Sharif Digital Repository

In the Ion Implanter system a controled current through a tungesten filament, supplies the heat which causes the thermoionic emmition to ionize the gas molecules. Then the negativly charged electrones that are boiled off the filament, and also the ones that are removed from the outer ring of the gas molecules during the ionization process, are attracted by an adjustable voltage source. In this thesis, two resonant converter topologies are proposed to designe and to implement the adjustable current and voltage sources for ion implantation system. Unlike the PWM converters soft switching techniques, used auxiliary circuits to reduce the switching losses and EMI noises, in the proposed resonant... 

The objective of this project is to design and control and optimize a single-stage three-phase three-switch unity power factor telecom rectifier. For this purpose, the topology of three-phase three-switch converter has been investigated for both isolated and un-isolated converters. Following a comprehensive investigation on the converter structure, the power dissipation factors have been detected and the quantity of the power dissipation has been calculated by analytical methods and it confirmed by simulation results. To avoid extra power losses some novel soft-switched structures for three-phase three-switched converters have been introduced. the proper operation of the soft-switched... 

In this project, the Line-Modulated Fixed Off-Time method is used as the current control strategy for a Power Factor Corrector (PFC) pre-regulator. A zero voltage switching PWM (ZVS-PWM) auxiliary circuit is configured to perform ZVS in the switches. To reduce conduction losses, the rectifier circuit and the PFC are combined to create bridgeless PFC and a new zero-voltage-switching is introduced for reduse switching loss. Soft commutation of the main switch with zero voltage is achieved without additional current stress. When main switch is turned off ,the voltage across the switch rises very slowly. when the current of the switch decays to zero the voltage across the switch is very low.A... 

Due to the growing oil price and environmental considerations, tendency to use local and environmentally friendly energy sources has increased.Bidirectional transmission can be one of the key features of the smart grid,so the use of car battery connected to the grid as local energy sources makes sense. This can provide network stability, especially during peak load times. Vehicles connected to grid (V2G) is an electric vehicle or a plug-in hybrid electric vehicles can delivered the electricity to the grid. These systems require either two separate power electronic converters can be used for transmission in either directions or a two-way transfer charger. The aim of this project is to design... 

In recent years, multiport bidirectional converters have been a center of attention in renewable energy systems. This research focuses on three-port bidirectional converters. First, series resonant bidirectional converter is precisely analyzed. This analysis includes sinusoidal, exact state space and small signal analysis through phasor concept. This converter can work in higher switching frequencies and higher power ratings in comparison with common DAB bidirectional converter due to its inductor impedance cancellation. To increase power rating a three-phase version is proposed which has reduced output filter capacitance. Then, three-port bidirectional resonant converter is proposed and... 

In this project the novel zero-voltage-switching topology for power factor correction bridgeless boost rectifier is proposed. By employing an improved ZVS pulse-width-modulation (PWM) switch cell, ZVS of all the main switches is achieved without additional current or voltage stress of main switches. Also for the auxiliary switch the zero-current-switching is provided. In all modes of opretion of this converter, the power path is provided by maximum two semiconductor so the conduction loss of converter is low as in conventional converter. With this features the efficiency of proposed converter is very high  

In some high voltage applications it is necessary for high voltage power supply (HVPS) to operate over a wide load and gain range. For instance a HVPS may be used to supply various microwave tubes. Our goal in this thesis is to design a HVPS which can provide a DC voltage between 0-15 KV and 0-5 KW. In convetional approaches, operating over wide load and gain range necessitates the switching frequency or duty cycle to swing over a wide range. This approach may disturb soft switching, consequently switching loss will increase. The control process will be more complex too. the wide swing range of switching frequency means that the HVPS needs to operate with low switching frequency too.... 

The electric vehicle inverter, as one of the most important components of the vehicle, needs to have a high efficiency and also be able to work at high temperatures. Due to passing a large part of the battery power through this part and being one of the components that has the biggest power in an electric vehicle , traction inverter Efficiency has a big impact on the total efficiency of the whole vehicle . By increasing the battery voltage of electric vehicles, in order to achieve a higher charging power, the electric vehicle inverter must be able to withstand a voltage of about 800 volts input .On the other hand, in electric car inverters, the goal is to reach a power density of 100kw / L.... 

As more renewables step in, the ongoing change will be drastic for the electrical grid. The energy sector must find new ways to balance energy production and consumption. Electric vehicle (EV) batteries are by far the most cost-efficient form of energy storage since they require no additional investments in hardware. A bidirectional EV charger is a new technology that enables energy to be pushed back to the power grid and auxiliary loads from the battery. The electrical requirements of the EV charger are examined in detail to find an appropriate power electronics converter to meet all the requirements. The CLLC resonant converter is a promising candidate for high efficient, bidirectional... 

In regard to the benefits of solar energy such as endlessness and pureness, design and implementation of a convertor for absorbing energy from solar cells is of interest. Thus, a suitable convertor with acceptable efficiency is designed to charge the batteries. In order to increase the efficiency and to decrease the electromagnetic interference, a novel method is proposed for soft switching. Due to the nonlinear behavior of solar cells and also variations of their input energy with respect to the change of solar emission and temperature, two controllers - one for maximum power point tracking from solar cells and the other to appropriately charge the 48-volt batteries - are designed....