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排序方式: 共有520条查询结果,搜索用时 187 毫秒
1.
This article proposes an active balancer, which features bidirectional charge shuttling and adaptive equalization current control, to fast counterbalance the state of charge (SOC) of cells in a lithium-ion battery (LIB) string. The power circuit consists of certain bidirectional buck-boost converters to transfer energy among the different cells back and forth. Owing to the characterization of the open-circuit voltage (OCV) vs SOC in LIB being relatively smooth near the SOC middle range, the SOC-inspected balance strategy can achieve more precise and efficient equilibrium than the voltage-based control. Accordingly, a compensated OCV-based SOC estimation is put forward to take into account the discrepancy of SOC estimation. Besides, the varied-duty-cycle (VDC) and curve-fitting modulation (CFM) methods are devised herein to tackle the problems of slow equalization rate and low balance efficacy, which arise from the diminution in balancing current as the SOC difference between the cells decreases in the later duration of equalization especially. The proposed strategies have taken the battery nonlinear characteristic and circuit parameter nonideality into account and can adaptively modulate the duty cycle with the SOC difference to keep balancing current constant throughout the balancing cycle. Simulated and experimental results are given to demonstrate the feasibility and effectiveness of the same prototype constructed. Compared with the fixed duty cycle and the VDC methods, the proposed CFM has the best balancing efficiency of 81.4%, and the balance time is shortened by 27.1% and 18.6%, respectively. 相似文献
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Siba Prasada Panigrahi Santanu Kumar Nayak Sasmita Kumari Padhy 《International Journal of Adaptive Control and Signal Processing》2008,22(7):705-716
This paper presents a neuro‐fuzzy network (NFN) where all its parameters can be tuned simultaneously using genetic algorithms (GAs). The approach combines the merits of fuzzy logic theory, neural networks and GAs. The proposed NFN does not require a priori knowledge about the system and eliminates the need for complicated design steps such as manual tuning of input–output membership functions, and selection of fuzzy rule base. Although, only conventional GAs have been used, convergence results are very encouraging. A well‐known numerical example derived from literature is used to evaluate and compare the performance of the network with other equalizing approaches. Simulation results show that the proposed neuro‐fuzzy controller, all parameters of which have been tuned simultaneously using GAs, offers advantages over existing equalizers and has improved performance. From the perspective of application and implementation, this paper is very interesting as it provides a new method for performing blind equalization. The main contribution of this paper is the use of learning algorithms to train a feed‐forward neural network for M‐ary QAM and PSK signals. This paper also provides a platform for researchers of the area for further development. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
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数字微波无线通信系统中的中频自适应均衡器 总被引:1,自引:0,他引:1
余燕平 《浙江大学学报(工学版)》1996,30(5):554-561
在数字微波无线通信系统中,由于多径衰落引起码间干扰,使系统性能恶化,必须采用抗多径衰落的措施.中频频域均衡器(IFE)由于结构简单而且经济,在衰落不十分严重的情况下性能良好,因而在数字微波系统中被广泛采用.本文比较了几种常用的IFE,并着重对自适应谐振武中频均衡器的两种调节方法作了研究.模拟计算得到的signature曲线表明,这种均衡器对非最小相位(MMP)信道的传输性能有很大的改进,且两种调节法可达到相近的结果,如选择其中较简单的调节法,可以简化硬件结构. 相似文献
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A model of a linear digital communication system is introduced and adaptive equalization in general is explained. A five-tap transversal equalizer is designed, breadboarded and tested in a 60 Mb/s burst mode modem in a quasi-linear and a non-linear channel under the following configurations:
- 1 Parabolic, linear and combination of parabolic and linear delay distortions were inserted after the non-linearity (TWTA).
- 2 Case 1 was repeated with distortions inserted before the non-linearity.
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王烨 《西安邮电学院学报》2009,14(5):40-42,50
首次提出一种新型数字光接收机模型,改进了其中均衡器的设计;以S.D.Personick理论为基础,推导并计算了此光接收机基于"最坏情况"下判决时刻的噪声平均功率。研究结果表明,此模型在输入脉冲展宽较为严重的情况下表现出了良好的噪声性能;进而提高了数字光接收机的灵敏度,优化了数字光纤传输系统的误码性能;为改善数字光接收机性能指标提出了新的途径。 相似文献
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