Submitted By:-

Devesh Gupta

Himmat Singh

Project Guide

Sarita Kumari

Contents:-

Introduction

Single phase power circuit

Three phase power circuit

Why the need for single-phase to three-phase power conversion?

Circuit Diagram

Working

Advantage of three phase over single phase

Introduction

A phase converter is a device that converts electric power

provided as single phase to three phase. The majority of phase

converters are used to produce three-phase electrical power

from a single-phase source, thus allowing the operation of

three-phase equipment at a site that only has single-phase

electrical service. Phase converters are used where three-

phase service is not available from the utility, or is too costly

to install due to a remote location. A utility will generally

charge a higher fee for a three-phase service because of the

extra equipment for transformers and metering and the extra

transmission wire.

SINGLE-PHASE POWER CIRCUITS

Introduction :-

Single-phase electric power refers to the distribution of alternating

current electric power using a system in which all the voltages of

the supply vary in corresponding exactly.

Single-phase distribution is used when loads are mostly lighting

and heating, with few large electric motors.

A single-phase supply connected to an alternating current electric

motor does not produce a revolving magnetic field; single-phase

motors need additional circuits for starting, and such motors are

uncommon above 10 or 20 kw in rating.

THREE-PHASE POWER CIRCUITS

Introduction:

Almost all electric power generation and most of the power

transmission in the world is in the form of three-phase AC circuits.

A three-phase AC system consists of three-phase generators,

transmission lines, and loads.

There are two major advantages of three-phase systems over a

single-phase system:

1) More power per kilogram of metal form a three-phase machine;

2) Power delivered to a three-phase load is constant at all time,

instead of pulsing as it does in a single-phase system.

Why the need for single-phase to three-

phase power conversion?

Residential/Commercial expansion needing increased water

demands

• Remote pumps (submersible/booster)

• Increased pump HP (moving water further distances)

Increased activity in energy sector

• Oil/Natural gas wells

• De-watering pumps

Circuit Diagram

A three phase converter creates a three-phase power supply from a

single-phase supply. A digital signal processor (DSP) is used to

control power electronic devices to generate a third voltage, which

along with the single voltage from the supply creates a balanced

three-phase power supply.

AC power from the utility is converted to DC, then back to AC. The

power-switching devices used in this process are insulated-gate

bipolar transistors (IGBT).

In this type of digital phase converter the input rectifier consists of

IGBTs in series with inductors. The IGBTs are controlled by the DSP

to draw current from the single-phase line in a sinusoidal fashion.

The output inverter consists of IGBTs that draw on the power of the

DC bus to create an AC voltage.

Working

A voltage created by power-switching devices like IGBTs is not

sinusoidal. It is a pulse-width modulated (PWM) waveform very high

in harmonic distortion.

This PWM voltage is then passed through an inductor filter system

that produces a sine-wave voltage with less than 3% total harmonic

distortion (standards for computer grade power allow up to 5% THD).

The converters operate at 95%–98% efficiency. When the converter

is energized with no load, it consumes very little power.

Working

Advantage of three phase over single

phase Three phase power distribution requires lesser amount of copper or

aluminium for transferring the same amount of power as compared to

single phase power

The size of a three phase motor is smaller than that of a single phase

motor of the same rating.

Three phase motors are self starting as they can produce a rotating

magnetic field. The single phase motor requires a special starting

winding as it produces only a pulsating magnetic field.

The ripple factor of rectified dc produced from three phase power is

less than the dc produced from single phase supply.

Three phase motors have better power factor regulation.

Three phase generators are smaller in size than single phase

generators as winding phase can be more efficiently used.