Liao Chenglin

Recursive modeling and online identification of lithium-ion batteries for electric vehicle applications

For safe and reliable operation of lithium-ion batteries in electric vehicles, the real-time monitoring of their internal states is important. The purpose of our study is to find an easily implementable, online identification method for lithium-ion batteries in electric vehicles. In this article, we propose an equivalent circuit model structure. Based on the model structure we derive the recursive mathematical description. The recursive extended least square algorithm is introduced to estimate the model parameters online. The accuracy and robustness are validated through experiments and simulations. Real-road driving cycle experiment shows that the proposed online identification method can achieve acceptable accuracy with the maximum error of less than 5.52%. In addition, it is proved that the proposed method can also be used to estimate the real-time SOH and SOC of the batteries.

Research on positioning technique of wireless power transfer system for electric vehicles

The relative position of the energy transmitting coil and the energy receiving coil has a great influence on the transfer efficiency of the wireless power transfer systems. The transfer efficiency has a marked fall when the two coils are misaligned. Thus it is important to know the exactly position of the two coils to achieve high system efficiency. This paper focuses on the positioning solution for guiding the electric vehicles to the charging area and ensuring the alignment of the two coils. This solution is based on the RFID(radio frequency identification) technique and combined with the magnetic field coupling method to achieve high accuracy and large scale in positioning. The RFID is considered as one of the most preferable ways for the position estimation in indoor and local environment. The positioning system calculates the real-time position of the vehicle in the parking area. Then the position signal is sent to the screem to show the driver where the car actually is. When the two coils are well aligned, the wireless power transfer system can start charging the vehicle.

Realization of an energy management strategy for a series-parallel hybrid electric vehicle

This paper primarily describes an energy management strategy which has been applied to a series-parallel hybrid electric vehicle, whose front wheels are driven by engine-ISG hybrid system and rear wheels by two wheel motors respectively. Energy management strategy determines how energy flows in hybrid electric vehicles, and therefore has a significant impact on the fuel economy of HEV. After an introduction of the power system of the SPHEV a rule-based energy management strategy is presented. To better support this strategy, equivalent fuel consumption rate is adopted as a uniform standard of fuel economy. The situation that the internal combustion runs with low fuel efficiency is reduced for the most part. Simulation and vehicle test results reveal the feasibility of the proposed energy management strategy.

Modeling and simulation of traction control of Hybrid Electric Vehicle

Slipping drive wheels can provide little lateral force, thus when drive wheels are slipping, the front wheel drive vehicles will lose turning ability, while the rear wheel drive vehicles will spin. Compared to the conventional vehicles, HEVs are more easily to slip when driving on slippery road, since the electric motor can provide large drive torque under low speeds. In this paper, the dynamic modeling of a HEV which consists of engine modeling, ISG modeling and vehicle dynamics is realized and a traction control strategy based on the said modeling is proposed, and effectiveness of the traction control strategy is verified by simulation. The present traction control strategy consists of the PID control to the ISG and the logic gate control to the engine.

State-of-Charge Estimation of Lithium-Ion Battery Using Multi-State Estimate Technic for Electric Vehicle Applications

For reliable and safe operation of lithium-ion batteries in electric vehicles, the monitoring of the internal states of the batteries such as state-of-charge (SOC) is necessary. The purpose of this work is to present a novel SOC estimation algorithm. In this work, an equivalent circuit model (ECM) as well as the parameter identification method are studied. Then, the model structure of the battery in the state-space form is further investigated. Based on the model structure analysis, a novel SOC estimation algorithm is proposed using multi-state technic and Extend Kalman Filter (EKF). Some improvements are then introduced to improve the convergence and tracking performance of the algorithm in electric vehicle applications. The performances of the algorithm are validated through some experiments and simulations. Validation results show that the proposed SOC estimation algorithm can achieve an acceptable accuracy with the mean error being less than 2.72%.

Research on the Flexray communication protocol based on AUTOSAR and it's multi-node test

As a new generation of car bus, Flexray adopts time trigger method and has high data transfer rate, high reliability and good real-time character, which has been recognized for next generation automotive bus network. AUTOSAR provides a unified platform and reduce the cost of car manufacturers integrate. Its network management standards provide a standard for designing the network management protocol for the automotive vehicle. This paper researches the distributed communication management protocol for Flexray based on AUTOSAR and later make a three nodes examination by FreeMASTER.

The coordinated control of motor regenerative braking torques defined by accelerator pedal and brake pedal of electric vehicle

Driver can operate accelerator pedal and brake pedal to control the driving force and the braking force exerted on vehicle. For electric vehicles, it is possible that the braking force can be controlled by manipulating the accelerator pedal because of the regenerative braking function. In this paper, fuzzy control theory is employed to calculate regenerative braking force during releasing accelerator pedal based on the accelerator pedal opening and its change rate. Two modes are designed to coordinate the braking forces defined by accelerator pedal and brake pedal. One mode is engine braking imitation mode, and the other is auxiliary braking mode. The simulation results show that engine braking imitation mode can provide the similar driving feel to internal combustion engine vehicle. Auxiliary braking mode changes the traditional driving habit, but it has much higher regenerative efficiency. Auxiliary braking mode is suitable for the city driving condition which has frequent braking requirement.

Notice of Retraction Real-time and Reliability Analysis of FlexRay Bus

Real-time communication system is widely used to smart grid. The real-time performance and reliability are compared between CAN bus and FlexRay bus in theory. Then a steer-by-wire system experimental platform, which using the FlexRay bus, is built to verify the analysis results. The test results show that FlexRay bus has strong real-time performance and high reliability and are more suitable for high-speed, large capacity, strong and highly reliable real-time field bus communication networks. FlexRay bus has a good application prospects in the future smart grid and real-time control network.

Fault analysis and protection strategy on Contactless Power Transfer system for electric vehicle

In this paper, the principle of a Contactless Power Transfer (CPT) system is introduced, the situation of CPT system for electric vehicle about excessive startup current, coil short, system overheating and load open circuit are analyzed and research. According to the actual operating conditions of CPT system may exist fault, ready to power on protection strategy, the short circuit protection strategy, over heat protection strategy and open circuit protection strategy is presented. Experimental results show that these protection strategies are very important for the safety of CPT system.

FEM simulation and experiment of a novel shielding structure of wireless power transfer system

The resonant coils are the significant part of the whole wireless power transfer system. The magnetic field leakage will cause the human exposure to time-varying electromagnetic fields problems and low coupling coefficient. In this paper, a 3D model is established to simulate the magnetic field. A new shielded structure is proposed in this paper. A comparasion of the magnetic field between shielded structure and unshielded structure is presented in this paper. An experiment of 8kw and 10kw wireless power transfer system are established in this paper. And as the results of simulation and experiment, the new shielded structure achieve the higher coupling coefficient and suppress the magnetic field leakage.