峰值电流模式斜坡补偿电路研究

针对峰值电流控制模式变换器的不稳定性问题,分析了斜坡补偿的基本原理和峰值电流控制电路的稳定性原理.主要介绍了由射极跟随器构成的斜坡补偿电路及其参数设计,用以实现在大范围调整占空比时变换器电路的稳定性.以采用峰值电流控制模式的全桥移相变换器为设计实例来设计补偿电路参数,并通过电路实验获得了良好的补偿信号和稳定的变换器控制性能,由此证明了该设计方法的可行性.     

Sliding mode control with integral augmented sliding surface: design and experimental application to an electromechanical system

In this study, an integral augmented sliding mode control (SMC + I) has been proposed to improve control performance of systems. Stability of the closed-loop system is guaranteed in the sense of Lyapunov stability theorem. The effectiveness of the control solution is established by the stability analysis of the closed-loop system dynamics. The proposed controller is adopted to control speed of an electromechanical system. The experimental set-up reflects the emphasis on the practicability of the proposed sliding mode controller. The experimental results are presented and compared with the results obtained from conventional sliding mode control and Proportional + Integral + Derivative (PID) control. The experimental results verify that the proposed controller provides favorable tracking performance, faster and smoother speed regulation with regard to parameter variations and disturbances. The present study shows that the proposed controller, with its straightforward solution, is easily applicable to industrial problems and an alternative to conventional PID and sliding mode controllers.     

单电感双输出Boost变换器的复合控制方案

为减小单电感双输出Boost变换器的交叉调节,提出一种复合控制方案。建立变换器仿射非线性数学模型,基于微分几何理论证明所建模型满足精确反馈线性化条件,构造出相应输出函数实现系统的线性化和解耦,进而分别为线性系统设计内模控制器和状态反馈控制器,并对满足控制系统稳定要求的反馈系数选取进行分析。与现有控制方法进行仿真比较,结果表明,所提控制方案具有更好的动态调节特性、更优的控制性能和更小的交叉调节。实验结果进一步验证了所提控制方案的可行性。     

三电平直流变换器混杂系统建模与控制

建立了三电平直流变换器的混杂自动机模型,并提出了相应的闭环控制算法,算法核心是使系统进入周期循环稳定的工作中并对输出电压进行调节,能够同时满足电感电流连续模式和不连续模式,具有宽负载范围。将输出电压稳压调节问题转化为离散状态转换条件选择问题,推导了离散状态转换条件。使用Matlab/Simulink中的状态流程图实现了基于混杂自动机的三电平直流变换器控制系统,并进行了详细的仿真以检验闭环控制算法的正确性。仿真结果表明,三电平直流变换器在4种工作模式下稳态性能均良好,模式切换过程中动态响应快超调小。     

基于逆系统理论的VSC-HVDC新型控制

在讨论电压源型高压直流输电(VSC-HVDC)的控制策略中,根据所给出的拓扑结构,建立三相静止系统下的数学模型;再根据控制需要,通过派克矩阵,将VSC-HVDC转换为dq0旋转坐标下的数学模型;通过逆系统理论,将非线性VSC-HVDC系统强制线性化。同时,为了实现直流输电系统有功和无功的解耦控制,选择直流电流和换流站交流输入输出电流作为反馈来设计相应的控制器,并采用李亚普诺夫间接法证明了所提出的控制策略下VSC-HVDC闭环非线性系统的稳定性。计算机数值仿真显示,大扰动下的系统动态响应特性较好,可实现无功、有功的解耦控制,且具有一定的鲁棒性。     

基于CPLD的双级矩阵变换器研究与实现

提出了一种完全基于CPLD(复杂可编程逻辑器件)的双级矩阵变换器的实现方案.该方案摒弃了常规的采用DSP(数字信号处理器)计算占空比、CPLD进行调制的思路,将调制部分的占空比计算也完全集成到CPLD内部,同时采用了状态机输出整流逆变开关状态.实验结果表明了这种方案的可行性,为日后生产双级矩阵变换器的专业集成芯片及工业化打下了基础.     

Adaptive saturated finite‐time control algorithm for buck‐type DC‐DC converter systems

To enhance the convergent rate and robustness of buck‐type DC‐DC converter system, a new finite‐time voltage regulation control algorithm is proposed in this paper. First, an average state space‐based model is analyzed, which considers both the parameters uncertainties and the variations of load and input voltage. By using saturation finite‐time control theory, at the first step, in the absence of disturbance, a new fast voltage regulation control algorithm is designed, which can guarantee that the output voltage converges to the reference voltage in a finite time. Because the saturation constraint is considered during the controller design, the duty ratio function of the converter satisfies the constraint between 0 and 1. Second, in the presence of disturbance, a finite‐time convergent disturbance observer is designed to estimate the unknown disturbances in a finite time. Finally, a disturbance observer‐based finite‐time voltage regulation control algorithm is developed. Compared with PI (Proportional‐Integral) control algorithm, circuit simulations show that the proposed algorithm has a faster regulation performance and stronger robustness performance on disturbance rejection.     

桥式直接交交斩波变换器及换流策略研究

为解决交流斩波功率变换器中双向全控电力电子开关结构复杂、换流过程繁琐的问题,研究了一种新颖的桥式直接交交斩波变换器,并提出了与之相适应的非互补控制换流策略。首先通过改进变换器结构和功率流向,取代了单管组合式双向全控开关的设计方案,简化了多路驱动电路间的隔离设计,使线路分布参数的影响较小,开关器件与驱动电路的一致性好,成本降低。换流策略设计了有源、续流和死区3种工作模式以及多种性质负载条件下的换流路径,消除了输出电压失控区间,且不使用电流极性检测环节。最后设计了功能样机,在多种负载条件下进行了性能测试。实验结果验证了方案的有效性。     

宽输入电压范围下隔离型全桥Boost变换器的高效率控制

本文提出了一族隔离型的Buck-Boost变换器以适应宽输入电压范围并要求隔离的应用场合,以全桥(Full-Bridge,FB)Boost变换器作为其典型电路之一在文中展开分析。考虑占空比的丢失,提出了基于移相控制的双沿调制策略以减小整个输入电压范围内的电感电流脉动。为实现变换器可靠高效的工作,提出了三模式双频控制策略。三模式双频控制策略下,输入电压被分为低、中、高三个电压区间,分别对应于FB-Boost变换器的Boost、FB-Boost和FB三个工作模式。由于FB-Boost模式下电感电流脉动较小,可以降低该模式下Boost单元的开关频率以减小开关损耗,进一步提高效率。为验证设计和控制策略的有效性,搭建了一台输入电压250～500V,输出电压360V,额定功率6kW的原理样机,整个输入电压范围内变换器都具有较高的效率,最高效率为97.2%。     

多电平Buck变换器的解耦控制与闭环设计

多电平直流变换器利用飞跨电容使得输入电压在串连的各开关管之间均分，以降低开关管的电压应力。但该变换器是一个多输入多输出，强耦合的非线性系统。该文建立了多电平Buck变换器的小信号模型，并采用一种新提出的控制方法将该变换器解耦成多个单输入单输出系统，然后进行控制闭环的设计。论文采用三电平Buck变换器进行了实验验证。实验结果表明，所建立的小信号模型是正确的，基于该模型设计的补偿网络可以使变换器具有较快的动态响应。实验结果也表明输出电压闭环和飞跨电容电压闭环是相互解耦的。     

CLLLC谐振变换器变频移相混合控制方法

针对CLLLC谐振变换器存在脉冲频率调制的电压增益范围不足、相移调制的效率较低的问题,提出了一种可同时调节开关管占空比与开关频率的变频移相混合控制方法.该方法可以根据输入电压范围与负载功率变化范围自由切换混合控制模态以实现宽范围软开关与高运行效率,具有极高的调节自由度,且通过移相控制降低了启动时的冲击电流从而实现了软启...     

基于柔性电感的恒频控制LLC谐振变换器

传统LLC谐振变换器采用变频控制,在输入电压变化范围较宽时开关频率变化范围宽,其磁性元件难以优化设计.将LLC谐振变换器中的谐振电感设计为柔性电感,通过改变柔性电感的电感而改变变换器的谐振频率,改变LLC变换器的输出特性,实现宽输入电压、宽负载范围内的恒频调压,进而可以实现变压器、电感、滤波电容等元件的优化设计.首先介...     

Common-duty-ratio control of input-series connected modular DC-DC converters with active input voltage and load-current sharing

This paper proposes a simple control method to achieve active sharing of input voltage and load current among modular converters that are connected in series at the input and in parallel at the output. The input-series connection enables a fully modular power-system architecture, where low voltage and low power modules can be connected in any combination at the input and/or at the output, to realize any given specifications. Further, the input-series connection enables the use of low-voltage MOSFETs that are optimized for very low R/sub DSON/, thus, resulting in lower conduction losses. In the proposed scheme, the duty ratio to all the converter modules connected in input-series and output-parallel (ISOP) configuration is made common. This scheme does not require a dedicated input-voltage or load-current-share controller. It relies on the inherent self-correcting characteristic of the ISOP connection when the duty ratio of all the converters is the same. The proposed scheme is analyzed using the average model of a forward converter. The stability and performance of the scheme are verified through numerical simulation, both in frequency domain and in time domain. The proposed control method is also validated on an experimental prototype ISOP system comprising of two forward converters.     

Two-degrees-of-freedom speed control of resonant mechanical system based on H∞ control theory

In industrial motor drive systems such as those used in industrial plants and robots, a torsional vibration is often generated as a result of the elastic elements present in the torque transmission systems. This vibration makes it difficult to achieve quick speed responses and may result in plant damage. Such systems are simply modeled as two-mass mechanical systems. The H^∞ control theory is applied herein to design a speed controller for the two-mass system. This controller determines closed-loop characteristics, including suppression of torsional vibration, rejection of torque disturbance and robust stability. Moreover, two types of two-degrees-of-freedom control systems, which includes the H^∞ controller, are proposed to improve command response. One is based on the TDOF PI control, in which the PI controller included in the H^∞ controller is rearranged for the TDOF system. Another is based on the model matching feedforward control, in which the prefilter and the feedforward compensator are added to the H^∞ controller. The proposed control system is applied to two types of resonant mechanical systems having different inertia ratio. Several examinations demonstrate that the proposed speed control system is useful for a resonant mechanical system.     

静止变频器分阶段启动控制策略研究

静止变频起动方式作为抽水蓄能机组的主要起动方式,具有启动电流可控,可频繁起动,调速范围宽等优点。转子处于低速状态时,根据机端电压计算出的转速不准确,造成传统的控制方法输出的电磁转矩误差较大。本文首先介绍同步电机静止变频系统的工作原理,进一步提出了一种改进型的静止变频器控制方法。在低速阶段整流电路采用开环控制其触发延迟角,使静止变频器持续提供充足的加速转矩,转子能够按照一定的加速度上升,逆变电路采用前馈控制和反馈控制使直流电流快速上升并维持在一定水平;在高速阶段采用双闭环控制整流电路触发延迟角,逆变电路采用负载换向法实现换向。本文还给出了闭环控制器参数设计方法,提高了直流回路的稳定性以及静止变频系统的动态性能。最后通过仿真验证了该控制策略的正确性和有效性。     

永磁同步电动机的有限时间跟踪控制

针对永磁同步电动机绕组相电流和转速强耦合特性,基于永磁同步电动机精确的数学模型,依据中继切换控制机制和有限时间收敛的终端滑动模态控制机制,研究了永磁同步电动机的有限时间跟踪问题,给出了其终端滑模控制器的设计方案。在所设计的控制作用下,闭环系统将在有限时间内达到平衡状态,保证了闭环系统所有信号的有界性和平衡点的全局稳定性,系统在有限时间内精确地跟踪给定的参考信号。对永磁同步电动机模型进行了数值仿真,结果表明,在所设计的终端滑模控制器作用下,系统的跟踪误差在有限时间内达到零,验证了所提算法的正确和有效性。     

基于三端等效电路模型的FB-ZVZCS变换器控制环路设计方法

为保证平均电流型控制方式下输出宽范围可调电源的全局稳定性,采用新型的三端等效电路模型对系统进行小信号建模,避免了传统平均模型不能预测次谐波振荡的问题。基于该模型给出了比例积分型电流补偿器的设计方法,获得良好的电流控制特性;分析了稳态工作点对系统控制环路设计的影响,给出了适合宽变工作点条件下电压外环的设计方法,在保证全局稳定性的同时,系统能获得更宽的控制带宽;利用该方法对一台最大电流4A、输出电压50~600 V连续可调的FB-ZVZCS变换器进行控制环路设计。实验结果表明,变换器在各稳态工作点具有良好的稳定性和动态特性,验证了设计方法的正确性。     

Small-gain technique-based adaptive fuzzy command filtered control for uncertain nonlinear systems with unmodeled dynamics and disturbances

This article studies the adaptive tracking control problem for a class of uncertain nonlinear systems with unmodeled dynamics and disturbances. First, a fuzzy state observer is established to estimate unmeasurable states. To overcome the problem of calculating explosion caused by the repeated differentiation of the virtual control signals, the command filter with a compensation mechanism is applied to the controller design procedure. Meanwhile, with the help of the fuzzy logic systems and the backstepping technique, an adaptive fuzzy control scheme is proposed, which guarantees that all signals in the closed-loop systems are bounded, and the tracking error can converge to a small region around the origin. Furthermore, the stability of the systems is proven to be input-to-state practically stable based on the small-gain theorem. Finally, a simulation example verifies the effectiveness of the proposed control approach.     

输入串联输出并联变换器的控制器设计及稳定性分析方法

输入串联输出并联(ISOP)变换器具有低电压、电流应力、模块化等优点,在高压至低压的功率变换领域得到广泛的应用。以输入电压平衡作为基本控制思想,结合ISOP变换器的等效双闭环控制框图,提出了相应的控制器设计方法及稳定性分析方法,在简化了控制器设计流程的同时提高了稳定性分析的可靠性。为了验证该方法的有效性,选取了双向高效能软开关DC-DC变换器——全桥LLC谐振变换器作为研究对象,对其小信号控制模型进行了进一步的推导和完善,并结合实例,完成了控制器的设计和稳定性的分析。最后,搭建了基于全桥LLC谐振变换器的2单元ISOP变换器实验平台,从起机过程、负载切换过程和功率平衡效果3个方面对上述结论进行了实验验证。