In order to solve the problem of State Of Charge (SOC) estimation error and ill-conditioned covariance in the iteration process caused by nonlinear transformation ignoring the high-order Taylor term in Extended Kalman Filter (EKF) algorithm, a Modified Covariance Approximate Second-Order Extended Kalman Filter (MVASOEKF) algorithm was adopted. Through the hybrid pulse power characteristic experiment, the internal parameters of the equivalent model were identified offline and the second-order RC equivalent battery model was established. The SOC was estimated on MATLAB/Simulink platform. The results show that the average absolute error value of EKF algorithm is about 2.0%, and the average absolute error value of MVASOEKF algorithm is about 0.5%. Compared with EKF algorithm, although MVASOEKF algorithm has more computation amount, but the SOC estimation accuracy has been significantly improved, and the convergence is better.

For the problems of high failure rate and low intelligence of the existing hidden exterior door handle, the optimization design was carried out to realize the functions of fault self-diagnosis, intelligent anti-pinch and autonomous deicing, so as to improve the safety and intelligence of the system. Experiments show that the intelligent hidden exterior door handle works properly, and the design is feasible.

In order to explore the influence of ambient temperature on the fuel consumption of Hybrid Electric Vehicle (HEV), this research team selected four HEVs with different technical routes to conduct several real driving fuel consumption tests at different temperatures. The results show that fuel consumption of Plug-in Hybrid Electric Vehicle (PHEV) and Range Extended Electric Vehicle (REEV) is apparently higher than lab fuel consumption test value, and that of None Off-Vehicle-Charging Hybrid Electric Vehicle (NOVC-HEV) and PHEV increases significantly under high and low temperature environments. Therefore, it is concluded that the WLTC test at room temperature cannot accurately reflect the real fuel consumption level of NOVC-HEV, REEV and HEV models, and the ambient temperature is an important factor affecting the fuel consumption of hybrid electric vehicles.

In order to explore the lightweight space of multi-purpose truck body, multidisciplinary optimization was carried out in three dimensions of performance, quality and cost. With the multi-purpose truck Body-In-White (BIW) as the research object, 46 design variables were selected, covering 1 680 sample points at 73 part thickness levels, and the optimal Latin hypercube method was used to conduct the experimental design of bending torsional stiffness, mode frequency, mass, and cost, to obtain the sensitivity of the part’s contribution to the BIW performance, and to establish a second-order polynomial response surface approximation model. Specifically, three groups of optimization solutions were formulated to maintain the basic performance level of the original body, the allowable stiffness decreased by 10%, and the modal fluctuation was 2 Hz; the allowable stiffness decreased by 20%, and the modal fluctuation was 4 Hz. The Pointer automatic optimizer was used to optimize the design with the minimum mass as the objective function. The results show that three optimization solutions can reduce the mass by 14.63 kg, 20.37 kg and 25.78 kg respectively.

With the structural characteristics of the passenger car side wall door opening as the research object to conduct compact design research, this paper elaborated systematically the principle, method and technical solution of the compact design. The hard point and section model of the door opening structure were obtained through structural disassembly. The hard point driven section was used for design, and the compact coefficient was defined and a parametric design table was established. The feasibility of battery layout and its impact on the door opening design were considered, to maximize the man-machine space within the limited vehicle size range as far as possible, improve the convenience of getting on and off the vehicle, and comprehensively consider multi-dimensional elements such as modeling, collision safety, lightweight, etc. Finally, the validity and feasibility of the design method were verified by analysis.

In order to facilitate algorithm development of power side door control system, this paper provided a driving force model and algorithm development strategy. The mechanical model of manual opening and closing and the driving force model of the actuator under the power side door hovering condition were created according to the layout parameters of the power side door components, the influence of longitudinal and transverse slope and door opening angle. The software MATLAB was used to generate simulation results, and formulate the algorithm development strategy of electric side door control system according to the simulation results. Finally, the accuracy of the model was verified by bench calibration.