Key Technology Research And Prototype Development Of Piezoelectric Proportional Flow Valve Controller

In recent years,with the rapid development of precision fluid control technology,gas proportional flow valve has been widely used in semiconductor manufacturing,biomedical and aerospace fields,and its requirements for precision,stability and rapidity are also increasing.Piezoelectric proportional flow valve has the advantages of fast response,small size and simple structure,which is the development direction of precision flow valve.However,the inherent nonlinearity of piezoelectric ceramics brings difficulties to the control system.In this paper,on the basis of analyzing the nonlinear causes of piezoelectric proportional flow valve,the adaptive particle swarm genetic optimization algorithm is used to identify the improved Prandtl-Ishlinskii hysteresis model,and a composite control combining the hysteresis inverse model and the model-free adaptive control algorithm is designed.The solution improves the overall control performance of the piezoelectric proportional flow valve.The main work of this paper is as follows:(1)Nonlinear analysis of piezoelectric proportional flow valve.Firstly,the basic structure of piezoelectric actuator and the working principle of piezoelectric proportional flow valve are introduced.On this basis,the nonlinear causes of flow valve are analyzed,which provides a theoretical basis for selecting the appropriate flow valve modeling method.(2)Establishment of hysteresis asymmetric model of piezoelectric proportional flow valve.Aiming at the problem that the traditional Prandtl-Ishlinskii model is difficult to describe the hysteresis asymmetric object,the memoryless polynomial is introduced to improve it,which can effectively describe the hysteresis asymmetric characteristics of piezoelectric proportional flow valve.The particle swarm optimization algorithm is used to identify the parameters of the hysteresis model.In order to avoid falling into the local optimal trap,the adaptive particle swarm genetic algorithm is obtained by introducing the genetic algorithm,which improves the model accuracy.Finally,the experiment verifies that the identification accuracy of the adaptive particle swarm genetic optimization algorithm is higher than that of the traditional particle swarm optimization algorithm,and further verifies the effectiveness of the improved Prandtl-Ishlinskii model.(3)Research on control algorithm of piezoelectric proportional valve.A compound control scheme based on improved Prandtl-Ishlinskii inverse model feedforward compensation control combined with model-free adaptive control algorithm is designed.The feedforward compensation controller is combined with the feedback controller to eliminate the hysteresis characteristics of the system,and improve the anti-disturbance and robustness of the system.The simulation results verify that the composite control algorithm can shorten the adjustment time,reduce the overshoot and steady-state error,and effectively improve the overall control performance of the flow valve.(4)Design and implementation of piezoelectric proportional flow valve controller.The hardware circuit and embedded software code of the controller are designed,and the overall experimental platform of piezoelectric proportional flow valve is built.The experimental results show that the adjustment time of the composite control algorithm is shortened by 60 %,and the overshoot and steady-state error are reduced by43 % and 17 %,respectively.The dynamic landing and recovery time indexes under sudden interference are also significantly improved.The effectiveness of the compound control algorithm is verified,which can realize fast and accurate gas flow control of flow valve.