Enhanced Reverse Recovery Performance in Superjunction MOSFET with Reduced Hole-Barrier

High reverse recovery charge (QRR) and resultant high switching losses have become the main factors that constrain the performance and application area of superjunction MOSFET (SJ-MOSFET). To reduce QRR, an SJ-MOSFET with reduced hole-barrier is proposed and demonstrated. By introducing a Schottky contact on the bottom of the n-pillar at the drain side, the barrier for the hole carrier is dramatically reduced in the reverse conduction state. As a result, the hole carrier in the drift region is significantly reduced, which results in a low QRR and enhanced reverse recovery performance. Compared with the conventional SJ-MOSFET (Conv-SJ-MOSFET), the proposed device achieves 64.6% lower QRR with almost no sacrifice in other characteristics. The attenuated QRR accounts for a 19.6% ~ 46.8% reduction in total power losses with operation frequency at 5 ~ 200 kHz, demonstrating the great potential of the proposed SJ-MOSFET used in power conversion systems.

The main types of wind turbines-generators in the power supply system

PURPOSE. Conduct a detailed analysis of existing wind turbines. Analyze the role, place and features of the functioning of wind power plants. Provide various options for generators and schemes for converting wind energy into electricity. Provide recommendations for improving the reliability of wind turbines in smart grids.METHODS. The article was prepared using analytical methods, statistical, theoretical, factorial and technical methods.RESULTS. A fixed speed asynchronous generator used in a wind power conversion system (WECS) without a power converter interface draws a significant portion of the reactive power from the grid. This configuration features simple, reliable operation. Wind turbine asynchronous generator with dual power supply. can improve overall power conversion efficiency by performing maximum power point tracking (MPPT), and an increase in speed of about 30% can improve dynamic performance and increase resilience to system disturbances that are not available for turbine types 1 and 2. The use of full-scale 100% power converters will significantly increase the productivity of SPEV wind energy conversion systems, but will slightly increase the cost of the power converter, up to 7% - 12% of the total equipment cost. By using a large number of pole pairs for all types of permanent magnet synchronous generator (PMG), the turbine gearbox can be removed. This type of wind energy conversion system is more resilient to grid disruptions compared to type 1, 2 and 3 wind systems. The review shows that types 3 and 4 technologies are used to most efficiently sell and recycle wind turbines in electricity markets.CONCLUSION. The article analyzes the features of the functioning of wind power plants operating on the grid. Various options for generators and schemes for converting wind energy into electricity are presented. A detailed analysis of existing wind turbines is provided. Recommendations are given for improving the reliability and efficiency of wind power plants in smart grids.

Statistical analysis of properties of non-fullerene acceptors for organic photovoltaics

From ~1500 published journal papers on organic photovoltaics (OPVs), we extracted OPV performance parameters of power conversion efficiency (PCE), open circuit voltage (VOC) and short circuit current density (JSC) and chemical structures of photovoltaic layer materials to investigate the relation between the extracted data of OPVs accompanied by non-fullerene acceptors (NFAs). Our analysis indicated that there was a suitable range of VOC for high PCE or JSC in NFAs. We also investigated the correlation between the performance parameters and chemical structures of small molecule NFAs. Our approach may enable us to provide new design strategy for high performance OPVs.

The Influence Factor Analysis of Symmetrical Half-Bridge Power Converter through Regression, Rough Set and GM(1,N) Model

Analysis of power converter performance has tended to be engineering-oriented, focusing mainly on voltage stability, output power and efficiency improvement. However, there has been little discussion about the weight relations between these factors. In view of the previous inadequacy, this study employs regression, rough set and GM(1,N) to analyze the relations among the factors that affect the converter, with a symmetrical half-bridge power converter serving as an example. The four related affecting factors, including the current conversion ratio, voltage conversion ratio, power conversion ratio and output efficiency, are firstly analyzed and calculated. The respective relative relations between output efficiency and the other three factors are obtained. This research can be referred to by engineers in their design of symmetrical half-bridge power converters.

A review on two-dimensional (2D) perovskite material-based solar cells to enhance the power conversion efficiency

With perovskite materials, rapid progress in power conversion efficiency (PCE) to reach 25% has gained a significant amount of attention from the solar cell industry.

Design and Development of a Hybrid DC-DC Converter for Solar-Battery-Based Standalone Milk Vending Machine

Dairying has become a major secondary source of income for several rural families. The easily perishable nature of milk increases the spoilage of the product and reduces the dairy farms' productivity in rural areas due to power supply shortage issues. In order to overcome the inaccessibility of proper preservation strategies, this chapter proposed a hybrid DC-DC converter for a solar battery-powered milk vending machine. This proposed system can work continuously and provides an uninterrupted power supply to maintain the milk quality at an optimum level. Moreover, the proposed system utilized a novel converter to reduce the number of power conversion stages and compact the system. Besides, the proposed converter can achieve a higher gain ratio with fewer components. Furthermore, a proper algorithmic-based control scheme has been implemented to maintain effective power flow management. Finally, to verify the feasibility and performance of the system, detailed results are obtained at different dynamic conditions, and various case studies are presented in this chapter.