Non-singular terminal sliding-mode control of DC–DC buck converters

This paper presents a non-singular terminal sliding mode control (NTSMC) method for DC–DC buck converters. The NTSMC method eliminates the singularity problem which arises in the terminal sliding mode due to the fractional power and assures the finite time convergence of the output voltage error to the equilibrium point during the load changes. It is shown that the NTSMC method has the same finite time convergence as that of the terminal sliding mode control (TSMC) method. The influence of the fractional power on the state trajectory of the converter is investigated. It is observed that the slope of the sliding line becomes larger with decreasing value of the fractional power which leads to a faster transient response of the output voltage during the load changes. The theoretical considerations have been verified both by numerical simulations and experimental measurements from a laboratory prototype.     

Control of DC–DC power converters in the presence of coil magnetic saturation

Engineers generally design control for power converters based on standard models that assume the involved passive components to be linear. In reality, the magnetic characteristics of these components are nonlinear (especially in the presence of large magnetic flux density in the ferromagnetic core). This nonlinearity, which is of the saturation type, is particularly pronounced in higher power coils. Therefore, a controller obtained from the standard models may not achieve the performance it is designed for under operational conditions where the nonlinearity of the components is not negligible. In this paper, the authors investigate the effect of coil magnetic saturation for certain converters is investigated. It is shown that the control performances actually deteriorate if such a feature is not accounted for in the converter modeling. A solution that explicitly accounts for the nonlinearity of coil characteristics is developed for two converters.     

UDE-based sliding mode control of DC–DC power converters with uncertainties

The DC–DC power converter plays an important role in solar systems to provide the stable DC bus voltage, but which is easily subject to various uncertainties and disturbances in practical operation. In this paper, an uncertainty and disturbance estimator (UDE) based sliding mode control approach is applied to improve the performance of power converters. The UDE is designed for the estimation of both the matched and mismatched uncertainties. To address the mismatched uncertainties, an adaptive sliding mode function is constructed with the compensation of the estimated uncertainties, which renders a chattering-free robust control law. Simulation and experimental results illustrate that the proposed control scheme achieves good dynamic performance, strong robustness and chattering reduction in the presence of uncertainties and disturbances     

Model predictive control of a DC–DC converter for battery emulation

A battery emulator is used instead of a real traction battery to supply an electric motor inverter on a test bed for hybrid and electric powertrains under deterministic conditions. The use of virtual battery models eliminates the need for expensive battery prototypes. Virtual battery properties such as chemistry, state of charge or state of health can be changed instantly. However, the control of a battery emulator is a challenging problem. Very fast reference tracking is required for battery impedance emulation but motor inverters act as constant power loads that have a negative influence on the tracking performance and can even lead to instability. In this paper an MPC strategy is proposed for solving this problem. Scheduling of local controllers is utilized in order to handle the nonlinear and destabilizing load. Furthermore, a fast algorithm is presented that allows real-time MPC subject to input and output constraints. Experimental results obtained with a battery emulator supplying an electric drive inverter demonstrate the performance of the stabilizing controller.     

Design of PWM with four transistor comparator for DC–DC boost converters

The DC-DC converter is used for different applications which needs higher voltages when compared to the input source. The boost converter is one of the most efficient methods to choose DC-DC Converter in different ways. The purpose of the proposed method is to reduce the area of VLSI design logic and power consumption. Boost converter topology is difficult because it has a large component. The proposed work of four transistor comparator based PWM (Pulse width Modulator) that can be used in DC-DC boost converter, which reduces the area, and power consumption of the entire system. This proposed work calculates the parameters of boost converter and the simulation performed using different duty cycle and parameters. Simulation results shows different duty cycles with different resistance and inductance parameters using boost converter. In addition to this the result carries out four transistor comparator output which is used to reduce the boost converter circuit design. PWM is based on the proposed four transistor comparator, which is used in the Cadence Virtuoso software using conventional CMOS technology.     

Robust digital control of a DC–DC buck converter with low frequency samplings

A robust DC?CDC converter which can covers extensive load change and also input voltage changes with one controller is needed. Then the demand to suppress output voltage change becomes still severer. We propose an approximate 2-degree-of-freedom (2DOF) digital controller which realized start-up response and dynamic load response independently. The controller makes a control bandwidth wider, and at the same time makes variations of the output voltage small at sudden changes of a load and an input voltage. In this paper, a new approximate 2DOF digital control system with additional zeros is proposed. Using the additional zeros, the second-order differential transfer characteristics between equivalent disturbances and a output voltage are realized. Therefore, the new controller makes variations of the output voltage smaller and the sudden changes of the load and the input voltage. This controller is actually implement on a DSP and is connected to the DC?CDC converter. Experimental results demonstrate that this type of digital controller can satisfy given severe specifications with low frequency sampling.     

Design of intelligent power controller for DC–DC converters using CMAC neural network

DC–DC converters are the devices which can convert a certain electrical voltage to another level of electrical voltage. They are very popularly used because of the high efficiency and small size. This paper proposes an intelligent power controller for the DC–DC converters via cerebella model articulation controller (CMAC) neural network approach. The proposed intelligent power controller is composed of a CMAC neural controller and a robust controller. The CMAC neural controller uses a CMAC neural network to online mimic an ideal controller, and the robust controller is designed to achieve L ₂ tracking performance with desired attenuation level. Finally, a comparison among a PI control, adaptive neural control and the proposed intelligent power control is made. The experimental results are provided to demonstrate the proposed intelligent power controller can cope with the input voltage and load resistance variations to ensure the stability while providing fast transient response and simple computation.     

低功耗DC/DC变换器

新型便携式电子产品的特点之一是轻巧。为此,可采用1～2节5~#电池通过高效率的DC/DC变换器产生 5V、 12V等稳定电压,以满足电子线路的需要。这里介绍一组美国LTC公司的低功耗、高效率的DC/DC变换器集成电路。其特点是:组成的稳压电源静态电流小、外围元件少(仅3～4个)、体积小(全部采用贴片式元件)、重量轻,效率高(80％左右)。     

DC

阳春三月，细雨绵绵，冷却了火爆的年前DC市场，但是也活跃离一部分即将崭露头角的新芽。纵观市场，几大品牌中要数尼康的销售情况最好，这主要是尼康的机器价位合理，外形时尚，功能全面，品质优良。比如尼康5200，这款机器500万像素，才两多块，而且外观十分小巧，性价比很高。     

Decentralized adaptive neural network control of cascaded DC–DC converters with high voltage conversion ratio

Decentralized output voltage tracking of cascaded DC–DC converters is an interesting topic to obtain a high voltage conversion ratio. The control purpose is challenging due to the load resistance changes, renewable energy supply voltage variations and interaction of the individual converters. In this paper, four novel decentralized adaptive neural network controllers are designed on the cascaded DC–DC buck and boost converters under load and DC supply voltage uncertainties. In the beginning, individual buck and boost converter average models that can operate in both continuous and discontinuous conduction modes are derived. Then, the interconnected and decentralized state-space models of cascaded buck and boost converters are extracted. These models are highly nonlinear with unknown uncertainties which can be estimated by neural networks. Further, two decentralized adaptive backstepping neural network voltage controllers are proposed on cascaded buck converters to deal with uncertainties and interactions. However, these control strategies are not applicable to a boost converter due to its non-minimum phase nature. Then, two novel decentralized adaptive neural network with a conventional proportional–integral reference current generator are developed on the cascaded boost converters. Practical stability of the overall system is guaranteed for the proposed controllers using Lyapunov stability theorem. Finally, four control strategies provide good quality of output voltage in the presence of uncertainties and interactions. Comparative simulations are carried out on cascaded buck and boost converters to validate the effectiveness and performance of the designed methods.     

合理选择DC—DC转换器

讨论线性稳压器、开关型DC－DC转换器、电荷泵等三种DC－DC转换器的特点、如何选用以及应用中的相关问题。     

DC260 DC220双龙出水

记者汪若菡报道柯达公司在'98中国国际照相机械摄影器材与技术博览会上向中国市场正式推出了柯达DC220和DC260数码照相机,其中DC220提供了百万像素(1152×864)和2倍光学加2倍数码的变焦镜头;DC260则具有超百万像素(1536 × 1024)和3倍光学加2倍数码变焦镜头。这两款相机的价格都在万元以下。另外,柯达还附送PICTURE EASY 3.02软件,它可以在WINDOWS 95和NT4.0上运行,能够使用户直接从数码相机、扫描仪、光盘或软、硬盘上获取图像,并对图像进行编辑。     

亿维发布UN CPU224 DC／DC／DC

2011年12月．亿维（UniMAT）正式发布了UN CPU224DC／DC／DC．订货号为UN214-1AD23—0XB0。这是一款由亿维研发部根据多年PLC模块的市场经验．历时1年研发出来的200系列自主品牌PLC控制器模块．在兼容西门子PLC功能的前提下,做了部分优化及功能增强。     

Analysis and design of a high efficiency bidirectional DC–DC converter for battery and ultracapacitor applications

This paper presents a high efficiency non-isolated bidirectional converter which can be employed as an interface circuit between ultracapacitors or batteries and DC bus voltage. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. So, the energy conversion through the converter is highly efficient. The proposed converter acts as a zero-voltage transition (ZVT) buck to charge an ultracapacitor or battery and acts as a ZVT boost to discharge an ultracapacitor or battery. The performance of the proposed converter with respect to abrupt load and operating mode change is shown through computer simulation results. The results confirm the aforementioned advantages and features of the proposed converter.     

DC—DC变换器的SPICE仿真

本文讨论应用ＳＰＩＣＥ通用集成电路计算机分析程序仿真ＤＣ－ＤＣ变换器的方法。着重论述脉冲变压器的回旋器组等效模型、脉宽调制器的等效模型以及双稳态触发器和常用逻辑电路的数学模型。恰当运用上述模型，可仿真所有类型的ＤＣ－ＤＣ变换器，包括谐振变换器、ＰＷＭ变换器、软开关变换器以及开关电容变换器。文中给出了一些实例。     

DC老祖宗

1995年3月10日,是数码相机发展史的大日子。第一部消费级数码相机QV-10便是在那天上市。当年QV-10的售价高达65,000日元,没记错的话,95年100日圆兑1美元左右,大概约人民币6400左右,不计通货膨胀,今时今日足够买到一部入门级DSLR。     

DC新闻

1SONY2GB高速记忆短棒现身PMA在PMA2005上,SONY发布了容量分别为2GB和1GB的Memory Stick Produo,其中2G日的版本是被设计用在支持传输速度最大80Mbps的设备上,工作温度-13°Ft0+185°F。     

DC行情

三星推出的新款卡片相机i6采用600万像素CCD，3倍光学变焦镜头，2．5寸液晶屏幕，1厘米微距。主体黑色卡片机身设计，金属防滑条采用了央扣型设计，使得整机在方正之亦充满流线感，轻薄而时尚。i6不仅能播放MP3音乐，还内建了影片播放程序，可以说该款相机整合了传统DC和MP4的功能。