Design of the Series Resonant Converter for Minimum Component Stress

For a given output voltage and power, the peak resonant capacitor voltage and peak inductor and switch currents of the series resonant converter depend strongly on the choice of transformer turns ratio and of tank inductance and capacitance. In this paper the particular component values which result in the smallest component stresses are determined, and a simple design strategy is developed. The procedure is illustrated for an off-line 200 W, 5 V application, and it is shown that an incorrect choice of component values can result in significantly higher component stresses than are necessary.     

逆变器并联驱动永磁同步电机容错控制研究

为了提高逆变器并联驱动永磁同步电机(PMSM)系统的运行可靠性,基于对比研究方式设计了两种逆变器并联驱动PMSM的容错控制方案,分别为正常通路电流补偿方案和等效电流补偿方案。两种容错控制方案均不同于传统方案,后者将故障逆变器整体隔离,前者则充分利用了所有逆变器非故障桥臂,以降低故障条件下的铜耗,并输出平稳转矩。此外,两种新型容错控制方案均结合了比例谐振电流控制器以实现对不对称参考电流的跟踪,避免了并联逆变器之间可能出现的环流。最后,通过PMSM并联驱动系统的容错控制试验,验证了新型容错控制策略的效果。     

Single-Stage Single-Switch Switched-Capacitor Buck/Buck-Boost-Type Converter

A new dc-dc converter featuring a steep step-down of the input voltage is presented. It answers a typical need for on-board aeronautics modern power architectures: power supplies with a large conversion ratio able to deliver an output voltage of 1–1.2 V. The proposed structure is derived from a switched-capacitor circuit integrated with a buck converter; they share the same active switch. The proposed solution removes the electromagnetic interference (EMI) emission due to the large di/dt in the input current of the switched-capacitor power supplies. Compared with a quadratic buck converter, it presents a similar complexity, a smaller reduction in the line voltage at full load (but less conduction losses due to smaller input inductor current and capacitor voltage), lower voltage stresses on the transistor and diodes, lower current stresses in the diodes, and smaller size inductors. A similar structure using a buck-boost converter as the second stage is also presented. The experimental results confirm the theoretical developments.     

High-performance front-end converter for avionics applications [aircraft power systems]

The distributed power systems of future commercial aircraft will adopt variable frequency generation (360 to 800 Hz). Front-end converters in the system will be required to have a high efficiency and a low total harmonic distortion (THD) of the input current. This paper explains the design of a zero-voltage-switching (ZVS) active-clamped isolated low-harmonic SEPIC rectifier for such applications. Utilization of the transformer leakage inductance for ZVS and a single-layer transformer design contribute to a high efficiency. An accurate averaged switch model has been developed, which shows that the control-to-input-current transfer function of this converter does not exhibit resonances observed in the conventional SEPIC. As a result, for closed-loop operation using average current control, damping of the coupling capacitor is not required. Operating at a switching frequency of 200 kHz, an experimental 100 W, 28 V output rectifier achieves a THD of 3-4% and efficiency exceeding 90% over the entire line frequency range.     

开绕组电机驱动用双逆变器死区效应补偿方法

与传统两电平逆变器的死区效应不同,开绕组电机驱动系统中双逆变器的开关死区将导致零序电压和零序电流,使绕组电流出现低频次谐波,影响系统的性能。提出了一种双逆变器开关死区导致的零序电压的补偿方案,通过扩展占空比最大的一路开关信号的导通时间,来插入一个补偿电压矢量,利用补偿电压矢量产生的零序电压抵消开关死区导致的零序电压,从而抑制系统的零序电压和零序电流。通过在开绕组感应电机驱动系统中的仿真和试验,验证了死区补偿方法的有效性。     

双Buck半桥逆变器输入电容电压脉动的分析

双Buck逆变器(DBI)是航空静止变流器(ASIs)的常用拓扑,从双Buck半桥逆变器(DBHBIs)两直流电感中分离出交流电感使得体积、重量进一步减小。在正常工作,尤其是负载短路情况下,双Buck半桥逆变器输入侧电容上的电压产生与输出同频的脉动。以交流电感分立的双Buck半桥逆变器为例,分析了在额定负载、短路、级联工作等情况下输入电容电压脉动的产生原因,给出了该脉动的定量计算方法,并由此得出了输入侧电容容值的选择依据。最后通过仿真和实验,验证了文中分析的正确性。该分析方法同样适用于其他半桥型逆变器拓扑。     

Steady-State Analysis of the Series Resonant Converter

The series resonant converter is analyzed in steady state, and for constant switching frequency the output current and voltage characteristics are found to be ellipses. The converter operating point can then be easily obtained by superimposing a load line on these elliptical characteristics. Peak resonant capacitor voltage and inductor current are also plotted in the output plane and are dependent to first order only on output current. When peak voltage and current are plotted in this manner, the dependence of component stresses on operating point is clearly revealed. The output characteristics are modified to include the effect of transistor and diode voltage drops, and experimental verification is presented.     

Low-harmonic thyristor rectifiers applying current injection

Application of the third harmonic current injection in three-phase full-bridge thyristor rectifiers is analyzed. Spectra of the rectifier output terminal voltages are derived. Results of the optimal current injection for diode bridge rectifiers are generalized for the thyristor rectifiers, and the waveform of the optimal injected current is derived. It is shown that for the optimal third harmonic current injection, the current injection network takes 8.571% of the rectifier input power from the thyristor bridge output terminals, regardless the thyristor firing angle. A current injection network with a passive resistance emulator that provides recovery of the power taken from the thyristor bridge output terminals is proposed. Volt-ampere ratings of the magnetic components are derived. An algorithm to control the switches in the resistance emulator is presented. Analytically obtained results are experimentally verified.     

Three-phase rectifiers that apply optimal current injection

A class of current injection based three-phase high power factor rectifiers is proposed. Low distortion of the input currents and high power factor are obtained applying near optimal current injection. The optimal current injection is discussed, and requirements it imposes to the current injection network are derived. A class of simple current injection networks that provide near optimal current injection, consisting of a transformer, two capacitors, and a number of resistors or resistance emulators is proposed. The power processed by the resistors or resistance emulators is shown to be 8.81% of the input power. Design of the current injection network is discussed, and dependence of the input current distortion on capacitance of the applied capacitors is analyzed. Volt-ampere rating of the transformer is shown to be only 0.16% of the input power. Effects caused by the output current ripple are studied, and a method for their compensation is proposed. Analytical results are experimentally verified. Switching resistance emulation is discussed and its feasibility is experimentally demonstrated     

Power Conditioning Systems for High-Power, Airborne, Pulsed Applications

The power conditioning portion of the high-power study that was performed for the Air Force Aeropropulsion Laboratory by the State University of New York at Buffalo is summarized. This effort defines the power conditioning system and critical component developments which will be required to interface the airborne 10-MW to 50-MW sources defined under separate study efforts with certain loads. Power conditioning systems are considered for use with magnetohydrodynamic generators and turbine driven alternators, both conventional and superconducting. The critical components required for each of the power conditioning systems are identified and then analyzed. The component analyses include estimations of development efforts necessary and of specific weights and volumes for components. The primary components considered are transformers (for alternator as well as for inverter use), switches, capacitors, and inductors. Weight algorithms are developed for each of the components. Following the component analyses, subsystems such as inverters and rectifier and filter packages are considered. The data for the various components and subsystems are then utilized for a comparison of the power conditioning techniques to be used with the various power sources. The weights and volumes of power conditioning systems for 8-point designs (8 variations of power, voltage, duty cycle, and total run time) are derived.     

涡轴发动机部件特性修正及更新方法

针对由航空发动机零部件制造、装配及性能退化引起的发动机模型与实际发动机之间的性能不匹配问题,提出1种基于粒子群优化算法(PSO)的发动机部件特性自动修正及更新方法。根据发动机部件级模型的输出数据和发动机性能分析软件GasTurb计算结果,以发动机关键测量参数所定义的目标函数最小为优化目标,利用PSO获取不同相对换算转速下的部件特性修正因子,并在线完成特性图的自动更新。并以某型涡轴发动机为对象进行仿真验证,结果表明:该方法可有效提高涡轴发动机部件级模型的精度,并直接输出更新后的部件特性。     

Bidirectional DC-to-AC inverter with improved performance

Switch-mode DC-to-AC inverters using DC-to-DC converter topology have many advantages over the traditional bridge-type inverter. A bidirectional power circuit combined with a nonlinear robust control is proposed to form a high performance inverter. The output voltage of the inverter can be stabilized regardless of large changes in input voltage and output current. The distortion near the zero crossing point can be minimized. The load of the inverter can be resistive, inductive, or capacitive. Simulation results and experimental verification are provided     

一种BT.656到XGA视频格式转换结构的FPGA实现

本文简化了常用的BT.656接口复合视频信号向1024×768的XGA视频信号转换的结构,在matlab中对该结构的核心转换模块进行了算法建模和仿真。在此基础上用HDL描述语言描述了整个转换结构的功能模型,并用matlab生成视频数据文件供modelsim工具作为输入,仿真后输出图像数据经matlab处理显示结果正确。最后在FPGA验证板上对整个视频格式转换模块进行了原型验证,输出视频信号清晰地显示在显示器上。     

基于系统级测量参量的红外成像仿真方法

针对新型红外成像系统的成像特性,通过对光电场景图像与系统输出图像特性的客观比较,推导了场景图像灰度到光电成像系统输出图像的灰度转换模型;首次提出了基于系统级的测量参数:SiTF、MTF、NETD、噪声等效背景照度的光电输出成像的仿真方法,并给出了仿真结果.最后现场试验验证了其合理性.     

Effects of output filter on cross regulation in SRC

Cross regulation performance of multioutput series resonant converter (SRC) topologies using capacitive or inductive filters is analyzed. The steady state cross regulation characteristics are derived using the state-plane techniques and are illustrated by the examples of two-output SRCs with capacitive and inductive filters. The characteristic curves show that over some range of output currents, the cross regulation performance of an SRC with an inductive filter is much improved over the SRC with capacitance filter and less dependent on the tolerances in leakage inductances and the loading on unregulated outputs. It is shown that the converter control characteristics of an SRC with an inductive filter are relatively unaffected by the addition of the second output. The theoretical results are verified by simulation     

LLC parallel resonant converter design by scaling the LC converter

An efficient and practical method for steady-state design of an LLC-type parallel resonant dc/dc converter (LLC-PRC) is presented. In general, the output characteristic curves of LLC-PRC can be obtained by multiplying the output curves of the LC-type parallel resonant converter (LC-PRC) by a ratio of the parallel and series inductances. The peak voltage and current stresses on the resonant elements also depend on the same ratio. The LLC-PRC with a filter inductor is examined for two conduction modes, continuous and discontinuous capacitor voltage conduction modes, to show the effect of the inductance ratio. A means to use the derived equations to obtain the zero current switching (ZCS) is given. Also, a design procedure, along with design examples, is given to illustrate the use of the equations and characteristic curves. An experimental LLC-PRC is built to ensure the validity of the equations and design examples     

测量三维湍流场的热线响应方程及热线校正方程

从Ｊｏｒｇｅｎｓｅｎ等效冷却速度公式出发推出了高阶精度的热线响应方程,它适用于密度不变低速条件下求解湍流场中时均速度和雷诺应力张量。应用该热线响应方程时不严格要求热线探头轴线与流场速度矢量完全一致,因此可简化热线测量的支撑和传动机构。导出的显式热线校正方程可保证校正精度。     

快速模型预测控制用于微型直升机航迹跟踪

为实现微型共轴无人直升机(MCUH)的航迹跟踪,考虑系统的状态和输入约束,利用非线性模型预测控制(NMPC)技术设计一种快速在线的控制器。首先,简化MCUH的非线性模型,利用系统的微分平坦特性生成满足直升机动力学的可行航迹,沿着该航迹对系统进行线性化,得到近似直升机非线性动力学的线性时变(LTV)模型。然后,将传统输出航迹跟踪NMPC问题转化为LTV-MPC优化问题,降低问题的复杂度,为确保航迹跟踪误差系统的指数渐近稳定,分别设计终端域和终端罚值。最后,通过数值仿真,验证快速在线NMPC策略的可行性。结果表明:设计的预测控制器误差控制精度高、求解速度快,可实现对有约束的时变航迹的跟踪。     

STATCOM装置主电路的设计

电力系统中要求电压稳定度和无功功率满足一定的技术指标，利用带独立直流电源的级联式多电平逆变器和多电平逆变器最优化谐波台阶式调制技术(OHSW)设计的STATCOM装置，可以使电力系统中的电压得到稳定以及无功功率和谐波得到有效补偿。本文主要介绍了STATCOM装置主电路的设计，主电路是STATCOM装置与系统进行交换有功功率与无功功率的环节。该装置具有输出谐波含量低、损耗小、性能可靠等优点。     

Properties of Low Precision Analog-to-Digital Converters

The problem of quantization and saturation noise introduced by the process of analog-to-digital conversion is addressed. Analog-to-digital converters (ADC) with even versus odd numbers of output states are compared. Expressions are derived and evaluated which yield the signal-to-noise ratio and the gain versus signal level input when the input signal has an assumed Gaussian probability density. The results presented should have application in all fields in which digital signal processing is performed.