This paper suggests improving the quality and performance of electrical grid by using Four
Chopper circuit in the DC –Link of the variable speed drive system with 12 pulse rectifier.
In addition, it analyses the effects on the ripple factor for bot
h current and voltage in DClink
and improving the system's stability.
For this study a variable speed drive system has been simulated and designed with the
proposed chopper and 12 pulse rectifiers. In order to confirm the ability of Using four -
quadrant chopper with rectifier circuits and its ability to improve the stability of the power
systems, a variable speed system has been simulated
Finally, A discussion of the results was introduced. The giving results show the advantages
of using the proposed chopper with variable speed drive systems.
In this study, we have developed a mathematical model, which formed the basis for
the development of a digital diagnostic model, for the question of the relation between the
engine torque (and therefore power), and the clearances in the basic and s
econdary
bearings of the crankshaft, to diagnose clearance values in these bearings, /which will
inevitably affect on the torque and the vibrations of the engine/, where multiple and
various grand-scale case experiments were carried out through simulation and arithmetic
experimentation on a diagnostic model, which constituted the first and main phase (the
instruction phase) of the full diagnosis. And at the end we discussed the results and put
some conclusions and recommendations to complete the work in the future.
The study of the dynamic behavior of the rolling ship on sea waves is one of most interesting topics, due to its close association with the ship stability and its direct impact on the efficiency of the work of some of the systems and processes inside
the hull. This research includes an explanation of the proposed mathematical model to study the dynamic behavior of the rolling ship on regular sinusoidal waves in order to calculate the Transfer Function of ship response continued to the act of wave-induced transverse oscillation and thus determine the frequency of resonance and the maximum value for the Transfer Function. A computer program was prepared to perform calculations according to the proposed model, which allowed studying the effect of some parameters of the investment of the vessel (ship speed, and the angle of its route for the main direction of spread of the waves) at a frequency of resonance and the maximum value for the Transfer Function, and also allowed to study the effect of Some of the parameters of the surrounding medium (wave frequency) to the maximum value for the Transfer Function. Through this research, it had been reached to extract mathematical equation which allows a precise and clear explanation of the dynamic behavior of the ship rolling on waves.
