一种超级电容储能的双向逆变电路及其控制策略

为解决数控机床加工中意外掉电退刀、伺服单元外接制动电阻产生能耗等问题,提出了一种超级电容储能的双向逆变电路,使得伺服系统在突然断电状态下,储能模块能够继续短时地给数控机床系统供电,完成断电回退的功能。该电路可以提供更高的输出电压和占空比,且在应用中可以取消伺服单元外接制动电阻而将制动能量循环利用,同时提出了相应的控制策略。该电路包括Buck/Boost电路、信号采样电路、PWM逻辑控制电路和互锁驱动电路,通过调节两路互为180°的PWM波占空比及充、放电信号来实现升、降压闭环控制,从而完成能量的双向传递。该拓扑简单、高效,性能稳定,以最少的功率器件实现大功率转换及输出。最后,实验波形验证了所提方案的可靠性。     

东芝三菱高压变频器在电厂600MW发电机组给水泵上的应用

本文简单介绍了大功率高压变频器在600MW机组电厂给水泵的应用。也简要介绍了该变频器的特点,以及在EPC项目中重点解决的一些难题。整个工程采用EPC方式,包括液力耦合器的改造和空水冷却器。     

具有软开关功能的三相谐振直流环节逆变器

为实现三相逆变器节能运行,提出一种具有软开关功能的三相谐振直流环节逆变器.直流侧的辅助谐振电路将参与换流过程,使直流环节电压在桥臂上的主开关动作之前变化到零,主开关能完成零电压软切换动作,通过降低开关损耗来实现逆变器节能运行.分析了1个开关周期内的电路工作流程.实验结果显示开关器件动作时处于软切换.因此,该辅助谐振电路结构对于研发节能型三相逆变器具有参考价值.     

A critical analysis of Z-source converters considering the effects of internal resistances

Nowadays Z-source networks are the most promising power converter networks that cover almost all electric power conversion (dc–dc, dc–ac, ac–dc and ac–ac) applications. However, the controller design is critical for Z-source converter (ZSC) due to the presence right-half-plane zero (RHPZ) in the control-to-capacitor-voltage transfer function. This RHPZ exhibits non-minimum phase undershoot in the capacitor voltage and also in the dc-link voltage waveforms. A perfect small-signal model is required to predict locations of the RHP zero and its dynamics. This paper contributes towards the small-signal analysis of ZSC under continuous conduction mode considering the parasitic resistance of the inductor, equivalent series resistance of the capacitor, internal resistances of active switch and forward voltage drop of the diode. The maximum allowable value of shoot-through duty ratio (STDR) and voltage gain for different values of the internal resistance and load resistance are discussed in this paper. The accuracy of the developed small-signal average model is compared with detailed circuit model in MATLAB/SIMULINK. Finally, the steady-state simulation results of ZSC are validated with hardware results.     

Enhanced power quality based single phase photovoltaic distributed generation system

This article presents a novel control strategy for a 1-? 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform.     

LCL滤波并网逆变器的控制策略

本文关于LCL滤波并网逆变器的控制研究,研究了最合适的关于LCL滤波并网逆变器的控制方案。在开关的频率保持在同一个水准的时候在一个开关的周期内,研究组进行了对于逆变器的多次采样研究,有效地减少了在数字技术下控制的延时情况,提高了系统中本来的控制范围与延时时间。在定量分析的方式下,小组中的研究人员已经证实的开展了对LCL滤波并网逆变器本质性能的研究,分析了它的优势性能。与常规有源阻尼多环结构相比,该方案采用电流单环控制即可实现系统稳定,无需增加传感器,从而简化了控制结构。在最后,研究人员也同时通过了实验来对LCL滤波并网逆变器的性能进行了验证分析。     

一种新的波导带通滤波器的优化设计方法

基于全波分析法、改进的阻抗倒置器模型和自适应微种群遗传算法,提出了一种设计波导带通滤波器的快速精确方法。该方法通过结合改进的阻抗倒置器模型和全波分析法,能够在设计带通滤波器,特别是带宽较宽的情况下获得较为精确的初值。在此基础上,通过采用自适应的微种群遗传算法对初值进行优化。该方法能在保证数值精确性的基础上,以较小的群体规模和较少的遗传代数获得比其他优化方法更好的回波损耗以及通带微调功能;在多优化变量的波导带通滤波器问题上,提出的混合方法优于传统的优化设计方法或其他遗传算法。     

Novel Cascaded Z-Source Neutral Point Clamped Inverter

Z-source Neutral point clamped (NPC) inverter inherits the advantages of Z-source inverter,which can buck-boost energy and allow the shoot-through states.At the same time,Z-source NPC inverter has high running efficiency and less harmonic content.Hence,it can be widely used in motor drives and fuel cell applications.When increasing the modulation index,one can only get smaller shoot through value in Z-source NPC inverter,therefore the output voltage of the inverter can not be boosted very high.In this paper,a novel cascaded Z-source neutral point clamped inverter is proposed by cascading two Z-source networks in series.An Alternative phase opposition disposition (APOD) carrier-based modulator is applied to control the proposed Z-source inverter.To confirm the operating principle of the new Z-source NPC inverter,a generic APOD carrier-based modulator for the cascaded Z-source NPC Inverter under Matlab/Sinmulink is built.The simulation results show that the boost factor has been increased from 1/(1-2D) for the traditional Z source NPC inverter to 1/(1-4D) for the proposed cascaded Z-source NPC inverter.A prototype of the cascaded Z-source NPC inverter has been set up.The experimental results verify that the new topology can increase the boost factor and expand the voltage regulation range of the inverter.     

RTD-HBT高速低功耗环形振荡器的分析

RTD与HBT是高频高速器件,共振隧穿二极管-异质结晶体管(RTD-HBT)环形振荡器有很好的应用前景.详细介绍了RTD-HBT高速低功耗环形振荡器的工作原理,建立了RTD,HBT及RTD-HBT环形振荡器的等效电路模型,并对RTD-HBT环形振荡器用Pspice模拟软件进行了电路模拟.模拟结果与预期结果一致,有助于指导该电路的设计.