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Technical Paper

Study on Braking Force Distribution Algorithm for Hybrid Electric Bus Based on EBS

In order to improve the braking energy recovery, a parallel hybrid electric bus simulation model with electric braking system (EBS) was established by co-simulation platform for the TruckSim and Matlab/Simulink in this paper. EBS makes the front and rear shaft braking force arbitrarily distributed, which is more effective to improve the rate of energy recovery and the braking stability. A braking force distribution algorithm for hybrid electric bus based on EBS was designed in this paper. Under the premise to meet the driver's needs and the ECE regulations, this braking force distribution method focuses on making the braking force distribute to the drive shaft to a maximum extent, so as to obtain the maximum energy recovery rate by the utilization of the motor regenerative braking. At last, the simulation in different operating conditions was used to analyze the braking energy utilization and the braking performance based on the simulation model.
Technical Paper

Braking Force Distribution and Coordinated Control Algorithm for Hybrid Electric Bus based on EBS

In order to improve the braking energy recovery and ensure the braking comfort, a new type of regenerative braking coordinated control algorithm is designed in this paper. The hierarchical control theory is used to the regenerative braking control algorithm. First, the front axle braking force and rear axle braking force are distributed. Then the rear axle motor braking force and mechanical braking force are distributed. Finally, the dynamic coordinated control strategy is designed to control pneumatic braking system and motor braking system. Aimed at keeping the fluctuation of the total braking force of friction and the regenerative braking force small during braking modes switch, a coordinated controller was designed to control the pneumatic braking system to compensate the error of the motor braking force. Based on Matlab/Simulink platform, a parallel hybrid electric bus simulation model with electric braking system (EBS) was established.
Technical Paper

A New Kind of Road Structure-Borne N&V Prediction Method Based on Combination of High-Frequency Parameterized Model of Bushes, Multi-Body Calculation on Adams and Finite Element Model

Road NVH are becoming one of important performance controlled during passenger vehicle NVH development, especially for these EV vehicles due to lack of traditional gasoline or diesel engines noise sources. Generally speaking, traditional CAE and multi-body dynamic approaches have several drawbacks respectively, such as it is extremely difficult to get precise inputs as excitation to CAE model and non-linear parts in suspensions perform complex high frequency dynamic characteristics that is hard to be dealt with in multi-body software. Therefore, structure-borne road noise prediction has become one of difficult NVH problems in vehicle industry and eagerly, needs a systematic and scientific method. Under this circumstance, a new kind of high frequency road N&V co-simulation method has been introduced here to predict road NVH performance for one brand vehicle. This new approach includes three steps.
Technical Paper

One New Transient Transfer Path Analyses of Vehicle Interior Vibration Excited by Vertical Speed Hump

Vertical excitations from obstacles on public road are typical and likely to increase vehicle interior vibration through major paths of wheel spindle-suspension-body. A new transient transfer path analysis (TTPA) methodology is presented combining the substructure reverse matrix method based on FRFs with operational excitation. Additionally, a new kind of experimental method is applied to solve an engineering problem and also validates the TTPA theory above. There are three steps in all. Firstly, vibration in Z direction of wheel spindle was collected in one proving ground and represented on MTS 320 road simulator bench after many times of iteration of piston signals. This procedure guarantees excitation decoupling in one certain direction so it leads to accurate frequency response functions (FRFs) under transient shocking excitation. Secondly, the new transient transfer path analysis approach was used to calculate vibration contribution of wheel-suspension-body.
Technical Paper

Parameters Analyses and Identification for Rubber Bush Based on Theoretical Dynamic Model with Effects of Temperature and Preload

A series connection of the KVBC (Kelvin-Voigt and Bouc-wen) theoretical model of rubber bush in automobile suspension is established. The numerical calculation model is also developed through Matlab/simulation and 9 parameters are identified. Experiments are conducted on the rubber bush on a bench for dynamic and static characteristics and to supply appropriate and reliable data for parameter identification. Based on this, preload and temperature are taken into consideration in an ordinary KVBC model as two important additional factors. As a result, it leads to developing a novel model with new parameter identification, which is validated under different conditions. This new modeling method of rubber bush has three advantages. First, it shows improved accuracy for solving non-linear problems in a multi-body calculation, which is useful for researchers and vehicle engineers.