SOC Definition of Battery Management System Used in Hybrid Vehicles

For the requirement of building up the battery management system (BMS) of hybrid vehicles(HEVs), the real time measurement and estimation of charge (SOC) of the Ni MH batteries are investigated, because the popular SOC definition is unsuitable under the condition of variable current discharge. The origin of this kind unsuitability are analyzed ,and the characteristics and existing problems of different kinds of SOC measuring methods are compared. On the basis of mentioned above, some corrections are given to the popular SOC definition, and the new conception of SOC is proposed. The corrected definition of SOC is suitable for the real time SOC estimation under the variable current condition of the batteries used in HEVs. Based on the corrected SOC definition, the computational model of the new SOC is built and simulated. Satisfactory result has been obtained from comparisons of the simulating results, which shows that the theoretical model provides a basis for optimizing the adaptation of power system to the hybrid vehicles (HEVs).     

The cooling structure of Ni MH batteries in hybrid electric vehicles

Focusing on Ni MH batteries used in hybrid electric vehicles (HEV), a simulation analysis of the flow and temperature fields of the cooling structure in existing batteries is carried out using computational fluid dynamics software. The results show that the temperature uniformity is poor. The uniformity of the flow and the temperature fields is improved by adjusting the baffle and battery positions, changing the tilt angle and the distance between the batteries, inserting wind plates and a coating insulation layer. The coating insulation layer achieves the best effect. Further simulation shows that the coating insulation layer method has the best effects. The results provide the design basis for thermal management program of Ni MH batteries in HEV.     

Optimized regenerative braking strategy for a medium hybrid electric vehicle cruising downhill

The regenerative braking process of hybrid electric vehicles (HEVs) cruising downhill was analyzed. Based on the charging efficiency, temperature model of battery, and efficiency model of the generator, instantaneous and global optimal control strategies were proposed, with the goal of maximum of instantaneous regenerative braking energy and total regenerative braking energy respectively. Regenerative braking energy efficiency on roads of differing slopes and slope lengths were obtained. The results show that global optimal control strategy is better than instantaneous optimal control strategy, and the steeper the slope or the longer the slope is, the more distinct the increase of regenerative braking energy efficiency with a global optimal control strategy is. The influence of battery temperature on efficiency of regenerative braking energy of HEVs was also discussed.     

Testing and modal analysis on multi stage planetarygearbox housing of shield tunnelling machine

The finite element model is developed for the multi stage planetary gearbox housing in shield tunnelling machine (STM), and the the eigenvalue problem is solved by using block Lanczos method, and then the low order natural frequencies and corresponding modes are extracted. Based on the theory of experimental modal analysis, the modal testing is made for the gearbox housing by pulse excitation method. The least squares complex frequency domain (LSCF) estimation method is used to analyze the modal data, and the natural characteristics of housing is obtained. According to the modal assurance criterion (MAC), the experimental modal parameters are validated. Modal analysis shows that the experimental data is coincided with analytical results, which indicates the accuracy of the theoretical model and testing method. The coupling sympathetic vibration is disappearing between the gears train and housing, the local vibration is large at the high speed side of gearbox housing, and the torsional mode is outstanding under operating condition. The research results provide theoretical basis and experimental support for the structural optimization of the gearbox of STM.     

Influence of flow-equilibrating device on purification of flue gas from MSW incineration

The influences of flow-equilibrating device on flue gas purification by spray drying are studied numerically with RNG k-ε turbulent model and stochastic droplet track model. The effects of flow-equilibrating device on flue gas streamline, droplets distribution, internal resistance, adhering ratio and purification efficiency are investigated. The flow field is more uniform and symmetrical after the flow equalization plate is added. The internal resistance decreases gradually with increasing diameter of the opening area of flow equalization plate. The percentage of droplet adhering on the wall is first increased, and then decreased when opening area diameter increases from 0.2 to 0.7 m. The maximum value reaches 38.2% when the diameter equals to 0.4 m. The purification efficiency for SO2 and HCl has increased after the plate is added. The desulphurization efficiency increases from 60.25% to 68.56%. HCl removal efficiency increases from 93.73% to 97.62%. The results can provide theoretical basis for flue gas purifying system optimization and parameters selection.     

State of charge estimation of lithium iron phosphate batteriesbased on adaptive Kalman filters

The Kalman filter algorithm can be used to estimate the state of charge (SOC) of power batteries, however, it easily causes divergence due to uncertain of system noise and its estimation performance is affected by model. An adaptive Kalman filter algorithm is adopted to dynamically estimate SOC of lithium iron phosphate batteries for application in electric vehicles. At first, an equivalent circuit model, appropriate for SOC estimation is built after studying battery models. Then some charging and discharging experiments are carried out for parameter identification and the results are verified. At last, the adaptive Kalman filter algorithm is used on this model for on-line SOC estimation under unknown interfering noise. Simulation results show that adaptive Kalman filter method can correct SOC estimation error caused by tiny model error online, and the estimate accuracy is higher than Kalman filter method. Adaptive Kalman filter algorithm can also correct the initial error. Full-cycle test in electric vehicles proves that the algorithm is appropriate for SOC estimation of lithium iron phosphate battery.     

Equalization charging research and application of lithium iron phosphate batteries group

Management system for Lithium iron phosphate(LiFePO4) power batteries group is built,based on car battery series charge features. Series charge experiment of power batteries group is carried out using battery charger. Single cell voltage and state of charge(SOC) is analyzed in series charge for batteries group. Dispersivity influence of single cell is studied on charge performance of the battery packs,small current supplementary charge equalization is proposed,to make single cell battery state of charge is basically almost the same. Theoretical analysis and experimental results show that single cell voltage difference is very large,but SOC difference is very small in the end of battery series charge. A novel battery packs charge equalization method is presented,which avoids the problem of some batteries overcharge and other batteries less chargedproblem.     

Development and application of continuouslyvariable transmission test facilities

Basic structure and speed control principles of rubber V belt continuously variable transmissions (CVT) are analyzed. A test bench on which the governing characteristics, carrying capacity, pulley diameters, and transmission efficiency of CVTs can be tested is developed. This test rig permits the measurement of speed, torque and axial displacements of moveable flanges. The experiment not only verifies the results of the theoretical analysis but also reveals the trend of governing characteristics and efficiency affected by the operating condition changes. These conditions include the speed ratio, rotational speed, and external load. Based on this investigation, a method for improving CVT efficiency is proposed. The feasibility of the test bench is demonstrated by the experiment, which has a guiding role for design and parameter matching of CVTs.     

Model predictive control for a plug-in hybrid electric vehicle

The dynamic programming is applied to model predictive control configuration, and a predictive control mathematics model is established for the fuel economy of plug-in hybrid electric vehicles (HEVs) based on spatial-domain. A global optimal method for plug-in HEVs is studied with dynamic programming, and the results indicate that the state of charge (SOC) is reduced slowly from the maximum at a trip’s initiation to the low threshold at the destination. The theoretical SOC slope is proposed to be taken as the reference slope of model predictive control, and the theoretical reference contrail of SOC is modified according to the especial driving modes in future. The results show that the predictive control effect of this method is approached to the calculation result of global optimal and fuel consumption is obviously reduced.     

Quick Charge Method of Hybrid Vehicle''s Battery

For the requirement of building up the battery management system of hybridelectric vehicle,the method of quick charge of batteries is investigatedunder the conditions of ensuring natural life of batteries. The characteristics of the general charge methods areanalyzed, and existing problems of these charge methods are discussed. In order to solve those problems, a new quick charge method for HEV batteries is proposed, which can shorten charge time under the variable-current condition of the battery pack,andcan sustain the state of charge (SOC) of batteries within the scope between 50% and 80%.     

Algorithm of removing outliers in SVR

The outlier and the measurement that an outlier does not fit the theoretical model in the regression problems are defined. The relationship between the theoretical model and the regression model in the regression problem is analyzed. An approximate theorem is proposed and verified by deleting outlier one by one to construct SVR to approximate the theoretical model. An algorithm of detecting outliers in the SVR problems is constructed based on the approximate theorem. The theoretical analysis of the convergence and effectiveness of the proposed algorithm is given. Then, the step-by-step search algorithm is introduced to improve the outlier removing algorithm to remove outliers in SVR with large-scale samples. The theoretical analysis shows that the improved algorithm is convergent and effective. Finally, the samples produced by two test functions and the samples in UCI data set are used for simulation, and the results show that the proposed algorithm is effective and robust.     

Powertrain parameter design for the electric vehicle considering driving cycle

In allusion to the defects of traditional theory matching method, the authors propose a new power matching method which combines theoretic calculation and cycle working condition together for powertrain of pure electric automobiles. Based on dynamic constraint, the peak power of motor is determined. In order to make the motor work in high efficiency area, the power needed by vehicles in ten cycles is analyzed and the motor rated power is determined. Regular effect pattern of battery parameters on dynamic property and driving range of entire vehicle is analyzed. With defining a conception of acceleration time influence factor and continue driving range influence factor, motor parameters are amended. The transmission ratio is optimized with taking the power of the entire vehicle as constraint and the maximum driving range in constant speed condition as object, and the driving range is greatly improved. The output power of battery in different SOCs is simulated, and it’s found that when the SOC closes to lower limit, the output power of battery is able to satisfy the demand of the vehicle.     

Wind Tunnel Tests of Long Span Half - through Arch Bridge Section Model

Wind induced vibration is one of the main control factors in the Long span bridge structure design. The wind tunnel tests for measuring the static wind forces on the bridge girder and the section model wind tunnel dynamic testing for Caiyuanba Yangtze River Bridge in Chongqing are introduced in this paper. The wind tunnel testing for measuring static wind forces and vortex- induced vibration test on the arch are introduced taking account of the influence between two arches. The main contents and outcomes of testing are presented. It is indicated that the bridge girder has excellent wind stability and the arch mechanical characters are rather complicated. The drag force on the hind arch varied a lot because of the font arch interference on the wind flow. The drag force on the hind arch will be negative when two arches are close to each other. It increases with the space of two arches. The results of testing will give the data of buffeting and vortex - induced vibration and flutter analysis of the bridge.     

Analysis on the lengths of spill flame under a horizontal projection at the building faade

The effects of heat release rate and opening size on the structure of spill flame beneath a horizontal projection are investigated. The lengths of the spill flame are obtained from digital videos combined with an image processing method. The theoretical model that describes the flow and combustion dynamics of spill flame under a horizontal projection is established. The air entrainment coefficient and the excess air ratio are determined by combing the theoretical model and the measured temperatures,which are about 0.12 and 3.7,respectively. The prediction formula for the flame length under a horizontal projection is thus obtained,which provides references for the passive fire prevention design by using horizontal projections.     

Parameter uncertainty analysis for probability distribution of bulk power systerm reliability

Component reliability parameters are of uncertainty and are affected by the component type, operation time, and weather conditions. So do the reliability indices of bulk power systems. The calculation of its probability distributions and its alteration law affected by parameters uncertainty are researched to provide practical engineering reference with exploring the impact of the parameter uncertainty on reliability assessment. The point estimate method is firstly proposed based on the two-loop Monte-Carlo simulation, and then the improved Monte-Carlo simulation is presented to enhance the calculation efficiency further. Moreover, their theories, merits and faults are explained in detail. It can be seen from the evaluation results for the RBTS power systems that the accuracy of the three methods are similar but the improved Monte-Carlo simulation has the highest efficiency, followed by the point estimate method. The IEEE-RTS 79 power system is evaluated by using the improved Monte-Carlo simulation, and the results verify its validity.     

Method of Measuring Rotational Speed for a High-speed Rotator Dynamic-balancing Testing System Based on DSP

The device of testing rotational speed is very important to dynamic-balancing testing system.Requirements for the device of testing rotational speed include: high-accuracy,stabilization,credibility,and shorter testing time.To the development of high-speed rotor dynamic-balancing testing system based on DSP(digital signal processing),the way of picking-up rotator reference signal,testing rotator speed based on DSP and the design of software are introduced.This new way of testing rotational speed in high-speed rotor dynamic-balancing testing system based on DSP is accurate,simple,convenient,the range of rotational speed which can test is broad,and the new way is very suitable to pick-up the amplitude and phase of vibration caused by unbalanced amount.     

Research on Current Situation and Trend of Control Strategies for Hybrid Electric Vehicles

The vehicle's driving performances is determined by the control strategies and constructions of hybrid electric vehicles (HEV). The constructions of HEV are classified according to the change of state of charge of battery pack, and a study on current situation and trend of control strategies for HEV is presented in this paper. The research indicated that the current control strategies for HEV are not perfect and need further optimization. The control strategies should realize the optimum match among engine, motor, battery and transmission according to the characteristics of each component and vehicle's driving conditions. Many aspects including the fuel economy, emission, the life of battery pack, drivability, the reliability of each component and HEV's manufacture cost should be considered in the control strategies. A study on the control strategies and its optimization that take account of the aspects mentioned above is a work emphasis in the future. This paper also points out the PHEV equipped with small motor, small engine and continuously variable transmission is an ideal system construction for getting optimal fuel economy, lower emissions, steady drivability, lower manufacture cost and HEV's mass.     

Parameter Design for the Power Train and Simulation of the Dynamic Performance of Elctrical Vehicle

The method and principle of the parameter design for the power train of EV is explored and discussed,then the parametersof EV. based on SC7101 are reasonably selected.The method of calculating the SOC of Lead_acid battery is provided and the relation among the electromotive force,the interior resistance, the polarized resistance and the SOC are analyzed. The capacity is compensated according to the relation between the capacity and the temperature, which is the basis on which the energy management system is designed and improved. The dynamic model which reflects the dynamic characteristics of the power train is established,then the dynamic performance of the EV based on SC7101 is simulated, and the factors that affect the continuous mileage of EV are analyzed,the measures to increase the continuous mileage are provided.The result shows that the analysis of the electric characteristics of battery and the dynamic model are correct,and the dynamic performance perfectly meets the need of the design target.     

Research and development of a testing control system for a heavy duty vehicle automatic mechanical transmission test bench

Automatic mechanical transmissions (AMT) are suitable for use in heavy duty vehicles. Bench testing is an important task of the research and development. Many objectives, such as AMT performance testing, matching AMTs with engines, and optimizing control rules, can be achieved through bench testing, thereby laying a foundation for AMT application. An AMT testing bench is built up based on a developed AMT. By analyzing the performance requirements of AMT bench testing for heavy duty vehicles, a testing controlling system scheme is proposed and methods of data acquisition and communication are analyzed. Control methods for actuators are proposed based on analyzing the characteristics of AMT actuators. A testing control program for AMT bench testing is developed based on the Delphi platform. The entire bench testing system possesses advances test functions.     

Energy Efficiency of Water Transportation System for Surface Water Source Heat Pump

The forms of water transportation, arrangement and operation of pumps contribute to the water transportation energy consumption, which influences the energy-saving effect of surface water source heat pump. The relation between the pumping height and energy consumption of pumps is found by analyzing the model of pump energy consumption. The concept and calculation of critical pumping height is presented considering the limited rate of system energy efficiency. Based on the principle that the pump power changes with water flow rate, the determination of pumps arrangement of one or two stage pumps is described with a concrete example. The influence of water flow rate on heat pumps and water pumps is analyzed, and the energy efficiency of constant and variable water volume are compared. The operation way of this example is concluded for the optimal system energy efficiency. It is found that there is a critical pumping height for the energy-saving effect of surface water source heat pump compared with the traditional system. Moreover, the operation strategies should be determined by the system optimal model since the energy consumptions proportions of heat pumps and water pumps are variable.