chapter 1 power electronic systems
DESCRIPTION
Chapter 1 Power Electronic Systems. Introduction Power Electronics versus Linear Electronics Applications. Power Electronic Systems. Block diagram Role of Power Electronics Reasons for growth. Linear Power Supply. Series transistor as an adjustable resistor Low Efficiency - PowerPoint PPT PresentationTRANSCRIPT
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-1
Chapter 1 Power Electronic Systems
• Introduction• Power Electronics versus Linear Electronics• Applications
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-2
Power Electronic Systems
• Block diagram• Role of Power Electronics• Reasons for growth
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-3
Linear Power Supply
• Series transistor as an adjustable resistor• Low Efficiency• Heavy and bulky
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-4
Introduction: Switching Power Electronics
Linear regulator
Goal: control VX such that Vo=Vo,REF
Plus: simple accurate, high-bandwidth
Minus: low efficiency
0P
torin transis dissipated ispower and
33%) 5V,Vo 15V,Vin :example(
diss
oX
in
o
oin
oo
in
out
IV
V
V
IV
IV
P
P
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-5
Switching power converters
Add filtering
Add real devices
Vo(t)
VIN <Vo>
Vo(t)
VIN <Vo>
Note:-only lossless elements -L, C energy storage
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-6
Switch-Mode Power Supply
• Transistor as a switch• High Efficiency• High-Frequency Transformer
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-7
Basic Principle of Switch-Mode Synthesis
• Constant switching frequency• pulse width controls the average• L-C filters the ripple
dS
on
T
oiS
oi vT
tdtv
TV
S
0
1
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-8
Application in Adjustable Speed Drives
• Conventional drive wastes energy across the throttling valve to adjust flow rate
• Using power electronics, motor-pump speed is adjusted efficiently to deliver the required flow rate
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-9
Power Processor as a Combination of Converters
• Most practical topologies require an energy storage element, which also decouples the input and the output side converters
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-10
Uninterruptable power supply - UPS
• Converter 1 rectifies line-frequency ac into dc• Capacitor acts as a filter; stores energy; decouples• Converter 2 synthesizes line-frequency ac to load
~load
Batt24V
220 V220 V
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-11
Power Flow through Converters
• Converter is a general term• An ac/dc converter is shown here• Rectifier Mode of operation when power from ac to dc• Inverter Mode of operation when power from ac to dc
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-12
Scope and Applications
Electrónica de Potência © 2008 Jose Bastos
Chapter 1 Introduction 1-13
Interdisciplinary Nature of Power Electronics