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Zhu B.,University of Technology, Sydney | Zhang N.,University of Technology, Sydney | Walker P.,University of Technology, Sydney | Zhou X.,University of Technology, Sydney | And 3 more authors.
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering | Year: 2015

As pure electric vehicles are considered to be a major growth trend in the automotive industry, research into and development of efficient electric powertrain systems and related control technologies have become popular research topics. The growing importance and use of multi-speed transmissions in these vehicles make shift schedule design and research a crucial aspect of the powertrain systems design of pure electric vehicles. This paper provides a gear shift schedule calculation method for pure electric vehicles, which includes a dynamic shift schedule and an economic shift schedule calculation method, demonstrating how to optimize the shift points and to produce the upshift and downshift lines based on the motor efficiency map. Through the establishment of a pure electric vehicle model, simulation results show that a properly designed shift schedule can improve the working region of the motor and can refine the dynamic performance and the economic performance of the vehicle. Finally, rig testing results are demonstrated to be comparable with simulations and indicate the correctness of the method. © IMechE 2014.

Zhou X.,University of Technology, Sydney | Walker P.,University of Technology, Sydney | Zhang N.,University of Technology, Sydney | Zhang N.,Hunan University | And 3 more authors.
Mechanism and Machine Theory | Year: 2014

The theoretical analysis of drag torques within a two-speed dual clutch transmission is presented in this article. The numerical models are developed to study the different sources of drag torques in dual clutch transmission. Simulations are performed in Matlab/Simulink platform to investigate the variation of drag torques under different operating conditions. Then an experimental investigation is conducted to evaluate the proposed model using an electric vehicle powertrain test rig. Outcomes of experimentation confirm that simulation results agree well with test data. Therefore the proposed model performs well in the prediction of drag torque for the transmission, and can be applied to assess the efficiency of the transmission. Results demonstrate that the entire drag torque is dominated by the viscous shear in the wet clutch pack and gear churning losses. This lays a theoretical foundation to future research on reducing drag torque and applications of drag torque in powertrain system efficiency optimization. © 2014 Elsevier Ltd.

Zhou X.,University of Technology, Sydney | Walker P.,University of Technology, Sydney | Zhang N.,University of Technology, Sydney | Zhu B.,BAIC Motor Electrical Vehicle Co Ltd
SAE Technical Papers | Year: 2013

This paper proposes an approach to optimize the economy performance of a two-speed electric vehicle (EV) by combining gear shifting schedule design and gear ratios selection. Mathematic models for the two-speed EV subsystems are developed, including those of the battery module, electric machine, the driver, transmission and vehicle. Then a procedure for obtaining the optimal gear ratio pairs and corresponding shift schedule for the two-speed EV is presented in detail. The optimized EV powertrain parameters can not only ensure that basic requirements in dynamic performance are achieved, but realize the optimal economic performance of the EV as well. In order to investigate the effectiveness of the proposed method for EV design, simulations based on the developed powertrain model is conducted using different test driving cycles, including NEDC and constant speed. Results of these simulations validate the effectiveness of the proposed optimization method. Copyright © 2013 SAE International.

Walker P.D.,University of Technology, Sydney | Zhu B.,University of Technology, Sydney | Zhu B.,BAIC Motor Electrical Vehicle Co. | Zhang N.,University of Technology, Sydney
Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME | Year: 2014

The purpose of this paper is to develop a comprehensive nonlinear model of a typical direct acting solenoid valves utilized for clutch control in wet dual clutch transmissions. To do so, mathematical models of the integrated electrohydraulic solenoid valve and wet clutch piston assembly are developed in the SIMULINK environment of MATLAB. Through simulation the operating characteristics of the control valve are analyzed, demonstrating that the valve achieves dual functionalities of high flow and accurate pressure control depending on demands. This is realized through the designed force balancing of the valve spool. The dependency of the system to system variables on input pressure and the influence of air content on dynamic response of the valve are investigated. The resilience of output pressure is demonstrated to these variables, indicating strong system reliability. Finally, the model is then validated using in situ experimental testing on a powertrain test rig. The comparison of experimental and simulated results for steady state pressure as well as step and ramp input responses demonstrate good agreement. Copyright © 2014 by ASME.

Walker P.D.,University of Technology, Sydney | Abdul Rahman S.,University of Malaysia, Terengganu | Zhu B.,University of Technology, Sydney | Zhu B.,BAIC Motor Electrical Vehicle Co. | Zhang N.,University of Technology, Sydney
Advances in Mechanical Engineering | Year: 2013

Pure electric vehicles (PEVs) provide a unique problem in powertrain design through the meeting of performance specifications whilst maximising driving range. The consideration of single speed and multispeed transmissions for electric vehicles provides two strategies for achieving desired range and performance specifications. Through the implementation of system level vehicle models, design analysis, and optimisation, this paper analyses the application of both single speed and two-speed transmission applications to electric vehicles. Initially, transmission ratios are designed based on grade and top speed requirements, and impact on vehicle traction curve is evaluated. Then performance studies are conducted for different transmission ratios using both single speed and two-speed powertrain configurations to provide a comparative assessment of the vehicles. Finally, multivariable optimisation in the form of genetic algorithms is employed to determine an optimal gear ratio selection for single speed and two-speed PEVs. Results demonstrate that the two-speed transmission is capable of achieving better results for performance requirements over a single speed transmission, including vehicle acceleration and grade climbing. However, the lower powertrain efficiency reduces the simulated range results. © 2013 Paul D. Walker et al.

Zhu B.,University of Technology, Sydney | Zhu B.,BAIC Motor Electrical Vehicle Co. | Zhang N.,University of Technology, Sydney | Walker P.,University of Technology, Sydney | And 3 more authors.
Advances in Mechanical Engineering | Year: 2013

Dual clutch transmissions (DCTs) are recognized as being suitable for electric drive applications as they can drive with high efficiency and achieve good shifting comfort. A two-speed DCT electric drivetrain is described in this paper, comprised of only two gear pairs and a final drive gear in the two-speed gearbox. The fundamental shifting control algorithm is provided. On the testing rig of University of Technology, Sydney (UTS) powertrain lab, shifting controls and some driving cycle controls were realized. The results demonstrated that the control algorithm functioned well both in transient shifting control process and in the driving cycle conditions. © 2013 Bo Zhu et al.

Wang Y.,Hunan University | Meng B.,Hunan University | Shen Y.,Hunan University | Wei Y.,BAIC Motor Electrical Vehicle Co. | And 4 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

The extended range electric vehicle (EREV or REEV), as a transition vehicle type from custom engine vehicle to the electric vehicle, has become a hot point of the global automobile industry research and development because it's no drop anchor for power shortage, high efficiency and low battery capacity required. In this paper, power component selection, power configuration, efficiency optimization and coordination control of EREV are analyzed. Combined with the independent developed EREV, the specific research of the key technologies is presented. In addition, we point out the notable related important research subjects and directions in this paper. © 2014 Chin. Soc. for Elec. Eng.

Shen Y.,Hunan University | Wang Y.,Hunan University | Meng B.,Hunan University | Yi D.,BAIC Motor Electrical Vehicle Co.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

To solve the cooperative control problem of the engine and generator in APU system, the speed switching-power following APU cooperative control strategy was proposed herein. Firstly, the power-speed switching table of the engine was designed according to the optimal brake specific fuel consumption (BSFC) curve. Then, a second order sliding mode controller of the engine speed was designed, which was based on the engine mean value model. Meanwhile, the PWM rectifier output power controller was designed, which was based on the direct power control algorithm. Through the closed-loop control of the engine speed and PWM rectifier power, the proposed control strategy forced the engine to run along the optimal BSFC curve. Finally, the joint simulation model was developed based on AVL Cruise and MATLAB/Simulink. The simulation results show that the proposed APU cooperative control strategy is excellent in aspects of power following and speed controlling accuracy, battery voltage, current and state of charge (SOC) fluctuations, as well as the operating points distributions. ©, 2015, China Mechanical Engineering Magazine Office. All right reserved.

Jiao J.-P.,Beijing University of Technology | Liu W.-H.,Beijing University of Technology | Liu W.-H.,BAIC Motor Electrical Vehicle Co. | He C.-F.,Beijing University of Technology | And 2 more authors.
Experimental Mechanics | Year: 2014

Nonlinear acoustic interactions at contact interfaces can be used to characterize defects or imperfect bonds at these interfaces. Most methods used to characterize nonlinear interactions consider only a portion of the nonlinear signature, such as nonlinearities caused by high-order harmonics or sidebands. We describe a signal processing algorithm that can extract three nonlinear indicators related to amplitude attenuation, phase shift, and harmonics. Two aluminum blocks were mounted together to form a contact interface and subjected to normal compressive loading. Experiments were conducted to investigate the nonlinear interactions between the ultrasonic waves and interfaces, with a focus on the influence of excitation levels, applied pressure, and surface roughness. The ultrasonic signals were then processed using the nonlinear feature extraction algorithm. We show that the nonlinear indicators can characterize the contact condition of interfaces, and that their sensitivities to pressure differ for interfaces of different roughness and over different pressure ranges. © 2013 Society for Experimental Mechanics.

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