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CSEE Journal of Power and energy Systems 2022年第3期8卷 710-720页

作者： Lin Yu Huadong Sun Shiyun Xu Bing Zhao Jian Zhang state key laboratory of Power Grid safety and energy Conservation China Electric Power Research InstituteBeijing100192China

The power system is experiencing a higher penetration of renewable energy generations(REGs).The short circuit ratio(SCR)and the grid impedance ratio(GIR)are two indices to quantify the system strength of the power system with *** this paper,the critical short circuit ratio(CSCR)is defined as the corresponding SCR when the system voltage is in the critical stable *** static voltage stability analysis,the mathematical expression of the CSCR considering the impact of GIR is *** maximum value of CSCR is adopted as the critical value to distinguish the weak power *** on the static equivalent circuit analysis,it is proved that the CSCR is still effective to evaluate critical system strength considering the interactive impact among ***,we find that the GIR can be neglected and the SCR can be used individually to evaluate the system strength when SCR>2 or GIR>*** correctness and rationality of the CSCR and its critical value are validated on ADPSS.

关键词： Critical short circuit ratio critical value grid impedance ratio maximum power transfer theorem static equivalent circuit analysis

Driving and Braking Control of PM Synchronous Motor Based on Low-resolution Hall Sensor for Battery Electric Vehicle

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Chinese Journal of Mechanical Engineering 2013年第1期26卷 1-10页

作者： GU Jing OUYANG Minggao LI Jianqiu LU Dongbin FANG Chuan MA Yan state key laboratory of automotive safety and energy Tsinghua University

Resolvers are normally employed for rotor positioning in motors for electric vehicles, but resolvers are expensive and vulnerable to vibrations. Hall sensors have the advantages of low cost and high reliability, but the positioning accuracy is low. Motors with Hall sensors are typically controlled by six-step commutation algorithm, which brings high torque ripple. This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor （PMSM） based on low-resolution Hall sensors. Field oriented control （FOC） based on Hall-effect sensors is developed to reduce the torque ripple. The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed. The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing. The braking control algorithms based on six-step commutation and FOC are studied. Two variants of the six-step commutation braking control, namely, half-bridge commutation and full-bridge commutation, are discussed and compared, which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces （EMF）, thus can deliver higher efficiency and smaller current ripple. The FOC braking is analyzed with the phasor diagrams. At a given motor speed, the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit, which is proportional to the motor speed. Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control, compared to six-step commutation braking control. Therefore, FOC braking is selected as the braking control algorithm for electric vehicles. The proposed research ensures a good motor control performance while maintaining low cost and high r

关键词： battery electric vehicle field oriented control low-resolution Hall sensor regenerative braking plug braking,six-step commutation braking

A Novel Pre-control Method of Vehicle Dynamics Stability Based on Critical Stable Velocity during Transient Steering Maneuvering

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 475-485页

作者： CHEN Jie SONG Jian LI Liang RAN Xu JIA Gang WU Kaihui state key laboratory of automotive safety and energy Tsinghua University

The current research of direct yaw moment control（DYC） system focus on the design of target yaw moment and the distribution of wheel brake force. The differential braking intervention can effectively improve the lateral stability of the vehicle, however, the effect of DYC can be improved a step further by applying the control of vehicle longitudinal velocity. In this paper, the relationship between the vehicle longitudinal velocity and lateral stability is studied, and the simulation results show that a decrease of 5 km/h of longitudinal velocity at a particular situation can bring 100° increasing of stable steering upper limit. A critical stable velocity considering the effect of steering and yaw rate measurement is defined to evaluate the risk of losing steer-ability or stability. A novel velocity pre-control method is proposed by using a hierarchical pre-control logic and is integrated with the traditional DYC system. The control algorithm is verified through a hardware in-the-loop simulation system. Double lane change（DLC） test results on both high friction coefficient（μ） and low μ roads show that by using the pre-control method, the steering effort in DLC test can be reduced by 38% and 51% and the peak value of brake pressure control can be reduced by 20% and 12% respectively on high μ and low μ roads, the lateral stability is also improved. This research proposes a novel DYC system with lighter control effort and better control effect.

关键词： vehicle dynamics direct yaw moment control critical stable velocity pre-control

Rule-based Fault Diagnosis of Hall Sensors and Fault-tolerant Control of PMSM

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Chinese Journal of Mechanical Engineering 2013年第4期26卷 813-822页

作者： SONG Ziyou LI Jianqiu OUYANG Minggao GU Jing FENG Xuning LU Dongbin state key laboratory of automotive safety and energy Tsinghua University

Hall sensor is widely used for estimating rotor phase of permanent magnet synchronous motor(PMSM). And rotor position is an essential parameter of PMSM control algorithm, hence it is very dangerous if Hall senor faults occur. But there is scarcely any research focusing on fault diagnosis and fault-tolerant control of Hall sensor used in PMSM. From this standpoint, the Hall sensor faults which may occur during the PMSM operating are theoretically analyzed. According to the analysis results, the fault diagnosis algorithm of Hall sensor, which is based on three rules, is proposed to classify the fault phenomena accurately. The rotor phase estimation algorithms, based on one or two Hall sensor(s), are initialized to engender the fault-tolerant control algorithm. The fault diagnosis algorithm can detect 60 Hall fault phenomena in total as well as all detections can be fulfilled in 1/138 rotor rotation period. The fault-tolerant control algorithm can achieve a smooth torque production which means the same control effect as normal control mode (with three Hall sensors). Finally, the PMSM bench test verifies the accuracy and rapidity of fault diagnosis and fault-tolerant control strategies. The fault diagnosis algorithm can detect all Hall sensor faults promptly and fault-tolerant control algorithm allows the PMSM to face failure conditions of one or two Hall sensor(s). In addition, the transitions between health-control and fault-tolerant control conditions are smooth without any additional noise and harshness. Proposed algorithms can deal with the Hall sensor faults of PMSM in real applications, and can be provided to realize the fault diagnosis and fault-tolerant control of PMSM.

关键词： electric vehicle permanent-magnet synchronous motor(PMSM) Hall sensors rule-based fault diagnosis fault-tolerant control

Torque-based Optimal Acceleration Control for Electric Vehicle

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 319-330页

作者： LU Dongbin OUYANG Minggao state key laboratory of automotive safety and energy Tsinghua University

The existing research of the acceleration control mainly focuses on an optimization of the velocity trajectory with respect to a criterion formulation that weights acceleration time and fuel consumption. The minimum-fuel acceleration problem in conventional vehicle has been solved by Pontryagin＇s maximum principle and dynamic programming algorithm, respectively. The acceleration control with minimum energy consumption for battery electric vehicle（EV） has not been reported. In this paper, the permanent magnet synchronous motor（PMSM） is controlled by the field oriented control（FOC） method and the electric drive system for the EV（including the PMSM, the inverter and the battery） is modeled to favor over a detailed consumption map. The analytical algorithm is proposed to analyze the optimal acceleration control and the optimal torque versus speed curve in the acceleration process is obtained. Considering the acceleration time, a penalty function is introduced to realize a fast vehicle speed tracking. The optimal acceleration control is also addressed with dynamic programming（DP）. This method can solve the optimal acceleration problem with precise time constraint, but it consumes a large amount of computation time. The EV used in simulation and experiment is a four-wheel hub motor drive electric vehicle. The simulation and experimental results show that the required battery energy has little difference between the acceleration control solved by analytical algorithm and that solved by DP, and is greatly reduced comparing with the constant pedal opening acceleration. The proposed analytical and DP algorithms can minimize the energy consumption in EV＇s acceleration process and the analytical algorithm is easy to be implemented in real-time control.

关键词： permanent magnet synchronous motor(PMSM) field oriented control(FOC) efficiency model electric vehicle energy optimal acceleration

Intelligent Vehicle Electrical Power Supply System with Central Coordinated Protection

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Chinese Journal of Mechanical Engineering 2016年第4期29卷 781-791页

作者： YANG Diange KONG Weiwei LI Bing LIAN Xiaomin state key laboratory of automotive safety and energy Tsinghua University

The current research of vehicle electrical power supply system mainly focuses on electric vehicles（EV） and hybrid electric vehicles（HEV）.The vehicle electrical power supply system used in traditional fuel vehicles is rather simple and imperfect;electrical/electronic devices（EEDs） applied in vehicles are usually directly connected with the vehicle＇s *** increasing numbers of EEDs being applied in traditional fuel vehicles,vehicle electrical power supply systems should be optimized and improved so that they can work more safely and more *** this paper,a new vehicle electrical power supply system for traditional fuel vehicles,which accounts for all electrical/electronic devices and complex work conditions,is proposed based on a smart electrical/electronic device（SEED） *** as an independent intelligent electrical power supply network,the proposed system is isolated from the electrical control module and communication network,and access to the vehicle system is made through a bus *** results in a clean controller power supply with no electromagnetic interference.A new practical battery state of charge（So C） estimation method is also proposed to achieve more accurate So C estimation for lead-acid batteries in traditional fuel vehicles so that the intelligent power system can monitor the status of the battery for an over-current state in each power *** protection methods are also used to ensure power supply *** and tests on a traditional fuel vehicle are performed,and the results reveal that the battery So C is calculated quickly and sufficiently accurately for battery over-discharge ***-current protection is achieved,and the entire vehicle＇s power utilization is *** traditional fuel vehicles,the proposed vehicle electrical power supply system is comprehensive and has a unified system architecture,enhancing system reliability and security.

关键词： vehicle electrical power supply battery management vehicle electrical system traditional fuel vehicle

Interaction of In-wheel Permanent Magnet Synchronous Motor with Tire Dynamics

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Chinese Journal of Mechanical Engineering 2015年第3期28卷 470-478页

作者： SONG Ziyou LI Jianqiu WEI Yintao XU Liangfei OUYANG Minggao state key laboratory of automotive safety and energy Tsinghua University

Drive wheel systems combined with the in-wheel permanent magnet synchronous motor（I-PMSM） and the tire are highly electromechanical-coupled. However, the deformation dynamics of this system, which may influence the system performance, is neglected in most existing literatures. For this reason, a deformable tire and a detailed I-PMSM are modeled using Matlab/Simulink. Furthermore, the influence of tire/road contact interface is accurately described by the non-linear relaxation length-based model and magic formula pragmatic model. The drive wheel model used in this paper is closer to that of a real tire in contrast to the rigid tire model which is widely used. Based on the near-precise model mentioned above, the sensitivity of the dynamic tire and I-PMSM parameters to the relative error of slip ratio estimation is analyzed. Additionally, the torsional and longitudinal vibrations of the drive wheel are presented both in time and frequency domains when a quarter vehicle is started under conditions of a specific torque curve, which includes an abrupt torque change from 30 N·m to 200 N·m. The parameters sensitivity on drive wheel vibrations is also studied, and the parameters include the mass distribution ratio of tire, the tire torsional stiffness, the tire damping coefficient, and the hysteresis band of the PMSM current control algorithm. Finally, different target torque curves are compared in the simulation, which shows that the estimation error of the slip ratio gets violent, and the longitudinal force includes more fluctuation components with the increasing change rate of the torque. This paper analyzes the influence of the drive wheel deformation on the vehicle dynamic control, and provides useful information regarding the electric vehicle traction control.

关键词： I-PMSM tire dynamics slip ratio estimation tire torsional vibrations longitudinal vibrations

Experimental study on filtration and continuous regeneration of a particulate filter system for heavy-duty diesel engines

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Journal of Environmental Sciences 2014年第12期26卷 2434-2439页

作者： Tao Tang Jun Zhang Dongxiao Cao Shijin Shuai Yanguang Zhao state key laboratory of automotive safety and energy Tsinghua University

This study investigated the filtration and continuous regeneration of a particulate filter system on an engine test bench, consisting of a diesel oxidation catalyst（DOC） and a catalyzed diesel particulate filter（CDPF）. Both the DOC and the CDPF led to a high conversion of NO to NO2 for continuous regeneration. The filtration efficiency on solid particle number（SPN） was close to100%. The post-CDPF particles were mainly in accumulation mode. The downstream SPN was sensitively influenced by the variation of the soot loading. This phenomenon provides a method for determining the balance point temperature by measuring the trend of SPN concentration.

关键词： Catalyzed diesel particulate filter Diesel oxidation catalyst Filtration Regeneration Balance point temperature

Influence of Tire Dynamics on Slip Ratio Estimation of Independent Driving Wheel System

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Chinese Journal of Mechanical Engineering 2014年第6期27卷 1203-1210页

作者： LI Jianqiu SONG Ziyou WEI Yintao OUYANG Minggao state key laboratory of automotive safety and energy Tsinghua University

The independent driving wheel system, which is composed of in-wheel permanent magnet synchronous motor（I-PMSM） and tire, is more convenient to estimate the slip ratio because the rotary speed of the rotor can be accurately measured. However, the ring speed of the tire ring doesn’t equal to the rotor speed considering the tire deformation. For this reason, a deformable tire and a detailed I-PMSM are modeled by using Matlab/Simulink. Moreover, the tire/road contact interface（a slippery road） is accurately described by the non-linear relaxation length-based model and the Magic Formula pragmatic model. Based on the relatively accurate model, the error of slip ratio estimated by the rotor rotary speed is analyzed in both time and frequency domains when a quarter car is started by the I-PMSM with a definite target torque input curve. In addition, the natural frequencies（NFs） of the driving wheel system with variable parameters are illustrated to present the relationship between the slip ratio estimation error and the NF. According to this relationship, a low-pass filter, whose cut-off frequency corresponds to the NF, is proposed to eliminate the error in the estimated slip ratio. The analysis, concerning the effect of the driving wheel parameters and road conditions on slip ratio estimation, shows that the peak estimation error can be reduced up to 75% when the LPF is adopted. The robustness and effectiveness of the LPF are therefore validated. This paper builds up the deformable tire model and the detailed I-PMSM models, and analyzes the effect of the driving wheel parameters and road conditions on slip ratio estimation.

关键词： electric vehicle (EV) driving wheel system tire dynamics slip ratio estimation characteristic frequency low-pass filter (LPF)

Multi-scale Studies of Glass Transition and Uniaxial Tensile Properties of a Commercially Available Epoxy Adhesive Using Experimental Measurements and Molecular Dynamics Simulation

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Chinese Journal of Polymer Science 2015年第3期33卷 465-474页

作者：姚力 state key laboratory of automotive safety and energy Department of Automotive EngineeringTsinghua University

In this study, the glass transition and uniaxial tensile properties of a commercially available epoxy adhesive were investigated using experimental measurements and molecular dynamics （MD） simulation. Differential scanning calorimetry （DSC） was used to study the change of glass transition temperature （Tg） with cross-link density （CLD）. Uniaxial tensile test was performed to measure the Young＇s modulus （E）, Poisson＇s ratio （v） and yielding strength （tyv）. In MD simulation, the complicated epoxy system was simplified as the mixture of two kinds of simple molecules, with the key information well preserved and the less important details omitted. The molecular model of the cross-linked epoxy network was constructed and its mechanical properties were calculated using MD simulation. Overall, the MD simulation results agreed with experimental ones, which proved the validity of the molecular model and justified the simplification method of the industry- level epoxy system.

关键词： Epoxy adhesive Glass transition temperature Uniaxial tension Experiment Molecular dynamics simulation.