空压机压力控制系统建模与动态特性研究

Research on System Modeling and Dynamic Characteristics of Air Compressor Pressure Control System

以螺杆式空压机供气系统为研究对象,在对其系统组成分析基础上,将空压机压力控制系统划分为储气罐子系统、电机子系统、压力控制子系统。空压机储气罐子系统采用实际气体状态方程式描述储气罐中气体P-V-T关系(范德瓦尔方程式),电机子系统采用三相感应电机转子磁场定向控制模型,储气压力控制子系统为电流反馈、速度反馈和压力反馈的三闭环控制结构(电机变频控制)。分别进行了电机变频控制和普通加、卸载控制模式下的数值仿真分析,结果表明对于文中构建的变频控制策略,系统具有良好的动、静态性能,能够根据用气量的变化自动调节转速大小,使压力比较精确地控制在给定值附近;普通加、卸载模式下,压力在pmin^pmax之间来回波动,在用气量波动比较大的场合,造成电机启动频繁的同时压力波动也会明显增大。

The gas supply system of screw type air compressor is researched in this paper.Based on the analysis of system composi- tion, the air compressor pressure control system is divided into the gas tank sub-system, motor sub-system and pressure control sub- system.In the gas tank sub-system, the P-V-T relationship is described using real gas equation of state （Van Derwal equation）;in the motor sub-system, three phase induction motor rotor field oriented control model is employed;the pressure control sub-system is three closed-loop control structure of current feedback, velocity feedback and pressure feedback （variable frequency control）.The numerical simulation analyses are carried out both under variable frequency mode and normal load/unload mode.The research results show that using the constructed variable frequency strategy, the system has good dynamic, static performance which means that the motor speed can adjust automatically to assure the gas pressure near a given value according to the variation of gas consumption.Under normal load/unload mode, the gas pressure fluctuates in the range of pmin-pmax;in occasions with large variation of gas consumption,not only the motor start and stop frequently, but also the pressure fluctuation significantly increases.