Current Reconstruction Techniques for Survivable Three-Phase PWM Converters

In high-performance three-phase pulsewidth-modulated (PWM) converter systems used in generator and motor drives, failure of current sensors will directly interrupt the system performance, and will even cause disastrous consequences. Redundancy in design is one of the popular choices to overcome this issue. However, this usually leads to an undesirable increase in size and cost. This letter presents two novel model-independent current reconstruction methods for three-phase PWM converter systems based on space vector modulation. Using the proposed sensor placement and software algorithm, phase currents within a three-phase converter can be reconstructed to an acceptable level of accuracy under single-survived-sensor ($S^3$) scenario. A hardware prototype is built and fault tolerant algorithm is implemented using a DSP (TMS320F2812). Experiments are conducted under worst-case scenario to verify the flexibility of sensor placement/converter layout and software algorithm.      

A Systematic Topology Evaluation Methodology for High-Density Three-Phase PWM AC-AC Converters

This paper presents a systematic evaluation approach of three-phase pulsewidth-modulated (PWM) ac–ac converter topologies for high-density applications. All major components and subsystems in a converter are considered and the interdependence of all the constraints and design parameters is systematically studied. The key design parameters, including switching frequency, modulation scheme, and passive values, are selected by considering their impacts on loss, harmonics, electromagnetic interference (EMI), control dynamics and stability, and protection. The component selection criteria as well as the physical design procedures are developed from the high-density standpoint. The concept of using the same inductor for harmonic suppression and EMI filtering is introduced in the design. With the proposed methodology, four converter topologies, a back-to-back voltage source converter (BTB-VSC), a nonregenerative three-level boost (Vienna-type) rectifier plus voltage source inverter (NTR-VSI), a back-to-back current source converter (BTB-CSC), and a 12-switch matrix converter, are analyzed and compared for high specific power using SiC devices. The evaluation results show that with the conditions specified in this paper, BTB-VSC and NTR-VSI have considerably lower loss, resulting in higher specific power than BTB-CSC and the matrix converter. The proposed methodology can be applied to other topologies with different comparison metrics and can be a useful tool for high-density topology selection.      

三相电压型PWM整流器建模与仿真

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,采用输入电压空间矢量定向,根据参考指令电压矢量直接计算空间电压矢量位置和作用时间,结合直接电流控制的方法进行电流跟踪控制,仿真结果证明了该方案的有效性.     

Soft Switching Circuit for Interleaved Boost Converters

A zero-voltage switching-zero-current switching interleaved boost converter is proposed in this paper. An active circuit branch in parallel with the main switches is added and it is composed of an auxiliary switch and a snubber capacitor. By using this interleaved converter topology, zero current turn-on and zero voltage turn-off of the main switches can be achieved and the reverse-recovery loss of boost diode can be reduced. In addition, the auxiliary switches are zero-voltage transmission during the whole switching transition. A prototype of boost converter rated at 1.2kW has been built to confirm the effectiveness of the converter     

三相PWM整流器直接功率控制的仿真研究

基于三相电压型PWM整流器的原理与结构组成,采用电压定向的不定频直接功率控制(VO-DPC),通过对其控制结构的分析,建立其MATLAB/SIMULINK仿真模型.根据仿真结果可以看出,直接功率控制的控制算法简单,而且可以提高整流器的功率因数,有效降低谐波含量.     

三相PWM整流器的前馈解耦控制与仿真研究

基于前馈解耦控制策略,研究了三相电压型PWM整流器的建模与控制问题。首先,在d-q旋转坐标系下建立了三相电压型PWM整流器的数学模型,给出了三相电压型PWM整流器的双闭环控制结构,按此方法确定了电压、电流PI调节器的设计方法。仿真结果表明该方法能使所设计的PWM整流器运行于单位功率因数,输出的直流电压稳定在期望值且具有快速的动态响应,满足了设计要求。     

A Universal Vector Controller for Four-Quadrant Three-Phase Power Converters

Power factor corrected (PFC) rectifiers, active power filters (APFs), static VAR compensators (STATCOM), and grid-connected inverters (GCI) are indispensable elements in distributed generation power systems. PFC rectifiers are essential for load side harmonic and reactive power correction, APFs can suppress the harmonics generated by nonlinear loads or sources, STATCOMs can control the power flow in the grid, while GCIs are the key elements bridging the renewable energy sources and the power grid. Previous theory and experiments have demonstrated that one-cycle control is capable of controlling all above mentioned three-phase converters, featuring excellent performance, simple circuitry, and low cost. This paper further unifies the control key equations for the previously mentioned converters, which results in a universal solution that realizes all these functions with a same controller. The concept has been verified by a 1-kVA prototype and supported by a series of experimental results     

A Model-Based Direct Power Control for Three-Phase Power Converters

The direct power control (DPC) technique has been widely used as a control strategy for three-phase power rectifiers due to its simplicity and good performance. DPC uses the instantaneous active and reactive power to control the power converter. The controller design has been proposed as a direct control with a lookup table and, in recent works, as an indirect control with an inner control loop with proportional-plus-integral controllers for the instantaneous active and reactive power errors. In this paper, a model-based DPC for three-phase power converters is designed, obtaining expressions for the input control signal, which allow the design of an adaptive control law that minimizes the errors introduced by parameter uncertainties as the smoothing inductor value or the grid frequency. A controller design process, a stability study of the system, and experimental results for a synchronous three-phase power rectifier prototype are presented to validate the proposed controller.     

A General PWM Strategy for Four-Switch Three-Phase Inverters

A general pulsewidth modulation (PWM) method for control of four-switch three-phase inverters is presented. The proposed vector PWM offers a simple method to select three or four vectors that effectively synthesize the desired output voltage, even in presence of voltage oscillations across the two dc-link capacitors. The method utilizes the so called space vector modulation, and includes its scalar version. Different vector combinations are compared. The effect of Wye and delta motor winding connections over the pulse width modulator is also considered. The common mode voltage generated by the four-switch three-phase converter is evaluated and compared to that provided by the standard six-switch three-phase inverter. Simulation and experimental results are presented to demonstrate the feasibility of the proposed approach     

双PWM型变流器协同控制策略仿真研究

为了抑制直流母线电压波动,提高交-直-交变流器的动态性能,需对其采用协调控制策略。本文对现有协调控制策略进行了总结,从功率平衡的角度,研究了交-直-交变流器的静态与动态模型。并在分析异步电动机动态模型的基础上,进行了交-直-交协调控制策略的仿真分析,仿真结果表明,这种控制算法具有直流母线响应速度更快、波动小等特点。     

A Novel Three-Phase Reference Sine-Wave Generator for PWM Inverters

A hybrid circuit for producing a three-phase reference sine wave required with PWM inverters is described in this paper. The principle of the circuit is simple and the implementation of the circuit is easy. The circuit has all the features discussed in the literature. The unit built has, apart from the three-phase sine waves, balanced three-phase square and triangular waves. A high-frequency triangular wave already available in the circuit can be used for the PWM control circuitry. The scheme can easily be extended to generate sine waves of any number of phases.     

A Comparative Study of Zero-Current-Transition PWM Converters

Zero-current-transition pulsewidth-modulation (ZCT-PWM) boost converters are conventional boost converters that use an active auxiliary circuit to turn off the main power switch with zero-current switching; the operation and properties of these converters are the focus of this paper. In this paper, the general operating principles behind all ZCT-PWM converters are reviewed, and the operation and properties of specific converters are discussed. The strengths and weaknesses of each converter are stated, and a new and improved ZCT-PWM boost converter is proposed and discussed. Experimental results obtained from an experimental ZCT-PWM boost converter prototype implemented with several of the auxiliary circuits discussed in this paper are presented, and the results confirm the superior performance of the proposed converter     

不平衡电网条件下三相VSR的建模与仿真

文章对不平衡电网条件下三相VSR进行分析与建模,得出采用开关函数描述的数学模型。为了利于控制系统设计,对三相静止坐标系下的数学模型进行坐标变换,得出两相同步旋转坐标系下的数学模型。针对不平衡电网条件下的三相VSR的功率分析与电流控制指令算法的设计,提出基于正负序同步旋转坐标系三维复空间瞬时功率。通过MATLAB2007a的Simulink仿真平台显示,陷波器能有效滤除不平衡电网电压中的负序分量,交流侧电流基本对称,并实现单位功率因数。仿真结果验证了所建模型的正确性。     

A Microprocessor-Based Synchronization Scheme for Digitally Controlled Three-Phase Thyristor Power Converters

This paper presents a microprocessor-based scheme that generates the necessary synchronization logical signals for three-phase static power converter control systems. The problem of detecting the phase-to-phase voltage zero-crossing in presence of noise generated by thyristor commutations in constant and in variable frequency supplies is discussed, and a microcomputer software solution is proposed.     

Trapezoidal Modulating Signal for Three-Phase PWM Inverter

Trapezoidal wave is suitable for the modulating signal of the microcomputer-based pulsewidth modulation (PWM) inverter for the use of motor drives because the switching patterns can be generated by means of on-line computation. The waveform is changed from a rectangular to a triangular wave.     

基于PWM变换器的新型无源无损软开关

详细分析了一种基于PWM变换器的新型无源无损软开关，并给出了其最优化设计步骤。通过一台满载输出功率为900w的带有该无源无损软开关的Boost变换器验证了其开关管实现零电流开通和零电压关断，并与传统的Boost变换器比较，验证其具有较高的效率。     

PWM开关变换器的建模方法综述

介绍了PWM开关变换器的主要建模方法:状态空间平均法、等效电路法、离散时域法、动态向量法以及等效小参量法,叙述了它们的理论依据,并分析了各自的优缺点。     

三相电压型PWM整流器空间矢量控制研究及仿真分析

以电压空间矢量控制的基本原理和概念为基础,结合Matlab／Simulink软件包构建了三相PWM整流器空间矢量控制系统的仿真模型,并详细给出各模型的具体参数。仿真结果显示,该方法简单,控制精度高,用于三相PWM整流器中具有良好的动、静态性能。     

一种新型软开关三相PWM逆变器拓扑的研究

本文提出了一种三相交流谐振环节软开关逆变器的电路拓扑及其控制方法。该拓扑采用正负斜率交替的锯齿载波．使所有功率开关器件的计通集中征锯齿载波的垂直沿处，在此时启动辅助谐振电路，完成功率开关器件的切换。分析软开关动作模式．并对各模式的过渡过程进行数学解析。对系统进行了仿真，仿真结果表明采用该控制方法能实现逆变器功率开关器件的零电压软开关动作。     

Benchmark Antenna Problems for Evolutionary Optimization Algorithms

A set of antenna-optimization problems is presented that satisfies the necessary requirements to form a test suite useful for measuring and comparing the performance of different evolutionary optimization algorithms (EAs) when they are applied to solve complex electromagnetic problems. The ability of the proposed test suite to find strong and weak points of any EA is illustrated by a complete study of four broadly used evolutionary algorithms carried out with the aid of the new test functions