Single-switch boost-buck DC-DC converter for industrial fuel cell and photovoltaics applications

The realization of dc-dc converters performs a vital function in exploiting renewable energy sources such as solar photovoltaic (PV) and fuel cell applications. This paper demonstrates a single-switch unidirectional buck-boost dc-dc converter for continuous power flow control, excluding the hybrid switched-capacitor. The proposed converter utilizes a limited number of passive components, only four diodes and three inductors required, in addition to six capacitors. The converter can operate at a wide input voltage range with continues input current. The converter has experimented under real-time conditions with 660 W PV system. The obtained efficiency ranges from 93% to 98%. Furthermore, the converter has interfaced with 550 W fuel cell operated under different fuel pressure. The realized efficiency ranges from 91% to 97%. The maximum measured inductance current ripple is limited to under 0.70 A in both scenarios, whereas 0.16 V is the maximum output voltage ripple.     

锂电池/超级电容混合动力系统及控制策略

混合动力轻轨车(Hybrid Light Rail Vehicle,HLRV)以锂电池作为主动力源,超级电容作为辅助动力源,具有良好的技术性与经济性。提出锂电池与超级电容分别通过Buck/Boost双向变换器并联于直流母线侧的储能主电路结构,以实现功率的双向调节并提高超级电容器利用率。为了提高系统输出功率以及减小电流纹波,采用三相交错并联结构。针对锂电池响应速度慢的问题,提出了超级电容响应负载变化,锂电池响应超级电容低频分量的间接功率控制策略。仿真结果验证了该系统以及控制策略的正确性。     

电动汽车的双向DC-DC变换器多模态控制方法

针对当前电动汽车功率控制过程中存在负载跳变抗干扰性能差、响应速度较慢等问题,提出一种应用于电动汽车的双向DC-DC变换器多模态控制方法。文章详细分析了电动汽车双向DC-DC变换器的拓扑结构和升降压控制模式;结合不同工况下的变换器工作状态,分析电压和电流模式控制,得出其电压、电流开闭环函数;利用多模态控制方法,由变换器的功能控制单元下达电压、电流环给定信号来实现功率波动平抑控制;在MATLAB中搭建了仿真模型。仿真结果表明,文章所提出的控制方法能够较好地实现双向DC-DC变换器的功率波动平抑功能,具有稳定性好、对负载跳变抗干扰性能强、响应速度快的特点。     

Three-phase step-up/step-down isolated dc-dc converter with wide-range duty cycle for low dc renewable energy sources applications

Renewable sources of low voltage are an important resource in power generation systems. Many provide high output current at low voltage, as the photovoltaic modules and fuel cells systems, therefore, become more popular considering the safety requirements. In this paper, a novel current-fed three-phase dc-dc converter with high-frequency isolation transformer is proposed. This one has the main features as high dc voltage gain, reduced switches count, minimize the volume of the output/input filters, the frequency ripple of the input current and output voltage are three times higher than the switching frequency, best losses distribution and reduced stresses in the circuit. Moreover, it operates with wide-range duty cycle, the soft-start can be used, which allows the input current and the output voltage to be started gradually. Operating with a duty cycle of 1/3 and 2/3, the input current ripple is canceled. The proposed converter is studied qualitatively and quantitatively, being presented the operation principle in continuous and discontinuous conduction mode, dc voltage gain in each operation mode, and the voltage and current stresses for the power components sizing. To validate the operation of the proposed converter, the laboratory design example and experimental results are presented to demonstrate the performance and validate the claims of the converter for wide load variation. Experimental results are presented for a 4-kW prototype, operating in R2 region for continuous conduction mode. Additionally, experimental results in R1 and R3 regions are obtained.     

Robust optimal control of bilinear DC-DC converters

This paper addresses the control problem of dc-dc converters. The control law synthesis considered here exploits the potential of LMI-based control approaches, which allow to cope with model uncertainty, disturbances and bilinearities to synthesize simple state-feedback controllers with a priori guarantee of stability in a large domain of initial and operating conditions. The aim of the paper is to contribute with a robust control framework to deal with the common requirements of regulated dc-dc converters. The correctness of the results has been verified both with numerical simulations and with experimental measurements from a laboratory prototype.     

Maximum Power Point Tracking Using Disturbance Observer-Based Sliding Mode Control for Estimation of Solar Array Voltage

Abstract

The output power of solar panel in photovoltaic systems is affected by changes in environmental and load conditions. Most currently developed MPPT control algorithms require measurements of panel output voltage, output current, and converter output voltage. In this paper, a new scheme that can cater to uncertainties in the environmental and load condition, is developed using a disturbance observer-based sliding mode control (DOSMC). The proposed DOSMC scheme obviates the need of using a panel output voltage sensor. The proposed scheme does not use a discontinuous control, thereby overcoming the problems of chatter normally associated with the conventional sliding mode control (SMC). The stability is proven in the sense of ultimate boundedness. The proposed scheme is validated by extensive simulation and laboratory experimentation under various scenarios of irradiation, temperature, and load conditions and compared with two existing popular schemes.     

A sinusoidal PAM-PWM inverter

A new strategy, using both PAM (pulse amplitude modulation) and PWM (pulsewidth modulation) in combination for a power inverter is described. The output waveforms in the proposed PAM-PWM inverter are investigated both theoretically and experimentally. The line-to-line voltage waveform includes the fundamental component and the sidebands of the carrier frequency. Lower-order harmonics are not included in the output waveform. The amplitude of the fundamental component increases 15 percent more than that of a conventional sine-wave inverter. Since each inverter arm does not operate during two-thirds of the period, the heat generated in the devices is reduced, i.e., the size of the inverter system can be minimized because of the reduction in the heat dissipating equipment.     

DC-DC变换器的大信号建模及鲁棒控制方法

本文从工程实践的要求出发,将建模和控制器的设计紧密结合,提出了一种新型DC-DC变换器大信号建模方法,基于这一模型,将线性时变不确定系统的鲁棒控制方法应用于DC-DC变换器的控制器设计.本文所提出的建模和控制器设计方法适用于全部四种基本PWM型DC-DC变换器.计算机仿真和实验证明,本文设计的控制器对输入电源电压扰动和线性负载电阻扰动具有良好的鲁棒性,且实现方案简单易行.     

Enhanced Control Design of Simple DC-DC Boost Converter-driven DC Motors: Analysis and Implementation

The DC-DC boost converter is one of the simplest power electronic devices that has not been yet exploited in a wide range of industrial applications due to control design difficulties caused by its model inherent special structure. Such an industrial application is the DC motor speed regulation that is studied in the present work. Particularly, in this article, a novel, non-linear control scheme for the duty ratio input of the converter is proposed, which is extensively analyzed and experimentally tested. The proposed design, though non-linear, results in a very simple scheme, ensures that the duty ratio takes values exclusively in the permitted range [0,1), achieves precise speed regulation even in cases of high unknown load disturbances, and does not depend on system parameters and states. Simultaneously, the design is formulated in a manner that provides a closed-loop passive system, which, as proven in the article, satisfies all these assumptions and properties that make possible the application of a new advanced non-linear method that strongly connects passivity with stability. Thus, the boundedness of all the closed-loop states and the stability and convergence to the desired steady-state equilibrium are directly concluded. The theoretical analysis is verified through extended simulation and experimental results.     

一种基于内置变压器的高增益双向DC-DC变换器

提出一种应用在储能系统的双向DC-DC变换器,其具有电压增益高、电压应力小和软开关范围宽的优势。通过将内置变压器集成在飞跨电容结构和2个交错的Buck/Boost结构中,可以同时实现电压增益高和电压应力小。内置变压器结构的特点是磁芯中的磁通可以相互抵消,避免了磁饱和,从而有效地减小磁性器件的体积。通过采用交错的结构,低压侧的电流纹波明显减少;通过调节占空比,实现变压器原、副两边的电压匹配,从而减少环流;同时,通过采用移相控制,可以单调地调节传输功率;合理设置参数后,所有MOSFET可以实现宽范围的软开关。详细给出了工作原理和稳态分析,并设计了额定功率为1kW的实验样机,以验证所述变换器的可行性。样机的效率在升压模式和降压模式下是相似的,这表明该变换器的效率是不受功率传输的方向影响的;在低压侧电压变化时,该变换器的效率变化不大。因此,所提变换器适用于需要高电压增益、宽电压侧电压范围的储能系统。