Comparison between Frequency Response of Pulsating Partially Premixed and Diffusion Flame

The objective of the current research is investigation of the pulsating flow effect on the size of partially premixed and diffusion flame, experimentally. The pulsation provided through a rotary ball valve in accordance with a variable speed motor arrangement increased the flame temperature and thus more heat is released. The used S-type thermocouple can measure the flame temperature at strouhal number [St] is 0 and 0.005 for the flow, the flame temperature has been measured at five planes as each plane has five radii. Fast Fourier Transform (FFT) has been used to determine the dominant frequency response of the pulsating flame temperatures. Increasing strouhal number of the mixture (LPG fuel and air) flow increases the turbulence intensity and thus the dominant frequency response of the pulsating flame increases. The dominant frequency at St=0 is larger than the dominant frequency at St= 0.005 for all the planes of the combustion chamber. Increasing strouhal number reduces the size of the pulsating partially premixed and diffusion flame by a maximum of 40 and 35 %, respectively. The pulsation process will optimize design of the burners.

Unidirectional DC/DC Converter with Voltage Inverter for Fast Charging of Electric Vehicle Batteries

The paper proposes the adaptation of the industrial plant’s power network to supply electric vehicle (EV) fast-charging converters (above 300 kW) using renewable energy sources (RESs). A 600 V DC microgrid was used to supply energy from RESs for the needs of variable speed motor drives and charging of EV batteries. It has been shown that it is possible to support the supply of drive voltage frequency converters (VFCs) and charging of EV batteries converters with renewable energy from a 600 V DC microgrid, which improves the power quality indicators in the power system. The possibility of implementing the fast EV batteries charging station to the industrial plant’s power system in such a way that the system energy demand is not increased has also been shown. The EV battery charging station using the drive converter has been presented, as well as the results of simulation and laboratory tests of the proposed solution.

Design and implementation of brushless doubly fed induction machine with new stator winding configuration

Brushless doubly fed induction machine has acquired relevance as a wind electric generator because of its relative merits over doubly fed induction generator. However, the main drawback of brushless doubly fed induction machine is the presence of torque ripples due to spatial and time harmonics caused by two stator windings and complex rotor structure. In this article, a special design of brushless doubly fed induction machine using delta-star connection in one of the two stator windings is proposed to reduce the torque ripples. Simulation of the new brushless doubly fed induction machine design is performed in ANSYS Maxwell software, and the results when compared with the conventional winding design validated the effectiveness of the new design in minimizing the torque ripples. Prototype of the new brushless doubly fed induction machine has been fabricated and tested in laboratory. Tests have been conducted in both synchronous and asynchronous modes of brushless doubly fed induction machine. Simple induction and cascade connections have been tested in asynchronous motoring mode. Motoring as well as generating conditions have been tested in synchronous mode. Test results show that the new brushless doubly fed induction machine has not only the desired characteristics for wind turbine generator but also capabilities suited for variable torque–variable speed motor applications as well as constant speed applications.