Jianwu Zhang

Control strategy design and experimental research on a four-shaft electronic continuously variable transmission hybrid electric vehicle

A new electromechanical power-splitting full-hybrid transmission with two shifting elements, namely a four-shaft planetary gear and an electronic continuously variable transmission, is introduced in this paper. This transmission was developed with the aim of combining all the advantages of an internal combustion engine and two electric motors in an optimal way so as to improve the power performance and the fuel economy. The architecture and analogy of the four-shaft planetary gear are analysed, a control strategy is designed, and the engine management system and hybrid control system are calibrated. To evaluate the performance, the control strategy and the calibrated results, nine tests were performed as per the New European Driving Cycle under various initial conditions, different maps and different thresholds. The test results indicate that a four-shaft planetary gear, electronic continuously variable transmission hybrid electric vehicle can realize good fuel economy and good emissions performance except for nitrogen oxide emissions. The best fuel consumption obtained was 5.4 l/100u2009km. The amount of nitrogen oxide emissions needs to be decreased by optimizing the control strategy of the hybrid control system and calibration of the engine management system in future research.

Multi-body dynamics and noise analysis for the torsional vibration of a power-split hybrid driveline

Two dynamic models are established to study the torsional vibration and noise characteristics of a power-split hybrid driveline. One is developed using mathematical rotational motion of the driveline components in matrix form. The other dynamic model of the hybrid driveline is built in the multi-body dynamic software ADAMS. The natural frequencies and vibration modes computed from the two methods show a remarkable agreement. Moreover, the noise source identification for the power-split hybrid driveline is also undertaken according to the acoustic measures on the test bench. This study can provide a valuable reference to the development of hybrid electric vehicle in the future.

Torsional vibration and acoustic noise analysis of a compound planetary power-split hybrid electric vehicle:

Theoretical and experimental analyses of torsional vibrations and acoustic noise for a deep hybrid electric vehicle driveline including an electric, continuously variable transmission are carried out. The dynamic and mathematical models with 16 degrees of freedom in a matrix form are developed for the torsional vibration characteristics of the hybrid driveline. On the other hand, the noise sources of the hybrid electric vehicle powertrain excited in the pure electric mode and the hybrid drive mode are tested and measured using acoustic and speed sensors. The noise orders and the frequency domain responses are constructed using signal treatment and torsional vibration analysis. The theoretical predictions for the natural frequencies and the corresponding vibration modes of the hybrid driveline are presented. The noise test results are also given in accordance with the torsional vibration modes of the hybrid driveline in the pure electric mode and the hybrid drive mode. The noise sources due to the self-excited and frequency-multiplied vibrations are found, focusing on the compound planetary gear set in the power-split electric, continuously variable transmission.

Study on the torsional vibration of a hybrid electric vehicle powertrain with compound planetary power-split electronic continuous variable transmission:

A torsional vibration dynamic model is established with the commercial software ADAMS to predict the torsional vibration characteristics of a compound planetary power-split hybrid electric vehicle. By calculating and simulating the built model in ADAMS, the natural frequencies and corresponding modes are obtained. The results agree well with previous work, which derives the conclusions by solution of the system dynamics equations of hybrid driveline. Moreover, the main factors that influence the torsional vibration of the powertrain under the excitation of engine and electric motors are analyzed by the forced vibration analysis. The calculated results show that the low frequencies occur mainly in the torsional vibration of wheels and vehicle, while the high orders are related to the torsional vibration of differential, sun gears and planets. The results also show that the amplitude of torsional vibration of driveline is the lowest when the damping and stiffness of torsional damper are 15u2009Nms/rad and 618u2009Nm/rad respectively, the halfshaft stiffness is 2760u2009Nm/rad and the rotational inertial of engine is 0.42u2009kgm2. The research can be used to support the further development of the power-split hybrid electric vehicle.

Optimal control of an electromagnetic power-split hybrid electric vehicle

A new electromagnetic power-split hybrid electric vehicle is introduced in this paper. This system, which has a dual-rotor brush motor, was developed with the aim of combining all the advantages of an internal-combustion engine and two electric motors in an optimal way so as to improve the power performance and the fuel economy. This system can be used as an electromagnetic, continuously variable transmission. The architecture and analogy of the electromagnetic power-split hybrid electric vehicle are analysed; a control strategy is designed and explained in detail. The system’s optimal zone is designed. To evaluate the performance and the control strategy, the tests were performed on the chassis dynamometer under the New European Driving Cycle. The economic performance of the electromagnetic power-split hybrid electric vehicle is analysed. The operational zones of the engines of an electromagnetic power-split hybrid electric vehicle and of a conventional vehicle were compared. The results indicate that the designed vehicle control strategy of the electromagnetic power-split hybrid electric vehicle worked properly under the New European Driving Cycle and that the engine worked in the optimized zone. The average fuel consumption under the New European Driving Cycle is 4.75 l/100 km; the saved petrol ratio is 41.3% compared with that of the related prototype vehicle.

Vibration and acoustic investigation for a deep hybrid transmission with power-split compound planetary gear set

A new compound planetary gear set was produced for hybrid transmission with advantages superior to classical Ravigneaux planetary gears. However, vibration and noise problems need more attention in order to meet the market demand. Vibration characteristics of the new power-split hybrid transmission with a four-shaft compound planetary gear set are investigated. An equivalent method for stepped shaft is proposed to simplify the motor E1 shaft. Based on six degrees of freedom of helical gear pair model and shaft-bearing model, a dynamic model for the planetary mechanism is established in pure electric driving mode. The numerical analysis of the distinctive natural frequencies and corresponding vibration modes is produced. Moreover, in order to identify the noise source, noise and vibration experiments are carried out on test rig. By comparing the numerical results and test data, the noise and vibration at a frequency of 696 Hz are evidently caused by the transverse vibration of motor E1 shaft, and the rotational vibration of ring gear exacerbates the vibration and noise. Not only the impact of torques from motors E1, E2 and semi-shaft but also the influences of carrier speed and preload on differential bearings are investigated.

Torsional Vibration Characteristics of a Power-split Hybrid System

A torsional vibration dynamic model is built to predict the torsional vibration characteristics of a power–split hybrid system. On the basis of this dynamic model, the system dynamic equations of hybrid driveline are set, from which the natural frequencies and relevant mode shapes under different driving modes are solved using the corresponding eigenvalue problem. The calculated results show that the low frequencies occur mainly in the torsional vibration of wheels and vehicle, the intermediate frequencies are relevant to the torsional vibration of the sun gears, the differential and the reducer, in general, and the high frequencies are related to the torsional vibration of planets.

Dynamic modelling and parametric optimization of a full hybrid transmission

In this paper, vibro-impact-induced gear whine radiated by full hybrid transmission equipped with a compound type power-split planetary gear train is investigated. For accurate simulations of the planetary gear set vibrations, an integrated dynamic model of the transmission is established using professional software MASTA, on which compliance effects of gear pairs, bearings, shafts, housing and planetary carrier are counted for. Numerical analyses are carried out for dynamic responses of the hybrid transmission. Bench tests are also conducted for the present model validation. Computational effort is made to recognize parametrically resonate patterns that cause gear whine in experiment. An optimal tooth modification design is presented for the real planetary gear set. It is shown by test results using the optimized planetary gear sets that gear whine responses of the gearboxes are considerably improved.

Precise model-based simulation for a deep hybrid transmission with compound planetary gear set:

Establishing a precise system level model for transmission system is quite necessary and feasible for today’s computer technology. Taking into account of the exact parameters and actual working condition, an accurate model for a new deep hybrid transmission with compound planetary gear set is constructed, which in consideration of the gravity and centrifugal effect. The system level model contains the gears, shafts, bearings, clutches, electric motors and the housings. Few studies are found to investigate structure influence in system level for noise, vibration and harshness performance. Validation for the simulation results with test in three typical working conditions is carried out, which shows a quite well agreement. Furthermore, some parameters for this compound planetary gear set are investigated. The results show that for radial clearance between the ratchet and ring gear the smaller the better, while the axial clearance between the ratchet and ring gear requires cautious consideration to realize a better vibration performance for different planetary gear set. In the case of carrier, the radius of the connection pawl and the thickness of the carrier input shaft have remarkable influence on vibration characteristics. The vibration amplitude is the lowest when these two values equaling to 55 and 7 mm, respectively. Other than that, it is interesting to notice that the carrier position has a significant influence on the system vibration in pure electric drive mode. It is shown that if the planet carrier is fixed and sun gear rotates as input, the position of carrier should keep planet gears at high gravity center and symmetrical distribution on both sides of carrier centerline in the gravitational direction. The vibrational magnitude is the smallest as the carrier rotating 50° along z axis for this compound planetary gear set.

Vibration analysis and acoustic identification for a power-split planetary gear set

Vibration and acoustic characteristics of a new power-split hybrid transmission with a four-shaft planetary for passenger car are investigated in this research. A dynamic model with three degrees of freedom for the new compound planetary is established in pure electric driving mode. The numerical analysis for distinctive natural frequencies and corresponding vibration modes of this system are produced. Furthermore, in order to identify the noise source, acoustic and vibration experiments are carried out. Moreover, the finite element model for the shell cover is studied for verification of structure vibration resonant frequencies. It is demonstrated by comparison between numerical results and test data that the noise at frequency of 692u2009Hz is evidently related to the transverse vibration of motor E1 shaft, and the structure vibration of shell cover at frequency of 2930u2009Hz is exactly contributed to noise source at frequency near 3029u2009Hz.