A Control Scheme for PWM Voltage-Source Distributed-Generation Inverters for Fast Load-Voltage Regulation and Effective Mitigation of Unbalanced Voltage Disturbances

This paper presents a control scheme for grid-connected pulsewidth-modulated voltage-source inverters (VSIs) featuring fast load-voltage regulation and effective mitigation of unbalanced voltage disturbances. To ensure perfect regulation of the voltage at the point of common coupling (PCC) and provide means for rejecting fast and dynamic voltage disturbances, the frequency modes of the disturbances to be eliminated should be included in the stable closed-loop system. Toward this, a hybrid voltage controller combining a linear with variable-structure control element is proposed for an inverter-based distributed-generation interface to regulate the voltage at the PCC. The proposed voltage controller can embed a wide band of frequency modes through an equivalent internal model. Subsequently, a wide range of voltage perturbations, including capacitor-switching disturbances, can be rejected. To account for unbalanced voltage disturbances, a dual-sequence voltage controller is proposed. To provide accurate and robust tracking of the generated active and reactive current trajectories, a newly designed deadbeat current control algorithm is proposed. The controller is designed under the practical considerations of inherent plant delays, which are associated with the digital implementation of the control algorithm, and the uncertain nature of the current dynamics. Theoretical analysis and comparative evaluation tests are presented to demonstrate the effectiveness of the proposed control scheme.     

Multilevel Multiphase Space Vector PWM Algorithm With Switching State Redundancy

Multilevel multiphase technology combines the benefits of multilevel converters and multiphase machines. Nevertheless, new modulation techniques must be developed to take advantage of multilevel multiphase converters. In this paper, a new space vector pulsewidth modulation algorithm for multilevel multiphase voltage source converters with switching state redundancy is introduced. As in three-phase converters, the switching state redundancy permits to achieve different goals like extending the modulation index and reducing the number of switchings. This new algorithm can be applied to the most usual multilevel topologies; it has low computational complexity, and it is suitable for hardware implementations. Finally, the algorithm was implemented in a field-programmable gate array, and it was tested by using a five-level five-phase inverter feeding a motor.      

Multilevel Multiphase Space Vector PWM Algorithm

In the last few years, interest in multiphase converter technology has increased due to the benefits of using more than three phases in drive applications. Besides, multilevel converter technology permits the achievement of high power ratings with voltage limited devices. Multilevel multiphase technology combines the benefits of both technologies, but new modulation techniques must be developed in order to take advantage of multilevel multiphase converters. In this paper, a novel space vector pulsewidth modulation (SVPWM) algorithm for multilevel multiphase voltage source converters is presented. This algorithm is the result of the two main contributions of this paper: the demonstration that a multilevel multiphase modulator can be realized from a two-level multiphase modulator, and the development of a new two-level multiphase SVPWM algorithm. The multiphase SVPWM algorithm presented in this paper can be applied to most multilevel topologies; it has low computational complexity and it is suitable for hardware implementations. Finally, the algorithm was implemented in a low-cost field-programmable gate array and it was tested in a laboratory with a real prototype using a five-level five-phase inverter.     

A Space Vector PWM Scheme for Multilevel lnverters Based on Two-Level Space Vector PWM

1. INTRODUCTION MULTILEVEL inverters are increasingly being used in high-power medium voltage applications due to their superior performance compared to two-level inverters, such as lower common-mode voltage, lower dv/dt, lower harmonics in output voltage and current, and reduced voltage on the power switches.     

A Space Vector Modulation Scheme to Reduce Common Mode Voltage for Cascaded Multilevel Inverters

Multilevel inverters can reduce the common mode voltage generated. Schemes have been reported for multilevel inverters that reduce the common mode voltage. However, most of the schemes result in reduced modulation depth, high switching losses, and high harmonic distortion. This paper proposes a space-vector modulation scheme to reduce common mode voltage for cascaded multilevel inverters. The proposed scheme can increase the voltage range of operation by about 17% and can produce lower total harmonic distortion than the previously proposed schemes. The scheme is explained for five-level inverter. The scheme can be easily extended to a n-level inverter. Both experimental and simulation results are provided.     

电压空间矢量PWM控制技术的探讨

本文利用SVPWM控制技术产生的正六边形旋转磁场,在基本电压矢量之间插入零电压矢量。利用得到的SVPWM波及傅立叶级数基本知识,证明了基频以下调速时,逆变器输出电压一频率比为恒值这一结论。这对准确而全面理解SVPWM控制技术、深刻掌握交流调速系统有关内容具有重要意义。     

Extended Voltage Swell Ride-Through Capability for PWM Voltage-Source Rectifiers

Voltage swells are one of the most harmful disturbances present in industrial power systems, being capable of severely damaging, breaking, or tripping converters. In the case of pulsewidth-modulation voltage-source rectifiers (PWM-VSRs), swells first saturate their control system and then force them into six-pulse operation if no precautions are taken. This paper presents an extended ride-through strategy enabling these converters to deal and cope with swells of up to 1.8 p.u. (IEEE Std. 1159 swell definition). The proposed strategy first fully exploits the dc-link voltage capacity by dynamically entering the overmodulation region, and secondly by drawing inductive current in case the former action does not suffice. Dynamic overmodulation makes possible the straight ride-through of 15% and 42% three-phase and single-phase swells, whereas the modulation index supervisor/control loop drawing inductive current enables the ride-through for greater magnitude disturbances, all the while avoiding saturation of the converter control system. This is realized using decision-making space vector modulation, and a control system built over a nonlinear control law directly obtained from the converter complex state variable model. In this way, linear and decoupled$d$–$q$axes dynamics are attained, ensuring a constant dynamic response throughout the whole operating range. Finally, experimental results from a TMS320C32 digital-signal-processor-based 5-kVA laboratory prototype subjected to typical industry single- and three-phase swells ranging from 5% to 50% are presented. These confirm the predicted performance and feasibility of the proposed voltage swell ride-through strategy for PWM-VSRs.     

A General Space Vector PWM Algorithm for Multilevel Inverters, Including Operation in Overmodulation Range

This paper proposes a simple space vector pulsewidth modulation algorithm for a multilevel inverter for operation in the overmodulation range. The proposed scheme easily determines the location of the reference vector and calculates on-times. It uses a simple mapping to generate gating signals for the inverter. A five-level cascaded inverter is used to explain the scheme. The scheme can be easily extended to a n-level inverter. It is applicable to neutral point clamped topology as well. Experimental results are provided for five-level and seven-level cascaded inverters     

电压空间矢量PWM控制的仿真研究

本文介绍了电压空间矢量调制的原理,并对电压矢量的合成做了详细分析,给出SVPWM调制方式与载波调制的关系及用载波调制的方法实现电压矢量控制的具体步骤。最后通过Matlab/simulink进行仿真验证。     

三相PWM整流器电压空间矢量控制的实现

提出了一种便于数字实现的三相PWM整流器电压空间矢量的控制算法，该算法采用输入电压空间矢量定向，根据参考电压矢量直接计算空间电压矢量的位置和作用时间；利用DSP（数字处理器）实现了三相PWM整流器全数字化控制，并得出了最终实验结果。     

不平衡电网电压下三相PWM整流器控制策略的研究

在不平衡电网电压下三相电压型PWM整流器的优越性能受到了很大的影响,其原因是由于直流电压产生了奇次谐波以及交流的电流产生了偶次谐波。三相PWM整流器直流侧电压的二次谐波以及在交流侧电流所产生的负序分量都将对整流器负载性能产生影响,同时还将影响直流侧电容寿命。文章提出一种新型不平衡观测器及其控制策略可有效地对不平衡电压进行补偿。通过此控制策略可同时抑制直流侧电压的2次谐波以及减小网侧电流的不平衡度。分析及仿真结果证明了此控制策略的有效性。     

A New Analog Controller for Three-Phase Four-Wire Voltage Generation Inverters

This paper introduces a new controller for three-phase four-wire inverters, with the control goal of generating high-quality three-phase output voltages for all sorts of linear/nonlinear and balanced/unbalanced loads. The proposed controller employs a circuit-level decoupling method, and it is implemented by logic circuitry in combination with a control core and a feedback signal processor. Almost all dc–dc control methods can be adapted as the control core, while the feedback signal processor can be implemented by either voltage compensator and/or current compensator. The implementation of the controller is simple and flexible with only logic and analog circuitry needed. Yet, it demonstrated experimentally excellent load handling and source voltage noise rejection ability. The prototype is tested under balanced and unbalanced resistive and nonlinear loads, as well as under extreme load transients. It is also tested with power from a noisy dc input source. In all cases, the prototype demonstrated high-quality output voltages.      

三相PWM整流器滞环空间矢量控制的研究

本文介绍了三相PWM整流器的一种基于不定频滞环的空间矢量脉宽调制（sVPWM）电流控制方法。该方法结合了滞环电流控制和SVPWM电流控制的优点,在取得快速电流响应的同时又能有效地降低开关频率,提高系统的运行效率。用Simulink模块库建立仿真模型,仿真结果表明了该控制策略的可行性。     

基于电压空间矢量的三相PWM整流器控制研究

首先建立了三相电压型PWM整流器的数学模型，并对其矢量控制策略进行了分析，在此基础上提出了一种简单的电压空间矢量算法，该算法根据参考电压矢量在坐标系上的分量直接计算电压空间矢量在各个扇区内的作用时间，实验结果验证了所提出控制算法的可行性。     

空间矢量脉宽调制在有源滤波器中的应用

文章针对典型的三相整流电路中产生的谐波对电网产生的影响,研究易于数字化的SVPWM,将其应用于并联有源电力滤波器内层跟踪控制中,给出一种补偿功能较为完善的并联有源电力滤波器及其控制方法。仿真结果表明：SVPWM调制用于并联有源滤波控制可以明显改进补偿的动态性能,提高滤波效果。     

基于空间电压矢量的三相电压型PWM整流器的研究

建立了三相电压型PWM整流器在三相静止坐标系和两相同步旋转坐标系下的数学模型,将双闭环工程设计方法应用于PWM整流器,研究了其前馈解耦控制策略。在此基础上结合空间矢量调制（SVPWM）的算法,设计了三相电压型PWM整流器控制系统,并在Matlab的Simulink中进行了系统仿真。仿真结果表明,设计方法可行,具有良好的动静态性能,实现了单位功率因数。     

Analysis of Output Current Ripple rms in Multiphase Drives Using Space Vector Approach

Multiphase variable-speed drives, supplied from two-level voltage source inverters (VSIs), are nowadays considered for various industrial applications. Although numerous pulsewidth modulation (PWM) schemes for multiphase VSIs, aimed at sinusoidal output voltage generation, have been developed, no detailed analysis of the impact of these modulation schemes on the output current ripple has ever been reported. This paper presents a comprehensive analytical analysis and comparison of the output current ripple caused by the application of three different continuous PWM schemes, using a five-phase VSI as an example. Main properties of sinusoidal PWM, fifth harmonic injection PWM, and space vector PWM are elaborated and analyzed using the harmonic flux concept. Space vector theory is applied in the analysis. As a result, harmonic distortion factors are obtained for each PWM scheme. Theoretical considerations are verified by simulations and experimental investigation using a custom-designed five-phase VSI-fed induction motor drive.      

General Modulation Strategy for Seven-Phase Inverters With Independent Control of Multiple Voltage Space Vectors

This paper focuses on the analysis of a seven-phase voltage-source inverter for high-performance motor drives. The problem of the modulation strategy of the inverter is solved by combining the multiple space vector representation with traditional carrier-based pulsewidth modulation. This approach leads to the definition of a general modulation strategy that can be usefully utilized in multimotor drives, as well as in multiphase motor drives for improving the torque density. The inverter output voltage capability is investigated, showing that the proposed modulation strategy is able to fully exploit the dc input voltage either in sinusoidal or nonsinusoidal operating conditions. The results obtained in the analytical investigation are confirmed by experimental tests.     

An Improved Deadbeat Current Control Scheme With a Novel Adaptive Self-Tuning Load Model for a Three-Phase PWM Voltage-Source Inverter

In this paper, an improved deadbeat current control scheme with a novel adaptive self-tuning load model for a three-phase pulsewidth-modulated (PWM) voltage-source inverter is proposed. First, to achieve high-bandwidth current control characteristics, an improved deadbeat current controller with delay compensation is adopted. The compensation method forces the delay elements, which are caused by voltage calculation, PWM, and synchronous frame rotation, to be equivalently placed outside the closed-loop control system. Hence, their effect on the closed-loop stability is eliminated, and the current controller can be designed with a higher bandwidth. Second, to relax the parameter sensitivity issue of the deadbeat controller and to realize a control scheme with reduced sensors, a novel adaptive self-tuning load model is emerged in the control structure. The adaptive model is designed with low computational demand to estimate in real time the load parameters (R,L) and the back-electromotive-force voltage simultaneously. A unified solution to the present nonlinear estimation problem is presented by adopting a parallel observer structure. Furthermore, the adaptive model has the necessary phase advance of the estimated quantities, which compensates for the total system's delay. Comparative evaluation results are presented to demonstrate the validity and effectiveness of the proposed control scheme     

基于TMS320F240的空间电压矢量PWM的实现

文中叙述了空间电压矢量（SVPWM）的基本原理，介绍了采用矩阵求妥两相邻向量作用时间的方法和用数字信号处理器TMS320F240生成对称空间电压矢量的方法，它的优异性能可以实时完成SVPWM的控制算法，且速度快，精度高。