Current Issue : October - December Volume : 2013 Issue Number : 4 Articles : 6 Articles
This paper presents a new hybrid cascaded H-bridge multilevel inverter motor drive DTC scheme for electric vehicles where each\r\nphase of the inverter can be implemented using a single DC source. Traditionally, each phase of the inverter requires ?? DC source\r\nfor 2?? + 1 output voltage levels. In this paper, a scheme is proposed that allows the use of a single DC source as the first DC source\r\nwhich would be available from batteries or fuel cells, with the remaining (?? - 1) DC sources being capacitors. This scheme can\r\nsimultaneously maintain the capacitors of DC voltage level and produce a nearly sinusoidal output voltage due to its high number\r\nof output levels. In this context, high performances and efficient torque and flux control are obtained, enabling a DTC solution for\r\nhybrid multilevel inverter powered induction motor drives intended for electric vehicle propulsion. Simulations and experiments\r\nshow that the proposed multilevel inverter and control scheme are effective and very attractive for embedded systems such as\r\nautomotive applications....
The development of electric vehicles power electronics system control comprising of DC-AC inverters and DC-DC converters\r\ntakes a great interest of researchers in the modern industry. A DC-AC inverter supplies the high power electric vehicle motors\r\ntorques of the propulsion systemand utility loads, whereas aDC-DC converter supplies conventional low-power, low-voltage loads.\r\nHowever, the need for high power bidirectional DC-DC converters in future electric vehicles has led to the development of many\r\nnew topologies of DC-DC converters. Nonlinear control of power converters is an active area of research in the fields of power\r\nelectronics. This paper focuses on a fuzzy sliding mode strategy (FSMS) as a control strategy for boost DC-DC converter power\r\nsupply for electric vehicle. The proposed fuzzy controller specifies changes in the control signal based on the surface and the surface\r\nchange knowledge to satisfy the sliding mode stability and attraction conditions. The performances of the proposed fuzzy\r\nsliding controller are compared to those obtained by a classical sliding mode controller. The satisfactory simulation results show\r\nthe efficiency of the proposed control law which reduces the chattering phenomenon. Moreover, the obtained results prove the\r\nrobustness of the proposed control law against variation of the load resistance and the input voltage of the studied converter....
The DriveSafe project was carried out by a consortium of university research centers and automotive OEMs in Turkey to reduce\r\naccidents caused by driver behavior. A huge amount of driving data was collected from 108 drivers who drove the instrumented\r\nDriveSafe vehicle in the same route of 25 kmof urban and highway traffic in Istanbul. One of the sensors used in theDriveSafe vehicle\r\nwas a forward-looking LIDAR.The data from the LIDAR is used here to determine and record the headway time characteristics\r\nof different drivers. This paper concentrates on the analysis of LIDAR data from the DriveSafe vehicle. A simple algorithm that\r\nonly looks at the forward direction along a straight line is used first. Headway times based on this simple approach are presented\r\nfor an example driver. A more accurate detection and tracking algorithm taken from the literature are presented later in the paper.\r\nGrid-based and point distance-based methods are presented first. Then, a detection and tracking algorithm based on the Kalman\r\nfilter is presented.The results are demonstrated using experimental data....
Channel estimation is a challenging task, especially in high mobility applications due to the rapid variation of the propagation\r\nenvironment. This paper presents a new technique that exploits past channel impulse responses (CIRs) in order to trace and\r\ncompensate Doppler frequency in mobile applications, enabling robust estimation of time-varying channel. Based on the fact\r\nthat channel taps at different time instants can be fitted with a sinusoidal wave, a joint estimator is proposed to estimate the\r\nchannel parameters. Therefore, the efficiency of the channel estimation can be improved and stringent delay requirements for\r\nthe communication systems can also be satisfied. Simulation results show that system performance in terms of bit error rate (BER)\r\nis significantly improved with the proposed algorithm....
The optimum functional characteristics of suspension components, namely, linear/nonlinear spring and nonlinear damper\r\ncharacteristic functions are determined using simple lumped parameter models. A quarter car model is used to represent the front\r\nindependent suspension, and a half car model is used to represent the rear solid axle suspension of a light commercial vehicle.\r\nThe functional shapes of the suspension characteristics used in the optimisation process are based on typical shapes supplied by\r\na car manufacturer. The complexity of a nonlinear function optimisation problem is reduced by scaling it up or down from the\r\naforementioned shape in the optimisation process.Thenonlinear optimised suspension characteristics are first obtained using lower\r\ncomplexity lumped parametermodels. Then, the performance of the optimised suspension units are verified using the higher fidelity\r\nand more realistic Carmaker model. An interactive software module is developed to ease the nonlinear suspension optimisation\r\nprocess using the Matlab Graphical User Interface tool....
In IEEE 1609, it uses IEEE 802.11 Enhanced Distributed Channel Access (EDCA) mechanism to access the channel. IEEE 802.11\r\nEDCA is a new wireless technology for wireless access in the vehicular environment (WAVE). It defines a new supplement to the\r\nexisting IEEE 802.11 MAC protocol. In IEEE 802.11 EDCA, the aim is providing a QoS support. While the system serves different\r\naccess categories (ACs), EDCA does not perform well under high load conditions. In order to improve the efficiency, we pay\r\nattention to the EDCA with transmit opportunity (TXOP) mechanism. We first proposed a Markov chain model and studied the\r\nbehavior. We extend the model to support IEEE 802.11 EDCA and presented a more accurate analysis under nonideal channel\r\nenvironment.We also compared it with that without TXOP mechanism under channel error environment....
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