Inverter elet Industrial, Notas de estudo de Tecnologia Industrial

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EEE 360

Energy Conversion and

Transport

George G. Karady & Keith Holbert

Chapter 9

Introduction to Motor Control and Power

Electronics

• Lecture

Power Electronics DC Motor

control

M

AC

Supply

Controlled

Rectifier

DC link

Motor

Armature

AC

Supply

Excitation

winding

Rectifier

Figure 9.3 Concept of a dc motor drive.

AC supply is rectified to obtain variable dc voltage

• The capacitor filters the DC voltage
• The motor speed is controlled by changing the supply voltage

Power Electronics AC Motor

control

Figure 9.7 Concept of induction motor drive.

The motor speed is controlled by the variation of supply voltage frequency

• Variable frequency AC voltage is produced by an inverter
• The inverter is supplied by Dc voltage
• The Dc voltage is produced by the rectification of AC supply voltage

M

AC

Supply

Rectifier Inverter

DC link

Motor

Variable

frequency

AC voltage

9.3 Semiconductor switches

9.3 Semiconductor switches

V

I

V

breakdown

Reverse bias

region

Forward bias

region

Anode Cathode

I

V

Figure 9.8 Diode symbol and ideal

current–voltage characteristic.

Figure 9.9 Typical medium

power diode

9.3 Semiconductor switches

V Figure 9.11 Power diode operation.

load

V

ac

I

load

R

load

V

diode

V

load

( t)

V

I

load

( t)

A

 t

deg

V

ac

(t )

V

V

diode

( t)

V

 t

deg

9.3 Semiconductor switches

Gate

Anode Cathode

I

gate

V

ACat

I

A

Figure 9.12 Thyristor or silicon

controlled rectifier (SCR) symbol.

Forward on

state

A

n

o

d

e

c

u

r

r

e

n

t

Anode-Cathode voltage

Reverse bias Forward bias

Reverse

breakdown

voltage

Forward breakdown voltage (V

FB

) vs.

gate current

i

g

i

g

i

g

i

g

i

g

Figure 9.13 Thyristor

current–voltage

characteristics.

9.3 Semiconductor switches

Figure 9.16 Two flat-

pack thyristors mounted

on a liquid-cooled heat

sink

9.3 Semiconductor switches

Figure 9.17 Light-fired thyristor used for HVDC transmission.

9.3 Semiconductor switches

Drain

D

S

Source

Gate

G

Figure 9.20 Power metal-oxide-

semiconductor field-effect

transistor (MOSFET) symbol.

Collector

Emitter

Gate

Figure 9.21 Insulated

gate bipolar transistor

(IGBT) symbol.

9.4.2 Single phase

Controllable Rectifiers

9.4.2 Controllable rectifiers

V

ac

(t )

V

I

ac

( t)

A

V

th

( t)

V

 t

deg

(a) AC voltage, current and

thyristor voltage

V

dc

( t)

V

I

dc

(t )

A

V

gate

(t )

V

 t

deg

Figure 9.29 Voltage and

current waveforms of the

single-phase thyristor-

controlled bridge rectifier

(b) DC voltage, current and

gate pulse

DC voltage is controlled by

the delay of firing

Operation analysis