共查询到20条相似文献,搜索用时 575 毫秒
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为了研究在车用热泵系统中,电子膨胀阀过热度设定值对系统制热性能的影响,搭建车用热泵系统实验台,在超低温工况-10 ℃下,通过电子膨胀阀对蒸发器出口过热度、压缩机排气口过热度进行控制,分析电子膨胀阀过热度设定值对系统主要制热性能参数的影响。结果表明:当主阀过热度设定值从1 ℃升高到9 ℃时,压缩机排气温度随之升高,系统制热量降低了14.2%,压缩机功率降低了20.0%。当补阀过热度设定值从10 ℃升高到30 ℃时,压缩机排气温度随之升高,系统制热量降低了23.0%,压缩机功率降低了29.2%。主阀过热度最优设定值为5 ℃,补阀过热度最优设定值为20 ℃,此时系统制热能效比达到最佳。 相似文献
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分析了目前汽车空调器流量控制中存在的一些问题,提出了由发动机转速决定的压缩机转速引起的开环控制与车内蒸发器过热度模糊闭环反馈控制的复合控制系统,介绍了一种具有智能判断和积分功能的自调整模糊控制器的电子膨胀阀流量控制设计,并提出了双过热度控制信号方法。试验结果表明,本文设计电子膨胀阀系统提高了汽车空调的调节品质,同时起到了电磁阀的作用。 相似文献
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针对中央空调系统高能耗问题,通过对系统结构及工作原理分析,以电子膨胀阀作为节流元件,针对系统节能与可靠运行的关键—电子膨胀阀的控制,提出了一种基于S7-200 PLC与MCGS组态监控的螺杆式冷水机组控制系统。采用增量型PID算法控制了电子膨胀阀开度,进而控制了制冷系统过热度,采用平衡负荷算法实现了压缩机四段容调能量调节。完成了控制系统的硬件设计、PLC控制程序以及MCGS组态软件设计。研究结果表明,该控制系统人机交互界面设计友好,智能化水平高,性能可靠。 相似文献
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吸气压力的控制是压缩机性能测试的难点之一。依据膨胀阀流量特性的分析,采用两种典型特性的膨胀阀对冷量大小不同的压缩机的测控,以及试验数据的偏差分析,得出了膨胀阀特性对压缩机性能精度影响的趋势,为制冷压缩机性能试验系统的设计及膨胀阀的选择提供了科学数据。 相似文献
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智能电动执行器双闭环模糊PID控制研究与仿真 总被引:2,自引:0,他引:2
电动执行机构采用单闭环位置控制,只有一种恒定的调节速度,难以实现阀门准确定位和柔性关断.研究采用位置 速度双闭环调节控制方式,以位置增量为自变量,建立速度给定的位置环模型和模糊参数自整定PID的速度环模型.仿真表明,该执行器可以完成变速调节,实现阀门快速准确定位和柔性关断. 相似文献
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传统空间遥操作系统中从端机械臂的运动速度完全取决于操作者的操作速度。为了提高空间遥操作系统的安全性,提出了一种基于操作者操作速度识别的自适应速度控制方法。结合深度学习的理论,提出了一种基于卷积神经网络(CNN)和门控循环单元(GRU)神经网络的融合模型来对操作者的速度进行识别分类。选取了九位受试者构建操作者速度样本库,将操作者的操作速度分为3类,最终识别准确率达到92.71%;并且在此基础上使用串级PID实现从端机械臂的自适应速度控制。实验表明:该模型对新操作者也可以准确识别,同时该模型准确性优于卷积神经网络和循环神经网络(RNN)的融合模型,实时性优于卷积神经网络和长短期记忆(LSTM)神经网络的融合模型;基于该模型的自适应速度控制可以在保证从端机械臂运动轨迹不变的前提下,降低机械臂的末端线速度,有助于提高空间遥操作系统的安全性。 相似文献
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M. Desbazeille R.B. Randall F. Guillet M. El Badaoui C. Hoisnard 《Mechanical Systems and Signal Processing》2010,24(5):1529-1541
This work aims at monitoring large diesel engines by analyzing the crankshaft angular speed variations. It focuses on a powerful 20-cylinder diesel engine with crankshaft natural frequencies within the operating speed range. First, the angular speed variations are modeled at the crankshaft free end. This includes modeling both the crankshaft dynamical behavior and the excitation torques. As the engine is very large, the first crankshaft torsional modes are in the low frequency range. A model with the assumption of a flexible crankshaft is required. The excitation torques depend on the in-cylinder pressure curve. The latter is modeled with a phenomenological model. Mechanical and combustion parameters of the model are optimized with the help of actual data. Then, an automated diagnosis based on an artificially intelligent system is proposed. Neural networks are used for pattern recognition of the angular speed waveforms in normal and faulty conditions. Reference patterns required in the training phase are computed with the model, calibrated using a small number of actual measurements. Promising results are obtained. An experimental fuel leakage fault is successfully diagnosed, including detection and localization of the faulty cylinder, as well as the approximation of the fault severity. 相似文献
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A model of engine dynamics is developed. The model is a MISO (Multi Input Single Output) linear model which has two inputs
and one output. One input is the spark timing, and the other is the ISCV (Idle Speed Control Valve) position. The output is
the angular speed of an engine. The reliability of the developed model is confirmed by comparing the measured response of
the engine to step inputs and external disturbance with the simulation results. In order to reduce the steady state error,
an integrator state is inserted to the state equation. An engine idle speed controller is designed using optimal control theory
based on the model. The performance variation of the controller to the various design parameters is simulated. On the basis
of the simulation and the experimental data, the design parameters are determined. The developed controller reduced the idle
speed drop caused by an external load change and recovered the desired idle speed in one second. 相似文献
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车辆转向梯形优化设计及其求解方法的研究 总被引:13,自引:0,他引:13
在现有文献研究的基础上,对车辆转向梯形优化设计模型的求解方法进行了探讨.通过对该模型的研究分析,用一般方法求解该模型,计算速度偏慢且容易陷入局部最优解.通过对实数遗传算法进一步研究,提出了一种改进算法.结合轮式车辆转向梯形机构的实例计算并与一般方法计算比较,证明该方法不仅可提高运算速度,而且增大了求得全局最优解的可能性. 相似文献
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本文依据复合减速机的设计要求,通过可靠性分析,建立了复合减速机交互多目标的最优化模型。在优化设计中,考虑了冷胶合强度的约束条件,根据弹性流体动力润滑理论,建立了齿轮最小油膜厚度计算公式,应用本文所提供的优化模型,对复合减速机进行了交互式多目标优化设计,并获得了有价值的结论。 相似文献
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在ERP实施绩效评价的现状分析的基础上,结合ERP实施的总体目标,提出了基于BSC(BalancedSoOrecard,平衡积分法)的ERP实施绩效评价指标体系,同时运用专家综合评价方法,进行了应用举例。 相似文献
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In most applications, preload is applied to double-nut ball screws to improve the positioning accuracy and rigidity. However, the applied preload degrades owing to wear, which lowers the positioning accuracy of the ball screws, and thus affects the accuracy of computer numerical control machine tools. In this study, to obtain the dynamic contact force and sliding velocities on the ball-raceway contact, we established a load distribution model and velocity variation model, respectively. Based on these models, we propose an accurate model for predicting the preload degradation of double-nut ball screws. The degraded preload of three ball screws was measured under high axial load-low speed, medium axial load-medium speed, and low axial load-high speed, with a running stroke of 7.2 million revolutions. The experimental results are in good agreement with the theoretical values calculated by the prediction model, which confirms the validity of the prediction model. Therefore, it was concluded that the proposed preload degradation model can accurately predict the performance and service life of double-nut ball screws. 相似文献
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在分析单相异步电机数学模型的基础上,基于Matlab/Simulink环境,建立电机的矢量仿真模型。该模型利用PID及逆变器等控制器件,通过交流-直流-交流进行变频后,来改变电动机的转速,实现异步电动机矢量控制变频调速。仿真结果表明:在Kp=2、Ki=20、Kd=0.1时,调速处于较佳的状态下,调速性能较好。 相似文献