1. Chapter 1 Power Electronic Systems
Introduction
Power Electronics versus Linear Electronics
Applications
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

2. Power Electronic Systems
Block diagram
Role of Power Electronics
Reasons for growth
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

3. Linear Power Supply Series transistor as an adjustable resistor
Low Efficiency
Heavy and bulky
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

4. Introduction: Switching Power Electronics
Linear regulator
Goal: control VX such that Vo=Vo,REF
Plus: simple accurate, high-bandwidth
Minus: low efficiency 
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

5. Switching power converters
Vo(t)
VIN
<Vo>
Add filtering
Vo(t)
VIN
<Vo>
Add real devices
Note:
only lossless elements
L, C energy storage
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

6. Switch-Mode Power Supply
Transistor as a switch
High Efficiency
High-Frequency Transformer
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

7. Basic Principle of Switch-Mode Synthesis
Constant switching frequency
pulse width controls the average
L-C filters the ripple
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

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

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

10. Uninterruptable power supply - UPS
220 V
220 V ~
Batt
24V
load
Converter 1 rectifies line-frequency ac into dc
Capacitor acts as a filter; stores energy; decouples
Converter 2 synthesizes line-frequency ac to load
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

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

12. Scope and Applications
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction

13. Interdisciplinary Nature of Power Electronics
Electrónica de Potência
© 2008 Jose Bastos
Chapter 1 Introduction