment of lithium battery,and the feasibility and effectiveness of the control algorithm are verified by the roll forming experiment of the negative electrode plate of lithium battery.The experimental results show that the fuzzy internal model compensation controller proposed in this paper can guarantee the forming precision of the fixed roll seam rolling of the pole piece and has good control performance.In this paper,we study the upgrading of fixed roll gap rolling technology for lithium battery electrode roll forming,which lays a theoretical foundation for the popularization of pump control technology in electrode rolling field. |
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