Power system overvoltages due to switching, lightning and other disturbances are the main problem for designers of the power transformers. Once some frequencies of the incoming surges match with some of the natural frequencies of transformer winding, the resonance phenomenon is expected in transformer winding. The resonant overvoltages may destroy the insulation between turns and cause to insul...

An operation of any electromechanical device, in that number electric machines, it is electric motors and generators, can be seen as: a) An impact of magnetic field on a piece of ferromagnetic material, b) An interaction of two magnetic fields: magnetic field of primary part and magnetic field of secondary part; the secondary magnetic field can be generated: either by a current flowing in a win...

There has been a growing concern recently about energy use and its adverse impact on the environment. Industrial motor uses a major fraction of total industrial energy uses. Conventional ceiling and table fans have the potential to improve on energy efficiency, but the enhancements described in this research study increase the device’s efficiency further, thereby permitting greater energy savin...

Three phase induction machines for traction applications in electric and hybrid electric vehicles can be used with a fixed gear due to the wide speed range enabled by field weakening. Although the induction machine is know as an extremely reliable and robust device, machine faults may occur. Machine faults which do not become detected may cause complete failure of the vehicle. Therefore, early ...

In this paper, a four-phase 8/10-pole dual armature-winding variable flux reluctance generator (DAW-VFRG) with double-redundant rectifier circuit is proposed for onboard generator. The integrating VFRG and armature winding structure improves fault-tolerant capability power density. Based on the airgap field harmonics analysis function theory, no-load back-EMF model inductance are deduced determ...

A new model reference adaptive system based estimation technique for vector control of real and reactive power a brushless doubly fed reluctance generator without shaft position sensor is proposed. The rotor speed being precisely observed in closed-loop manner by eliminating the error between measured estimated inverter-fed (secondary) winding current angles stationary frame. Contrary to existi...

A simple mechanical model is identified for a two-pole induction machine that has a four-pole extra winding as a force actuator. The actuator can be used to suppress rotor vibrations. Forces affecting the rotor of the induction machine are separated into actuator force, purely mechanical force due to mass unbalance, and force caused by unbalanced magnetic pull from higher harmonics and unipolar...

This paper describes the influence of rotor eccentricity synchronous reactive frequency doubler’s characteristics. Specifically, the research is concentrated on the influence of rotor eccentricity on increased frequency EMF E2 value, that is induced it stator’s secondary winding. To clarify this question the simulations by using the finite element method implemented in QuickField software, are ...

Torsional vibrations and resonance problems with synchronous machines are most frequently encountered in rotor systems with long shafts and large inertias constituting a weakly damped mechanical resonator which exhibits a low resonance frequency. It is impossible to obtain a effective mechanical damping for these torsional vibrations, but by using a power electronics device and an inductive or ...

Multi-phase (more than three phases) drives possess several advantages over conventional three-phase drives such as: reducing the amplitude and increasing the frequency of torque pulsations, reducing the rotor harmonic currents, reducing the current per phase without increasing the voltage per phase, lowering the dc link current harmonics and higher reliability. By increasing the number of phas...