Three-phase synchronous motors are widely used in the industrial motor driven systems. Variable frequency drives (VFDs) which allow soft-start of motors produce PWM voltage. Numerical relays are used in the protection schemes of these high voltage motors. The location of current transformer (CT) is an important criterion in the protection circuit. Impact of harmonics and the location of current...

The squared-field-derivative method for calculating eddy-current (proximity-effect) losses in round-wire or litz-wire transformer and inductor windings is derived. The method is capable of analyzing losses due to two-dimensional and three-dimensional field effects in multiple windings with arbitrary waveforms in each winding. It uses a simple set of numerical magnetostatic field calculations, w...

One of the most critical components in a step-up design like Figure 1 is the transformer. Transformers have parasitic components that can cause them to deviate from their ideal characteristics, and the parasitic capacitance associated with the secondary can cause large resonating current spikes on the leading edge of the switch current waveform. These spikes can cause the regulator to exhibit e...

1. Electrical Power Theory 1.1 Electrical Energy 1.2 Direct and Alternating Current 1.3 Three-Phase Systems 1.4 Star and Delta Connections 1.5 Phasor Representation 2. Electrical Generators 2.1 General Theory 3. Electrical Transformers 3.1 General Theory 3.2 Transformer Connections 4. Electrical Generator Configuration 4.1 Generator Rotor 4.2 Generator Stator 4.3 Excitation System 4.4 Generator...

Three-Phase four-wire distribution systems are facing severe power quality problems such as poor voltage regulation, high reactive power and harmonics current burden, load unbalancing, excessive neutral current, etc.This creates excessive neutral current both of fundamental and harmonic frequency and the neutral conductor gets overloaded. By integrating phase shifting into an extremely low zero...

The higher frequency transient signals generated as a result of a power system fault or disturbance provide the basis for an alternative approach to power system containing connectors and cables result in unsuitable operation of the system. However one major challenge is the need to ensure that the transients to be neutralized by electromagnetic compatibility (EMC) issues and cabling routes. T...

Submitted: Apr 21, 2013; Accepted: Jun 4, 2013; Published: Jun 22, 2013 Abstract: This paper presents a pulse doubling technique in a 36-pulse ac-dc converter which supplies direct torque-controlled motor drives (DTCIMD’s) in order to have better power quality conditions at the point of common coupling. The proposed technique increases the number of rectification pulses without significant chan...

A new integrated magnetic full wave dc/dc converter1 that provides flexible transformer design by incorporating an independent output inductor winding is introduced. The transformer is implemented on a traditional three-leg magnetic core. The inductor winding can be separately designed to control the output current ripple. The cross-sectional area of the inductor core leg can be reduced dramati...

This paper proposes a transformer-assisted pulsewidth-modulation zero-voltage-switching neutral-pointclamped (NPC) inverter. With the assistance of a transformer-assisted small-rating lossless auxiliary circuit, the main switches work with zero-voltage switching without suffering from any voltage/current spikes, under simple explicit control. The technique allows for higher operating frequency ...