汽油—甲醇双燃料发动机电控转换单元的研究

本文为了解决环境污染和能源短缺问题,在不改变原车发动机结构的前提下,采用STC51内核单片机,以及JY2X00单片机仿真开发系统,用软件硬件相结合的办法研制了一款适用于多车型汽油—甲醇发动机电控转换单元,该电控单元具有强大的控制能力,可实现对汽油喷射量/甲醇喷射量以及汽油甲醇智能转换的电子控制。测试结果表明,尾气中的C/H值有效降低并且大幅降低了硫元素的排放。

有轨电车用电控三位置转换开关控制方案

现代有轨电车在国内外迅猛发展,由于其低地板设计,三位置转换开关箱只能安装在车顶。目前常用的是手动操作转换开关箱,存在操作维护不便,有安全隐患等缺点。文中设计了一种电控三位置转换开关装置及控制电路,首次将其应用于低地板现代有轨电车,在司机室通过旋钮开关或按钮便可实现远程电动转换功能,极大地提升了操作便利及安全性。

双泵直压铆接机液压集成系统

该液压集成系统为满足用户对高频次铆接需求,减少设备运行故障,有效提高生产线的连续性,提供一种性能稳定、压力可显示调整、维修方便、操作简单的双泵电控转换液压集成。该液压系统采用模块化设计,尽量减少液压集成系统中作为控制单元的各类液压阀和流体通路,采用具有高稳定性能的插装阀和压力传感器来控制安全油压,减少铆接机在工作过程中的液压冲击、振动和噪声,减少机器故障,避免因管路泄漏而停机,使液压系统压力更加稳定,从而提高铆接效率。

Anti-reverse rotation startup method for sensorless brushless DC motor

In order to start up the brushless DC motor （BLDCM） without reverse rotation and smoothly switch the running state of the motor, a novel startup and smoothly switching method for a sensodess BLDCM is presented. Based on the saturation effect of the stator iron, six short voltage pulses are applied to determine the initial rotor position and the rotor can be found within 60°. After that, a series of short and long voltage pulses are used to accelerate the motor and the variation of the response current is utilized to detect the rotor position dynamically. When the motor reaches a certain speed at which the back-electromotive force （EMF） method can be applied, all the power devices are turned off and the running state of the motor is smoothly switched at the moment determined by the relationship between the terminal voltage waveform and the commutation phases. The experimental results verify the feasibility and validity of the proposed method.

A new high-performance AC/DC power factor correction switching converter based on one-cycle control technology and active floating-charge technology

A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.

Multi-mode controller IC for soft-switched flyback converter with high efficiency over the entire load range

This paper presents a multi-mode control scheme for a soft-switched flyback converter to achieve high efficiency and excellent load regulation over the entire load range. At heavy load, critical conduction mode with valley switching (CCMVS) is employed to realize soft switching so as to reduce turn-on loss of power switch as well as conducted electromagnetic interference (EMI). At light load, the converter operates in discontinuous conduction mode (DCM) with valley switching and adaptive off-time control (AOT) to limit the switching frequency range and maintain load regulation. At extremely light load or in standby mode, burst mode operation is adopted to provide low power consumption through reducing both switching frequency and static power dissipation of the controller. The multi-mode control is implemented by an oscillator whose pulse duration is adjusted by output feedback. An accurate valley switching control circuit guarantees the minimum turn-on voltage drop of power switch. The pro-totype of the controller IC was fabricated in a 1.5-μm BiCMOS process and applied to a 310 V/20 V, 90 W flyback DC/DC converter circuitry. Experimental results showed that all expected functions were realized successfully. The flyback converter achieved a high efficiency of over 80% from full load down to 2.5 W, with the maximum reaching 88.8%, while the total power consumption in standby mode was about 300 mW.

The control and optimization of macro/micro-structure of ion conductive membranes for energy conversion and storage

Ion conductive membranes(ICMs)are frequently used as separators for energy conversion and storage technologies of fuel cells,flow battery,and hydrogen pump,because of their good ion-selective conduction and low electronic conductivity.Firstly,this feature article reviews the recent studies on the development of new nonfluorinated ICMs with low cost and their macro/micro-structure control.In general,these new nonfluorinated ICMs have lower conductivity than commercial perfluorinated ones,due to their poor ion transport channels.Increasing ion exchange capacity(IEC)would create more continuous hydrophilic channels,thus enhancing the conductivity.However,high IEC also expands the overall hydrophilic domains,weakens the interaction between polymer chains,enhances the mobility of polymer chains,and eventually induces larger swelling.The micro-scale expansion and macro-scale swelling of the ICMs with high IEC could be controlled by limiting the mobility of polymer chains.Based on this strategy,some ef ficient techniques have been developed,including covalent crosslinking,semi-interpenatrating polymer network,and blending.Secondly,this review introduces the optimization of macro/microstructure of both perfluorinated and nonfluorinated ICMs to improve the performance.Macro-scale multilayer composite is an ef ficient way to enhance the mechanical strength and the dimensional stability of the ICMs,and could also decrease the content of per fluorosulfonic acid resin in the membrane,thereby reducing the cost of the perfluorinated ICMs.Long side chain,multiple functionalization,small molecule inducing micro-phase separation,electrospun nano fiber,and organic–inorganic hybrid could construct more ef ficient ion transport channels,improving the ion conductivity of ICMs.

Loop Compensator Design for DCM Peak-Current-Mode Control DC-DC Buckboost Converter

An analytic closed-form based loop compensator for direct current-direct current （DC-DC） buckboost converter in discontinuous conduction with peak current-mode control is proposed to increase efficiency of the desired process through systemization. As a result, the process saves a lot of computation time that can be translated into design cost savings. Finally, the output voltage regulation in the presence of audio susceptibility and output impedance is shown for verifying.

Comprehensive predictive control of neutral-point voltage balancing for back-to-back three-level NPC converters

A comprehensive predictive strategy was proposed for the neutral-point balancing control of back-to-back three-level converters. The phase currents at both sides and the DC-link capacitor voltages were measured for the prediction of the neutral-point current. A quality function was found to balance the neutral-point, and a metabolic on-times distribution factor was used as a predicator to minimize the quality function at each switching state. Simulation results show that the proposed method produces smaller ripples in tested signals compared with the established one, namely, 9.15% less in a total harmonic distortion(THD) of line-to-line voltage, 1.08% less in the THD of phase current, and 0.9 V less in the ripple of the neutral-point voltage. The obtained experimental results show that the main harmonics of the line-to-line voltage and the phase current in the proposed method are improved by 10 d B and 6 d B, respectively, and the ripple of neutral-point voltage is halved compared to the established one.

Establishment of Automated Multi-Range Multipliers Combined with TVC

An automated multi-range multipliers（range resistors）system is established for the AC voltage measurements by using a thermal voltage converter.It is performed automatically by selecting the appropriate multiplier whose voltage range contains the voltage to be measured without changing it manually through a new designed system.It consists of control part through a micro-controller controlled by specified prepared Lab-VIEW program and switching part through electronic relays in one circuit as clearly described in this work.It is used for measuring the ac voltage in the range from 1 V to 200 V.Also,it can be used for the voltage ranges up to 1 000 V by putting some factors into consideration.The AC-DC transfer differences for these multipliers combined with thermal voltage converter are determined automatically against another standard thermal voltage converter by using another Lab-VIEW program.

Non-inverting buck-boost DC-DC converter based on constant inductor current control

The hysteresis control combined with PWM control non-inverting buck-boost was proposed to improve the light load efficiency and power density.The constant inductor current control(CICC)was established to mitigate the dependence on the external components and device variation and make smooth transition between hysteresis control loop and pulse width modulation(PWM)control loop.The small signal model was deduced for the buck and boost operation mode.The inductor current slope control(ICSC)was proposed to implement the automatic mode transition between buck and boost mode in one switching cycle.The results show that the converter prototype has good dynamic response capability,achieving 94%efficiency and 95%peak efficiency at full 10 A load current.

Design and Implementation of a Digitally Controlled Photovoltaic System Using Series Connected Buck Converters

In PV （photovoltaic） power systems, a MPPT （maximum power point tracking） algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from complex physical environments in such PV power systems. To minimize the degradation of performances caused by these conditions, and therefore adding reliability and robustness, this paper presents an implementation of a digitally controlled system using a topology based on series connected DC-DC buck converters for a stand-alone PV power system applications, operating with local and autonomous controls, to track the maximum power points of PV modules in non ideal conditions. Simulations are carried out by using C-MEX S-functions under MATLAB-SIMULINK environment. A PV system of 1.44 kWc is described and simulation results are presented.

A Review of Direct Driven PMSG for Wind Energy Systems

This paper presents a comprehensive overview study of the DDPMSG （direct driven permanent magnet synchronous generator） for wind energy generation system. Wind turbine controls are provided. The PMSG （permanent magnet synchronous generator） is introduced as construction and model. Configurations of different power converters are presented for use with DDPMSG in wind systems at variable speed operation and maximum power capture. Control techniques for the system are discussed for both machine-side and grid-side in details. Grid integration is provided with focus on how to insure power quality of the system and the performance at disturbances.

High-Frequency Digital Controller Applied to Voltage Regulator Modules

Digital controllers are an interesting option for the next voltage regulator module （VRM） generation due to their wide programming possibilities. This paper discloses a very interested candidate to control DC-DC power converters, the Digital Signal Controller （DSC）. For that matter, a study was done by carrying out simulations and experimental results. Moreover, an additional voltage-input feed-forward （IVFF） algorithm is given in order to show the benefits of this technology. Finally, a complete analysis of the quantization effect is presented, and its influence over the controller performance is included.

Transcriptional regulatory circuits controlling muscle fiber type switching

Skeletal muscle fitness plays vital roles in human health and disease and is determined by developmental as well as physiological inputs. These inputs control and coordinate muscle fiber programs, including capacity for fuel burning, mitochondrial ATP production, and contraction. Recent studies have demonstrated crucial roles for nuclear receptors and their co-activators, and micro RNAs(mi RNAs) in the regulation of skeletal muscle energy metabolism and fiber type determination. In this review, we present recent progress in the study of nuclear receptor signaling and mi RNA networks in muscle fiber type switching. We also discuss the therapeutic potential of nuclear receptors and mi RNAs in disease states that are associated with loss of muscle fitness.

Control of organic–inorganic halide perovskites in solid-state solar cells: a perspective

Since the year of 2009 when the first appli- cation of organohalide lead perovskite as the light har- vester in solar cells was reported, tremendous attention has been devoted to these new types of perovskite-based solid-state solar cells and remarkable power conversion efficiency of over 20 % has been achieved to date. In this review, we first introduce the properties of organic- inorganic halide perovskites and then focus on the notable achievements made on the perovskite layer to improve the power conversion efficiency of solid-state perovskite solar cells, which is featured by process engineering of the state-of-the-art lead methylammoni- um triiodide perovskite and material control of lead triiodide perovskites and other newly emerged per- ovskites. In the end, we wish to provide an outlook of the future development in solid-state perovskite solar cells. Provided that the instability and toxicity of solid- state perovskite solar cells can be solved, we will wit- ness a new era for cost-effective and efficient solar cells.

Photovoltaic properties of ferroelectric solar cells based on polycrystalline BiFeO_3 films sputtered on indium tin oxide substrates

To study the ferroelectric photovoltaic effect based on polycrystalline films, preparation of high-quality polycrystalline films with low leakage and high remnant polarization is essential. Polycrystalline BiFeO3 （BFO） thin films with extremely large remnant polarization （2Pr = 180 ~aC/cm2） were successfully deposited on glass substrates coated with indium tin oxide using a modified radio frequency magnetron sputtering method. Symmetric and asymmetric cells were constructed to investigate the ferroelectric photovoltaic effect in order to understand the relationship between polarization and photovoltaic response. All examined cells showed polarization-induced photovoltaic effect. Our findings also showed that the ferroelectric photovoltaic effect is highly dependent on the material used for the top electrode and the thickness of the polycrystalline film.

Polyelectrolyte multilayer electrostatic gating of graphene field-effect transistors

We apply polyelectrolyte multilayer films by consecutive alternate adsorption of positively charged polyallylamine hydrochloride and negatively charged sodium polystyrene sulfonate to the surface of graphene field effect transistors. Oscillations in the Dirac voltage shift with alternating positive and negative layers clearly demonstrate the electrostatic gating effect in this simple model system. A simple electrostatic model accounts well for the sign and magnitude of the Dirac voltage shift. Using this system, we are able to create p-type or n-type graphene at will. This model serves as the basis for understanding the mechanism of charged polymer sensing using graphene devices, a potentially technologically important application of graphene in areas such as DNA sequencing, biomarker assays for cancer detection, and other protein sensing applications.