准优化PWM技术在级联型多电平变流器中的应用

级联型多电平变流器是目前高压变流器的主要拓扑结构之一，载波相移SPWM技术是级联型多电平变流器普遍采用的方法，但是这种方法的一个缺点是直流电压利用率较低，为了提高级联型多电平变流器的直流电压利用率，将准优化PWM技术应用于载波相移SPWM技术中，通过分析并利用MATLAB进行仿真，验证了这种方案的可行性。     

级联型有源电力滤波器的研究

把级联型变流器应用于有源滤波装置是实现大容量谐波补偿的重要途径。介绍级联型有源电力滤波器的基本原理,针对级联型拓扑结构基于瞬时无功功率理论改进了指令电流的计算,使其三相直流侧电压独立控制,满足有源电力滤波器运时对直流侧电压稳定性的要求。用载波相移—正弦脉宽调制(CPS-SPWM)实现电流跟踪控制,并对CPS-SPWM进行了数学分析,同时为了降低启动过程中直流侧电压和电流的过冲,设计一种直流侧预充电方案。最后通过仿真软件MATLAB/Simulink进行仿真验证设计可行性。     

多电平变流器在大功率风电系统中的应用

在分析多电平变流器在大功率风电系统中应用的优势基础上,介绍了二极管钳位式多电平、飞跨电容式多电平、级联型多电平、Boost-TL、VIENNA、有源中点钳位式多电平这六种结构在风力发电系统的应用。文章最后对这六种拓扑结构进行了比较和总结。     

级联型有源滤波器均压控制方法的研究

研究了级联型H桥有源滤波器（Active Power Filter,APF）的拓扑结构与控制方法;基于级联有源滤波器直流侧电压失衡问题,提出了一种分层控制思想,顶层主要是实现有功指令电流跟踪和相间电压的均衡,底层控制则是实现相内各H桥模块电压的均衡,从而有效的解决了相间电压和相内电压的均衡问题;使用仿真软件PSCAD/ EMTDC初步实现了该控制策略的仿真验证;最后,搭建以DSP+FPGA为控制核心的实验平台并进行试验验证。     

一种基于串联混合型有源滤波器的仿真新方法

分析了串联混合型有源滤波器(SHAPF)的拓扑结构及其复合检测控制方法,基于瞬时无功功率理论,利用仿真软件MATLAB构建了一种新的三相系统模型。仿真的结果验证该新方法可以有效的对串联混合型有源滤波器的工作情况进行分析和参数设计,具有仿真精度高、速度快的特点。     

载波相移技术在H桥级联多电平STATCOM中的应用

本文介绍了载波相移技术包括载波相移正弦脉宽调制（CPS-8PWM）和错时采样空间矢量调制（STS—SVM）的基本原理,提出了载波相移正弦脉宽调制和错时采样空间矢量调制在H桥级联多电平STATCOM中的实现方法,并进行了仿真验证。仿真结果表明,基于载波相移正弦脉宽调制和错时采样空间矢量调制的H桥级联多电平STATCOM能...     

高压IGCT三电平变流器的试验研究

IGCT元件的结构特点使其在高电压和大电流范围具有优越的性能，而IGCT元件的驱动和元件的高度集成化又使其使用很方便。使用IGCT元件的三电平电路结构在高压大功率变流器中得到广泛的应用。本文总结了IGCT变流器逆变部分目前国内外使用的拓扑结构，并在理论分析及仿真试验的基础上，设计了高压IGCT三电平变流器。对IGCT元件及变流器系统进行试验，并检验该变流器的工作性能。试验结果表明，该变流器达到了设计要求，具有良好的性能。     

基于DSP并联有源电力滤波器的研究

以并联有源电力滤波器为研究对象,并对其拓扑结构、补偿分量的检测算法、控制策略等问题做了较系统的研究,在该基础上介绍一种基于DSP的并联型有源电力滤波器的设计。通过仿真实验对有源电力滤波器数学模型、检测算法及控制策略的有效性和实用性进行了验证。结果表明所设计的有源滤波器具有良好的谐波补偿特性、自适应补偿能力。     

多电平级联型变流器的研究与应用

在现有的多电平变流器中,级联型变流器以其结构简单、控制方式简便的优点在高压、大容量的工业领域得到越来越广泛的应用。本文对其基本的拓扑结构、控制策略、以及研究现状作了较为详细的讨论。     

H桥级联多电平逆变器相移SVPWM技术的研究

载波相移SPWM调制法是级联型逆变器的主流控制方法,其等效载波频率高、谐波特性好、功率单元之间输出功率平衡。而空间矢量法谐波特性好、电压利用率高、控制方法简单便于数字实现。文中针对H桥级联型多电平逆变器的结构特点,综合采用载波移相SPWM法和空间矢量法,并用一种新的空间矢量算法取代传统的方法。该算法中无需三角函数和无理数计算,计算过程非常简单,节约了计算时间,结果更为准确。最后通过系统仿真验证该算法的正确性和有效性。     

New single-stage PFC regulator using the Sheppard-Taylor topology

This paper describes a new usage of the DC/DC converter developed by D.I. Sheppard and B.E. Taylor in 1983 for achieving high power factor and output regulation. This converter may be viewed as a cascade of a modified boost stage and a buck stage, with the two stages sharing the same active switch. Two possible operation regimes are described. In the first regime, the converter's input part, which is a modified boost converter, operates in discontinuous mode, and the output part, which is a buck converter, operates in continuous mode. In this regime, high power factor is naturally achieved, and the output voltage is regulated by duty-cycle modulation via a simple output feedback. In the second regime, the input part operates in continuous mode, and the output part operates in discontinuous mode, with duty-cycle modulation maintaining a high power factor and frequency modulation regulating the output. Some comparisons between the Sheppard-Taylor converter and conventional boost and buck cascade are given in the paper     

Feed-Forward Space Vector Modulation for Single-Phase Multilevel Cascaded Converters With Any DC Voltage Ratio

Modulation techniques for multilevel converters can create distorted output voltages and currents if the dc-link voltages are unbalanced. This situation can be avoided if the instantaneous dc voltage error is not taken into account in the modulation process. This paper proposes a feed-forward space vector modulation method for a single-phase multilevel cascade converter. Using this modulation technique, the modulated output voltage of the power converter always generates the reference determined by the controller, even in worst case voltage unbalance conditions. In addition, the possibility of optimizing the dc voltage ratio between the H-bridges of the power converter is introduced. Experimental results from a 5-kVA prototype are presented in order to validate the proposed modulation technique.      

A background calibration technique for multibit/stage pipelined and time-interleaved ADCs

A digital background calibration technique to compensate for the nonlinearity and gain error in the sub-digital-to-analog converter (SDAC), and the operational amplifier finite dc gain in multibit/stage pipelined analog-to-digital converter (ADC) is proposed. By injecting subtractive calibration voltages in a modified conventional multibit multiplying DAC and performing correlation based successive coefficient measurements, a background calibration is performed. This calibration technique does not need an accurate reference voltage or an increasing in the SDAC resolution. A global gain correction essential for time-interleaved ADCs is presented. Simulation results show that in the presence of realistic capacitor and resistance mismatch and finite op-amp gain, this technique improves the linearity by several bits in single and multi-channel pipelined ADC.     

A 60 Channel PCM-ADPCM Converter

Coding techniques based on adaptive linear prediction and quantization are well suited to signals carried by telephone channels and can provide, with a per channel rate of 32 kbits/s, a level of quality compatible with the specifications of the conventional 64 kbit/s rate. The ADPCM technique described in this paper features a simple adaptive quantization scheme and a tenth-order linear prediction adaptive filter realized as a cascade of five second-order sections. Besides superior performance characteristics, the nonaccumulation of degradations in tandem connections is achieved. The implementation is a 60 channel PCM-ADPCM converter, called TMN 162. It is a fully digital equipment which offers a doubling of the capacity of digital links in telephone networks.     

A high-performance ZVS full-bridge DC-DC 0-50-V/0-10-A power supplywith phase-shift control

This paper presents a high-performance DC-DC switching mode power supply designed to deliver a regulated 0-50 V/0-10 A output. The proposed power supply is based on a modified version of the zero-voltage switching (ZVS) full-bridge (FB) phase-shift DC-DC converter, which incorporates commutation auxiliary inductors to provide ZVS for the entire load range as well as a commutation aid circuit to clamp the output diode voltage. The control strategy is based on two control loops operating in cascade mode. The inner loop maintains a regulated output current, whereas the external voltage loop regulates the output voltage, independently of load and input-voltage changes. In order to obtain a high-reliability converter, the control circuit has been implemented using just two integrated circuits (ICs). The phase-shift regulator UC3875 IC generates the gate drive signal to the MOSFET's. The control loop regulators are implemented using the TL074 IC. A theoretical analysis was conducted, and experimental results were obtained for a 0-50 V/0-10 A power supply operating at 100 kHz     

Buck or boost tracking power converter

A cascade of buck and boost converter is presented here. The control operates in a manner that the converter is either in buck or boost (BOB) mode on a cycle by cycle basis. It transitions between the modes seamlessly to provide a tracking power conversion function for modulating the power supply of a variable envelope radio frequency (RF) power amplifier. The control algorithm and its implementation using switched capacitor circuits is described. Simulation and measured experimental results including converter efficiency, tracking accuracy, and spectrum at the output of the RF power amplifier are provided. This control technique allows seamless transition between the buck and boost modes while tracking RF envelopes with bandwidth greater than 100 kHz, and maintaining extreme accuracy and extremely low ripple. The efficiency of this converter operating at 1.68 MHz is close to 90% over a wide range of conversion ratios. The area of the power converter is extremely small allowing this to be integrated into a cellular telephone. The controller was integrated as part of a larger power management IC as well as a discrete IC.     

A novel single-phase soft-switched rectifier with unity power factor and minimal component count

A novel, single-phase soft-switched boost AC-DC rectifier that operates with power-factor correction is proposed in this paper. The rectifier is a modified boost voltage-doubler converter well suited for low-line-input applications. It operates with fewer conduction losses and half the switch voltage stresses found in a standard boost converter. Soft switching in the converter is achieved using a zero-current-switching quasi-resonant technique. In the paper, the converter and its modes of operation are discussed and analyzed. The method of control is explained, and a design procedure is derived and then demonstrated with an example. The feasibility of the converter is shown with experimental results obtained from a prototype.     

Single chip integration for motor drive converters with power factor capability

In this paper, an innovative converter topology is presented that allows to improve the performance of electronically commutated motor drives, aimed to equip home appliances. The proposed topology is based on a modified C-dump converter configuration, where the energy recovery stage acts as an active power factor controller (PFC) for offline operation. This is made possible by introducing a new technique to manage the free-wheeling energy that is recovered back to the dc bus by a suitable high frequency (HF) transformer. The proposed approach allows to omit the PFC stage that is included in motor drives devoted to home appliance applications in order to comply with power quality requirements. Moreover, the proposed converter topology features only low side or high side configuration switches, allowing to simplify the design of the drive and easily integrate the power semiconductors in a single chip exploiting smart power technologies. Simulations and experimental results confirm the validity of the proposed approach.     

一种采用倍流同步整流的高效率AC/DC变换器

文章介绍了一种基于不对称半桥的改进型AC/DC变换器。为了提高低压大电流应用场合的变换器效率,变换器次级采用倍流同步整流技术,而初级开关管能自然实现零压开通。因而,变换器的次级整流损耗和初级功率开关管损耗被大大降低。文中详细分析说明了电路的具体工作过程和设计要求,最后,仿真结果验证了电路设计的合理性。     

调速传动用四象限级联中压变频器（下）

由于性能优良,H桥级联变频器在中压调速传动中得到最广泛应用。通常这类变频器H桥中的交一直变换都采用二极管整流,使之不能四象限工作。把二极管整流改为PWM整流（AFE）,变频器就可以四象限工作,但需在整流输入端增加电感和电容,控制也复杂。本文建议改用IGBT整流／回馈单元,器件按同步开关模式工作．使变频器成为具有与常规H桥级联变频器同样性能的四象限变频器,且不必像AFE那样增加电感和电容．控制也特别简单。矩阵变换器Mc是一类性能优良的PWM交一交直接变频器。通过三相／单相MC桥的级联可以实现四象限中压变频。文中介绍了安川公司的Mc桥级联中压变频器,并把它和基于整流／回馈单元的H桥级联中压变频器进行比较。