Improved Interleaved Single-Ended Primary Inductor-Converter forSingle-Phase Grid-Connected System

The generation of electricity based on renewable energy sources,parti-cularly Photovoltaic(PV)system has been greatly increased and it is simply insti-gated for both domestic and commercial uses.The power generated from the PV system is erratic and hence there is a need for an efficient converter to perform the extraction of maximum power.An improved interleaved Single-ended Primary Inductor-Converter(SEPIC)converter is employed in proposed work to extricate most of power from renewable source.This proposed converter minimizes ripples,reduces electromagnetic interference due tofilter elements and the contin-uous input current improves the power output of PV panel.A Crow Search Algo-rithm(CSA)based Proportional Integral(PI)controller is utilized for controlling the converter switches effectively by optimizing the parameters of PI controller.The optimized PI controller reduces ripples present in Direct Current(DC)vol-tage,maintains constant voltage at proposed converter output and reduces over-shoots with minimum settling and rise time.This voltage is given to single phase grid via 1�Voltage Source Inverter(VSI).The command pulses of 1�VSI are produced by simple PI controller.The response of the proposed converter is thus improved with less input current.After implementing CSA based PI the efficiency of proposed converter obtained is 96%and the Total Harmonic Distor-tion(THD)is found to be 2:4%.The dynamics and closed loop operation is designed and modeled using MATLAB Simulink tool and its behavior is performed.

Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.

A high precision time-to-digital converter based on multi-phase clock implemented within Field-Programmable-Gate-Array

In this paper, the design of a coarse-fine interpolation Time-to-Digital Converter (TDC) is implemented in an ALTERA’s Cyclone FPGA. The carry-select chain performs as the tapped delay line. The Logic Array Block (LAB) having a propagation delay of 165 ps in the chain is synthesized as delay cell. Coarse counters triggered by the global clock count the more significant bits of the time data. This clock is also fed through the delay line, and LABs create the copies. The replicas are latched by the tested event signal, and the less significant bits are encoded from the latched binary bits. Single-shot resolution of the TDC can be 60 ps. The worst Differential Nonlinearity (DNL) is about 0.2 Least Significant Bit (LSB, 165 ps in this TDC module), and the Integral Nonlinearity (INL) is 0.6 LSB. In comparison with other architectures using the synchronous global clock to sample the taps, this architecture consumed less electric power and logic cells, and is more stable.

A LOW POWER TIME-TO-DIGITAL CONVERTER FOR ALL-DIGITAL PHASE-LOCKED LOOP

Time-to-Digital Converter (TDC) is a key block used as the phase/frequency detector in an All-Digital Phase-Locked Loop (ADPLL). Usually, it occupies a large proportion of ADPLL's total power consumption up to about 30% to 40%. In this paper, the detailed power consumption of different components in the TDC is analyzed. A Power Management Block (PMB) is presented for the TDC to reduce its power consumption. A 24-bits TDC core with the proposed PMB is implemented in HJTC 0.18 μm CMOS technology. Simulation results show that up to 84% power reduction is achieved using our proposed technique.

A General Approach for Direct Conversion of Single Phase AC to AC Converter for Induction Heating System

This paper signifies the study of modeling and simulation of a single phase matrix converter for induction heating system. The working principle and the control method, using PID are revealing in detail. The performance of the system is carried out in MATLAB/Simulink environment with pulse width modulation switching strategy by varying the duty cycle. PID control is employed to obtain the better performance for a specified input supply for various output frequencies. The proposed control strategy of AC to AC converter has been discussed with a wide range of operating frequencies and results in low Total Harmonic Distortion.

Optimized Model Based Controller with Model Plant Mismatch for NMP Mitigation in Boost Converter

In this paper,an optimized Genetic Algorithm(GA)based internal model controller-proportional integral derivative(IMC-PID)controller has been designed for the control variable to output variable transfer function of dc-dc boost converter to mitigate the effect of non-minimum phase(NMP)behavior due to the presence of a right-half plane zero(RHPZ).This RHPZ limits the dynamic performance of the converter and leads to internal instability.The IMC PID is a streamlined counterpart of the standard feedback controller and easily achieves optimal set point and load change performance with a single filter tuning parameterλ.Also,this paper addresses the influences of the model-based controller with model plant mismatch on the closed-loop control.The conventional IMC PID design is realized as an optimization problem with a resilient controller being determined through a genetic algorithm.Computed results suggested that GA–IMC PID coheres to the optimum designs with a fast convergence rate and outperforms conventional IMC PID controllers.

DC–DC Converter with Pi Controller for BLDC Motor Fuzzy Drive System

The Brushless DC Motor drive systems are used widely with renewable energy resources.The power converter controlling technique increases the performance by novel techniques and algorithms.Conventional approaches are mostly focused on buck converter,Fuzzy logic control with various switching activity.In this proposed research work,the QPSO(Quantum Particle Swarm Optimization algorithm)is used on the switching state of converter from the generation unit of solar module.Through the duty cycle pulse from optimization function,the MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor)of the Boost converter gets switched when BLDC(Brushless Direct Current Motor)motor drive system requires power.Voltage Source three phase inverter and Boost converter is controlled by proportional-integral(PI)controller.Based on the BLDC drive,the load utilized from the solar generating module.Experimental results analyzed every module of the proposed grid system,which are solar generation utilizes the irradiance and temperature depends on this the Photovoltaics(PV)power is generated and the QPSO with Duty cycle switching state is determined.The Boost converter module is boost stage based on generation and load is obtained.Single Ended Primary Inductor Converter(SEPIC)and Zeta converter model is compared with the proposed logic;the proposed boost converter achieves the results.Three phase inverter control,PI,and BLDC motor drive results.Thus the proposed grid model is constructed to obtain the better performance results than most recent literatures.Overall design model is done by using MATLAB/Simulink 2020a.

Unified algorithm of single-phase active AC-DC converters and its applications

This paper discusses a novel boost single-phase active AC-DC converters, named low-end semi-controlled bridge AC-DC converter. By analysis, its topology and principle can be derived from the conventional single-phase power factor corrector （ PFC）. But it has also some differences, such as power device positions, inductor type, input voltage waveform detection and induction current detection, so its design is also different. The converter is implemented by employing two current detection approaches, i.e., current transformer detection and shunt resistor detection. Consequently, it can provide a steady DC output voltage with a low voltage ripple, approximately unitary input power factor and 2.5 kW output power. The experimental results show validity of the theoretical analysis.

基于对称控制的三相并网变流器单输入单输出阻抗建模与分析

三相并网变流器的不对称控制结构会导致频率耦合效应,降低其接入弱电网的稳定裕度,增加了阻抗分析的复杂度。首先,该文提出一种三相并网变流器的对称控制策略,以消除由锁相环和直流电压环引起的频率耦合效应。该控制策略通过在控制环路中引入直流电压环q轴补偿,以形成对称的直流电压闭环结构,同时引入对称锁相环,消除传统锁相环的非对称动态特性。因此,三相并网变流器可建模为单输入单输出的阻抗复矢量形式,进而可采用标准奈奎斯特准则进行阻抗稳定性分析,能够直观地说明控制器对系统阻抗特性的主导作用。然后,对并网变流器的阻抗特性进行分析,得出弱电网中对称锁相环的带宽对系统稳定性有着至关重要的影响,并且,不同运行工况也会改变并网变流器的阻抗特性,进而影响系统的稳定性。最后,仿真和实验结果验证了所提控制策略对频率耦合效应抑制的有效性以及阻抗特性分析的准确性。

A Study of Power Loss for 3 Phase Voltage Source Converter of Elevator

In this paper,to study the power loss of converter for elevator,The analysis is to establish relationship between parameters(current,voltages and losses in the inverter and converter) relevant for sizing of major components of the drive was done.) For high PWM(pulse width modulation) frequency like in elevator applications of fpwm =10kHz,switching losses are dominant and are about 2/3 of the total losses on IGBT switch.Transition from continuous 3 phase to discontinuous 2 phase PWM results in 50% reduction of switching loses on IGBT devices providing that PWM is not done over 60deg angle in a particular phase when current has maximum value.Total losses on IGBT(conduction + switching) are reduced approximately by ～1/3 what is still a significant reduction.Two phase PWM with reduced losses can be used for applications when acoustic noise due to increased current ripple is not significant and fall back solution to regular 3 phase PWM when drive operates under rare extreme conditions resulting in increased heat sink temperature.The analysis will be examined by further laboratory testing simulating 60% duty cycle on a dynamometer.

弱电网下并网变流器相位裕度的分频段补偿方法

在弱电网条件下,针对并网变流器各控制环节与电网阻抗之间交互作用,容易引发系统振荡而造成失稳问题,文中提出一种分频段相位补偿控制策略。首先,建立dq坐标下的并网变流器输出导纳矩阵模型,针对在低频段由锁相环引起的变流器输出导纳的负阻尼特性,不改变锁相环动态特性而通过分析锁相环对控制系统的影响路径,加入含积分元素的补偿矩阵抵消锁相环的负阻尼影响,同时简化导纳模型;进而,引入仅含常数元素的补偿矩阵实现超前校正,对电流环带宽外的负阻尼进行相位补偿,使导纳矩阵元素在全频段为正实部,为并网控制系统提供正阻尼,从而增强并网变流器的稳定性。最后,通过仿真和实验在不同短路比条件下对文中提出的补偿方案进行验证,证明所提方案的有效性。

对称故障下变流器控制对差动保护影响及优化策略

变流器输出故障特征的强可控性给交流系统继电保护带来了严峻挑战。该文分析并网线路发生对称故障时跟网型变流器的控制响应过程,从故障期间变流器电流控制目标不能自动匹配故障回路功率需求的角度,分析推导变流器网侧电压相位发生跳变并不断旋转的变化特征。受故障回路阻抗约束,变流器输出短路电流相位与网侧电压相位同步变化,造成并网线路差动保护性能严重下降。基于变流器网侧电压相位变化机理,从电流控制目标与锁相环控制两个维度,提出兼顾保护需求和供电需求的变流器控制优化策略。仿真结果表明,并网线路对称故障时所提策略能有效抑制两侧电流相位差,显著提升了差动保护动作性能。

两桥臂交叉解耦不平衡控制策略研究

由于非不平衡控制策略中没有考虑线电压和相电流的相角差,造成三相电网的有功、无功电流无法完全补偿。为了解决这一问题,根据电压电流相角差,推导出单相补偿器中无功参考补偿电流与负载电流的关系,提出一种两桥臂交叉解耦不平衡控制策略,利用多变量滤波器和交叉解耦双复系数滤波器优化锁相环,精确锁定三相不平衡电网的电压频率和相位,对2个单相背靠背变换器的无功电流分别控制,进而利用两桥臂变换器补偿三相不平衡无功。实验结果验证了所提两桥臂交叉解耦不平衡控制策略,可抑制三相有功不平衡及补偿三相不平衡无功,将三相电流的不平衡度从150.0%降低至2.6%,三相电网功率因数从0.257提升至0.997,减少了三相无功补偿器的开关管个数。

宽增益高效率CLLLC变换器的变频双移相调制策略

在输入电压宽范围变化时,变频调制CLLLC变换器存在开关频率变化范围宽的问题,而移相调制CLLLC变换器难以实现宽范围零电压导通(ZVS)。为了实现宽输入电压CLLLC变换器的高效率,该文提出一种变频双移相调制方法。通过同时调节开关频率、一次侧全桥和二次侧全桥之间的移相角,拓宽CLLLC变换器的增益并提高其效率。采用时域分析法求解变频双移相调制CLLLC变换器的电压增益与谐振电感电流有效值,并分析频率以及移相角对电压增益和谐振电感电流有效值的影响。最后,通过搭建一台100~300 V输入、48 V/400 W输出的实验样机,验证了理论分析的正确性。

三相CLLC谐振变换器磁集成平面变压器设计与优化

三相CLLC谐振变换器凭借其高效率、大容量、低器件应力等优势而受到广泛关注。然而,多相结构的磁性元件数量多、体积大,是制约功率变换器尺寸的主要因素。随着宽禁带(WBG)半导体器件的出现,功率变换器的开关频率显著提高,这也为印制电路板(PCB)绕组的使用提供了有利条件。与传统绕线式绕组相比,PCB绕组的扁平特性更适用于平面磁性元件。此外,由于高频带来的低电感需求也使得基于PCB绕组的平面磁性元件更有利于实现集成。该文提出一种新型的基于PCB绕组的电感和变压器的集成结构,详细分析磁心结构的磁路模型,并给出集成磁件的优化设计方法,最后通过搭建一台基于SiC器件的800 V/10 kW的实验样机进行验证。实验结果表明,该集成方案可有效减小变换器的体积和损耗,具有高功率密度和高效率。

柔直换流阀用相变冷却工质击穿特性研究

相变冷却技术冷却效率高、安全可靠,有望攻克柔直换流阀散热瓶颈,实现其高压、大容量发展,在换流阀冷却领域具有良好的应用前景。为实现相变冷却换流阀绝缘系统可靠设计,该文设计研制了三相态相变冷却工质可调频绝缘特性测试专用平台,并以换流阀用相变冷却工质为研究对象,依据换流阀典型运行工况,利用专用测试平台开展了相变冷却工质三相态、50~300 Hz频率范围的绝缘击穿特性研究。得到了相变冷却工质击穿特性随工质相态及电压频率的变化规律,分析了相变冷却工质不同相态的击穿机理,揭示了工质相态和电压频率变化对冷却工质击穿特性的影响机制。研究工作不仅解决了高频下相变冷却工质的三相态耐压测试方法问题,且所得研究成果为相变冷却柔直换流阀的绝缘设计奠定了基础,同时可指导相变冷却技术在其他电力电子器件及装备上的应用。

串并联型海上风电场机组均压控制

针对串联型风机簇产生弃风的问题,在直流侧添加基于超级电容的储能单元,并在串联簇中设置一台参考机组,通过控制双向DC/DC变换器的吸收、释放电能,使同串联簇中除参考机组之外的其他机组向直流汇集母线上输出的功率相同,使直流风机风电功率和风机出口电压一致,实现基于超级电容储能的直流机组的均压控制,以此减少直流风机串联簇各机组间的风电功率差,降低弃风率。针对传统两相DC/DC变换器电感电流纹波大,两相电流不均衡等问题,采用了一种移相均流控制策略。最后,在Matlab/Simulink搭建了仿真模型,仿真结果验证了所提出的策略的有效性。

基于功率切换模型的三相VSC切换控制方法

三相电压源变换器(voltage source converter,VSC)工作过程可视为在不同开关状态(即不同子系统)下的切换,是一种典型的切换系统。基于切换系统理论,提出一种三相电网平衡条件下基于功率切换模型的三相VSC切换控制策略。相较于传统基于线性化模型的三相VSC控制方法,所提方法具有模型精确无近似,控制参数少,控制器实现简单,无需复杂的坐标旋转变换和脉冲宽度调制过程,对于电路参数不确定具有强鲁棒性等优点。相较于传统基于电流切换模型的三相VSC切换控制策略,所提方法具有模型更便于系统分析与切换规则设计且提升了系统延迟条件下系统稳定性等优点。仿真及实验比较结果证明了所提方法的有效性及优越性。

双有源桥变换器双移相控制动态特性优化方法

为了提高双移相控制的双有源桥DAB(dual active bridge)变换器负载切换的动态响应性能及减小电流应力,研究了1种改进型双移相NDPS(novel dual phase shift)控制方法,通过改变传统双移相TDPS(traditional dual phase shift)控制内移相角移动方向,重构了传输功率与移相比的关系,增大了移相比调节范围。研究了电流应力最小化条件下双移相控制最优移相比的求解方法,对比分析NDPS与TDPS控制方式负载切换时的动态响应特性。最后搭建了DAB变换器实验平台对理论分析进行实验验证,实验结果表明,轻载条件下,基于电流应力最小化方法得到的最优移相比组合可以有效减小电流应力,同时NDPS比TDPS控制方式有更好的动态响应特性。

考虑CVT输出特性的换流变剩磁测算方法

特高压换流变空载合闸时,其剩磁会改变铁心磁通的大小和方向,极易造成严重的励磁涌流,导致换流变无法正常投入运行。针对换流变剩磁测算,分析电容式电压互感器(CVT)输出数据存在误差是由系统频率变化引起的,根据误差式进行校正并基于电压积分法给出考虑CVT输出特性的换流变剩磁测算方法。在PSCAD/EMTDC中搭建相关仿真模型,对Y、D桥换流变的电压正向、负向峰值处分别进行分闸实验,并根据所提测算方法确定换流变剩磁。利用校正前、校正后以及监测的换流变剩磁完成选相合闸对比实验,实验结果表明所提方法能够有效测算换流变剩磁,为励磁涌流抑制手段提供参考依据。