倍流整流方式ZVS PWM全桥变换器的控制系统设计

采用了一种将峰值电流控制模式与移相软开关技术相结合的移相控制全桥(FB)ZVS—PWM变换器。阐述了峰值电流控制的各项特点，给出了实际斜坡补偿电路及设计方法。仿真结果验证了该方案的可行性。     

低压大电流大功率软开关全桥变换器拓扑结构分析

分析研究了低压大电流全桥变换器电路拓扑结构。分别介绍了功率变压器初级移相控制零电压(ZVS)PWM和移相控制零电压零电流(ZVZCS)PWM软开关全桥变换器主电路拓扑结构,以及功率变压器次级适宜采用的不同电路拓扑形式,并对其优缺点进行了对比分析。文中简要说明了在变换器输入级加入功率因数校正环节的必要性。     

移相全桥DC/DC变换器ZVS控制的研究与实现

在中大功率应用场合,零电压开关控制的移相全桥PWM DC/DC变换器近年来受到越来越多的关注,并被广泛地应用于工程中,其可靠性越来越受到人们的重视。文章详细介绍了这种变换器的ZVS控制原理及其实现中存在的主要问题,利用电源仿真软件SIMetrix对变换器进行了仿真,最后根据仿真参数结果设计了移相控制零电压开关PWMDC/DC全桥变换器样机,验证了该研究的正确性。     

双有源桥双向DC-DC变换器的多模式控制

双有源桥(Dual Active Bridge,DAB)双向DC-DC变换器能够双向传输功率,实现零电压开关(ZVS),且功率密度高,能够很好地应用到电力自动化设备中。文中详细介绍了DAB变换器的三种常见的控制方式,分别是移相控制、单PWM和双PWM控制。针对变换器存在低载运行时环路电流大、零电压开关范围受限制的缺点,提出一种多模式控制,拓宽了零电压开关的范围,降低了电流的有效值和峰值,使变换器效率提高。最后用MATLAB软件进行仿真,验证了方案的可行性。     

LLC谐振变换器PFM+PWM混合控制方法研究

LLC谐振变换器在特定的谐振腔参数设计及电路寄生参数的影响下,通常会出现高频段频率对增益的调节作用大大减弱甚至失去调节作用的现象,造成其在宽范围输出电压应用场合的设计困难,在数字化控制电源中,PFM结合移相控制或PWM控制是有效的解决途径。分析了特定条件下LLC谐振变换器采用单一的PFM或PWM控制时存在的问题,提出了有效的PFM+PWM混合控制设计方法,并以2000W宽范围输出电压LLC谐振变换器设计实践为例进行了实验验证。     

PS—FB—ZVSPWM DC／DC变换器中副边占空比丢失问题的研究

移相控制ZVSPWM DC／DC全桥变换器是变换器的一个研究热点,诸如高性能、高效率、低噪声、低污染等理论问题急待研究。副边占空比丢失是移相全桥PWM DC／DC变换器中的一个重要现象,文章以移相全桥ZVSPWM DC／IX;变换器电路模型为基础,结合变换器谐振电路的工作特点,对变换器副边占空比丢失的原因进行了详尽的分析,阐述了全桥变换器滞后臂比超前臂更难实现ZVS的原因,最终得到了移相全桥ZVSPWM DC／DC变换器死区时间和工作频率的设置条件与解决副边占空比丢失的措施。     

双向全桥DC-DC变换器的优化控制研究与实现

双向全桥DC-DC变换器是固态变压器的重要组成部分,双向全桥DC-DC变换器采用移相的控制方式,但简单的单移相控制方式下存在较大的回流功率,根据相关文献里提到的双重移相控制原理分析内移相占空比与传输功率和回流功率的关系。针对减小甚至消除回流功率这一目标,对内移相占空比进行优化计算。最后搭建实验样机,将单移相控制和优化控制进行实验对比,实验结果证实该优化方法正确性和可行性,具有一定应用价值。     

移相控制ZVC PWM DC／DC全桥变换器的设计

就谐振软开关技术在DC／DC变换器中广泛应用,介绍了一种移相控制ZVC PWM DC／DC全桥变换器的设计方法,其包括功率开关管参数选取、主变压器设计、换流电感设计、缓冲电容选择及参数验算等。     

基于PWM AC-AC变换的电压补偿器设计

介绍在配电系统中一种新型的电压补偿器,即在自耦变压器中集成PWM AC-AC变换器(每相4个IGBT元件)。其电压补偿控制模块根据系统控制对象的特点,选取数字化控制芯片TMS320LF2407,设计了基于DSP的PWM实现方式。在正常工作状况下,PWM变换器工作在旁路方式,电源功率直接传输给负荷,自耦变压器只吸收励磁电流;而当电压降低时,变换器将电压迭加(补偿)上去,以保持负荷端电压为额定值,同时通过自耦变压器增加一定的输出功率。在设计中没有使用诸如成组电容器/电感等这些储能元件,造价低,响应速度快。     

基于模糊PI的复合电源双向DC-DC变换器研究

针对电动汽车复合电源中基于传统PI的双重移相控制双有源桥DC-DC变换器在负载和输入电压出现扰动时存在动态响应速度慢和超调量大的缺陷,通过有机结合传统PI和模糊逻辑控制,提出基于模糊PI的双重移相控制策略。首先分析双重移相控制下变换器的具体工作过程和功率特性,然后阐述基于模糊PI的双重移相控制实现方式,并详细说明模糊PI控制器的设计方法。最后通过实验论证所提出的控制策略可以有效提高变换器的动态响应速度和鲁棒性,减小输出电压波动。     

Low-harmonic GTO converter for fundamental power factorcompensation

A low-harmonic GTO (gate turn-off) thyristor AC-to-DC converter with line current lead-lag phase shift control ability is proposed and analyzed. The converter can be used either as a low-harmonic GTO-controlled rectifier or a fundamental input power factor compensator in a power supply system. The effect of PWM (pulse width modulation) current phase number on the harmonic contents and converter output voltage control range is investigated. Lower order input current harmonics are eliminated over a wide range, using a specially designed PWM current pattern. The effect of the PWM current pulse number on the power factor compensation characteristic is investigated     

移相全桥软开关变换器的研究和设计

DC/DC变换器主要向着高效率、高功率密度、高质量输出和高可靠性方向发展.移相全桥软开关变换器的研究在这方面也显得较为突出.本文主要针对变换器的性能进行研究,设计一种能够实现升压的高效隔离DC-DC变换器,并使之广泛应用.     

A new control strategy to improve the performance of a PWM AC to DCconverter under unbalanced operating conditions

Abnormal harmonics of significant magnitude are generated at the output and input terminals of a PWM (pulse-width-modulated) AC-to-DC power converter under unbalanced operating conditions. A new control strategy is presented to selectively cancel the generated lower-order abnormal harmonics at the output and input terminals and thereby to preserve the high-performance features of a PWM AC-to-DC power converter. The proposed technique essentially involves computing the sequence components of the unbalanced input supply and suitably counter-unbalances the PWM gating signals of the power converter switches to cancel the generated abnormal harmonics. The technique is essentially a feedforward approach and is suitable for higher-power GTO (gate turn-off thyristor) type PWM AC-to-DC power converters. A procedure for implementing this technique in real time is discussed. Selected results are verified experimentally on a prototype PWM AC-to-DC power converter     

PWM半桥变换器电路仿真

随着电力电子技术的迅速发展,PWM型DC-DC变换器的应用日益广泛。如今,高性能、高效率、小型化和轻量化越来越成为各类DC-DC变换器追求的目标。文中优选电路结构简单、容易控制的半桥电路作为直直变换拓扑,在剖析了脉宽调制对称半桥变换器工作原理及特性后,设计出270 V直流输入、360 V直流输出、输出功率为500 W变换器的相关参数。切实了解SG1525芯片脉冲产生原理后,设计出控制电路参数,从而搭建出完整的闭环系统。详尽分析了所得出仿真结果,并以此验证了理论分析和工程设计的正确性。     

H桥级联多电平逆变器相移SVPWM技术的研究

载波相移SPWM调制法是级联型逆变器的主流控制方法,其等效载波频率高、谐波特性好、功率单元之间输出功率平衡。而空间矢量法谐波特性好、电压利用率高、控制方法简单便于数字实现。文中针对H桥级联型多电平逆变器的结构特点,综合采用载波移相SPWM法和空间矢量法,并用一种新的空间矢量算法取代传统的方法。该算法中无需三角函数和无理数计算,计算过程非常简单,节约了计算时间,结果更为准确。最后通过系统仿真验证该算法的正确性和有效性。     

Output ripple analysis of switching DC-DC converters

State space averaging methods are used to derive time-invariant models that bound the envelope of trajectories of pulsewidth modulated (PWM) dc-dc converters. The results are compared to conventional averaging methods used in power electronics, and it is shown that, at times, designing a dc-dc converter based on the averaged output of a converter can be ineffective because peak output values sometimes significantly deviate from the averaged output. This paper attempts to quantify this deviation by using both small-signal transfer functions and nonlinear models to model the maximum and minimum values of outputs of PWM converters. Issues in simulation and control loop design are also mentioned.     

DC-side shunt-active power filter for phase-controlled magnet-loadpower supplies

Phase-controlled thyristor rectifiers are still the preferred choice in high-power AC/DC converters. This paper shows that their steady-state and dynamic performance can be greatly enhanced for applications requiring high-precision fast-response performance by means of a hybrid structure using a shunt pulse-width modulation (PWM) active filter. In this hybrid structure, the rectifier is designed to handle the bulk of the output power, whereas the PWM converter is only used for harmonic cancellation and current-error compensation under transient conditions. This results in a small power rating for the shunt-active filter. A suitable control scheme is proposed and implemented in this paper for the rectifier and PWM converter. Experimental results are provided to validate the proposed concept     

Optimal PWM Control of Switched-Capacitor DC–DC Power Converters via Model Transformation and Enhancing Control Techniques

This paper presents an efficient and effective method for an optimal pulsewidth-modulated (PWM) control of switched-capacitor dc-dc power converters. Optimal switching instants are determined based on minimizing the output ripple magnitude, the output leakage voltage and the sensitivity of the output load voltage with respect to both the input voltage and the load resistance. This optimal PWM control strategy has several advantages over conventional PWM control strategies: 1) it does not involve a linearization, so a large-signal analysis is performed; and 2) it guarantees the optimality. The problem is solved via both the model transformation and the optimal enhancing control techniques. A practical example of the PWM control of a switched-capacitor dc-dc power converter is presented.     

PWM-controlled SRC with inductive output filter at constantswitching frequency

By using the PWM control scheme in the series resonant power converter (SRC) with inductive output filter, the converter can be operated at a constant frequency. This converter has lower switching loss than the PWM converter and better control characteristics than the ordinary SRC. Since the peak current in the present converter equals the load current, it has the lowest possible peak current stress among converters. The analysis and the performance characteristics of the converter operating at a constant switching frequency are presented. Experimental results are given to confirm the analytical work     

A hybrid structure using phase-controlled rectifiers andhigh-frequency converters for magnet-load power supplies

Thyristor rectifiers are still the preferred choice for large magnet power supplies. However, large harmonic voltages, resulting in large current ripple, and slow dynamic response are major drawbacks of these converters. This paper presents a topology and a control technique for hybrid large-power high-precision magnet power supplies. The system consists of a phase controlled rectifier connected in series with a high-frequency PWM converter. The rectifier is designed to handle the main output power and the PWM converter is used only for harmonics cancellation and error compensation. A feedforward control scheme is proposed to ensure that the desired power sharing is maintained during both the steady state and transient operations. The operating principles of the proposed structure are discussed in the paper, and the results from a 1 kVA experimental setup are provided to validate the proposed topology