Carrier-Based Modulation Technique for Matrix Converter

This paper presents a carrier-based modulation method for a matrix converter. By using the offset voltage and changing the slope of carrier, it is possible to synthesize the sinusoidal input currents with the unity power factor and desired output voltages. The proposed method is equivalent to the so called space vector pulsewidth modulation method. The proposed method uses a new point of view to understand the matrix converter modulation method such as the voltage source inverter (VSI) modulation method. Using the proposed method, this paper presents the two-phase/three-phase modulation method and dynamic/steady-state overmodulation method for the matrix converter. These methods are well developed in the study of a VSI. By the proposed steady-state overmodulation method, it is possible to synthesize the fundamental component of output voltage to be equal to that of input voltage at the cost of some distortion of input current. The feasibility of the proposed modulation method has been verified by a computer simulation and experimental results. These results show that the proposed carrier-based modulation method can be implemented easily without any tables. It can be used for the application where a higher voltage transfer ratio is essential     

A Comprehensive Study of a Hybrid Modulation Technique for the Neutral-Point-Clamped Converter

This paper presents a hybrid modulation technique for the three-level neutral-point-clamped converter. A modulation strategy, based on two modulation signals per phase, was presented previously. This strategy completely removes the low-frequency voltage oscillations that appear at the neutral point (NP) in some operation conditions. However, it also has a major drawback: it significantly increases the switching losses of the converter. The proposal in this paper combines such a modulation strategy with sinusoidal pulsewidth modulation (SPWM). The main characteristic of this hybrid modulation is the reduction in switching losses at the cost of some low-frequency voltage oscillations at the NP. The amplitude of these oscillations can be controlled by varying the combination of the two strategies. The performance of the hybrid modulation is analyzed and compared with the original strategies. Power losses and oscillation amplitudes on the dc-link capacitors are evaluated. Experimental results show how the hybrid modulation performs by balancing the dc-link capacitors.      

Efficient Modulation Technique for a Four-Leg Fault-Tolerant Neutral-Point-Clamped Inverter

This paper presents a new low-loss modulation technique for the hybrid three-level four-leg converter. The total losses of the converter are reduced by about 18% on average compared to the standard three-leg neutral-point-clamped converter. Furthermore, the low-frequency voltage oscillation in the neutral point is completely cancelled, and the maximum benefit of the dc-link voltage is obtained. All these facts, together with the fault-tolerant ability due to the fourth leg, make this topology very interesting for applications such as wind generation, in which it is important to maximize efficiency and reliability. Some experimental results confirm the good performance of the proposed modulation technique.     

Comparisons of Space-Vector Modulation and Carrier-Based Modulation of Multilevel Inverter

This paper studies the relations of space-vector modulation (SVM) and carrier-based pulse-width modulation (PWM) for multilevel inverter. The PWMs' generation of SVM can be achieved by carrier-based PWM scheme, but the modulated wave of SVM is acquired by vectors' calculations and switching-states' selection. Based on different selection of redundant switching-states, there are many types of SVM modulated waves, some of which can function equivalently through proper selection of common-mode injections in the case of carrier-based PWM, the others have more freedoms in switching-states' selection than carrier-based PWM. Selection of more switching-states in SVM is propitious to optimize the output voltage, balance the dc power and so on. Then an improved PWM scheme is proposed based on the modulation waves of three-level SVM, which reserves the main advantages of SVM, and can be achieved easily. Finally, a five-level test circuit is built to verify this PWM scheme.     

Closed-Loop Control of a Three-Phase Neutral-Point-Clamped Inverter Using an Optimized Virtual-Vector-Based Pulsewidth Modulation

This paper presents a closed-loop control scheme for the three-level three-phase neutral-point-clamped dc-ac converter using the optimized nearest three virtual-space-vector pulsewidth modulation, which is a modulation that produces low output-voltage distortion with a significant reduction of the dc-link capacitance. A new specific loop modifying the modulating waveforms is proposed to rapidly control possible perturbations in the neutral-point voltage balance. An online estimation of the load displacement angle and load linear/nonlinear nature is introduced at no extra cost. The remaining part of the control is analogous to the control for a two-level converter with an appropriate interfacing to the selected modulation. The closed-loop control is designed for the case of a renewable-energy source connected to the ac mains, and its performance is analyzed through simulation and experiments.     

混合型级联多电平变换器调制策略研究

多电平变换器的调制策略与其主电路拓扑密切相关。文章首先讨论了几种多电平变换器的拓扑特点,推荐了一种混合型多电平变换器,分析了它的几种调制策略和频谱特性,并进行了电路仿真,比较了它们之间的优劣,给出了连续调制方式下的频谱表达式,仿真验证了结果的正确性,最后总结了几点有用的结论。     

矩阵变流器的控制策略研究

矩阵变流器的拓扑结构采取一个整流级连接逆变级,并且中间直流环节没有体积庞大的储能环节,使该系统具有较高的功率密度。同时该系统还具有高功率因数和良好输入输出波形等优点,适用于交流调速系统以及其他的控制场合。本文对基于间接矩阵变流器的调制策略进行了深入的研究,采用空间矢量调制策略对整流级和逆变级进行调制,并仿真验正其控制策略的正确性。     

开关变换器的跨周期调制模式

该文提出了一种新的开关变换器的调制模式一跨周期调制(Pulse cycle Skip Modulation,PSM),分析和研究了其工作原理及控制特性,给出了PSM的状态方程.调制度、响应速度、效率与电路参数之间的关系.同PWM调制模式相比,PSM具有更好的调制特性.     

基于片内PID补偿器的高压Buck变换器设计

设计了一种基于片内PID补偿并具有宽输入电压范围的高压Buck变换器.该变换器采用有源电感、有源电容以及密勒电容实现片内PID补偿,从而简化了芯片外围电路的设计.通过改变PID补偿器中低频极点的位置,实现增益补偿,以保证在整个输入电压范围内反馈环路的稳定性.使用Matlab和HSpice软件对环路进行建模、分析和设计.结果表明,该变换器在8～30V的输入电压范围内可以稳定地工作,线性调整率小于0.013%/V.     

A Space Vector Modulation Strategy for a Back-to-Back Five-Level HVDC Converter System

The dc-capacitor voltage drift is the main technical drawback of a multilevel diode-clamped converter (DCC) system. This paper proposes a space vector modulation (SVM)-based switching strategy that takes advantage of the redundant switching states of the SVM to counteract the voltage drift phenomenon of a five-level DCC-based back-to-back high-voltage direct-current (HVDC) converter system. The proposed strategy is based on online minimization of a quadratic cost function, associated with the voltage deviations of the dc capacitors. The salient feature of the proposed strategy is that it enables voltage balancing of the dc capacitors with no requirements for offline calculations, additional controls, or auxiliary power circuitry. Performance of the proposed SVM-based balancing strategy for a back-to-back HVDC converter system, based on time-domain simulation studies in the PSCAD/EMTDC environment, is evaluated and experimentally verified. The studies demonstrate capability of the proposed SVM strategy to control and maintain voltage balance of dc capacitors.      

功率变换的模糊型跨周调制模式

该文提出了一种功率变换的模糊型跨周调制模式(Fuzzy Pulse Skip Modulation,FPSM),它是基于作者提出的功率变换跨周调制(Pulse Skip Modulation,PSM)机理的一种优化模式。PSM是功率变换的一种新调制模式,它具有效率高、响应速度快、鲁棒性强等特点。该文给出了FPSM输入输出变量的隶属函数、模糊控制规则和解析结果。分析表明FPSM除具PSM之优点外;同时较PSM有效降低了变换器的输出电压纹波,消除了音频噪音影响。     

Indirect Adaptive External Neuro-Control for a Series Capacitive Reactance Compensator Based on a Voltage Source PWM Converter in Damping Power Oscillations

A series capacitive reactance compensator (SCRC), using a voltage source converter to inject a controllable voltage in quadrature with the line current of a power network, is capable of rapidly providing a specified and controllable magnitude of capacitive reactance compensation independent of the line current. Moreover, with a suitably designed external controller, the SCRC can also be used to damp low-frequency power oscillations in a power network. Conventionally, linear control techniques are used to design the SCRC external controller around a specific operating point, where the nonlinear system equations are linearized. However, at other operating points its performance degrades. Nonlinear adaptive neuro-controllers offer an attractive approach to overcome this degradation problem. In this paper, an indirect adaptive external neuro-controller (INDAEC) using two radial basis function neural networks (RBFNNs) is proposed to improve the damping performance of an SCRC connected to a power network. This nonlinear INDAEC needs no mathematical model of the SCRC or the power network. It provides the SCRC with improved damping performance over a wide range of system operating conditions. This is shown by results on a single machine infinite bus power system, as well as a multimachine power system     

矩阵式变换器的研究现状与调制策略综述

矩阵变换器(Matrix Converter,简称MC)作为一种新型的电力变换器,具有输入输出特性好、输入功率因数可控、无中间储能环节、能量可双向传递的特点;采用不同控制算法,可实现整流、逆变、变频、斩波等功能,在交流传动系统中有着良好的应用前景.     

矩阵式变换器的调制策略综述

矩阵式变换器所含开关较多,数学模型复杂,控制繁琐,因而在矩阵式变换器的实际应用中,采用适当的调制策略加以实现,这是保证系统稳定可靠运行的一个至关重要的环节。本文在矩阵式变换器拓扑结构和换流方法的基础上,详细综述了三相-三相交流矩阵式变换器的几种调制策略,最后对矩阵式变换器的调制策略进行了展望。     

Separate Absorption and Modulation Mach-Zehnder Wavelength Converter

A monolithic separate absorption and moduation region (SAM) wavelength converter is demonstrated. The transmitter consists of a sampled-grating DBR (SGDBR) laser and a series-push-pull Mach-Zehnder modulator. The preamplified receiver is composed of a flared semiconductor optical amplifier and a quantum-well pin photodetector. Integrated resistors and capacitors are used to minimize microwave losses and remove the need for external bias tees. The design, fabrication, and operation of this photonic integrated circuit is presented. Small-signal response measurements show a device bandwidth in excess of 20 GHz. Operation at 40 Gbps with NRZ data shows less than a 2.5-dB power penalty across the 32-nm laser tuning range with no additional power penalty for conversion to the input wavelength.     

一种基于载流子的双栅MOSFET解析模型

提出一种全新的基于载流子求解的双栅MOSFET解析模型.针对无掺杂对称双栅MOSFET结构,该模型由求解泊松方程的载流子分布和Pao-Sah电流形式直接发展而来.发展的解析模型完全基于MOSFET的基本器件物理进行直接推导,结果覆盖了双栅MOSFET所有的工作区:从亚阈到强反型和从线性到饱和区,不需要任何额外假设和拟合参数.模型的预言结果被2D数值模拟很好地验证,表明该解析模型是一个理想的双栅MOSFET建模架构.     

应用于数字DC-DC转换器的高分辨率数字脉宽调制器设计

数字控制在电力电子领域的优势使得数字脉冲宽度调制的使用日益增加,然而其分辨率不足一直是制约开关电源领域中数字控制技术发展的主要因素之一。针对高分辨率数字脉冲宽度调制的应用需求,该文提出一种基于高速进位链结构的高分辨率数字脉冲宽度调制电路。该电路采用计数器、比较器、固定相移锁相环单元及高速进位链的混合结构,有效地提高了分辨率,并在Altera的Cyclone IV低成本现场可编程门阵列器件上实现。实验结果显示,当输入参考时钟工作频率为70 MHz时,该结构的分辨率可达到56 ps。此外,该电路还具有较宽的开关频率调节范围及较好的线性度等优点。     

一种基于载流子的双栅MOSFET解析模型

提出一种全新的基于载流子求解的双栅MOSFET解析模型. 针对无掺杂对称双栅MOSFET结构，该模型由求解泊松方程的载流子分布和Pao-Sah电流形式直接发展而来. 发展的解析模型完全基于MOSFET的基本器件物理进行直接推导,结果覆盖了双栅 MOSFET所有的工作区:从亚阈到强反型和从线性到饱和区,不需要任何额外假设和拟合参数. 模型的预言结果被2D数值模拟很好地验证，表明该解析模型是一个理想的双栅MOSFET建模架构.     

一种基于载流子的双栅MOSFET解析模型

提出一种全新的基于载流子求解的双栅MOSFET解析模型.针对无掺杂对称双栅MOSFET结构,该模型由求解泊松方程的载流子分布和Pao-Sah电流形式直接发展而来.发展的解析模型完全基于MOSFET的基本器件物理进行直接推导,结果覆盖了双栅MOSFET所有的工作区:从亚阈到强反型和从线性到饱和区,不需要任何额外假设和拟合参数.模型的预言结果被2D数值模拟很好地验证,表明该解析模型是一个理想的双栅MOSFET建模架构.     

Sigma-Delta调制及其在低噪声DC-DC变换器的应用

分析了传统PWM调制和Sigma-Delta调制在噪声性能方面的差异,以及它们对DC-DC变换器输出噪声的影响。在Chartered 0.35μm CMOS工艺条件下实现了一个基于二阶Sigma-Delta调制的低噪声DC-DC变换器,并对其中Sigma-Delta调制模块进行了流片验证。测试结果表明,Sigma-Delta调制模块能够将环路带宽内噪声抑制到-50 dB左右,并且未引入与开关频率有关的谐波成分。仿真结果表明,DC-DC变换器输出电压噪底能够达到-60 dB以下。