基于模糊PID的茶叶烘干机恒温控制系统研究

目前茶叶用烘干机的燃煤热风炉存在能耗高、热效率低的问题,而且大多采用人工控制,温度稳定性差,品质也难以保证。为此,采用模糊控制技术对热风温度进行恒温控制,根据热风炉热风温度的高低,通过变频器自动调节热风炉的排烟量,控制热风温度达到恒定,在满足烘干需要的同时,减小能量损耗,保证茶叶品质。同时,应用MATLAB软件对模糊PID恒温控制系统进行仿真。结果表明,该系统可以有效控制热风温度,达到恒温控制的目的。     

基于模糊神经网络PID控制的花茶烘焙温控系统设计

针对花茶烘焙时对温度的精细化要求,提出由模糊控制、神经网络和PID组合算法构成的控制系统,实现对温、湿度的可靠控制,达到对鲜花快速去湿干燥的目的。系统将温度和湿度的误差e和误差率ec作为输入变量进行模糊化处理,确立隶属度函数,通过模糊推理和解模糊化生成输出量,为PID控制系统提供优化的调控因子△K,精准控制执行单元。系统采用RBP神经网络算法对模糊控制过程进行精细实时变量调控,以Delta(δ)函数和梯度下降算法为学习规则调整网络加权系数w、中心向量cij和基宽向量bij。系统利用Matlab软件进行数据仿真,对比传统PID控制和模糊控制,验证模糊神经网络PID组合控制的优越性,数据分析表明组合控制系统对温度的响应速度和数据的精确性都明显改善,扰动补偿和抗干扰能力有效提高,系统鲁棒性更好。     

豆粉喷雾干燥塔遗传模糊PID串级控制系统仿真

目的:提出一种遗传模糊PID串级系统。方法:以出口温度为主被控量,进风温度为副被控量构成一个串级调节系统,主回路采用遗传模糊PID控制器,副回路采用PI控制器。结果:仿真试验表明,与经典PID控制相比,串级遗传模糊PID控制具有调节时间短、鲁棒性好等优点。结论:遗传模糊PID串级豆粉干燥塔喷雾系统可以提高豆粉的生产质量。     

微波干燥恒温控制系统的设计

为改善微波干燥作物的品质,设计微波干燥恒温控制系统.恒温控制系统由AT89S52单片机、ADS90温度传感器以及其他的电子元件构成,通过对干燥室内部温度和被干燥物质量进行实时动态监控,并自动控制微波干燥过程的温度,从而保证作物干燥后的品质.结果表明,使用该系统干燥的作物样品品质明显优于对照样品.     

模糊PID控制器在浸出车间石蜡加热器温度闭环控制中的应用

石蜡加热器是浸出车间石蜡尾气回收工艺中的重要设备,石蜡加热器温度闭环系统是典型的非线性、时变、不确定性系统,难以建立精确的数学模型。为提高石蜡加热器电动调节阀温度闭环控制效果,以检测石蜡加热器的温度偏差（e）和温度偏差变化率（ec）为输入,模糊PID控制器的KP、KI、KD为输出,构造了二输入三输出的模糊PID控制器。以西门子S7-300 PLC为下位机,WINCC组态软件为上位机,采用STEP 7软件编写模糊PID控制的算法程序,并将程序下载到S7-300 PLC存储卡中,利用S7-300 PLC对电动调节阀开度进行调节,从而实现石蜡加热器温度闭环控制。模糊PID控制器应用于浸出车间石蜡加热器温度闭环控制系统可以减少系统超调量,具有响应速度快、稳定性高等优点,提高了石蜡加热器温度闭环控制系统的运行效率。     

食品冷冻干燥过程温度的模糊控制

研究了冷冻干燥过程温度的模糊控制 ,达到了既满足升温快又满足无超调的工艺要求。     

Microwave vacuum drying of foods with temperature control by power modulation

Microwave power modulation during drying was evaluated to guarantee mild temperatures, reducing burning spots when producing sweet potatoes snacks. Samples were peeled, sliced, blanched, and microwave vacuum dried with (MWVDc) and without (MWVD) controlling the temperature (60 °C) with a PID system. MWVD used constant power, while MWVDc adjusted the power input based on samples' temperature target. Moisture content was reduced from 4.5 g g⁻¹ (db) to 0.4 g g⁻¹ (db), resulting in water activity lower than 0.55. MWVD processing time was about 80, 15, and 10 min at 300, 1500, and 2700 W, respectively, resulting in dried samples with dark areas due to hot spots. The power modulation in MWVDc resulted in intermediary drying time (50 min) and uniform color products without burnings. This study demonstrated that automated temperature control leads to high-quality sweet potato chips by microwave processing.     

Improving grape quality using microwave vacuum drying associated with temperature control

ABSTRACT:  Microwave (MW) vacuum dehydration using temperature to control the level of MW power demonstrated potential in improving the performance of the process. Product surface temperature measured by an infrared temperature sensor was used to control MW power at any level between 0 and 3 kW. Multiple linear regression analysis indicated an r ²= 0.942 for prediction of final moisture content and r ²= 0.985 for prediction of puffed character of grapes based on product temperature, time, specific energy, fresh fruit sugar, and fresh fruit moisture content. Temperature was found to be the most significant predictor. The elemental and compound contents of grapes dried using MW vacuum was compared to sun-dried raisins. The grapes dried using MW vacuum exhibited better preservation. Vitamin A was found in the MW-vacuum-dried grapes but none was detected in the raisins, and Vitamin C, thiamine, and riboflavin were also higher in the MW-vacuum-dried grapes than in the raisins.     

涂布机干燥箱温度模糊自适应PID控制

涂布机干燥箱温度系统具有非线性、强耦合、时变的特性,用普通PID控制器,温度偏差范围大。模糊自适应PID控制器可以适时调整K p、K i、K d的参数值。仿真及实用结果表明:模糊自适应PID控制器比常规PID控制器在干燥箱温度控制中具有更好的效果。     

基于模糊PID的豆粉喷雾干燥塔监控系统设计

针对喷雾干燥大滞后、强耦合的非线性特点,设计了一套基于模糊PID的豆粉喷雾干燥塔监控系统。根据工艺要求对喷雾干燥塔采取了串级模糊控制方案,主回路采用模糊PID控制,副回路采用PI控制;上、下位机监控采用组态王和西门子S7-300系列PLC。仿真试验表明,串级模糊PID控制与常规PID控制相比具有响应速度快、超调量小和鲁棒性强等优点。