Heat Transfer and Thermal Design of Finned Frames for TEFC Variable-Speed Motors

This paper addresses the evaluation of the heat transfer capability of a finned frame for different velocities of the cooling fan and different numbers and dimensions of the fins. As the heat transfer is highly dependent on the air speed and turbulence, separate evaluations are done in four axial sectors of four different frames. For each frame, each sector is thermally isolated and evenly heated by an internal cylindrical heater with controlled losses. The experimental results allow computing the local transfer coefficient on each axial sector in terms of the fin dimensions and cooling air velocity, and using these empirical coefficients, it is possible to evaluate the thermal capability of the frames and/or to compute the temperature gradient needed to dissipate certain losses. Based on these results, a simple and accurate method to size finned frames is proposed.      

Trinary Hybrid 81-Level Multilevel Inverter for Motor Drive With Zero Common-Mode Voltage

This paper proposes a trinary hybrid 81-level multilevel inverter for motor drive. Benefiting from the trinary hybrid topology of the inverter, 81-level voltages per phase can be synthesized with the fewest components. Bidirectional DC-DC converters are used not only to inject power to the DC links of the inverter but also to absorb power from some DC links in cases with a lower modulation index. The higher bandwidth of DC-DC converters alleviates the ripples of DC-link voltages caused by the load current. The space vector modulation used here, which selects voltage vectors that generate a zero common-mode voltage in the load, works at a low switching frequency. With up to 81-level voltages per phase, the total harmonic distortion is small, and the relationship between the fundamental load voltage and the modulation index is precisely linear. A vector controller is used to control an induction motor, which results in a high dynamic response for speeds or torques. The performance of the proposed inverter for the motor drive is confirmed by simulation and experiment.     

用于Quad-rotor飞行器的无刷直流电机驱动系统设计

引言 Quad-rotor飞行器是固联的刚性十字交叉结构的小型无人飞行器,具有固定倾角,由四个独立电机驱动螺旋桨组成。它通过平衡四个螺旋桨产生的力来改变升力和飞行姿态,以实现稳定盘旋和精确飞行。无刷直流电机是集交流电机和直流电机优点于一体的机电一体化产品,既具有交流电机结构简单、运行可靠等优点,     

混合滤波系统中无源电力滤波器的优化设计

混合型有源滤波器能否按其工作原理实现预期的谐波抑制效果,在很大程度上还有赖于无源滤波器的优化设计。文章首先介绍了由小容量有源滤波器和无源滤波器串联构成的混合电力滤波系统,继而建立了其无源部分的优化模型,采用改进的遗传算法对系统的投资成本、无功补偿和滤波效果三个方面进行了优化设计研究。为克服算法的早熟收敛现象,引入了混沌算子来增加种群的多样性。工程算例的仿真计算验证了该方法的正确性和可行性,且综合性能较好,C程应用价值较高。     

一种用于雷达量测的滤波算法

在雷达跟踪系统中,广泛使用混合坐标系下扩展卡尔曼滤波器（EKF）和转换卡尔曼滤波器（CMKF）两种算法,但是当目标距离较远时,这两种滤波器由于量测方程非线性的影响,误差较大,甚至导致滤波发射。本文计算了传统EKF滤波器引入的线性化误差,并在此基础上提出一种新的滤波算法（NDRKF）。计算机仿具结果表明,该算法减小了线性化误差的影响,较明显地改善了滤波顺的性能。     

An Embedded Common-Mode Suppression Filter for GHz Differential Signals Using Periodic Defected Ground Plane

A novel low-cost filter design for common-mode noise suppression in high-speed differential signals is proposed. It is realized by periodically etching the dumbbell-shape defected ground structure (DGS) to perturb the return current of the common- mode noise. A transmission-line model for the proposed structure is also developed with good agreement to the full-wave simulation and measurement result. It is found that over 20 dB suppression of common-mode noise can be achieved over a wide frequency range from 3.3 to 5.7 GHz with 3 cascaded DGS cells, while the differential signals still keep good signal integrity in eye-pattern observation. The common-mode current, which generally results in common-mode EMI, on the attached input/output cable is also proved to be efficiently suppressed (15 dB in average) within the stopband by the proposed filter.     

A Broadband and Miniaturized Common-Mode Filter for Gigahertz Differential Signals Based on Negative-Permittivity Metamaterials

A novel wideband and miniaturized common-mode noise suppression filter is proposed based on the concept of an effective negative-permittivity metamaterial (MM) transmission line (TL). The propagation properties for the odd and even modes in the proposed structure are derived from the TL theory and Bloch theorem. Two- and four-port equivalent-circuit models are developed to explain the common-mode suppression characteristics. The dispersion relation has a good agreement with the full-wave simulation and measurement result. Based on the low-temperature co-fired ceramic fabrication technology, miniaturized common-mode filters with four and eight cells are realized using the concept of the effective negative-permittivity MM. For the four-cell structure, the filter size is $0.16~{mmb{lambda}}{hbox{g}} times 0.26~{mmb{lambda}}{hbox{g}}$ with the corresponding real size of ${hbox{3.2}}~{hbox{mm}}times {hbox{5.12}}~{hbox{mm}}$. It is found that the common-mode noise can be reduced over 10 dB from 3.8 to 7.1 GHz with the fractional bandwidth of 60% in the frequency domain, and is reduced over 50% for voltage amplitude in the time domain. More importantly, the differential signal integrity, in terms of insertion loss and group delay in the frequency domain and eye diagrams in the time domain, is not degraded within the wide stopband. To our best knowledge, it is the first broadband common-mode filter designed for gigahertz differential signals based on the concept of MM TL with most compact size.      

CCD相机系统中驱动电路的设计

目前,线阵CCD图像传感器的种类很多,驱动时序的产生方法也是多种多样.CCD时序驱动电路的设计是CCD应用的关键,只有设计出符合要求的驱动时序,CCD器件才能稳定可靠的工作.常用的驱动方法存在某些缺点.在详细了解线阵CCD器件μPD795,分析其驱动时序与电路逻辑后,没有使用常规方法,而是使用CPLD进行功能的实现.该方法采用CPLD产生驱动,按要求写好VHDL代码产生可执行文件,通过JTAG接口下载到可编程器件中.实验结果表明该电路稳定可靠,在线阵CCD驱动电路中具有一定的代表性.     

一种具备高镜像抑制比的带通滤波器设计

介绍一种高镜像抑制比的带通滤波器的设计。在音频领域里所接触的大多为实数滤波器,滤波器的频率点具备对称性的特点,这就对信号处理领域带来很大的麻烦,如AM、FM中频滤波时产生的镜像频率,会对正常的搜台产生很大的干扰。此设计利用复数滤波器的特点,设计出一种具备高镜像抑制比的带通滤波器,应用于数字调谐收音机解调系统里面。由于采用的是全集成的复数带通滤波器,节省了传统的外部中频滤波器的成本及空间;实测镜像抑制比达40 dB,大大降低了搜台的误操作,提高了整机系统的信噪比,在信号处理领域有一定的借鉴意义。     

无序量测的次优递推滤波器

在多平台多传感器组合跟踪等领域,由于通信的时间延迟,常常出现各传感器量测不能按照正常时序发送到数据处理中心的情形.为解决无序量测的滤波问题,本文提出一种次优递推滤波器OOSMF(Out-of-Sequence Mea-surements Filter),该滤波器估计精度高、计算量和存储量较小、输出无延迟.仿真实验验证了算法的可行性和有效性.     

小型倾转旋翼机的无刷直流电机驱动器设计

为了实现小型倾转旋翼机螺旋桨的可靠驱动,以ADuC7060微控制器为核心,采用反电势法设计了一种无位置传感器无刷直流电机驱动器。利用MOSFET作为开关器件,给出了桥式逆变电路和位置检测电路的原理图。针对螺旋桨负载的特点,利用MATLAB优化了三段式起动方法的起动加速曲线,并对转子位置检测电路中滤波电容产生的相移进行了补偿。通过调试表明,无刷直流电机能够带载可靠起动,并通过PWM平稳调速,验证了设计的有效性。本文网络版地址:http://www.eepw.com.cn/article/145573.htm     

GSM- R路测系统的研究

论文主要介绍了GSM—R路测中的重要数据及路测系统的开发．重点是基于VC的路测软件的开发过程。     

DFIG-Based Power Generation System With UPS Function for Variable-Speed Applications

The power generation system with a doubly fed induction generator (DFIG), which can be used as an autonomous power system after the loss of mains in a distributed generation network, is described. After the mains outage, a fixed frequency and an amplitude of the output voltage are obtained, despite the variable rotor speed. For this reason, it can be successfully applied in the variable-speed wind turbines, adjustable speed water plants, or diesel engines. Moreover, the stand-alone operation of DFIG is useful in a flywheel-based high-energy rotary uninterruptible power supply system. An output voltage is controlled directly by the synchronization of an actual voltage vector with the reference vector represented in a synchronously rotating polar frame. The rotor current angular speed is obtained as a result of vectorial phase-locked loop operation. Any sensors or estimators of the rotor speed or position are unnecessary. Both amplitude and angle control loops are linear. The use of stand-alone operation in grid-connected systems requires mains outage detection. Also, the grid voltage recovery requires a method of synchronization and soft connection of a generator to the grid. The proposed methods of output voltage control, synchronization, and detection of mains loss were tested in a laboratory system.      

混合动力电动汽车驱动系统设计与实现

本文阐述了混合动力电动汽车的结构和工作原理，设计并实现了一种基于SVPWM矢量控制的混合动力车驱动控制系统，给出了控制系统的软件流程，并对关键模块做了较详细的说明。驱动单元现场运行情况良好，其工作波形证明了其控制系统设计的正确性。     

Seven-Level Shunt Active Power Filter for High-Power Drive Systems

In high-power adjustable-speed motor drives, such as those used in electric ship propulsion systems, active filters provide a viable solution to mitigating harmonic related issues caused by diode or thyristor rectifier front-ends. To handle the large compensation currents and provide better thermal management, two or more paralleled semiconductor switching devices can be used. In this paper, a novel topology is proposed where two active filter inverters are connected with tapped reactors to share the compensation currents. The proposed active filter topology can also produce seven voltage levels, which significantly reduces the switching current ripple and the size of passive components. Based on the joint redundant state selection strategy, a current balancing algorithm is proposed to keep the reactor magnetizing current to a minimum. It is shown through simulation that the proposed active filter can achieve high overall system performance. The system is also implemented on a real-time digital simulator to further verify its effectiveness.      

Design of a VDC System for All-Wheel Independent Drive Vehicles

It is shown that the vehicle dynamic control (VDC) system can improve the vehicle handling and active safety of driver and passengers considerably. The control of vehicle yaw moment through differential braking, based on the vehicle dynamic state feedbacks, is a traditional way of VDC. In this study, a new VDC system for a four motorized-wheels electric vehicle has been developed, for which the traction of each wheel can be controlled individually. Using this feature, the new VDC system provides the desired tractive force of vehicle and the desired external yaw moment through the integrated control of wheel motors. The structure of the control system is a multilayer type, which has been developed by using independent controllers, designed in accordance with the appropriate theories.     

塑烧板除尘控制系统设计与实现

塑烧板除尘控制系统是目前世界上新型的工业除尘系统,在国内应用处于起步阶段,其计算机控制更是无一定的模式可循。因此,加大其计算机控制模式的研发具有深远的意义。介绍了以西门子控制系统为核心的硬件构架和软件体系结构,综合运用现代控制理论,采用先进的控制模式和控制方法,实现了一个可靠而先进的系统控制平台。     

H∞ Filter Design for Uncertain Discrete-Time Singular Systems via Normal Transformation

This paper concerns the robust H_∞ filtering problem for discrete-time singular systems with norm-bounded uncertainties. Based on the admissibility assumption of singular systems, a set of necessary and sufficient conditions for the existence of the desired filters is established, and a normal filter design method under the linear matrix inequality framework is developed. A numerical example is given to illustrate the application of the proposed method.     

Efficient Design of Cosine-Modulated Filter Banks via Convex Optimization

This paper presents efficient approaches for designing cosine-modulated filter banks with linear phase prototype filter. First, we show that the design problem of the prototype filter being a spectral factor of $2M$th-band filter is a nonconvex optimization problem with low degree of nonconvexity. As a result, the nonconvex optimization problem can be cast into a semi-definite programming (SDP) problem by a convex relaxation technique. Then the reconstruction error is further minimized by an efficient iterative algorithm in which the closed-form expression is given in each iteration. Several examples are given to illustrate the effectiveness of the proposed method over the existing ones.