3) Advancements In Inverter Technology For Industrial Applications

An Inverter is simply an electronic device that converts low voltage DC battery power 230 volts AC (Alternating Current) electrical power. They are used in applications ranging from microwaves laptops to satellite systems X-Ray machines etc. Most industrial applications require high frequency high voltage power supply. These increased power requirements have lead to significant development in inverted technology.
Significant improvements have been made to the traditional pulse width modulations (PWM) Inverters to make power distribution system more efficient and more suitable to reactive power (var) compensation and harmonic filtering. This includes using multilevel inverters, zero current switching and other power switching devises. Space application involves high power (hundreds of kilowatts to megawatts) systems. Large power conditioning mass reductions are required to enable this megawatt power System. Therefore inverter design for space applications represents the state - of - the- art in power conditioning technology. Different features such as design parameters, output a characteristics, switching components etc of these inverters used in space application are discussed in the II part of the paper.

2) Adaptive Piezoelectric energy harvesting circuit

This paper describes an approach to harvesting electrical energy from a mechanically excited piezoelectric element. A vibrating piezoelectric device differs from a typical electrical power source in that it has a capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. An analytical expression for the optimal power flow from a rectified piezoelectric device is derived, and an “energy harvesting “ circuit is proposed which can achieve this optimal power flow. The harvesting circuit consists of an ac-dc rectifier with an output capacitor, an electrochemical battery, and a switch-mode dc-dc converter that controls the energy flow into the battery. An adaptive control technique for the dc-dc converter is used to continuously implement the optimal power transfer theory and maximize the power stored by the battery. Experimental result reveal that the use of the adaptive dc-dc converter increases power transfer by over 400% as compared to when the dc-dc converter is not used.

1) AC Cable Versus DC Cable Transmission for Offshore Wind Farms

A large interest in renewable energy systems has been developed to mitigate the green house effect. In Western Europe, the focus is thus, on wind power and especially on offshore locations, due to higher energy production, a longer expected life time and lack of suitable wind turbine sites on land. A DC cable is the preferred choice when connecting large offshore wind farms to the grid. The utilization of the Dc cables was enabled by the new HVDC transmission technology using voltage sourced converters.

The offshore wind farms that are being built today use an AC connection to shore and the distances to shore are also quite moderate. This paper describes three different solutions with a DC connection the shore and compares the cost and losses of a DC system with a traditional AC system that is used as a reference. DC systems will be competitive solutions in ten years and have several advantages compared with an AC system. This paper includes several reasons for selecting a DC cable is the preferred choice when connecting large offshore wind farms, to the grid.

The offshore wind farms that are being built today use an AC connection to shore and the distances to the shore are also quite moderate. This is a well-known technology and a natural step for the first off-shore wind farms. However in ten, years when the experiences from the first offshore wind farms have been evaluated and the next expansion starts, the alternatives with a DC grid will become cost-effective solutions. The future wind farms will becomes larger and will be situated at a farther distance from shore. The connection to the onshore transmission grid must be at a point with high short circuit capacity and the onshore distance, therefore is expected to be greater in the future.

The cost of power electronics will be significantly lower in the future and the losses will continue to decrease, so the advantages will outweigh the disadvantages.

New Technical Seminar Topics in Engineering

Wide Range of Seminar Topics and its abstracts for students in different branches in Engineering Field. (Electrical, Mechanical, Electronics, Civil, Chemical, Computer, Automobile etc).