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The study of the effects of the backlash phenomena appearing in a dual geared transmission system is presented in this paper. Particularly, the way that the backlash phenomena affect the behavior of a dual ac drive used for a cement kiln and especially the effect of these malfunctions in the two motors and the electrical equipment are investigated using simulation and experimental results. The equations of motion of a real dual drive kiln installed at the cement plant of TITAN Cement SA in Achaia, Greece are described, the electric parts as well as the control strategy are analyzed and a simulation model of the whole system using the MATLAB/SIMULING software is presented. In addition a laboratory simulating system has been developed and experimental results are also shown in this research work.

During the transient operation of a synchronous generator, a lot of variations in the operation of the machine appear, which are unavoidable and can cause significant oscillations of the load angle Θ and the electromagnetic torque. These oscillations can lead the generator to pole slipping. A fault, which is possible to occur, is a short-circuit at the supply of the excitation system of the synchronous generator. In this paper we investigate the performance of the machine during a short-circuit at the excitation, while the synchronous machine is connected to the grid. Particularly, the waveforms of all the currents, stator, field and damper, the electromagnetic torque and the field in the air-gap are derived and studied.

Rotor electrical faults are common types of faults in squirrel cage induction motors and have been investigated in detail in steady state condition for grid-connected induction motors. In this paper, this type of fault is studied in case of inverter driven motors. Inverter input and output currents are studied for the fault indicative frequency components. The harmonics which are induced to the inverter input current give the ability of fault detection under low load and low motor severity fault condition in both motor steady-state and transient operation.

This paper deals with the experience gained from the conversion of a conventional vehicle to a hybrid electric vehicle (HEV).The resulting concept vehicle is a hybrid SUV that features an additional electric drivetrain, which is composed of a three – phase asynchronous motor, a battery pack, the power converters and the transmission system. The placement of the electric and the conventional propulsion system forms a parallel topology. The operation of the electric drive system is characterized by two opposite directions of power flow, during the acceleration and the deceleration of the vehicle (regenerative braking). The energy management is achieved by two electronic power converters; a bidirectional DC/DC Boost/Buck converter and a three-phase DC/AC inverter, both of which have been designed and constructed at the laboratory. The motor control is carried out by a microcontroller according to Direct Torque Control technique. Finally, some characteristic experimental results of the constructed system are presented.

In this work, the suitability of three dc – dc converters for application in a PEM fuel cell system is examined. Investigation of boost converter, interleaved boost converter and interleaved boost converter with switch capacitors takes place. The efficiency of each converter at different load values is compared and the harmonic content that each of them produces is examined. Two different scenarios are presented. In the first one the system was designed to generate a converter output voltage of 50 V and in the second the output voltage is 100 V.