Sharif Digital Repository

Calculating leakage inductances between windings of multi-winding traction transformers is one of the most important schemes in design procedure. In this paper, a new analytical method and finite element models have been introduced for electromagnetic modeling of traction transformers with four split windings. Using these methods, the leakage inductances between the split windings are calculated and the methods have been validated with the help of experimental data gathered from a typical 4000kVA cast-resin dry-type transformer. Some reformations are employed to improve the finite element results and effects of these reformations on accuracy of the models are studied. Employing the validated... 

This paper investigates the multiple output full bridge based DC-DC converter and derives the analytical expression for its cross regulation. The effect of input voltage is studied and a topology is proposed that boosts the input voltage by a single stage structure. The proposed converter is based on Z-Source Inverter. In addition, the modulation scheme of the converter is presented. Simulation and experimental results are presented to verify the analytical study  

The transformer leakage inductance (TLI) is an important parameter in the design phase of the isolated power supplies. Hence, the TLI estimation before the transformer construction is very useful for the designers. The previous works considered an ordered winding turn arrangement (WTA) for the transformers. This assumption considers only ideal windings which may result in a significant error from what will be achieved after the construction of the transformer. This article concentrates on the transformers with nonideal windings in which the turns are not ordered. The uneven distribution of the turns in the layers is mainly due to the wrapping machine error. Hence, for a specific transformer... 

Current and force calculations in different short-circuit conditions are required for short-circuit performance analysis of a multi-winding traction transformer which is one of the most important requirements in its design process. This paper extends the available low-frequency three-winding star equivalent circuits to develop a novel equivalent circuit for the four-winding traction transformers. The leakage inductances of the traction transformer are determined and employed to calculate the parameters of this developed star model. It is shown that the star equivalent circuit is a valid and appropriate model to simulate the steady-state and dynamic performance of the traction transformer... 

Calculating leakage inductances between windings of multi-winding Traction transformers is one of the most important schemes in design procedure. In this paper, analytical and finite element methods (FEM) have been introduced for electromagnetic modeling of traction transformers with four pancake split windings. Using these models, the leakage inductances between the split windings are calculated and the models have been validated with the help of experimental data gathered from a typical 4000kVA cast-resin dry-type transformer. Some reformations are employed to improve the FEM results and effects of these reformations on accuracy of the model are studied. Employing the validated models, the... 

Dual active bridge isolated bidirectional DC converter (DAB-IBDC) has a poor efficiency at light loads and non-unity voltage conversion ratio. In this paper the current stress of the converter is analyzed and the effect of maximum phase shift ratio and leakage inductance on the current stress of the converter is investigated. In order to increase the efficiency of the converter and reduce the current stress, the current stress optimization has been done and the design procedure is presented. Simulation results are used to validate the results of the theoretical analysis. © 2017 IEEE  

In switching power supplies, the transformer leakage inductance (TLI) is of considerable practical significance. Ordered winding is the certain assumption in previously reported works for the calculation of the TLI value. However, disordered windings are usually unavoidable in practice and their effect on the value of the TLI is considerable. The problem becomes more complex when the number of winding turns increases. In this paper, the effect of winding disorder on the TLI value is investigated. In disordered wrapping, the winding turns arrangement (WTA) of each produced transformer is different from the others. Thus, each produced transformer has an exclusive TLI value in a disordered... 

Single-phase, outer-rotor squirrel cage induction motors are widely used in ceiling fan applications. Furthermore, they can be employed for pumps, and in-wheel hub drives. In this article, an analytical model based on magnetic equivalent circuit is proposed to evaluate the performance of the motor. The influence of rotor slots' skewing, stator end windings, slots' leakage inductance, and core saturation are included in the model. Furthermore, the windings' copper losses and the core's iron losses are calculated using the proposed model. The results of the presented model are compared with those of time variant finite element analysis (TVFEA) and experimental measurements close agreement... 

The demand for bidirectional DC/DC converters is increasing because of their potential capability for sustainable energy conversion systems where the power is to be captured from or stored in energy storage elements. This paper presents a three-phase series resonant bidirectional converter which is suitable for high power applications. The converter consists of two three-phase full bridge networks, the resonant tanks and a high frequency three-phase transformer. All switches can work either in ZVS or ZCS mode. The voltage drop on leakage inductances is minimized by choosing the switching frequency close to the resonant frequency, allowing high efficient power conversion. The phasor analysis... 

Resolvers, due to their robust structure, are widely used in automation systems. The need for accurate position estimation beside the precise control of present PM motors, persuade machine designers to select a resolver with high pole numbers. By the aid of concentrated winding topologies high pole numbers is accessible. Among different topologies of concentrated windings fractional slot (FS) type has been focused by a lot of researches. FS concentrated winding (FSCW) offers high pole number under limited slots, identical on tooth coils, short end winding, and compact design. However, depending on the topology, there are major drawbacks, such as magnetic noises, high sub-harmonics, high... 

A major problem in a multiple output converter structure is the different power flow via its various outputs. This problem leads to unwanted input DC-link voltage. This paper studies full bridge based DC-DC converters with multiple outputs. The effect of power flow variation is studied and a regenerative converter topology which controls the DC-link voltage by space voltage vector modulation technique is proposed. The proposed converter has a fast response to control the DC-link voltage in an acceptable band. Simulation and experimental results are presented to verify the analytical studies. © 2018 IEEE  

LLC resonant converter has been used widely as dc-dc converter for achieving constant dc voltage. In this paper, an LLC resonant converter, by adding an inductance to its conventional topology and considering the rectifying stage stray inductances, is proposed for an adjustable wide range regulated current source (20-200 A dc) for using as ion implanter's filament power supply. The additional inductor increases output current adjustment range and efficiency, especially at light loads. Transformer's leakage inductances and rectifying stage stray inductances have been considered. Because of these inductances, the rectifier stage always works in continuous conduction mode, and its conduction...