Chaochun Yuan

A hydrophilic separator for high performance lithium sulfur batteries

Rechargeable lithium sulfur batteries have been regarded as one of the most promising power source systems for next generation EVs or HEVs. However, the low utilization of active materials, rapid capacity degradation, and poor rate capability seriously restrict their large-scale applications in commercial markets. Herein, a novel strategy, using a hydrophilic separator which is prepared by auto-oxidization and self-polymerization of a dopamine monomer onto the surface of conventional hydrophobic separators, is reported to improve the electrochemical performance of Li–S batteries. The cells with the hydrophilic separator show significantly enhanced cycle performance. At a rate of 0.2 C, the battery demonstrates an initial capacity of 1271 mA h g−1, and the capacity can still remain at 1020.3 mA h g−1 after 30 cycles, which improves 77% compared with the cells using conventional separators.

Fuzzy Chaos Control for Vehicle Lateral Dynamics Based on Active Suspension System

The existing research of the active suspension system (ASS) mainly focuses on the different evaluation indexes and control strategies. Among the different components, the nonlinear characteristics of practical systems and control are usually not considered for vehicle lateral dynamics. But the vehicle model has some shortages on tyre model with side-slip angle, road adhesion coefficient, vertical load and velocity. In this paper, the nonlinear dynamic model of lateral system is considered and also the adaptive neural network of tire is introduced. By nonlinear analysis methods, such as the bifurcation diagram and Lyapunov exponent, it has shown that the lateral dynamics exhibits complicated motions with the forward speed. Then, a fuzzy control method is applied to the lateral system aiming to convert chaos into periodic motion using the linear-state feedback of an available lateral force with changing tire load. Finally, the rapid control prototyping is built to conduct the real vehicle test. By comparison of time response diagram, phase portraits and Lyapunov exponents at different work conditions, the results on step input and S-shaped road indicate that the slip angle and yaw velocity of lateral dynamics enter into stable domain and the results of test are consistent to the simulation and verified the correctness of simulation. And the Lyapunov exponents of the closed-loop system are becoming from positive to negative. This research proposes a fuzzy control method which has sufficient suppress chaotic motions as an effective active suspension system.

Research of electronic stability program based on the Mu control theory

In this paper, the Mu control method is employed to design controller for improved performance and robustness of electronic stability program system. The vehicles always undertake various effects including external disturbances, moreover, the vehicle control system has model errors in fact. The primary design techniques for electronic stability program control system maybe degrade the performances of vehicle. General uncertainties and external disturbances which can cause vehicle unstable are considered. A new controller for electronic stability program control system is constructed based on Mu control theory. The results show that the control system with Mu controller has fine dynamic characteristic, robust stability and robust performance, and the electronic stability program with the proposed control strategy can provide greater vehicle stability.

Sensor Fault-Tolerant Control of Electric Power Steering for Electric Vehicles

The existing research of the electric power steering (EPS) system less focuses on the safe and reliable operation. Especially the application of fault-tolerant theory to EPS of electric vehicles (EV) actually. In this paper, EPS is built based on sensor fault-tolerant control for EV. Then, the riccati equation is introduced constantly correcting weight matrix Q and R. Finally, a co-simulation analysis is conducted in MATLAB to evaluate the proposed fault-tolerant controller. It is shown that the design had a positive effect in that it could effectively improve performance due to sensor failure. And, a rapid control prototype is built based on dSPACE, a hardware-in-the-loop simulation platform, in order to conduct a real EV test. The results of test are consistent to the simulation and verified the correctness of simulation. The proposed research ensures the steering safety, enhances the EPS stability, and improves the driving comfort.

µ control of vehicle active suspension and electric power steering system

The integrated control model of active suspension and electrical power steering system was established. General uncertainties which can cause vehicle unstable were considered. An integrated controller for both active suspension and electric power steering system of vehicle was constructed based on µ control theory. The µ control law minimized an objective function (H2 norm) for a given controller structure, accounting for requirements of steering torque amplification, steering response, steering feel and the performances of vehicle. The calculated structured singular value and simulation results showed that the steering feel, dynamics performances of vehicle and the control systems robustness were all distinctly improved.