Fast‐scale bifurcation in power‐factor‐correction buck‐boost converters and effects of incompatible periodicities

In this paper, we derive the discrete‐time model for the power‐factor‐correction (PFC) buck‐boost converter in terms of a stroboscopic switching map. Fast‐scale instability is analysed through a fold diagram, which exposes the periodicity of the operation as well as the locations of the critical phase angles of the line voltage at which instability begins to occur along a half‐line cycle. The asymmetrical locations of the critical phase angles along a half‐line cycle is explained in terms of ‘under‐developed’ bifurcation. Border collision bifurcations are observed and analysed in detail. Copyright © 2006 John Wiley & Sons, Ltd.     

基于Buck电路的BLDCM调速系统设计

为了获得转速平稳、调节快速的无刷直流电机(BLDCM)输出,对BLDCM控制和驱动系统进行了设计。分析了BLDCM的运行原理和转矩波动原因,并采用Buck电路直接驱动解决了转矩波动的问题。针对传统PID调速慢、精度低以及参数调节困难等问题,采用了BP神经网络对PID进行参数调节。在MATLAB/Simulink仿真平台上搭建了系统的各个模块并进行仿真。结果表明,所设计的系统调节速度快,控制过程中超调小,转速平稳,转矩波动减小。     

基于FPGA的静止电压稳定优化器设计

基于FPGA设计的Buck-Boost型静止电压稳定优化器,直接串联于市电与敏感负荷之间,当供电电压发生电压骤升或骤降时,可快速稳定电压,确保敏感负荷不受影响;采用前端整流装置代替固定储能装置可获取更长的故障穿越时间,采用单同步旋转坐标系软件锁相环(SSR F-SPLL)技术实现电网电压同步,而采用电压双闭环控制技术改善了系统的响应速度:试验结果表明,该装置能快速稳定电压骤升骤降,并能较好地抑制谐波.     

A portable multifunctional power box

In this study, we used a microcontroller to provide and control power to multiple sources using the highly efficient energy storage provided by the direct current (DC) bus of a lithium iron phosphate (LiFePO₄) battery. Through multiple loops, high-efficiency buck and boost conversion, and DC-to-alternating current (AC) conversion, the power box can quickly and simultaneously provide three sets of voltage outputs, 5-V DC, 19–22-V DC, and 110-V AC, to different electronic devices. Multiple sets of conversion output voltages were achieved using multiple sets of conversion circuits, in parallel to the DC bus. Compared with a single conversion output voltage, the multiple sets of conversion output voltages from the energy storage battery had a higher practicability. For a single output voltage, the battery provided a suitable voltage to different electric devices via a substage converter, thus lowering the overall conversion efficiency. For practical applications such as camping, blackouts, long journeys, emergencies, and rescues, the multiple sets of converted voltage outputs offer substantial functional convenience. For safety control, we used a single-chip controller to quickly detect various overcurrent situations.     

Design and optimization of buck and double buck converters by means of geometric programming

This paper describes a new method for determining the optimal components values and switching frequencies of buck DC–DC converters. First, we revisit some concepts of the optimization technique named geometric programming. Then, we observe that the problem of converter designing can be modeled by means of an objective function and certain constraints which can be written in a specific form known as the posynomial form. The constraints involve expressions that depend on magnitudes such as efficiency, bandwidth, and current and voltage ripples.     

基于Buck拓扑全桥逆变器主电路的研究

高频开关电源随着开关频率的提高,开关损耗成为影响电源效率的主要因素。笔者在探讨开关电源软开关实现技术的基础上提出了Buck拓扑的高频电源SCR全桥谐振逆变器主电路模型,同时给出了其控制策略。通过逆变器主电路模型主要工作点仿真波形分析,证明了该Buck拓扑的SCR全桥谐振逆变器的可行性。该电路利用全控电力开关管电流过零时的自然关断特点实现了功率可调的SCR全桥谐振逆变器在零电流下关断的软开关技术。     

新型小功率DC／DC变换器的研制

介绍了以UC3573为核心构成的电压控制型脉宽调制(PWM)变换器,并对拓扑电路各个参数进行分析和计算。实验结果表明:该变换器具有频响快、负载调整率高、输出电压稳定、纹波小的优点,是一种性能可靠的实用型变换器。     

基于MATLAB的Buck/Boost直流变换器仿真

对Buck和Boost直流变换器电路进行介绍,并且应用Matlab分别进行建模、仿真。在仿真过程中,改变触发脉冲的占空比,从而改变变换器的输出电压、电流,与理论分析结果进行比较。     

Signal flow graph modelling of interleaved buck converters

This paper presents a systematic development of unified signal flow graph model for an interleaved buck converter system operating in continuous inductor current mode. From this signal flow graph small, large‐signal and steady‐state models are developed, which are useful to study the converter dynamic and steady‐state behaviour. Converter performance expressions like steady‐state voltage gain, efficiency expressions and other small‐signal characteristic transfer functions are derived. Development of unified signal flow graph is explained for a 3‐cell interleaved converter system. Derivation of large, small‐signal and steady‐state models from the unified signal flow graph is demonstrated by considering a 2‐cell interleaved buck converter system. Large signal model was programmed in TUTSIM simulator, and the large‐signal responses against supply, load disturbances were predicted. Signal flow graph analysis results are validated with PSIM simulations. Further, the mathematical models obtained from the signal flow graph modelling are in agreement with those obtained from the state‐space averaging technique. Copyright © 2003 John Wiley & Sons, Ltd.     

Controller Design Using Ant Colony Algorithm for a Non-inverting Buck–Boost Chopper Based on a Detailed Average Model

In this article, the non-inverting buck–boost converter and its operation modes are scrutinized. The closed-loop stability of the converter in buck and boost modes is analyzed, and the necessity of using an appropriated controller is demonstrated. Then the application of an adapted ant colony optimization to design a feedback controller is proposed, and a controller based on its existing model is tuned. Simulation and experimental results obtained from the ant colony optimization designed controller are then compared with a controller designed with the classic method. Although the simulation and experimental results prove the efficiency of the proposed control approach, a significant difference between controller behavior in practice and simulation is obvious. Finding these differences, more detailed models, including all parasitic elements, in the buck and boost modes are derived. Applying the proposed model in controller design illustrates that the desired performance of the converter can be guaranteed with a simple proportional-integral (PI) controller. The suggested ant colony-based controller is again tuned based on the more detailed model, which improves the performance of the converter system even more. Furthermore, good agreement between analytical and experimental outputs validates the accuracy of the modeling and simulation.