The poor quality of voltage and current of a conventional inverter fed induction machine is due to the presence of harmonics and hence there is significant level of energy losses. The nine level inverter is used to reduce the harmonics. The inverters with a large number of steps can generate high quality voltage waveforms. The concept of multilevel inverters, introduced about 20 years ago entai...

This paper presents a predictive torque and flux control algorithm for the synchronous reluctance machine. The algorithm performs a voltage space phasor pre-selection, followed by the computation of the switching instants for the optimum switching space phasors, with the advantages of inherently constant switching frequency and time equidistant implementation on a DSP based system. The criteria...

Power systems are subjected to small–signal oscillations that can be caused by sudden change in the value of large loads. To avoid the dangers of these oscillations, the Power System Stabilizers (PSSs) are used. When the PSSs can not be effective enough, installation of the Thyristor–based compensators to increase the oscillations damping is a suitable method. In this paper, a Static Synchronou...

In the conventional structure of the wind turbines along with the doubly-fed induction generator (DFIG), the stator is directly connected to the power grid. Therefore, voltage changes in the grid result in severe transient conditions in the stator and rotor. In cases where the changes are severe, the generator will be disconnected from the grid and consequently the grid stability will be attenu...

The present paper formulates the state space modeling of doubly fed induction generator (DFIG) based wind turbine system for the purpose of the stability analysis. The objective of this study is to discuss the various modes of operation of the DFIG system under different operating conditions such as voltage sags with reference to variable wind speed and grid connection. The proposed control met...

Conduction spectroscopy measures the current I through a nanosystem as a function of the voltage V between two electrodes. The differential conductance, dI/dV, has peaks that can be assigned to resonance conditions with different electronic levels of the system. Between these increments, the current has roughly constant plateaus. We discuss how measurements of the current vs. voltage can be use...

Introduction Superficial X-ray therapy is one of the most important treatment methods in radiotherapy especially in the treatment of superficial skin lesions (Up to 300 kVp). Quality of the X-ray beam that can be expressed by Half-Value Layer (HVL), are important indices for this type of treatment effective energy of photon and Homogeneity Coefficient (HC). Materials and Methods The HC of the s...

Excitation control of synchronous machine is done in order to keep the terminal voltage constant. This paper describes the advantage of using a nonlinear technique called Dynamic Inversion (DI) in order maintain the voltage at the terminals constant. An excitation model which includes the excitation system stabilizer (ESS) and the transient gain reduction (TGR) blocks is considered. The referen...

This paper proposes decentralized improved synergetic excitation controllers (ISEC) for synchronous generators to enhance transient stability and obtain satisfactory voltage regulation performance of power systems. Each generator is considered as a subsystem, for which an ISEC is designed. According to the control objectives, a manifold, which is a linear combination of the deviation of generat...

The majority of industrial controlled induction machine drives are connected to the mains via a diode bridge. However, if reduction of harmonic currents and / or regenerative operation is desired, replacing the diode bridge by an active front-end (AFE) is required. This paper describes two models of an AFE: a power balance model disregarding switching effects, and an ideal switching model of a ...