制冷系统自抗扰解耦控制

Active Disturbance Rejection Decoupling Control for Refrigeration Systems

针对制冷系统具有非线性、强耦合、大时滞且难以建立精确数学模型等特点,设计了一种改进的自抗扰解耦控制器。首先,通过引入线性修正项设计了非齐次有限时间收敛的扩张状态观测器,保证了观测器误差在有限时间内能够快速收敛到0,进而通过构造Lyapunov函数证明了其有限时间收敛的特性;采用静态解耦方法将制冷系统解耦为两个单输入、单输出系统,实现了制冷系统过热度和蒸发温度的独立控制;最后,利用改进的扩张状态观测器估计动态耦合和其他扰动并补偿到非线性误差反馈控制中,实现了制冷系统的动态解耦并改善了控制效果。仿真结果表明,该控制器不仅能较好实现解耦并具有良好的动态特性,而且具有更好的抗扰性和较强的鲁棒性,同时约有2%的节能效果。

Because the refrigeration systems are normally with such features as nonlinearity, strong coupling and large delay and it is difficult to establish precise mathematical models for them, an improved active disturbance rejection controller （ADRC） with decoupling control algorithm is proposed. First, a non-homogeneous finite-time convergent extended state observer （ESO） is designed by adding linear correction terms to the algorithm to ensure that the observer error converges to 0 quickly in a finite time. Then its finite-time convergent property is proved by using a Lyapunov function. A static decoupling process is applied to decouple the refrigeration system into two single-input and single-output systems, realizing the independent control over the superheat and evaporation temperature of the refrigeration system. The dynamic coupling and other disturbances are estimated by the improved ESO and compensated to the nonlinear error feedback control, which achieves the dynamic decoupling of the refrigeration system and improves the control results. Simulation results reveal that the proposed method realizes a better decoupling control with good dynamic characteristics, better disturbance rejection and robustness. Moreover, it saves about 2% energy.