逆变电源瞬时反馈控制方法的研究

文中对逆变电源各种瞬时值反馈控制方法进行了对比研究,带电感电流内环的电压瞬时值反馈要获得与电容电流内环瞬时值反馈控制的效果,必须引入负载电流前馈;带电压微分内环的逆变电源控制系统与带电容电流内环的逆变电源控制系统相比,在理论上两种控制方案是等同的。     

瞬时值反馈逆变电源研究

逆变电源中传统控制方案存在不足,在这些反馈系统中往往加入积分环节来减小静差,但在实际系统运行的过程中不一定起到了相应的作用。文中介绍了一种基于电容电流内环的输出电压外环瞬时值反馈的逆变电源控制方案;建立系统模型;分析了调节器中积分环节对系统的影响,并通过仿真进行验证。     

基于环流反馈的逆变器并联系统仿真分析

对于逆变器并联系统,各模块输出电压之间如若存在幅度和相位上的差异,势必会产生在模块间流动的环流。文中在逆变器并联系统环流产生机理分析的基础上,对是否加入环流反馈时系统的阻抗和稳定性进行了分析,证明采用环流反馈可以增大系统环流阻抗,在保持输出电压不变的前提下有效地减小了环流,最后通过Simulink仿真证明此方式的有效性。     

一种快速瞬态响应无输出电容LDO的研究与设计

设计了一种基于自适应偏置放大器的具有快速瞬态响应的无输出电容LDO.自适应偏置放大器在发生负载瞬态响应时能够调节自身偏置电流以提供较大的输出电流来增加摆率;瞬态响应提升电路通过减小负载电容充放电电流而减小了输出电压的建立时间;通过并联反馈补偿来提高环路的稳定性.仿真结果表明,所设计的无输出电容LDO最大输出电流200mA,最小跌落电压200mV,静态电流仅16μA,全负载正负阶跃变化响应时间分别为2.5μs和3.5μs.     

反馈电路的分类与判别

电子线路中的反馈,是指将线路系统输出端的信号取出一部分送回该系统的输入端,构成反馈环路。反馈的极性有正反馈和负反馈。反馈的作用有直流反馈与交流反馈。反馈的方式有电压并联、电压串联、电流并联、电流串联反馈。     

一种新型UPS无互联线并联下垂特性控制

传统的UPS无互联线并联下垂特性控制是采用频率下垂和幅度下垂来调节输出电压。这种控制方法虽然是有效的，但是它容易导致系统正反馈。文中提出了一种基于神经网络解耦控制的下垂特性控制方案。这种新的控制方法能有效地克服传统下垂特性控制的局限性。由仿真结果得，该方案下逆变电源均分负载电流的效果好，而且系统动态响应性能高。     

并联型有源电力滤波器直流侧电压柔性控制策略

针对并联型有源电力滤波器的直流侧电压控制特点,提出了一种对直流侧电压进行柔性控制的并联型有源电力滤波器控制策略。该策略中,在直流侧电压控制部分引入反馈低通滤波器,削弱直流侧固有谐波对输出电流控制的影响;在电流控制的输出部分通过增加直流侧电压前馈系数,抵制在变换桥中可能引入的直流侧电压谐波影响。仿真结果表明直流侧电压柔性控制策略能够降低APF系统补偿后的电源电流总谐波畸变率,从而改善并联型有源电力滤波器的谐波补偿性能。     

互阻抗放大器的设计

大多数工程师都知道,设计互阻抗放大器需要一个足够大的电阻,以把输入电流转换成一个在合理范围内的输出电压。为了使电路稳定,需要在反馈电阻上并联一个足够大的电容。本文将说明在确保互阻抗放大器具有尽可能大的带宽以及保证系统稳定的情况下,如何计算反馈电容值。     

一种直流并联电源的输出纹波抑制技术研究

直流电源可以通过并联有效提高输出电压电流的可靠性,但在提高可靠性的同时,也会存在输出电流电压纹波相较单个直流电源增加的问题,针对此问题,文中以直流降压斩波电路为例,对其在并联工作模式下输出电压与电流纹波进行分析,提出采用双脉宽调制方式对输出的电流电压纹波进行抑制,并给出了理论抑制效果计算值,最后通过实验,对工作在该调制模式下的并联直流电源输出电流电压纹波进行了数据采集,通过与常规单脉宽调制方式下的输出纹波进行比较,结果表明双脉宽调制方式可有效对并联电源的输出电流电压纹波进行抑制。     

反馈放大电路信号单向传递的条件

在反馈电路中,信号的逆向传递可能导致设计失败,要得到可靠的输出信号,需要进行精确的阻抗匹配计算和分析。在此采用等效变换的方法,对各类反馈电路进行等效变换,根据反馈控制模型和电路网络理论详细分析了电压并联反馈、电流串联反馈、电压串联反馈和电流并联反馈四种反馈放大电路信号单向传递的条件。     

CO2激光器高压高频充电电源的应用研究

为改善现有CO2激光器工频充电电源体积、重量大、充电精度低等缺点,开展高频高压充电电源的研究,研制一台采用全桥逆变结构和串联谐振软开关电路、输出电压36 kV、输出平均充电功率为10 kJ／s的高频高压充电电源。该电源系统采用三相380 VAC作为供电系统,大功率智能功率模块（IPM）作为全桥逆变电路,逆变交流信号经串联谐振电路及高频脉冲变压器得到高压脉冲信号,高压脉冲经整流给负载电容充电;同时,电源应用电压、电流双闭环控制系统,输出电压、电流经采样及放大反馈到电源控制芯片SG3525,SG3525通过判断反馈信号的大小控制输出PWM驱动信号的占空比。实验结果表明：电源输出电压36 kV,输出平均功率为10.8 kJ／s,充电效率为0.82,电源纹波系数为1％。电源系统保证了激光器稳定工作在30 Hz条件下。     

基于前馈加双环控制的逆变电源设计

介绍一种前馈加双环控制技术的逆变器,它的双环控制包括一个电容电流内环控制和一个瞬时电压外环控制。通过分析该控制策略的工作原理,应用DSP TM320F2812对控制系统进行了设计。试验结果显示逆变器有很好的正弦波输出波形,快速的动态响应,优良的负载特性和高精度的输出电压。     

单相光伏逆变器的改进型并网控制方法

单相光伏并网逆变器通常采用双闭环控制和电网电压前馈控制的策略,其中双闭环的外电压环为采用PI恒压控制逆变前直流侧电压,分析比较了准比例谐振调节和PI调节两种电流内环的输出外特性,通过对电流内环采用准比例谐振控制的控制系统进行分析建模,建立了逆变器的单相并网仿真模型。仿真结果显示电流内环采用准比例谐振控制能实现并网电流的无静态误差控制,并减小电网频率偏移对并网电流的影响。仿真及实验得到的输出正弦电流波形良好,基于该并网控制策略的光伏逆变器能以高功率因数向电网发电,动态响应快、鲁棒性强、跟踪精度高、并网电流的THD明显优于传统方法,从而验证了改进后模型的可行性和实用性。     

A novel control scheme for the multilevel rectifier/inverter

A novel three-level pulsewidth modulation (PWM) rectifier/inverter is proposed: this single-phase three-level rectifier with power factor correction and current harmonic reduction is proposed to improve power quality. A three-phase three-level neutral point clamped (NPC) inverter is adopted to reduce the harmonic content of the inverter output voltages and currents. In the adopted rectifier, a switching mode rectifier with two AC power switches is adopted to draw a sinusoidal line current in phase with mains voltage. The switching functions of the power switches are based on a look-up table. To achieve a balanced DC-link capacitor voltage, a capacitor voltage compensator is employed. In the NPC inverter, the three-level PWM techniques based on the sine-triangle PWM and space vector modulation are used to reduce the voltage harmonics and to drive an induction motor. The advantages of the adopted th-ree-level rectifier/inverter are (1) the blocking voltage of power devices (T1, T2, S_a1-S_c4) is clamped to half of the DC-link voltage, (2) low conduction loss with low conduction resistance due to low voltage stress, (3) low electromagnetic interference, and (4) low voltage harmonics in the inverter output. Based on the proposed control strategy, the rectifier can draw a high power factor line current and achieve two balance capacitor voltages. The current harmonics generated from the adopted rectifier can meet the international requirements. Finally, the proposed control algorithm is illustrated through experimental results based on the laboratory prototype.     

新能源并网逆变器入网电流通用控制

太阳能电池、风力发电,以及燃料电池等新能源发电中的并网逆变器技术的研究已经成为一个重要的研究方向。为了消除逆变器输出电流中的高次谐波,通常采用LCL滤波器对谐波进行处理。但是LCL滤波器是无阻尼三阶系统,使输出容易产生谐振,因此逆变器电流控制器的研究成为了研究的热点。本文就当今使用较为热门的电容电流内环、入网电流外环的双闭环控制策略进行分析,使用MATLAB／Simulink进行仿真,并在仿真中加入功率因数（PF）的验证。从仿真结果看出该方案可有效地避免入网电流谐振,入网电流能很好地跟踪并网电压,达到同频同相,功率因数约等于1,并且在FFT谐波分析中达到满意的效果。     

Suppression of line voltage related distortion in current controlled grid connected inverters

The influence of selected control strategies on the level of low-order current harmonic distortion generated by an inverter connected to a distorted grid is investigated through a combination of theoretical and experimental studies. A detailed theoretical analysis, based on the concept of harmonic impedance, establishes the suitability of inductor current feedback versus output current feedback with respect to inverter power quality. Experimental results, obtained from a purpose-built 500-W, three-level, half-bridge inverter with an L-C-L output filter, verify the efficacy of inductor current as the feedback variable, yielding an output current total harmonic distortion (THD) some 29% lower than that achieved using output current feedback. A feed-forward grid voltage disturbance rejection scheme is proposed as a means to further reduce the level of low-order current harmonic distortion. Results obtained from an inverter with inductor current feedback and optimized feed-forward disturbance rejection show a THD of just 3% at full-load, representing an improvement of some 53% on the same inverter with output current feedback and no feed-forward compensation. Significant improvements in THD were also achieved across the entire load range. It is concluded that the use of inductor current feedback and feed-forward voltage disturbance rejection represent cost-effect mechanisms for achieving improved output current quality.     

Microprocessor based robust digital control for UPS withthree-phase PWM inverter

This paper describes a novel method of robust (insensitive to system parameter variations and load current changes) and fast digital control for an uninterruptible power supply (UPS) with a three-phase PWM inverter. The purpose of this paper is to propose a method by which characteristics better than those by conventional methods are obtained using an algorithm simpler than that of conventional methods. The experiments show that the purpose is achieved and the proposed method offers a total harmonic distortion of 0.6% of the output voltage waveform at a full nonlinear load. The analysis shows that the stability of the method is sufficient. Three features of the method are: (a) a capacitor current observer for stabilization and a disturbance observer for robustness are used to compensate the time lag by the computation and the disturbances, in a minor loop of the capacitor current through an inductor-capacitor filter of the inverter; (b) new models of the inverter and the disturbances are established to simplify these observers; and (c) the output voltage control loop can be designed easily and exactly because the minor loop realizes a rapid and robust control of the current     

A series-resonant DC/AC inverter for impedance-load drives

A DC/AC inverter without cycloconversion configured by a half-bridge series-resonant inversion (HB-SRI) circuit is presented. The inverter is a series resonator with two auxiliary switches in shunt with the resonant capacitor so as to configure adaptively the output current suitable for impedance load. The output sinusoidal voltage is synthesized by a series of equal-amplitude quasisinusoidal pulses (QSPs) and the corresponding current is formed by unequal QSPs and adaptively phase-shifts to the impedance load. The presented HB-SRI is operated by frequency modulation with a constant-on time control. System modeling and waveform syntheses for the output sinusoidal voltage and its current are clearly derived, A typical design example of a 500 W HB-SRI inverter is examined to assess the system performance. The power efficiency is over 90% when the inverter output is above 200 W. The total harmonic distortions (THDs) for various impedance loads are all within 6%