查看更多>>摘要：The widespread use of internal combustion engines (ICEs) to power vehicles has serious negative consequences for the environment and human health. Therefore, for three decades, changes in the automotive industry have been observed aimed at total or partial electrification of vehicle drive systems. The effect of these activities are successively introduced to the consumer market vehicles with hybrid (HEV) and electric (EV) drives. This article proposes an original version of the energy management system in a hybrid vehicle. The capabilities of a hybrid energy storage system (HESS) consisting of batteries and ultracapacitors units were explored through simulation. The most important parameters of the proposed strategy have been optimized. The simulation tests conducted confirmed many benefits of using an additional energy source. The applied changes in the energy management system reduced the level of fuel consumption, the maximum temperature, and the value of the charging and discharging currents of the batteries. This makes it possible to extend the service life of primary energy storage and reduce operating costs. It also has a positive effect on the environment, not only by reducing the emission of harmful effects of combustion but also by reducing the costs of disposal of used batteries.
查看更多>>摘要：A zigzag transformer is a key segment of the electric power system. The optimal design of the zigzag transformer is important for transformer designers to provide a required return path for earth faults and to ensure proper operation of a power system. The two most important parameters of the zigzag transformers are no-load losses and leakage impedance. The accurate calculation of both factors helps to minimize the overall cost of the transformer. Therefore, the prediction of leakage reactance in the zigzag transformer using analytical or numerical methods is an essential part of the early designing stages of the transformer. This paper provides several two- and three-dimensional finite element models. The main purpose of these models is to evaluate the accuracy of the different models for the calculation of the leakage reactance. An analytical formula and a complete procedure for the calculation of the leakage reactance in the zigzag transformer are also provided, which will help the researchers and transformer designer to optimize this type of transformer. The prototype is also manufactured and tested to verify the accuracy of the analytical method and finite element models for the calculation of the leakage reactance. The simulation and experimental results show that the finite element calculation cannot only obtain accurate leakage reactance values (magnetostatic analysis), but also provides better accuracy in the no-load losses (transient analysis).
查看更多>>摘要：Aiming at the problems of low control precision and poor anti-disturbances ability of permanent magnet spherical actuator (PMSA), an active disturbance rejection trajectory tracking control method based on nonlinear extended state observer (NESO) is proposed in this paper. Firstly, the multivariable and strong coupling mathematical model of the PMSA is obtained by rigid body rotation coordinate transformation and the Lagrange dynamic equation. Then, the tracking differentiator is used to reduce the influence caused by the expected trajectory jump. In addition, NESO is designed to observe and calculate coupling of the system, external disturbance, and model error online. Finally, the nonlinear control law is used to compensate for the observed disturbance, and the stability is proved based on the Lyapunov equation. Simulation and experimental results show that the proposed control scheme can achieve decoupling and tracking control of the complex system in the presence of model error, random disturbance, and other uncertain factors, has good control accuracy and response speed, and has strong robustness to uncertain disturbances.
查看更多>>摘要：In this paper, a novel adaptive control method is presented, aimed at robustifying the terminal voltage of the photovoltaic generator, interfaced by the current-mode-controlled buck DC-DC converter load, and based on conductance estimation. The photovoltaic generator, which is integrated into the buck converter and a battery storage unit, is continuously affected by the operating point of the system and environmental variables, thus presenting a nonlinear behavior. Furthermore, the development of small-signal equations reveals a potentially unstable condition when the system is used as a micro-grid with a battery storage unit. This study shows that when the nonlinear behavior of the photovoltaic generator is combined with a typical nominal controller, designed for a single nominal operating point and due to the possibility of an unstable condition, it forces the controller to operate mostly outside the nominal operating point. These conditions result in significantly varied closed-loop performance. In contrast, an almost perfect loop gain performance can be achieved when implementing an adaptive controller based on an online conductance estimation method. Applying estimator results and injecting its value in real-time into the inverse-based plant controller results in an adaptive controller. Therefore, the closed-loop performance of the system integrated with an adaptive controller achieves an almost nominal response throughout the operating range.
查看更多>>摘要：This paper proposes a new simple method based on the simulation of a short-distance running race in athletics to track the maximum power point (MPP) for photovoltaic (PV) power systems, which can improve the tracking speed and search accuracy. In detail, the DC-DC boost converter is utilized to transfer the power of PV panels to a load and follows the MPP all the time, regardless of the environmental temperature and variant solar irradiance. In the MPP search method based on the proposed short-distance running algorithm (SDRA), an appropriate duty ratio value will be found so that the load receives the highest electrical power from the PV energy system. As a result, the SDRA method has excellent MPP tracking ability with high convergence speed and no oscillation. The efficiency of the proposed method is verified by simulation and experiments. The proposed SDRA method overcomes the obstruction of local traps to achieve global MPP. The results have shown that the SDRA method has advantages in terms of better convergence speed and performance than the particle swarm optimization (PSO) and grey wolf algorithm (GWA) methods when they are operated under the same conditions.
Jacek Lukasz Wilk-JakubowskiPawel StawczykStefan IvanovStanko Stankov...
8页
查看更多>>摘要：The search for fast and environmentally safe methods of fighting fires has been a particularly important topic in recent years. Many academic centres are conducting research on the use of Deep Neural Networks to detect flames. One of the most promising is the acoustic method of extinguishing flames. In theory, an acoustic extinguisher can be applied to extinguish fires of different classes because acoustic waves pass through solids, liquids, and gases. In principle, the technology described in the article can be used to extinguish B-and C-class fires when gases or liquids are burning. Until now, the known studies have been conducted only for low-power acoustic extinguishers. Therefore, there is a need to fill a theoretical and practical gap in this respect (scientific novelty). The result of the activities is the development of new techniques for extinguishing flames with the use of Deep Neural Networks, and then extinguishing flames using a high and very high power loudspeaker applied to the acoustic extinguisher. The main aim of this paper is to present the possibilities of using Deep Neural Networks to detect fires, as well as the results of research on the extinguishing of flames with the use of square waveforms with Amplitude Modulation (AM) for several frequencies, which is also a scientific novelty, including the minimum acoustic power and sound pressure level as a function of a distance from the output of the acoustic system. On this basis, it became possible to determine the minimum power delivered to the extinguisher and the minimum sound pressure level that causes the extinguishing effect at given input parameters.
查看更多>>摘要：Narrowband power line communication has become a major focus of research with its applicability extending to residential facilities. This article examines data transmission over flexible AC power line cables stretching from the elevator control panel to the cabin. In previous studies, there has been no significant attempt to characterize the Power Line Communication (PLC) channel and noise of an elevator system. In this article, a vector network analyzer and mixed domain oscilloscope along with coupling devices are used to conduct power line channel noise and response measurements for an elevator system. The acquisition of channel transfer functions corresponding to both idle and moving states of the elevator is carried out for the 9 kHz-500 kHz frequency range. A mathematical model is provided for the average frequency response of the PLC channel. The main source of noise is the inverter that supplies power to the motor. The channel exhibits notable variations for frequencies less than 281 kHz while staying relatively consistent for the 281 kHz to 500 kHz frequency range as the elevator changes from idle to moving state. Reed Solomon and convolutional codes along with interleaving to spread erroneous bits are utilized in this work to simulate an orthogonal frequency division multiplexing transceiver. By systematically selecting subcarrier frequencies that do not overlap with the harmonic noise components, simulation results have demonstrated reliable data recovery for signal-to-noise ratio greater than 4 dB.
NSTL
Kaunas Univ Technology