Advanced Materials Research Vols. 724-725

Abstract: This paper presents a new power allocation method in the electrical hybrid energy storage system composed by batteries and supercapacitors (SCs) for electric vehicles (EVs). Based on the speed of EVs, the new power sharing strategy, adapted to different kinds of load profiles, regulates the SC state of charge (SOC). By comparison, the new strategy showed the shortest accelerating time and least power losses, which can efficiently improve dynamic performance and energy utilization rate.

Abstract: As a class of nonlinear loads in the power system, electric vehicle chargers will produce a certain harmonic pollution for the grid. Before the construction of charging stations, it is necessary for electric vehicle charger (station) connected to the grid to simulate and predict harmonics. The models of single charger and charge station are built separately in order to simulate and analysis the impact of a single and multiple chargers on power quality. The factors of the harmonic current ratio (HRI) and the current total harmonic distortion (THD_I) varied with the charging power and the number of the chargers are discussed and analyzed. The generation mechanism of harmonic counteraction and interaction between the chargers are analyzed. The simulation results show that: because of the impedance of the system and the transformer, the harmonic current ratio (HRI) and the current total harmonic distortion (THD_I) both increase firstly to some extent and subsequently decrease gently with the increase of the number of the chargers in the same power charging. This phenomenon has nothing to do with the harmonic counteraction and how that happen is discussed and analysis in this paper. And the phenomenon of harmonics interaction and counteraction occurs with the increase of the number of the chargers in different power charging, and the current total harmonic distortion (THD_I) declines and tends to maintain a relatively stable value.

Abstract: Brushless DC motor has simple structure, great power density, torque output and high efficiency. It has a broad application prospect for electric vehicle. The conventional scheme of BLDCM drive system adopts motor ontology, power drive circuits and position sensor. BLDCM is usually used with the mode of 3-phase 6-state PWM. Due to its structure and commutation strategy, it has many problems to be solved if works on electric vehicle. The basic operating principle of Brushless DC motor and the basic power drive system was discussed. In addition, investigated the torque ripple, flux-weakening speed control and brake energy regeneration for electric vehicle. Solving these problems can promote BLDCM and electric vehicle industry.

Abstract: The bond graph method is used to analyse and model dynamics of hybrid electric system based on Ravigneaux Planetary Mechanism. Bond graph models are built in different structural form, general equations of torque and speed are derived, and operating modes achieved in different structural form are in consideration. At the same time, requirements of control system in different operating modes are illustrated and analysed, which help lay the foundations for modeling and simulation of HEV system based on Ravigneaux Planetary Mechanism.

Abstract: Electric Vehicles (EVs) have been the important tendency of future vehicle development. This paper discusses the performance and features of EVs with AC drive system, and analyzes two dominating control schemes of AC motor dynamic model, i.e., Vector Control (VC) and Direct Torque Control (DTC). Principles, advantages, disadvantages, research hot spots and developing directions of the two control schemes were carefully presented. Moreover, the paper points out that the two difficulties of AC drive system are improving low-speed performance and dynamic performance.

Abstract: A starting experiment has been conducted to investigate the effect of ignition timing on the starting characteristics for linear engine designed by the research group independently. The fuel injection pulse and ignition timing are controlled by the electronic control unit (ECU) which is developed based on the piston displacement. The combustion characteristics of the engine in starting process are studied based on the cylinder pressure measured by the transient pressure sensor. The result shows that the best ignition timing for linear engine starting is 2.4mm~2.8mm when the fuel injection pulse is 5.4ms and this best region of ignition timing is also meet the requirement of the combustion in the next several cycles.

Abstract: This paper studies energy efficiency of the entire EV charging network.In conjunction with the research, listing first and second level energy efficiency indexs.Determine weight coefficient of the first-level index based on the group-G1 method, with entropy weight method to identify weight coefficient of the second-level index. Finally create the model of energy efficiency assessment of EV charging network with hierarchical synthesis method. Through field measurement and calculation, this model can better impress the energy efficiency level.

Abstract: Experimental research on the effect of excess air ratio on dynamic and emission performance of turbocharged lean-burned CNG engine. The 12 test conditions contain engine speeds of 1300r/min, 1600r/min, and 1900r/min, with 25%, 50%, 75%, 100% load separately. When keeping other combustion boundary conditions unchanged, the excess air ratio has little effect on engine output torque at almost all test conditions, but has obvious effect on CH4 and NOx emission. With the excess air ratio increasing, the emission of CH₄ has increased while the NOx emission has decreased significantly. When the λ value is in the range of 1.4-1.45, the emission level is lower.

Abstract: This paper reports the establishment of a piezoelectric vibration energy harvester for electric vehicle (EV) applications. Finite element analysis results, which agree experimental outcome well, have demonstrated that the piezoelectric vibrator can produce 1 V DC electric signal under 2 mm amplitude mechanical vibration at lower frequency. The energy harvester comprising two piezoelectric vibrators connected in series charged a Ni-MH secondary battery from 1.17 V to 1.24 V. It is verified that this piezoelectric energy harvester can be used in EVs and will potentially improve the energy use efficiency and performance of EVs.

Abstract: Utilizing Socket Send () function to package the required CCP commands.Vehicle information terminal restore the data into CAN frames and achieve the purpose of remote calibration by parsing Socket nested word.Introduced the development of host computer for electric vehicles’ RMON .Including hardware configuration and development of the Information Center,the analysis of calibration database and the design of software for vehicles’ monitoring and calibration.Clarify the calibration process and fault diagnosis technology.