首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到17条相似文献,搜索用时 186 毫秒
1.
When boost power factor correction (PFC) circuit works with large scale load fluctuations, it is easy to cause a higher total harmonic distortion and a lower power factor because of traditional controllers and inductor cur- rent mode. To solve this problem, this paper proposes a PFC control system, which can operate with load fluctuations up to 1 000 W by using duty cycle feed-forward control theory to achieve smooth switching mode. The duty cycles in the next period of the control system are pre-estimated in the current cycle, which enhances the speeds of AD samplers and switching frequency, and reduces the cost and volume of the equipment to some extent. Introductions of system decoupling and feed-forward of input-voltage greatly improve the system performance. Both theoretical simulation and experimental results prove the advantage of the proposed scheme.  相似文献   

2.
Instead of manual polishing work for aluminum wheel hub (hub) surface, a new planetary scroll surface polishing method based on the rotation and revolution of hub in abrasives is presented in this paper. Since conventional barrel rotation polishing mode is unsatisfactory, shorter polishing period and lower energy consumption are expected. The surface polishing mechanism of the proposed method is ghen introduced. The influence of cutting velocity, cutting angle, abrasive on surface polishing quality and efficiency, as well as the correlation of the revolution velocity and the rotation velocity of hub are discussed. Experimental results show that high surface polishing quality and efficiency can be achieved with the new polishing method implying that a dustless clean working environment is realized.  相似文献   

3.
To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultra- capacitors (UCs) could be a solution. The high power density feature of UCs can improve the performance of battery/UC hybrid energy storage systems (HESSs). This paper presents a parallel hybrid electric vehicle (HEV) equipped with an internal combus- tion engine and an HESS. An advanced energy management strategy (EMS), mainly based on fuzzy logic, is proposed to improve the fuel economy of the HEV and the endurance of the HESS. The EMS is capable of determining the ideal distribution of output power among the internal combustion engine, battery, and UC according to the propelling power or regenerative braking power of the vehicle. To validate the effectiveness of the EMS, numerical simulation and experimental validations are carried out. The results indicate that EMS can effectively control the power sources to work within their respective efficient areas. The battery load can be mitigated and prolonged battery life can be expected. The electrical energy consumption in the HESS is reduced by 3.91% compared with that in the battery only system. Fuel consumption of the HEV is reduced by 24.3% compared with that of the same class conventional vehicles under Economic Commission of Europe driving cycle.  相似文献   

4.
Using composite field arithmetic in Galois field can result in the compact Rijndael S-Box. However, the power con- sumption of this solution is too large to be used in resource-limited embedded systems. A full-custom hardware implementation of composite field S-Box is proposed for these targeted domains in this paper. The minimization of power consumption is implemented by optimizing the architecture of the composite field S-Box and using the pass transmission gate (PTG) to realize the logic functions of S-Box. Power simulations were performed using the netlist extracted from the layout. HSPICE simulation results indicated that the proposed S-Box achieves low power consumption of about 130 μW at 10 MHz using 0.25 μm/2.5 V technology, while the consumptions of the positive polarity reed-muller (PPRM) based S-Box and composite field S-Box based on the conventional CMOS logic style are about 240 μW and 420 μW, respectively. The simulations also showed that the presented S-Box obtains better low-voltage operating property, which is clearly relevant for applications like sensor nodes, smart cards and radio frequency identification (RFID) tags.  相似文献   

5.
The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advantages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica- tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.  相似文献   

6.
Dynanfic forces are the main factor that influences the axle weight measurement accuracy of moving vehicle. Empirical mode decomposition (EMD) is presented to separate the dynamic forces contained in the axle weight signal. The concept and algorithm of EMD are introduced. The characteristic of the axle weight signal is analyzed. The method of judging pseudo intrinsic mode function (pseudo-IMF) is presented to improve the weighing accuracy. Numerical simulation and field experiments are conducted to evaluate the performance of EMD. The result shows effectiveness of the proposed method. Maximum weighing errors of the front axle, the rear axle and the gross weight at the speed of 15 km/h or lower are 2.22%, 6.26% and 4.11% respectively.  相似文献   

7.
Particle swarm optimization (PSO) is an efficient, robust and simple optimization algorithm. Most studies are mainly concentrated on better understanding of the standard PSO control parameters, such as acceleration coefficients, etc. In this paper, a more simple strategy of PSO algorithm called θ-PSO is proposed. In θ-PSO, an increment of phase angle vector replaces the increment of velocity vector and the positions are decided by the mapping of phase angles. Benchmark testing of nonlinear functions is described and the results show that the performance of θ-PSO is much more effective than that of the standard PSO.  相似文献   

8.
An optimization method for time-delayed feedback control of partially observable linear building structures subjected to seismic excitation is proposed. A time-delayed control problem of partially observable linear building structure under horizontal ground acceleration excitation is formulated and converted into that of completely observable linear structure by using separation principle. The time-delayed control forces are approximately expressed in terms of control forces without time delay. The control system is then governed by Itoe stochastic differential equations for the conditional means of system states and then transformed into those for the conditional means of modal energies by using the stochastic averaging method for quasi-Hamiltonian systems. The control law is assumed to be modal velocity feedback control with time delay and the unknown control gains are determined by the modal performance indices. A three-storey building structure is taken as example to illustrate the proposal method and the numerical results are confirmed by using Monte Carlo simulation.  相似文献   

9.
An addition scheme applicable to time-delay integration (TDI) CMOS image sensor is proposed,which adds signals in the charge domain in the pixel array.A two-shared pixel structure adopting two-stage charge transfer is introduced,together with the rolling shutter with an undersampling readout timing.Compared with the conventional TDI addition methods,the proposed scheme can reduce the addition operations by half in the pixel array,which decreases the power consumption of addition circuits outside the pixel array.The timing arrangement and pixel structure are analyzed in detail.The simulation results show that the proposed pixel structure can achieve the charge addition with negligible nonlinearity,therefore the power consumption of the periphery addition circuits can be reduced by half theoretically.  相似文献   

10.
The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI (proportion integral) control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.  相似文献   

11.
我们都知道在调试和改装发动机的同时,汽车的动力性和燃油经济性一贯是大家研究的重点。但在某种意义上大家会想方设法地去提高发动机的动力加速性能,却很大程度上增加了油耗。针对这一技术上的矛盾,我们尝试在发动机进气和点火系统上做出一些小的改动,从而能够适应国内大学生方程式赛车在国际上的成熟化。  相似文献   

12.
资源的有限性、环境的承载力和高速发展的经济所带来的矛盾正日益显现。转变生产方式,实现低能耗、低排放、高效率的生产模式已迫在眉睫。雅安市在实现低碳经济的转变过程中做了大量的工作,但也存在一定的问题。通过对中小企业低碳生产过程中出现的问题进行分析,找出从体制、机制和技术上进行创新和引导的方法,以政府为导向,以技术改革为支撑,以考核机制为保障,探寻中小企业实现低碳生产的道路。  相似文献   

13.
The sleep mode which works upon low arrival traffic is introduced in IEEE802.16e standard to reduce the power consumption of the mobile access terminal. Due to the rapid growth in the sleep interval in the exponential growth algorithm prescribed in IEEE802.16e, the power saving efficiency of the mobile access terminal is limited and the average delay time of receiving data frames is prolonged when the arrival rate of data frames is low. To obtain lower power consumption and shorter average delay time, the l...  相似文献   

14.
为提高设计制作类高职实训课程的教学效果,提出了一种数字校园环境下结合仿真实验教学的PBGS教学模式。该教学模式基于建设的课程网络平台,以分组完成不同仿真制作项目为载体,以学生为主体,将线上与线下、仿真与实践有机结合,并以改革考核方式引领教学活动的开展。这种教学模式被用于天线安装与调试实训课程,实践表明,学生更好地理解了天线相关抽象概念,学生的动手能力和学习兴趣得到了提高,教学效果更好。  相似文献   

15.
山东省三十年商业发展与消费方式变迁   总被引:1,自引:0,他引:1  
在由传统计划经济向市场经济转型的过程中,随着社会经济的变迁,居民的消费方式也在不断发生显著的变化。众所周知,转型期居民消费方式之所以会发生变化,可以从政治、经济、文化、社会等许多方面的内外因素中探寻原因,而市场化进程中商业的迅速发展无疑是相当重要的因素之一。这里主要探讨山东省在市场化进程中随着商业发展,人们消费观念和消费方式的发展演变,以揭示二者之间的相互关系。  相似文献   

16.
针对一种新型混联式汽车电泳涂装输送机构控制方法存在收敛时间较长问题,提出一种有限时间收敛滑模控制方法。首先采用解析法对机构进行运动学分析,并基于拉格朗日法建立输送机构动力学模型;提出一种快速终端滑模有限时间收敛控制方法,实现新型混联式输送机构控制的有限时间收敛;然后设计有限时间滑模观测器,实时观测被控对象模型中的不确定参数以及外部随机干扰并加以前馈补偿,以进一步提高系统鲁棒性,同时解决快速终端滑模控制存在的抖振问题;最后运用Lyapunov稳定性理论证明该控制方法的稳定性,利用MATLAB对控制方法进行仿真,并将其应用于新型混联式输送机构样机进行实验,结果表明该控制器具有跟踪误差小、稳态精度高、响应速度快、鲁棒性好的特点。  相似文献   

17.
针对窄脉冲、高峰值功率的光脉冲难以产生的问题,研究了基于多模激光器的超短脉冲产生技术。由于没有锁模的多模激光器的输出呈现不规则变化,故难以产生超短脉冲。通过对主动锁模和被动锁模的相关理论及方法分析,详细阐述了锁模激光器产生超短激光脉冲的原理,并重点研究了基于主动锁模和被动锁模的几种超短脉冲产生方法。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号