Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 5 Articles
Emerging non-volatile memories based on resistive switching mechanisms attract\r\nintense R&D efforts from both academia and industry. Oxide-based Resistive Random Acces\r\nMemories (OxRAM) gather noteworthy performances, such as fast write/read speed, low\r\npower and high endurance outperforming therefore conventional Flash memories. To fully\r\nexplore new design concepts such as distributed memory in logic, OxRAM compact models\r\nhave to be developed and implemented into electrical simulators to assess performances at\r\na circuit level. In this paper, we present compact models of the bipolar OxRAM memory\r\nbased on physical phenomenons. This model was implemented in electrical simulators for\r\nsingle device up to circuit level....
Nowadays, the doubly-fed induction generators (DFIGs) based wind turbines (WTs) are the dominant type ofWTs. Traditionally,\r\nthe back-to-back converters are used to excite the rotor circuit of DFIG. In this paper, an indirect matrix converter (IMC) is\r\nproposed to control the generator. Compared with back-to-back converters, IMCs have numerous advantages such as higher level\r\nof robustness, reliability, and reduced size and weight due to the absence of bulky electrolytic capacitor. According to the recent grid\r\ncodes wind turbinesmust have low voltage ride-through (LVRT) capability. In this paper a new crowbar system is proposed so that\r\nalong with the control system it protects the IMC from large fault currents and supports the grid voltage dips during grid faults.\r\nThis crowbar system is provided using the existing converter switches to establish a short circuit mode without any extra circuitry.\r\nEven in severe fault conditions, the duration of short circuit mode is quite small so the control system will be activated shortly after\r\nthe fault to inject reactive power as required by new LVRT standards. Therefore, the new LVRT standards are well satisfied without\r\nany extra costs. PSIM simulation results confirm the efficiency of the proposed method...
This paper describes the performance prospect of scaled cross-current tetrode\r\n(XCT) CMOS devices and demonstrates the outstanding low-energy aspects of\r\nsub-30-nm-long gate XCT-SOI CMOS by analyzing device operations. The energy\r\nefficiency improvement of such scaled XCT CMOS circuits (two orders higher) stems\r\nfrom the ââ?¬Å?source potential floating effectââ?¬Â, which offers the dynamic reduction of effective\r\ngate capacitance. It is expected that this feature will be very important in many medical\r\nimplant applications that demand a long device lifetime without recharging the battery....
Thepower electronic interface between a satellite electrical power system (EPS) with a photovoltaicmain source and battery storage\r\nas the secondary power source is modelled based on the state space averaging method. Subsequently, sliding mode controller is\r\ndesigned for maximum power point tracking of the PV array and load voltage regulation. Asymptotic stability is ensured as well.\r\nSimulation of the EPS is accomplished using MATLAB. The results show that the outputs of the EPS have good tracking response,\r\nlow overshoot, short settling time, and zero steady-state error.The proposed controller is robust to environment changes and load\r\nvariations. Afterwards, passivity based controller is provided to compare the results with those of slidingmode controller responses.\r\nThis comparison demonstrates that the proposed system has better transient response, and unlike passivity based controller, the\r\nproposed controller does not require reference PV current for control law synthesis...
Capacity enhancement and operational flexibility are two of the important limitations of the centralized shunt APF (APFsh) unit.\r\nThese limitations can be conquered by the operation of multiple APF units in parallel and connected back to back by a common\r\nDC link capacitor. In that case, a circulating current (CC) flows within the APFsh units. This CC flow becomes out of control when\r\nthe APFsh units operate in hysteresis based current controlled mode. One of the difficulties of this CC flow control or reduction is\r\nthe variable switching frequency of the APFsh units. In this paper, themodel for CC flow is derived by the switching dynamics study\r\nof the APFsh units. It is found that the selection of design parameters plays an important role in the amount of CC flow. Detailed\r\nsimulation, analysis, and real-time performance show how the selection of design parameters affects the CC flow and the reduction\r\nof CC flow can also be achieved at an acceptable level by the proper selection of design parameters....
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