汽油机GDI技术的研究状况及展望

通过介绍汽油机缸内直喷技术相对于PFI的优点,并从GDI按工况区的分层控制策略、扭矩控制策略、喷油定时控制策略等方面介绍GDI发动机的研究状况。阐述GDI发动机开发中的一些技术难点,并指出GDI的一些新技术展望。

Ultra-Supercritical——A Preferential Choice for China to Develop Clean Coal Technology

The ultra-supercritical pressure coal-fired power-generation technology (USCT) isa mature, advanced and efficient power generation technology in the world. Comparisonsamong several principal clean coal power-generation technologies show that USCT withpollutant-emission control equipment is superior to others in efficiency, capacity, reliability,investment and environment protection etc. Analyzing the main problems existing in thermalpower industry, it is concluded that the USCT is the preferential choice for China to developclean coal power-generation technology at present. Considering the foundation of thepower industry, the manufacturing industry for power generating equipment and otherrelated industries, it is concluded that China has satisfied the qualifications to develop USCT.

Control strategy for multi-pump emulsion power station in coal mine face

Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion power station. Analyzing the operating characteristics of hydraulic supports, the number of simultaneously operating supports is obtained by means of pressure parameter and time history at a certain time, which is a theory base for development of control system to multi-pump emulsion power station.

Improved Voltage Control Strategy for Photovoltaic Grid-Connected System Based on DoubleLayer Coordination Control

An improved automatic voltage coordination control strategy （AVCCS） based on ;automatic voltage control （AVC） and battery energy storage control （BESC） is proposed for photovoltaic grid-connected system （PVGS） to mitigate the voltage fluctuations caused by environmental disturbances. Only AVC is used when small environ- mental disturbances happen, while BESC is incorporated with AVC to restrain the voltage fluctuations when large disturbances happen. An adjustable parameter determining the allowed amplitudes of voltage fluctuations is introduced to realize the above switching process. A benchmark low voltage distribution system including ]？VGS is established by using the commercial software Dig SILENT. Simulation results show that the voltage under AVCCS satisfies the IEEE Standard 1547, and the installed battery capacity is also reduced. Meanwhile, the battery＇s service life is ex- tended by avoiding frequent charges/discharges in the control process.

Emerging two-dimensional metallenes:Recent advances in structural regulations and electrocatalytic applications

Benefiting from the ultrahigh specific surface areas,highly accessible surface atoms,and highly tunable microscopic structures,the two-dimensional metallenes as nanocatalysts have displayed promising performance for various electrocatalytic reactions.Herein,we reviewed recent advances on metallenes in structural regulations including defect,phase,strain,interface,doping,and alloying engineering strategies and their applications in energy electrocatalytic reactions involving oxygen reduction reaction,carbon dioxide reduction reaction,hydrogen evolution reaction,and small molecules oxidation reaction.Finally,we proposed the future challenges and directions in this emerging area.

Data-driven nonlinear control of a solid oxide fuel cell system

Solid oxide fuel cells (SOFCs) are considered to be one of the most important clean,distributed resources. However,SOFCs present a challenging control problem owing to their slow dynamics,nonlinearity and tight operating constraints. A novel data-driven nonlinear control strategy was proposed to solve the SOFC control problem by combining a virtual reference feedback tuning (VRFT) method and support vector machine. In order to fulfill the requirement for fuel utilization and control constraints,a dynamic constraints unit and an anti-windup scheme were adopted. In addition,a feedforward loop was designed to deal with the current disturbance. Detailed simulations demonstrate that the fast response of fuel flow for the current demand disturbance and zero steady error of the output voltage are both achieved. Meanwhile,fuel utilization is kept almost within the safe region.

A novel digital control strategy of three-phase shunt active power filter under non-ideal mains voltages

A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.

Analysis and design of over-current limit control strategies applied in aeronautical power supplies

Some Over-Current Limit Control strategies are analyzed and designed to meet the demands of high reliability and rapid dynamic response in the aeronautical power supply applications. The control schemes are both effective in DC-DC converters and DC-AC converters. Controller models are set up, and the over-current limit operation principles of analogy and digital control are analyzed too. An 800VA aeronautical power supply bas been constructed to verify the performance of the proposed control strategy in various cases such as the sudden load change and the constant load. The analysis and experiments confirm the advantages of the proposed over-current limit strategies as follows： simple,effective and reliable.

Control Strategies for PM Synchronous Machine Controlled Rectifier Intended for Heavy-Duty Vehicle

In order to charge batteries and supply all the electrical devices like wheel-motors used in a heavy-duty hybrid electric vehicle, a solution consists in using an assembly permanent magnet generator driven by a diesel engine and a three-phase insulated gate bipolar transistor/diodes bridge controlled rectifier connected to the battery. In this work, hysteresis current control strategies combined with a judicious current sensing mode for the assembly permanent magnet synchronous machine-controlled rectifier are investigated. Main issues first concern the different kinds of transistors switching modes allowed by the proposed current sensing mode when the machine operates either as a generator or as a motor. Second, the modulated hysteresis method is presented, which merges the performances of robustness and dynamic of the classical hysteresis method and imposes the switching frequency alike pulsewidth modulation techniques. A test bench at reduced power permits to test the switching modes as well as classical and modulated hysteresis methods for both motor and generator operating modes and to validate the simulation predictions. The digital signal processor algorithm elaborated for the control strategy is flexible and adaptable to all kinds of transistor switchings and machine operating modes.

Design and application of electric oil pump in automatic transmission for efficiency improvement and start–stop function

For the purpose of improving efficiency and realizing start–stop function, an electric oil pump(EOP) is integrated into an 8-speed automatic transmission(AT). A mathematical model is built to calculate the transmission power loss and the hydraulic system leakage. Based on this model, a flow-based control strategy is developed for EOP to satisfy the system flow requirement. This control strategy is verified through the forward driving simulation. The results indicate that there is a best combination for the size of mechanical oil pump(MOP) and EOP in terms of minimum energy consumption. In order to get a quick and smooth starting process, control strategies of the EOP and the on-coming clutch are proposed. The test environment on a prototype vehicle is built to verify the feasibility of the integrated EOP and its control strategies. The results show that the selected EOP can satisfy the flow requirement and a quick and smooth starting performance is achieved in the start–stop function. This research has a high value for the forward design of EOP in automatic transmissions with respect to efficiency improvement and start–stop function.

Hybrid Dynamic Modeling and Control of Molten Carbonate Fuel Cell Stack Shutdown

A hybrid automaton modeling approach that incorporates state space partitioning, phase dynamic modeling and control law synthesis by control strategy is utilized to develop a hybrid automaton model of molten carbonate fuel cell (MCFC) stack shutdown. The shutdown operation is divided into several phases and their boundaries are decided according to a control strategy, which is a set of specifications about the dynamics of MCFC stack during shutdown. According to the control strategy, the specification of increasing stack temperature is satisfied in a phase that can be modeled accurately. The model for phase that has complex dynamic is approximated. The duration of this kind of phase is decreased to minimize the error caused by model approximation.

Tuning strategies and structure effects of electrocatalysts for carbon dioxide reduction reaction

Carbon dioxide emissions have increased due to the consumption of fossil fuels,making the neutralization and utilization of CO_(2) a pressing issue.As a clean and efficient energy conversion process,electrocatalytic reduction can reduce carbon dioxide into a series of alcohols and acidic organic molecules,which can effectively realize the utilization and transformation of carbon dioxide.This review focuses on the tuning strategies and structure effects of catalysts for the electrocatalytic CO_(2) reduction reaction(CO_(2)RR).The tuning strategies for the active sites of catalysts have been reviewed from intrinsic and external perspectives.The structure effects for the CO_(2)RR catalysts have also been discussed,such as tandem catalysis,synergistic effects and confinement catalysis.We expect that this review about tuning strategies and structure effects can provide guidance for designing highly efficient CO_(2)RR electrocatalysts.

Innovative Control Strategy for Islanded Small Hydro Power Plant

In many developing countries, there are regions where the electrical grid is weak or nonexistent. However, in these areas, large amounts of distributed energy sources, such as hydro, are often available and could be suitably exploited. To this aim, the low head hydro power plants can play a significant role. In fact, recent technological advances in mini-hydro turbines and decreasing costs of static electricity conversion devices enable to realize suitable power plants for an efficient and profitable exploitation of these sites. One of the major challenges is the integration of the above-mentioned power plants into autonomous electrical systems, islanded and/or disconnectable from the main distribution network. In this paper, an innovative control strategy for a low head hydro power plant supplying users in small clusters of villages is proposed.

Impact Analysis of EV Charging with Mixed Control Strategy

EVs （electric vehicles） have been widely accepted as a promising solution for reducing oil consumption, air pollution and greenhouse gas emission. The number of EVs is growing very fast over the years. However, the high adoption of EVs will impose a burden on the power system, especially for neighborhood level network. In this paper, we propose a mixed control framework for EV charging scheduling to mitigate its impact on the power network. A metric for modeling customer＇s satisfaction is also proposed to compare the user satisfaction for different algorithms. The impacts of the proposed algorithms on EV charging cost, EV penetration and peak power reduction are evaluated with real data for a neighborhood level network. The simulation results demonstrate the effectiveness of the proposed algorithms.

Current Limiting Characteristic Analysis of Magnetic-controlled Switcher Type Fault Current Limiter

A novel magnetic-controlled switcher type fault current limiter (FCL) based on the topology of the saturated iron core high temperature superconducting FCL is proposed. The magnetic field distribution of the FCL iron core is analyzed by FEA software ANSYS. The current limiting characteristic is investigated by both 3-D field-circuit coupled simulation and Matlab. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively,and the FCL has the advantages of simple and reliable structure, flexible control strategy. The simulation and experimental results prove that the theoretical expectation and current limiting performance is satisfactory for practical use.

Optimal Configuration for Distributed Generations in Micro-grid System Considering Diesel as the Main Control Source

This paper proposes an optimal configuration of the distributed hybrid renewable generations based on the stand-alone micro-grid system, considering the diesel as the main control source. Due to the natural sources and load of user changes randomly and the non-tinearity of the power output by renewable generations, an intelligent optimization method based on the improvement of the genetic algorithm and the control strategy are discussed. The instance analysis is compared with the optimization result of the hybrid system based on HOMER （hybrid optimization of multiple energy resources） and GA （genetic algorithm） method on Matlab software. The simulation result of the optimal configuration showed the new hybrid renewable system and would improve the power supply situation which decreased the cost of energy greatly compared with the conventional form of power supply system which was operated only by diesel. The conclusion of the comparing result between HOMER and GA method shows the advantages of the strategy for the diesel as main control sources.

Research and Design of Coordinated Control Strategy for Smart Electromechanical Actuator System

In order to improve the frequency response and anti-interference characteristics of the smart electromechanical actuator(EMA)system,and aiming at the force fighting problem when multiple actuators work synchronously,a multi input multi output(MIMO)position difference cross coupling control coordinated strategy based on double‑closed-loop load feedforward control is proposed and designed.In this strategy,the singular value method of return difference matrix is used to design the parameter range that meets the requirements of system stability margin,and the sensitivity function and the H_(∞)norm theory are used to design and determine the optimal solution in the obtained parameter stability region,so that the multi actuator system has excellent synchronization,stability and anti-interference.At the same time,the mathematical model of the integrated smart EMA system is established.According to the requirements of point-to-point control,the controller of double-loop control and load feedforward compensation is determined and designed to improve the frequency response and anti-interference ability of single actuator.Finally,the 270 V high-voltage smart EMA system experimental platform is built,and the frequency response,load feedforward compensation and coordinated control experiments are carried out to verify the correctness of the position difference cross coupling control strategy and the rationality of the parameter design,so that the system can reach the servo control indexes of bandwidth 6 Hz,the maximum output force 20000 N and the synchronization error≤0.1 mm,which effectively solves the problem of force fighting.

Transient Analysis and Control Strategies for a Quad-lnverter Multiphase Multilevel Motor Drive in Faulty Conditions

In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs （voltage source inverters） supplying the open-end windings of a dual three-phase induction motor is considered, quadrupling the power capability of a single VSI with given voltage and current ratings. In healthy conditions, the control algorithm is able to generate multi-level voltage waveforms, equivalent to the ones of a three-level inverter and to share the total motor power among the four dc sources in each switching period. This sharing capability is investigated under post-fault operating conditions, when one VSI must be completely insulated due to a severe failure on it. In this case, the conversion power unit can operate with a reduced power rating by a proper modulation of the remaining three VSIs. The whole ac motor drive has been numerically implemented, and the effectiveness of the proposed control strategies under healthy and post-fault operating conditions have been proved.

Optimization control strategy for single-phase permanent magnet generator based on voltage ripple

A method of feedforward compensation for electromotive force(EMF) in the single-phase permanent magnet linear generation system and a research in the performance of the single-phase PMLG system are presented.A general mathematical model for the single-phase permanet magnet linear generator(PMLG) system is established and the current loop,voltage loop and the feedforward control are studied based on it for the control system.Then this paper analyses the transfer function of the power system,optimizes current loop and voltage loop parameters by engineering algorithm,and calculates the optimal control parameters.An EMF feedforward compensation method is developed to optimize the control system which improves dynamic performance of the power system but does not affect the steady-state performance.The result of this research verifies the correctness and rationality of the design for the control system.

Computer Controlled High Precise, High Voltage Pules Generator

High precise, high voltage pulse generator made up of high-power IGBT and pulse transformers controlled by a computer are described. A simple main circuit topology employed in this pulse generator can reduce the cost meanwhile it still meets special requirements for pulsed electric fields (PEFs) in food process. The pulse generator utilizes a complex programmable logic device (CPLD) to generate trigger signals. Pulse-frequency, pulse-width and pulse-number are controlled via RS232 bus by a computer. The high voltage pulse generator well suits to the application for fluid food non-thermal effect in pulsed electric fields, for it can increase and decrease by the step length 1.