Novel communication method between power converters for DC micro-grid applications

Communication between power converters is vital for high performance DC micro-grids controls. However, for residential DC micro-grid applications, using external communication link would increase the system cost, and reduce the system flexibility and reliability. This paper presents a novel method to enable the conventional DC/DC converters to transmit data via the common DC Bus. With this technology, cost-effective low bandwidth communication links between power converters can be established within a DC micro-grid, and advanced distributed control algorithms can be developed. A reliable communication with 2 kbps transmission rate has been implemented between the Boost converters through the common input DC bus

DC power line communication based on power/signal dual modulation in phase shift full bridge converters

For intelligent DC distributed power systems, data communication plays a vital role in system control and device monitoring. To achieve communication in a cost effective way, power/signal dual modulation (PSDM), a method that integrates data transmission with power conversion, can be utilized. In this paper, an improved PSDM method using phase shift full bridge (PSFB) converter is proposed. This method introduces a phase control based freedom in the conventional PSFB control loop to realize communication using the same power conversion circuit. In this way, decoupled data modulation and power conversion are realized without extra wiring and coupling units, and thus the system structure is simplified. More importantly, the signal intensity can be regulated by the proposed perturbation depth, and so this method can adapt to different operating conditions. Application of the proposed method to a DC distributed power system composed of several PSFB converters is discussed. A 2kW prototype system with an embedded 5kbps communication link has been implemented, and the effectiveness of the method is verified by experimental results

Research on the Application of Deep Learning-based BERT Model in Sentiment Analysis

This paper explores the application of deep learning techniques, particularly focusing on BERT models, in sentiment analysis. It begins by introducing the fundamental concept of sentiment analysis and how deep learning methods are utilized in this domain. Subsequently, it delves into the architecture and characteristics of BERT models. Through detailed explanation, it elucidates the application effects and optimization strategies of BERT models in sentiment analysis, supported by experimental validation. The experimental findings indicate that BERT models exhibit robust performance in sentiment analysis tasks, with notable enhancements post fine-tuning. Lastly, the paper concludes by summarizing the potential applications of BERT models in sentiment analysis and suggests directions for future research and practical implementations

Direct sequence spread spectrum based PWM strategy for harmonic reduction and communication

Switched mode power supplies (SMPSs) are essential components in many applications, and electromagnetic interference is an important consideration in the SMPS design. Spread spectrum based PWM strategies have been used in SMPS designs to reduce the switching harmonics. This paper proposes a novel method to integrate a communication function into spread spectrum based PWM strategy without extra hardware costs. Direct sequence spread spectrum (DSSS) and phase shift keying (PSK) data modulation are employed to the PWM of the SMPS, so that it has reduced switching harmonics and the input and output power line voltage ripples contain data. A data demodulation algorithm has been developed for receivers, and code division multiple access (CDMA) concept is employed as communication method for a system with multiple SMPSs. The proposed method has been implemented in both Buck and Boost converters. The experimental results validated the proposed DSSS based PWM strategy for both harmonic reduction and communication

The inverted hexagonal phase is more sensitive to hydroperoxidation than the multilamellar phase in phosphatidylcholine and phosphatidylethanolamine aqueous dispersions

AbstractThe effect of phase behaviour (hexagonal II phase and lamellar phase) on the peroxidation of membrane phospholipids has been investigated in dilinoleoyl phosphatidylcholine (DLPC)/dilinoleoyl phosphatidylethanolamine (DLPE) aqueous dispersions. Peroxidation was initiated with a water-soluble radical inducer 2,2′-azobis (2-amidino-propane) dihydrochloride (AAPN). The phospholipid morphology was monitored by 31P-nuclear magnetic resonance (NMR). Phospholipid hydroperoxides (PCOOH and PEOOH) were determined by chemiluminescence high-performance liquid chromatography (CL—HPLC). In pH-induced phase transition systems, DLPE in the bilayer state was much less oxidized than in the hexagonal II state. In composition-induced phase transition systems, the formation of total hydroperoxides and the consumption of α-tocopherol in the hexagonal II phase were greater than in the bilayer phase. These data suggest that the hexagonal II phase is more sensitive to hydroperoxidation than the bilayer phase in phospholipid aqueous dispersions

Separation and purification of low-molecular-weight chondroitin sulfates and their anti-oxidant properties

Low-molecular-weight chondroitin sulfate was obtained by degradation of chondroitin sulfate using hyaluronidase. Then, separated with sephadex G25, DEAE-52, and finally purified with AKATA superpeptide separation system and fluorescence-assisted carbohydrate electrophoresis. The main compo-nents detected by high performance gel-filtration chromatography were disaccharide, tetrasaccharide, hexasaccharide with molecular weight of 521, 1024 and 1527 Da, respectively. The anti-oxidant activity of these three oligosaccharides in vitro showed that the reducing power (maximum value at 10 mg/mL) and superoxide anion radical scavenging abilities were increased (maximum value at 4 mg/mL) with an increased in their concentration. There were no significant differences of the anti-oxidant properties between those three oligosaccharides.

Wireless power and data transfer via a common inductive link using frequency division multiplexing

For wireless power transfer (WPT) systems, communication between the primary side and the pickup side is a challenge because of the large air gap and magnetic interferences. A novel method, which integrates bidirectional data communication into a high-power WPT system, is proposed in this paper. The power and data transfer share the same inductive link between coreless coils. Power/data frequency division multiplexing technique is applied, and the power and data are transmitted by employing different frequency carriers and controlled independently. The circuit model of the multiband system is provided to analyze the transmission gain of the communication channel, as well as the power delivery performance. The crosstalk interference between two carriers is discussed. In addition, the signal-to-noise ratios of the channels are also estimated, which gives a guideline for the design of mod/demod circuits. Finally, a 500-W WPT prototype has been built to demonstrate the effectiveness of the proposed WPT system

Power conversion and signal transmission integration method based on dual modulation of DC-DC converters

For the development of communication systems such as Internet of Things, integrating communication with power supplies is an attractive solution to reduce supply cost. This paper presents a novel method of power/signal dual modulation (PSDM), by which signal transmission is integrated with power conversion. This method takes advantage of the intrinsic ripple initiated in switch mode power supplies as signal carriers, by which cost-effective communications can be realized. The principles of PSDM are discussed, and two basic dual modulation methods (specifically PWM/FSK and PWM/PSK) are concluded. The key points of designing a PWM/FSK system, including topology selection, carrier shape, and carrier frequency, are discussed to provide theoretical guidelines. A practical signal modulation-demodulation method is given, and a prototype system provides experimental results to verify the effectiveness of the proposed solution

Techno-economic Assessment of a Hybrid Off-grid DC System for Combined Heat and Power Generation in Remote Islands

Hybrid renewable energy systems that combine heat and electricity generation is an achievable option for remote areas where grid is uneconomical to extend. In this study, a renewable-based system was designed to satisfy the electrical and thermal demands of a remote household in an off-grid Greek island. A hybrid DC system consisted of a combination of photovoltaic modules, wind turbine, electrolyzer-hydrogen tank, fuel cell and batteries were analysed using HOMER Pro software. Based on the optimal obtained system, it is found that such a system can satisfy both electrical and thermal load demand throughout the year in a reliable manner