Simulation Analysis of New Energy Vehicle Engine Cooling System Based on K-E Turbulent Flow Mathematical Model

New energy vehicles have better clean and environmental protection characteristics than traditional fuel vehicles.The new energy engine cooling technology is critical in the design of new energy vehicles.This paper used oneand three-way joint simulation methods to simulate the refrigeration system of new energy vehicles.Firstly,a k-εturbulent flow model for the cooling pump flow field is established based on the principle of computational fluid dynamics.Then,the CFD commercial fluid analysis software FLUENT is used to simulate the flow field of the cooling pump under different inlet flow conditions.This paper proposes an optimization scheme for new energy vehicle engines’“boiling”phenomenon under high temperatures and long-time climbing conditions.The simulation results show that changing the radiator’s structure and adjusting the thermostat’s parameters can solve the problem of a“boiling pot.”The optimized new energy vehicle engine can maintain a better operating temperature range.The algorithm model can reference each cryogenic system component hardware selection and control strategy in the new energy vehicle’s engine.

Mathematical model for the thermal process of controlled cooling of wires and its numerical simulation

The mathematical model for the thermal process of billets rolling has beenestablished, including transporting in air and temperature-holding cover, descaling withhigh-pressure water, and the process of rolling and cooling in water box. The calculated data by themodel have been compared with the measured data and the results show that the model is right andcreditable. Based on the model, the main thermal characters of rolling line have been simulated andthe influence of all the parameters on the temperature of rolling has been analyzed.

Mathematical Modeling,Field Calibration and Numerical Simulation of Low-Speed Mixed Traffic Flow in Cities

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A Practical Approach of Developing Mathematical Model for All Speed Governors

The paper introduced a special approach for diesel’s all-speed-governor modeling, which, in some cases, could solve the knotty problem frequently met in computer simulation of diesel propulsion system or diesel generating set. Suppose that it is hard to get a control-oriented governor mathematical model when the general approaches, the analytical approach or the experimental approach, are applied, and that an open-loop step response of the diesel engine and its system is available by means of computer simulation, the critical three parameters of a governor mathematical model, the proportional gain K_p, integral time constant K_i, and derivative time constant K_d, can be determined by use of PID tuning method which are widely applied in industrial process control. This paper discussed the train of thought of the approach, precondition, procedure, several modifications of the classical PID model, and some points for attention. A couple of case studies were given to demonstrate the effectiveness of this approach.

基于Fuzzy-PID的棉花打顶升降装置设计与试验

为解决棉花打顶机作业过程中由于仿形时与刀盘移动滞后、定位精准度低,导致的棉花漏打、过打及伤苗的问题,基于模糊控制技术对棉花打顶装置高度控制系统进行研究。以3MDZF-6棉花打顶机升降系统为分析对象,确定了刀盘在升降过程中的定位精度要求。以液压阀-液压缸为对象,在AMESim中建立打顶升降装置的控制模型,并将其导入到MatLab中,设计相应的模糊规则和模糊控制器,对其进行仿真分析,从超调量和响应时间两方面验证了PID和模糊PID控制方法的可行性。仿真结果表明:无外界干扰的情况下,PID参数分别为100800、500、30时,输入信号达到稳态的响应时间为0.55s;模糊PID控制下输入信号达到稳态的响应时间为0.31s。经过对比分析固定参数PID控制和模糊PID控制在不同扰动下的控制效果,发现模糊PID控制系统的超调量为0.84%,输入信号达到稳态所需的时间为0.39s,小于固定参数PID的0.64s。该方法实现了打顶升降装置的位移控制,提高了刀盘的定位精度及控制系统的抗干扰性和鲁棒性,可为棉田环境下的棉花打顶升降装置的精确控制问题提供借鉴。

基于改进PID算法的钢铁行车系统建模与控制

行车是钢铁物流过程中最重要的设备之一,其运行的稳定性、安全性至关重要。综合考虑了负载摆动对行车系统的影响,利用拉格朗日方程对钢铁物流行车系统进行动力学建模,分析了系统动能和广泛力,并搭建了滑轨行车仿真实验平台。针对传统比例积分微分(PID)控制器在不确定、非线性系统中控制性能不理想的问题,采用模糊PID和误差反向传播(BP)神经网络自适应调整控制器参数,提高了系统的动态性和抗干扰性。将两种改进的智能PID控制算法与传统PID进行了仿真实验对比。结果表明,采用BP神经网络优化的PID控制器(BP-PID)和模糊PID性能均优于传统PID,且BP-PID的响应速度更快、鲁棒性更强。

基于模糊PID的变幅液压缸伺服位置自适应同步控制技术

液压系统中存在许多非线性因素,例如摩擦、死区和溢流等。这些非线性特性会影响伺服位置的精度和同步性能,导致控制系统的不稳定和误差积累。为此,提出基于模糊PID的变幅液压缸伺服位置自适应同步控制技术。考虑变幅液压缸伺服系统的运行结构,分析变幅液压缸动力,构建液压缸以及伺服阀的数学模型;利用伺服输出流量和压降的关系,获取速度前馈控制信号;将其反馈到系统中,设计模糊自适应PID同步控制器,实现变幅液压缸伺服位置同步控制。实验结果表明,所提方法对液压缸的同步效果很好,有效减少了液压缸伺服位置控制的误差,在不同信号干扰下,有效提高其控制稳定性和同步性能,控制器超调量平均约为0.059%,响应速度较快。

基于RBF神经网络PID算法的锅炉水温控制与研究

针对过程控制实验中水温控制的PID算法参数难以整定的问题,提出了一种基于径向基函数(Radial Basis Function,RBF)神经网络整定PID的算法,并以仿真与实验相结合的方式应用于水温控制实验中。通过使用阶跃响应曲线法辨识锅炉水温数学模型;设计用RBF神经网络整定PID参数的方法,针对对象模型进行仿真;最后将整定的PID参数应用于水温控制实验验证,并与常规PID方法进行实验比较。结果表明,RBF神经网络整定PID控制器的控制方法具有更好的鲁棒性和自适应性,能取得良好的控制效果。

Dynamic Simulation of the Aircraft Environmental Control System

The dynamic research of aircraft environmental control system (ECS) is an important step in the advanced ECS design process. Based on the thermodynamics theory, mathematical models for the dynamic performance simulating of aircraft ECS were set up and an ECS simulation toolbox (ECS_1.0) was created with MATLAB language. It consists of main component modules (ducts, valves, heat exchangers, compressor, turbine, etc.). An aircraft environmental control system computer model was developed to assist engineers with the design and development of ECS dynamic optimization. An example simulating an existing ECS was given which shows the satisfactory effects.

Optimal Design and Force Control of a Nine-Cable-Driven Parallel Mechanism for Lunar Takeoff Simulation

Traditional simulation methods are unable to meet the requirements of lunar takeo simulations, such as high force output precision, low cost, and repeated use. Considering that cable-driven parallel mechanisms have the advantages of high payload to weight ratio, potentially large workspace, and high-speed motion, these mechanisms have the potential to be used for lunar takeo simulations. Thus, this paper presents a parallel mechanism driven by nine cables. The purpose of this study is to optimize the dimensions of the cable-driven parallel mechanism to meet dynamic workspace requirements under cable tension constraints. The dynamic workspace requirements are derived from the kinematical function requests of the lunar takeo simulation equipment. Experimental design and response surface methods are adopted for building the surrogate mathematical model linking the optimal variables and the optimization indices. A set of dimensional parameters are determined by analyzing the surrogate mathematical model. The volume of the dynamic workspace increased by 46% after optimization. Besides, a force control method is proposed for calculating output vector and sinusoidal forces. A force control loop is introduced into the traditional position control loop to adjust the cable force precisely, while controlling the cable length. The e ectiveness of the proposed control method is verified through experiments. A 5% vector output accuracy and 12 Hz undulation force output can be realized. This paper proposes a cable-driven parallel mechanism which can be used for lunar takeo simulation.

Some Equivalence Transform Methods for Simulating Models in Control Systems

In this paper two classes of equivalence transform methods for solving ordinary differential equations are proposed. One class of method is the equivalence integral transform method for special differential algebraic problems. The advantage of this class of method is such that the amount of work calculating one integration with parameters becomes that of two interpolations, when the system of nonlinear equations is solved on the right hand side function. The other class of method is the equivalence substitution method for avoiding calculating derivative on the right hand side function. In order to avoid calculation derivatives, two equivalence substitution methods are proposed here. The application instances of some special effect of the equivalence substitution methods are given.

基于模糊PID的动态履带张紧力控制系统研究

履带张紧力是影响履带可靠性的主要因素,保持履带张紧力的稳定性有利于提高履带服役寿命,使整车在越野工况中发挥出优越的性能。在对托带轮、负重轮、诱导轮以及履带张紧器的几何关系及受力分析的基础上,建立了履带张紧力的理论估算模型,通过与多体动力学仿真结果进行比较,验证了履带张紧力理论估算模型的正确性。在此基础上,基于模糊比例‑积分‑微分(proportional‑integral‑derivative,简称PID)控制理论设计了一种履带张紧力控制系统,可通过转动诱导轮曲臂来调整履带的松紧度。仿真结果表明:该控制系统能够快速、准确地达到期望履带张紧力,可有效地抑制车体振动的情况及托带轮所受履带的冲击载荷,增加了履带车辆行驶的可靠性。与传统的诱导轮固定方式相比,该控制系统可有效降低接地段履带的动态张力,且没有加剧履带脱轮的风险。

飞行器自调平系统的模糊PID控制研究

平台调平控制是一个重要且复杂的过程,很难用一个精确的数学模型来描述,而传统的PID控制稳态精度不高、抗干扰性差,难以满足复杂环境下的自适应调平需求。因此,设计了模糊PID控制算法来对飞行器发射平台进行调平,介绍了模糊PID控制的设计方法,系统采用AMEsim和MATLAB/Simulink联合仿真,并将传统PID控制和模糊PID控制的仿真结果对比。仿真结果表明:模糊PID控制的平台调平相较于传统PID控制具有更高的控制精度和动态性能,调节速度提高了40%以上,无超调,无滞后,具有更好的抗干扰性和鲁棒性。使用AMEsim对平台调平系统建模,大大的提升了设计效率,在MATLAB中设计控制算法利用该软件强大的计算能力,使仿真的结果更加精确可靠。

一阶时滞系统的模糊内模PID控制参数整定

针对工业现场复杂的时变系统存在的经典PID控制调节复杂、效应滞后、超调量大、稳定性差等问题,将模糊控制与内模PID控制相结合,并对滤波参数进行优化调整以适应复杂工业系统。首先,在完成模型辨识后,将内模控制等效为PID反馈控制,采用麦克劳林展开,并加入一阶时滞模型,形成等效反馈控制器的传递函数;其次,利用模糊控制策略,设计模糊内模PID控制器,利用偏差和偏差变化率实时调整内模PID的滤波参数λ;最后,分别利用MATLAB软件和功率控制装置进行仿真和测试。实验结果表明,模糊内模PID控制具有更快的响应速度和更小的超调。

积分分离PID在集热管热损测试系统中的应用

首先,分析集热管热损测试系统温度控制过程的物理模型,推导出集热管温控系统的传递函数表达式,得知集热管热损测试系统为非线性系统。针对集热管热损测试系统的非线性,研究了积分分离PID控制算法,阐述该算法原理,设计控制器相关参数,结合集热管热损测试系统对该算法和常规PID算法进行系统性能仿真对比分析。结果表明,采用该算法设计的测试系统温度控制过程响应速度更快,控制精度达到±0.5℃,适用于相关温度控制场合。

基于单神经元PID水平炮控系统稳定控制

为保证坦克行进间炮塔始终处于稳定位置,针对系统齿隙进行非线性补偿。利用径向基函数(radical basis function,RBF)神经网络对炮塔水平方向调速系统进行系统辨识,同时采用齿隙死区模型代表齿隙环节,建立水平向的模拟炮控系统;提出一种单神经元PID控制器;模拟外界扰动,利用计算机对控制过程完成仿真。仿真结果表明:在给定条件下,考虑齿隙因素,炮塔水平向位置与稳定位置的误差始终足够小。

基于PID参数优化的高炉加热炉壳温度控制研究

高炉的炉壳是承受极高温度、腐蚀和机械应力的部件,炉壳温度过高或过低都可能导致热应力、脱渣等问题,从而影响高炉的正常运行和寿命。通过有效的炉壳温度控制,可以保护炉壳免受过高温度和腐蚀的侵害,延长高炉的使用寿命,因此提出基于PID参数优化的高炉加热炉壳温度控制方法。利用空气定压比热、加热炉蓄热室通道面积、蓄热体比热容等多个参数确定高炉加热炉能量平衡方程,采用拉氏变换建立高炉加热炉数学模型。以加热炉数学模型为基础,遗传算法通过变异、交叉和复制等操作优化加热炉PID控制器参数。利用参数优化后的PID控制器、功率调整器、FP93导电仪表、加热管以及温度测量仪组成高炉加热炉壳温度控制架构,实现高炉加热炉壳温度控制。实验结果表明,所提方法可准确检测高炉加热炉壳的温度,控制精度以及效率高,高炉加热炉壳温度控制效果好。

基于PID控制器的半主动悬架联合仿真分析

为了提高被动悬架的性能,改善车辆行驶时的平顺性,文章采用ADAMS与Simulink联合仿真的方法,对基于比例-积分-微分(PID)控制器的二自由度半主动悬架进行研究。在ADAMS中建立二自由度半主动悬架动力学仿真模型并通过Control模块输出到Simulink中,在Simulink中以滤波白噪声法生成不同车速下的B级路面模型;并采用PID控制器,分别以簧载质量加速度和主动控制力作为控制器输入量及输出量,获得并分析了车身的垂直加速度、悬架的动行程、轮胎动载荷的时域特性。仿真结果表明,采用PID控制器的半主动悬架在不恶化操稳性和安全性的情况下,在不同车速阶段可显著改善车身垂直加速度,提高乘坐舒适性;同时联合仿真极大地简化了建模过程,使仿真更加直观。

基于模糊PID融合的特种起重机伸缩臂自动控制

为了提升特种起重机伸缩臂控制精度,提出基于模糊PID融合的特种起重机伸缩臂自动控制方法。针对特种起重机伸缩臂的整体结构,对伸缩臂受力展开了分析。以受力分析结果为基础建立伸缩臂数学模型,对该模型进行推导后获取伸缩臂传递函数,将其与设计的模糊PID融合控制器相结合,实现对特种起重机伸缩臂自动控制。实行位移响应测试、末端姿态位置与末端作用力测试,测试结果表明,所提方法所得结果与期望值基本一致,说明该方法的精度高、可靠性强。

GWO-PID控制算法的汽车线控转向系统研究

为了提高汽车转向系统工作性能,对其线控转向系统进行了研究。首先,在对线控转向系统结构与原理分析基础上,建立其动力学模型;基于MATLAB/Simulink软件,建立其仿真模型。在此基础上,研究线控转向系统PID控制算法,对前轮转角进行控制。为进一步提高系统稳定性,采用灰狼算法对PID参数进行优化。最后,采用双移线实验工况进行仿真实验;结果表明所研究的转向系统具有良好的转向性能、GWO-PID控制算法较之PID控制算法可使汽车转向相关关键指标参数更快达到稳态值,提高了汽车转向稳定性和行车安全性。