CNC车削加工中凸变椭圆活塞的实现原理

介绍一种软靠模与硬靠模相结合的车削加工系统。应用步进电机驱动刀具进给,通过计算机控制技术实现刀具的高频微位移往复运动,实现中凸变椭圆活塞裙部加工的车削加工。系统还通过计算机对加工误差进行实时补偿,有效提高了加工精度和效率,获得良好的效果。     

CNC车削加工中凸度椭圆活塞的实现原理

介绍一种软靠模与硬靠模相结合的车削加工系统。应用步进电机驱动刀具进给,通过计算机控制技术实现刀具的高频微位移往复运动,实现中凸变椭圆活塞裙部加工的车削加工。系统还通过计算机对加工误差进行实时补偿,有效提高了加工精度和效率,获得良好的效果。     

中凸变椭圆活塞裙面车削系统的开发

本文介绍了一种实用的中凸变椭圆活塞车削系统，采用偏心振动机构产生椭圆截面成型所需的高频往复运动，采用微机控制的步进电机单元实现纵向中凸型线成型，经济可靠，容易实现，且有较好的柔性，实际加工结果表明，该系统能高速、高精度地实现活塞裙面的车削加工。     

自由活塞斯特林制冷机用直线电机性能仿真与测试

介绍了自由活塞斯特林制冷机用动磁式直线电机结构。采用Ansoft软件对直线电机进行有限元仿真,配合自由活塞制冷机整机仿真软件,研究了直线电机性能及整机制冷性能。采用三组不同外气隙参数的直线电机进行试验验证,结果表明:直线电机性能对整机性能影响较大,且直线电机的定位力会影响动子系统的固有频率,降低自由活塞制冷机的制冷效率;外气隙参数对直线电机性能影响较大,经比较:0.5 mm为外气隙优选参数,并且,在生产过程中须保证直线电机的径向加工精度。     

16V240ZJ钢顶铝裙活塞中凸度椭圆外轮廓的“软靠模”加工

论述无硬靠模加工活塞中凸变椭圆外轮廓的数控加工方法及工作原理、数学模型建立和实际问题的处理方法；介绍了ＰＴＣ－Ⅱ活塞数控车削系统的主要性能和特点。     

16V240ZJ 钢顶铝裙活塞中凸变椭圆外轮廓的“软靠模”加工

论述无硬靠模加工活塞中凸变椭圆外轮廓的数控加工方法（即软靠模加工）及工作原理、数学模型的建立和实际问题的处理方法；介绍ＰＴＣ－Ⅱ活塞数控车削系统的主要性能和特点。     

活塞变椭圆型面建模及数控仿形加工过程分析

活塞作为典型的汽车关键零部件,在切削加工方面具有很强的工艺特点。其中活塞中凸变椭圆型面的加工又是活塞最核心的关键工序,其加工方法有立体靠模仿形加工和采用数控高频直线伺服刀架的软靠模加工两种形式。本文研究以高频直线伺服刀架系统的软靠模为加工技术的活塞型面建模技术。     

浅析ECK2150A数控活塞变椭圆车床的创新

根据船用柴油机变椭圆活塞加工的工艺特点,开发一种专用于大功率船用柴油机变椭圆活塞加工的数控车床ECK2150A,关键执行部件直线伺服电机频响超过465HZ/-3dB,加工尺寸稳定性变化小于0.015mm,能够满足X2/a+Y2/b=1等变椭圆异形截面的加工.系统阐述了该车床在机床整体布局,高频响高精度直线伺服系统,活塞数据处理软件和直线伺服电机控制卡方面的创新.     

自由活塞直线发电机系统上止点稳定控制

自由活塞直线发电机系统是由直线发动机与直线电机耦合而成,将燃料的化学能直接转化成电能的一种发电装置。活塞运动的控制是该系统控制中的难点,其活塞上止点对系统稳定运行的影响大,所以必须保证上止点的稳定。文章中提出一种基于活塞中点速度预测的电磁力控制策略,根据检测到的活塞中点速度,调节电磁力负载,使得活塞运动上止点保持稳定。为验证该控制策略的控制效果,搭建了仿真模型,并对搭建的系统仿真模型进行了试验验证,试验结果与仿真吻合较好。仿真研究表明,在发动机喷油量发生随机波动时,该控制策略很好地稳定了活塞运动上止点。     

PC控制活塞机加工

可编程序控制器用于活塞车削加工自动化，投资少，见效快，易于实现，它工作可靠，便于维护和修理。着重论述Ｉ／Ｏ分配图，车削活塞加工程序梯形图及工作原理。由于ＰＣ控制器是计算机产品。所以程序设计方便，易于修改，便于调试，为普及应用打下了良好的基础。     

Comparison of a synergetic battery pack drive system to a pulsewidth modulated AC induction motor drive for an electric vehicle

A new battery configuration technique and accompanying control circuitry, termed a synergetic battery pack (SBP), is designed to work with lithium batteries, and can be used as both an inverter for an electric vehicle AC induction motor drive and as a battery charger. In this paper, the performance of a synergetic battery pack during motor drive operation is compared via computer simulation with a conventional motor drive which uses sinusoidal pulse width modulation (SPWM) to determine its effectiveness as a motor drive. The study showed that the drive efficiency was compatible with the conventional system, and offered a significant advantage in the lower frequency operating ranges. The voltage total harmonic distortion (THD) of the SBP was significantly lower than the PWM drive output, but the current THD was slightly higher due to the shape of the harmonic spectrum. In conclusion, the SBP is an effective alternative to a conventional drive, but the real advantage lies in its battery management capabilities and charger operation     

An operation control strategy for a virtual pumped storage system based on a linear motor

储能技术是智能电网的关键技术之一，对新能源大规模并网消纳、实现"两个替代"、完成能源结构转型具有重要意义。根据热力学原理分析，等温压缩空气储能技术在理论上具有更高的效率，因此提出了基于等温压缩空气储能原理的虚拟抽水蓄能系统，以及适用于该系统稳定运行的恒功率运行控制策略和适用于电力系统对储能电站功率可调控需求的功率调整运行控制策略，采用基于SVPWM的磁场定向矢量控制方法，借助MATLAB/SIMULINK平台，研究其基于直线电机的系统运行控制策略，通过仿真验证控制策略的可行性。     

A linear encoder using a chiaroscuro and its extension to switched reluctance motor drive

In switched reluctance motor drives, the on–off switching angle of each phase switch should be accurately controlled to stabilize torque and speed. However, as the speed of a motor increases, the switching angle is prone to deviate from a preset value. Because the accuracy of the switching angle largely depends on the resolution rate of the equipped encoder, which provides a digital controller with positional information of the rotor. It also relies on the sampling performance of the digital controller. To solve these problems, a new linear encoder is proposed. It consists of a chiaroscuro plate, phototransistors and a simple logic circuit. The resolution rate of the proposed encoder is sufficiently high owing to its inherent linear characteristic. It is, moreover, not affected by the sampling performance of the microprocessor. Consequently, an accurate on–off switching signal can be produced at any desired position with high precision, regardless of the speed of motor. It also can save system cost due to its simple structure. The validity of the proposed encoder scheme is verified by experiments, and then, the result is compared to that of the conventional scheme.     

A novel maximum power fuzzy logic controller for photovoltaic solar energy systems

The maximum power tracking problem and efficient energy utilization of a stand-alone photovoltaic array (PVA) feeding voltage controlled linear and nonlinear loads is studied. A novel and simple on-line fuzzy logic-based dynamic search, detection and tracking controller is developed to ensure maximum power point (MPP) operation under excursions in solar insolation, ambient temperature and electric load variations. A computer simulation model of the PVA renewable utilization scheme including the effects of temperature and solar irradiation changes was developed and fully simulated. The load voltage is controlled by a DC chopper and kept constant at the required rated voltage. A permanent magnet DC motor (PMDC) driving a fan-type load was connected in parallel to an RL passive load. A speed control scheme is also used for the PMDC motor drive so that the drive can be operated at specified speeds. Different controllers have been employed in the unified PVA scheme to control three separate loads at MPP tracking condition namely voltage at load bus and speed of the PMDC motor. The main objective of the paper is to present a novel enhanced, cost-effective MPP detector (MPPD) and dynamic MPP tracking (MPPT) controller for a hybrid mix of electric loads.     

Controlled feeding of lignocellulosic substrate enhances the performance of fed-batch enzymatic hydrolysis in a stirred tank reactor

High initial viscosity in the high-solids (>15% (w/v)) enzymatic hydrolysis of lignocellulose is problematic especially in stirred tank reactor concepts. One potential way to avoid the high viscosity is the fed-batch feeding of lignocellulosic material to the reactor. In the current study the hydrolysis of filter paper with final concentration of 19.1% (w/w) was evaluated with different fed-batch procedures. Feeding was based on visual observation, stepwise feeding and the power requirement of the stirrer motor. All the fed-batch procedures resulted in similar yields within 30 h (47–49%) which were higher than with the batch process in similar reactor (38%). However, the mixing behavior was superior in the power based feeding as the instantaneous power of the stirrer motor was kept lower (<10 W) than in other fed-batch procedures (>20 W). The power controlled procedure was further evaluated with different enzyme doses, tip speeds and the power levels of substrate feed. Further study showed that the power controlled feeding is applicable also to other hydrolysis and mixing conditions if power levels of substrate feed are set correctly. Higher (15 FPU/g) enzyme dose caused shorter feeding time (3.0 ± 0.5 h) and lower energy consumption during the feeding period (14 ± 3 Wh) compared with lower (5 FPU/g) enzyme dose (7.0 ± 1.3 h and 33 ± 5 Wh, respectively). The tip speed and the power level of substrate feed had fewer effect on these factors. The performance of the hydrolysis process can thus be enhanced by the substrate feed controlled by the power of the stirrer motor.     

A DC linear motor with a square armature

One of the advantages in using DC linear motors for low speed linear drives is that the position and speed of these motors can be precisely controlled with the help of a feedback circuit. In addition, linear motors get rid of the rotary-to-linear conversion mechanism, hence reduce the weight cost backlash and dynamic complexity which produces friction, and eventually minimizes the space required by the drive. The neodymium-iron-boron (NdFeB) permanent magnet with high energy product has been used as the field source of these motors thus reducing the size and weight of the motors further. This paper describes the analysis of flux and force in a DC linear stepping motor built with NdFeB magnets. In order to verify the experimental results obtained for determining the performance of the motor, a computational method has been employed to compute the flux distributions throughout the machine. The discrepancy between the measured and computed values of axial and radial flux at most points ranges between 8% and 16% while the discrepancy between the measured and computed values of starting thrust is in the range between 4% and 13%     

Experimental analysis of a transfer function for an air cooled evaporator

A transfer function to model a direct expansion air cooled evaporator, inserted in a vapor compression refrigeration plant, is deduced by means of experimental analysis. For inlet air temperatures onto the evaporator and refrigerant mass flow rate variable in appropriate ranges, the evaporator dynamic behavior is simulated by a linear model with delay. The results of transfer function are compared with experimental data, obtained by applying both step inputs and periodic changes to the refrigerant mass flow rate. The influence of the hunting, typical of a thermostatic expansion valve, is also estimated experimentally and then validated by the transfer function, obtaining a good agreement. These results could be applied to obtain a control algorithm for the refrigerant mass flow rate feeding the evaporator, by varying the speed of the compressor motor.     

Speed control of a PV powered DC motor driving a self-excited3-phase induction generator for maximum utilization efficiency

Photovoltaic (PV) powered DC motors driving dedicated loads (e.g. water pumps) are increasingly used in the remote rural areas of many developing countries. The key to their success is simplicity (direct coupling, no DC-AC conversion, no storage batteries, etc.). Because of the relatively high cost of the PV array, the system designer is interested in maximizing its utilization efficiency. A PV powered DC motor can also be used to drive a three-phase self-excited induction generator (SEIG). This arrangement is useful as part of an integrated renewable energy system (IRES), which takes advantage of the inherent diversity of wind and solar energy in most developing countries to improve power quality. The SEIG is driven by a wind-turbine, DC motor, or both. Another advantage of this arrangement is its versatile control characteristics through the DC motor control. This paper describes a technique to maximize the utilization efficiency of the PV array by controlling the field current of the DC motor through a DC chopper     

Conductors of a linear induction motor

In this paper, the joint effect on the thrust and attraction forces of a linear induction motor is discussed and a control algorithm to compensate for such effects is presented. The algorithm is based on the vector control technique and takes into account the variation of the secondary resistance of the LIM when a joint enters the active zone of the LIM. The algorithm was tested by simulation on a sample of linear motor elevator system. Simulations have shown that the fluctuations of the thrust and attraction forces where decreased significantly     

DSP-based solutions for AC motor drives

The advent of programmable digital signal processors (DSPs) is creating a revolution in monitoring, control, and testing of motor drives. Their special architecture and high performance make it possible to implement a wide variety of nontrivial control and measurement algorithms at high sampling rates and reasonable cost. AC motor drives are typically a complex combination of linear, nonlinear, and switching elements. High-frequency converters add another dimension of complexity because of their fast dynamics. Real time systems, therefore, demand the use of high speed data-acquisition and control. DSPs meet the processing requirements imposed by such systems. In this letter, we study the features that make DSPs highly effective computational engines. We explore some applications requiring the high performance of DSPs. The issues involved in adopting a system architecture, selecting a DSP, and developing software for an application are discussed. The methodology described presents broad guidelines that can be intelligently applied to develop DSP-based solutions to meet specific requirements.