Simulation of Switching Operation Based on Virtual Reality Method

Design and implementation of a real-time training environment for protective relay

Raising operation voltage of power conversion circuit is effective in reducing conduction loss. It requires power switching device to have high breakdown voltage. High voltage Si power device requires bipolar operation to reduce conduction loss sufficiently. However, bipolar operation worsens the switching characteristics of the device especially in turn off operation; such as reverse recovery for PiN diode and tail current for IGBT. The high critical electric field of SiC semiconductor realizes high break down voltage majority carrier device with substantially low on resistance. It can achieve fast switching capability for it only requires conducting and blocking majority carrier in the device for switching operation. This paper demonstrates the fast high voltage switching operation of SiC Schottky barrier diode (SBD) and MOSFET with comparing to the conventional Si device.

In order to offer a training platform for the trainees, we designed an operational training system of marine auxiliary boiler running in the PC independently. According to the layout of the real boiler systems, we constructed marine auxiliary boiler 3D model by 3DS MAX and Creator, then realized the operational requirements of the real ship based on Vega API program under MFC frame program. The system can apply various virtual operations and meet the training requirements of the auxiliary boiler system operating and management to some extent.

This paper deal with structure for low inductance and high heat operation of silicon carbide (SiC) power module, which attracts attention in terms of high withstand voltage, high efficiency and high heat operation in recent years. First, the parasitic inductance of the power module of two types of structure; a conventional structure which forms the current path in a planar manner and a structure formed three-dimensionally is investigated using electromagnetic field analysis. In addition, thermal resistance of two types of power modules are experimentally evaluated from heat radiation performance. Experimental and simulated results reveals that the three-dimensionally formed power module is superior in the current path, resulting in lower parasitic inductance as well as smaller switching loss. Moreover, on state resistance and leakage current are evaluated at the junction temperature of 250 °C and the problems of power module package under high temperature environment is also investigated.

High voltage direct current (HVDC) consists of two converters working as a rectifier and inverter which are connected, through transformers and high voltage equipment, to two high voltage AC (HVAC) power networks. Such electrical infrastructures are spreading thanks to the advantages they offer and the possibility of overcoming the limits of the most widespread HVAC technology. The first operational HVDC system dates back to 1954, created between the island of Gotland in the Baltic Sea and the mainland (Sweden), with a power of 20 MW which has over time been replaced with a 260 MW bipole transmission system. Other plants, all using mercury vapor valves, followed over the years, including: in 1965, the connection of Sardinia with the continent; in 1970, the Pacific DC Intertie, connecting the Pacific Northwest region and Los Angeles, United States; in 1973, the Nelson River Bipole in Canada. Only since the 1970s, with the development of high voltage semiconductor converters, HVDC transmission systems, which had already proven indispensable for crossing long stretches of sea or for connecting electrical systems with different frequencies, began to show competitiveness also for the transmission of great powers over very long distances. HVDC allows the long-distance transmission of large quantities of energy and installation costs are compensated by lower losses (breakeven point around 600-800 km). They are very useful in case of marine connections: being able to cross long stretches of sea, unlike HVAC which has limitations dictated by the need to compensate for the capacity of AC cables. Moreover, HVDC allows the interconnection between big consumption centers and geographical areas in which we have large availability of renewable sources (see for example the three DC corridors, made up of underground cable of ± 525 kV, which in Germany are being laid for transfer sustainable energy from the north of the country to the south). Finally, by crossing two converters directly facing each other (BackToBack) it allows the connection of alternating current networks that are not synchronous with each other (e.g. the first at 50 Hz and the second at 60 Hz). Among the main advantages, environmental impact aspects must also be considered, including those relating to electric and magnetic fields. After an introduction related to HVDC technology, the seminar will highlight the innovative aspects that need to be considered in simulations and measurements in electric and magnetic fields, considering that there are new aspects such as high static currents and voltages which are not present in traditional HVAC infrastructures. In particular, a couple of topics of interest are represented by the measurement of the static electric field due to the high voltage connection between the valve room and the power cables and the measurement of the disturbances generated by the harmonics along the DC lines.

The objective of this paper is to present two concepts which may assist fellow human factors personnel in selling safety and training programs to hard nosed managers in industry and government. Most often, proposed training and safety programs are presented to management as a means of making employees happy and safe. The justification for the program is that management owes its employees a happy and safe working environment. However, managers are judged by their superiors based on the extent to which they provide a product or service at a reasonable cost.

Knowledge-based safety training system (KBSTS)— A prototype implementation

17 - Dynamic IGCC system simulator

A new circuit scheme, dual oxide thickness–multiple threshold voltage complementary metal oxide semiconductor (CMOS) (DOT-MTCMOS) which can suppress the stand-by tunnel leakage in ultra-thin gate oxide metal semiconductor field effect transistors (MOSFETs) is proposed. In this circuit, a power switch is inserted in series with CMOS circuits. The power switch consists of a high Vth MOSFET with relatively thick gate oxide, in order to suppress not only subthreshold leakage but also tunneling leakage in the stand-by mode, while the CMOS circuit consists of low Vth MOSFETs with ultra-thin gate oxide for the high speed and low voltage operation. Using this circuit scheme, we can utilize the high drive current of ultra-thin gate oxide MOSFETs in the future where the scaling limit of the gate oxide thickness will not be determined by the stand-by power. An application of this scheme to a low voltage operation, hence low power circuit, is also demonstrated.

Photodiodes (PDs) which convert optical signals to electrical signals have been widely used in many fields. In contrast to pin PDs, in uni-traveling carrier (UTC) PDs, the absorption layer is p type doped and only photo-generated electrons are transported, which results in several superior characteristics including super high speed operation, high saturation current and low voltage operation. In this work, high speed InP based waveguide UTC-PDs have been fabricated by Zn diffusion doping for the first time to our knowledge, in contrast to the in situ doping of previous UTC-PDs. Diffusion doping will make it much easier for the UTC-PDs to be integrated with high quality passive waveguide and multi-quantum well (MQW) based active devices for photonic integrated circuit (PIC) applications. UTC-PDs with 3 × 15, 3 × 25 and 3 × 50 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> absorption areas are fabricated, all having over 50 GHz bandwidth at -1V bias voltage. At -3 V bias, the RF power at 40 GHz shows no saturation at up to 17 mA photocurrent for the 3 × 25 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> PD.

A chiral‐homeotropic LC cell is demonstrated to possess a very high contrast and low operation voltage. Using a 120° twist angle and an LC mixture with dielectric anisotropy of Δ∍= −6, the operation voltage is reduced to 2.5Vrms. This operation mode is useful for both transmissive and reflective displays. Low voltage operation of such a TFT‐LCD would reduce the power consumption and lower the cost of driving electronics.

Flexible inkjet-printed dual-gate organic thin film transistors and PMOS inverters: Noise margin control by top gate

Drop-out fuse is the most commonly used type of protection switch for 10kV distribution lines and distribution transformers. The operations of opening and closing drop-out fuses are high-risk processes, and such live maintenance accidents can be fatal. This paper presents a framework of a training system for drop-out fuse operation. The developed system is based on HoloLens mixed reality and speech recognition technology to train students for drop-out fuse operation. The system has two modules: drop-out fuse structure and drop-out fuse operation. Three modes of operation are included in each module: learning, practice, and evaluation, which can be visited according to the students’ level of skill. The proposed training system has low cost, occupies small space, can be used at any time, and guarantees the personal safety of students during the training operation.

Microactuators based on PbZr1-xTixO3 (PZT) and TiNi shape memory alloys (SMAs) are compared using microelectromechanical systems (MEMS) micropumps and microvalves as typical devices. The advantages of PZT-based microactuation include large actuation forces and high operating frequencies, leading to high operating pressures and flow rates. Disadvantages include high operating voltages and low strains. TiNi SMA-based microactuators can achieve high flow rates at low operating voltages, due to their high recoverable strains; however, they suffer from low operating frequencies and high power consumption. For both microactuation schemes, additional structures are usually required to realize the reciprocating motion required for MEMS devices. When used in MEMS, the thicknesses of PZT and TiNi SMA films range up to several microns. The thickness dependence of properties relevant to microactuation of PZT and TiNi SMA thin films are discussed and compared.

With the advancement in technology, the need for high efficient, switching speed and compact size of converters are gaining popularity. These converters require power devices having high breakdown voltage, thermal conductivity, switching frequency and operating temperature. Silicon devices exhibit limitations in switching frequency and operation at high temperature. The limitations of Si devices lead to advancements of wide band gap devices. The superior electrical properties of WBG devices make them potential candidates for use in high temperature, voltage and switching speed converter applications. Among the many WBG devices, silicon carbide, diamond and gallium nitride are a promising candidates. This paper deals with comparisons between conventional Si and GaN devices and highlights overall state of the art and future trends of GaN devices.