Design considerations of an SEPIC PFC converter for driving multiple lighting LED lamps

This paper presents a single‐ended primary inductance power‐factor‐correction converter (SEPIC PFC) for driving multiple lighting LED lamps. With the aid of this converter, high power factor and high efficiency can be achieved by a simple single‐stage circuit with low device stress features. A burst‐mode dimming method is used to regulate the current and brightness of multiple LED lamps. A laboratory prototype is also built and tested. With the prototype, high power factor can remain under universal input voltage operation and individual lamp brightness control. Copyright © 2008 John Wiley & Sons, Ltd.     

Modelling,design and stability analysis of an improved SEPIC converter for renewable energy systems

In this paper, a detailed modelling and analysis of a switched inductor (SI)-based improved single-ended primary inductor converter (SEPIC) has been presented. To increase the gain of conventional SEPIC converter, input and output side inductors are replaced with SI structures. Design and stability analysis for continuous conduction mode operation of the proposed SI-SEPIC converter has also been presented in this paper. State space averaging technique is used to model the converter and carry out the stability analysis. Performance and stability analysis of closed loop configuration is predicted by observing the open loop behaviour using Nyquist diagram and Nichols chart. System was found to stable and critically damped.     

一种新型三电平直流变换器的仿真研究

文章提出了一种新型的隔离式三电平直流变换器的拓扑,它是在传统的两电平变换器的基础上提出来的.在这种新型拓扑中,每个开关管的电压应力都比两电平时降低了一半,并且滤波器的体积也明显减小,使其更适用于高电压大功率场合,且拓扑极具对称性,这样方便了工作原理的分析及控制电路的设计.文章以SEPIC三电平直流变换器为例,分析了该变换器的工作原理,给出了控制策略.通过仿真结果,验证了工作原理和控制策略的正确性,比如电压应力低等特点.     

FPGA implementation of current-sharing strategy for parallel-connected SEPICs

The attempt echoes to evolve an equal current-sharing algorithm over a number of single-ended primary inductance converters connected in parallel. The methodology involves the development of state-space model to predict the condition for the existence of a stable equilibrium portrait. It acquires the role of a variable structure controller to guide the trajectory, with a view to circumvent the circuit non-linearities and arrive at a stable performance through a preferred operating range. The design elicits an acceptable servo and regulatory characteristics, the desired time response and ensures regulation of the load voltage. The simulation results validated through a field programmable gate array-based prototype serves to illustrate its suitability for present-day applications.     

Non‐isolated single‐switch DC–DC converters with extended duty cycle for high step‐down voltage applications

Several new topologies of single‐switch non‐isolated DC–DC converters with wide conversion gain and reduced semiconductor voltage stress are proposed in this paper. Most of the proposed topologies are derived from the conventional inverse of SEPIC (Zeta) converter. The proposed topologies can operate with larger switch duty cycles compared with the existing single switch topologies, hence, making them well suitable for high step‐down voltage conversion applications. With extended duty cycle, the current stress in the active power switch is reduced, leading to a significant improvement of the system losses. Moreover, the active power switch in some of the proposed topologies is utilized much better compared to the conventional Zeta and quadratic‐buck converters. The principle of operation, theoretical analysis, and comparison of circuit performances with other step‐down converters are discussed regarding voltage and current stress and switch silicon utilization. Finally, simulation and experimental results for a design example of a 50 W/5 V at 42‐V input voltage operating at 50 kHz will be provided to evaluate the performance of the proposed converters. Copyright © 2014 John Wiley & Sons, Ltd.     

一种新型三电平智能变压器的研究

研究了一种新型的三电平智能变压器拓扑。以SEPIC变换器为例,将多电平技术应用到智能变压器中,使得开关管的电压应力得到大幅下降,同时也减小了滤波器的体积。分析了其工作原理和开关模态,并设计了带电容均压控制的电压瞬时值反馈控制策略。最后,完成了一台500 W单相原理样机,通过实验验证了新型拓扑及控制策略的正确性,充分体现了SEPIC式三电平智能变压器的优越性。     

基于MATLAB的单端初级电感变换器的研究

单端初级电感变换器(SEPIC)作为一种DC-DC变换器既可以实现升压,也可以实现降压,而且转换效率较高,适用多种场合.该文详细分析了SEPIC拓扑结构的工作原理,提供了一种较为简单的各元件参数的选取方法,并给出了推导过程.重点阐述了电流连续模式(CCM)和临界连续工作模式(TM)下的工作机制,并利用MATLAB软件搭...     

基于SEPIC变换器的高功率因数LED照明电源设计

针对LED驱动电源功率因数低的问题,依据LED照明电源的特点,选择SEPIC电路作为主电路拓扑实现功率因数校正(PFC)和LED电流控制。传统的SEPIC电路用于功率因数校正时都工作在断续模式下,通过对SEPIC电路的分析,证明了临界连续模式下SEPIC电路也可以实现PFC,并推导出输入输出电压比和功率因数关系的公式,得出当输入输出电压比很小时,功率因数值很高。该电源用单级电路同时实现功率因数校正和LED电流控制,相对两级功率因数校正电路,所用器件少,损耗低,尺寸小,尤其适合空间狭小的照明电源电路。通过实验证明理论分析的正确性。     

一种适用于SEPIC变换器的可拓展电压增益单元电路

因寄生参数的影响,基本DC/DC变换器的升压能力受到了限制.针对单端初级电感转换器(SEPIC)变换器提出了一种可拓展电压增益单元电路,通过在基本SEPIC变换器外围接入所提电压增益单元可有效提升变换器输入-输出电压增益,并降低开关器件的电压应力,该变换电路还具备基本SEPIC变换器输入电流连续、低纹波的优点.同时所提...     

新型无均衡管理光伏锂电储能发电模组及其MPPT控制策略

为解决既有基于锂电无均衡管理(NBCM)的光伏锂电储能发电模组存在的光伏电池面板与锂电池之间需要严格的电压匹配及其带来的能效损失问题,改善光伏电池面板串级阴影效应以及功率变换器高频开关耦合产生的对地漏电流效应,提出一种改进的NBCM光伏锂电储能发电模组拓扑结构,其控制单元由前级光伏电池自适应电压均衡单元和后级SEPIC馈电升降压(SFBB)变换单元构成。在此基础上,提出一种基于极值搜索控制(ESC)和Lyapunov开关耦合控制的2-Lyap ESC最大功率点跟踪(MPPT)控制策略,以提高NBCM光伏锂电储能发电模组内串联光伏电池模块的MPPT输出能效,优化模组能量管理。仿真结果验证了该拓扑及MPPT控制策略的有效性。