Transcript
Power Electronics
Content
Introduction
Chapter 1 Power Electronic Devices
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Introduction
Outline What is power electronics? The history Applications About this course
I. What is power electronics?
1) Definition
Power Electronics: is the electronics applied to conversion and control
of electric power.
Range of power scale :
milliwatts(mW) megawatts(MW) gigawatts(GW)
A more exact explanation:
The primary task of power electronics is to process and control the
flow of electric energy by supplying voltages and currents in a form
that is optimally suited for user loads.
Conversion of electric power
Other names for electric
power converter:
-Power converter
-Converter
-Switching converter
-Power electronic circuit
-Power electronic converter
Electric Power Converter
Power output
Power input
Control input
Power electronic system
Generic structure of a power electronic system
Control is invariably required.Power converter along with its controller
including the corresponding measurement and interface circuits, is
also called power electronic system.
Power Converter
Control input Controller
Reference
Power input
Power output
Feedback (measurements of output signals )
Feedforward ( measurements of input signals )
A typical power electronic system
The task of power electronics has been recently extended to also ensuring the currents and power consumed by power converters and loads to
meet the requirement of electric energy sources.
Power Converter
Measurements
Controller Reference
Power input
Power output
Electric Motor light heating other electric equipment power converter
Electric utility battery other electric energy source power converter
Source
Load
io
Vo
ii
Vi
2) Relation with information electronics
A Classification of electronics by processing object
Other classifications of electronics
Electronics
Information electronics: to process information Power electronics: to process electric power
Electronics
Vacuum electronics: using vacuum devices, e.g, vacuum tubes devices
Solid (Solid state) electronics: using solid state devices,
e.g, semiconductor devices
Electronics
Physical electronics: physics,material,fabrication, and manufacturing of electronic devices
Applied electronics: application of electronic
devices to various areas
3) The interdisciplinary nature
William E. Newell’s description
Power electronics is the interface between electronics and power.
Power Electronics
学
Electronics
Power
学
Control
Continuous,
discrete
连续、离
散
Static & rotating
power equipment
Devices,circuits
Relation with multiple disciplines
Power electronics is currently the most active discipline in electric power engineering.
Power electronics
electronics electr
Electric machines
Circuit Ct theory
Systems& Control theory
Control
theory
Signal processing
Simulation & computing
electronics
Solid state
physics
Electromagnetics
Power systems
4) Position and significance in the human society
Electric power is used in almost every part and everywhere of modern
human society.
Electric power is the major form of energy source used in modern
human society.
The objective of power electronics is right on how to use electric power,
and how to use it effectively and efficiently, and how to improve the
quality and utilization of electric power.
Power electronics and information electronics make two poles of
modern technology and human society: information electronics is the
brain, and power electronics is the muscle.
II. The history
Mercury arc rectifier Vacuum- tube rectifier
Thyratron
Invention of Thyristor
Applicat ion of fast- switching fully- controlled semiconductor
devices
Power diode Thyristor
GTO GTR
Power MOSFET Thyristor
(microprocessor)
IGBT Power MOSFET
Thyristor (DSP)
Pre-history
1st phase
2nd phase
3rd phase
1957
1900
late 1980s
mid 1970s
III. Applications
Industrial applications
Motor drives
Electrolysis
Electroplating
Induction heating
Welding
Arc furnaces and ovens
Lighting
Transportation applications Trains & locomotives Subways Trolley buses Magnetic levitation Electric vehicles Automotive electronics Ship power systems Aircraft power systems
Utility stems applications High- voltage dc transmission(HVDC)Flexible ac transmission(FACTS)Static var compensation & harmonicssuppression: TCR, TSC, SVG, APFCustom power & power quality controlSupplemental energy sources :wind, photovoltaic, fuel cellsEnergy storage systems
Power supplies for electronic equipment
Telecommunications
Computers
Office equipment
Electronic instruments
Portable or mobile
electronics
Residential and home appliances
Lighting
Heating
Air conditioning
Refrigeration & freezers
Cooking
Cleaning
Entertaining
Applications in space technology
Spaceship power systems
Satellite power systems
Space vehicle power systems
Other aplications
Nuclear reactor control
Power systems for particle accelerators
Environmental engineering
Trends It is estimated that in developed countries now 60% of the electric
energy goes through some kind of power electronics converters before it is finally used.
Power electronics has been making major contributions to: --better performance of power supplies and better control of electric
equipment --energy saving --environment protection reduction of energy consumption leads to less pollution reduction of pollution produced by power converters direct applications to environment protection technology
IV. A simple example
A simple dc-dc converter example
Input source:100V
Output load:50V, 10A, 500W
How can this converter be realized?
Dc-dc converter
+ -
+
-
V
50V
R
5Ω
I
10A
Vg
100V
Dissipative realization
Resistive voltage divider
+ -
+
-
V
50V
R
5Ω
I
10A
Vg
100V
Pout=500W Pin=1000W
+
-
50V
Ploss=500W
Series pass regulator:
transistor operates in active region
+ -
+
-
V
50V
R
5Ω
I
10A
Vg
100V
Pout=500W Pin≈1000W
+
-
50V
Ploss≈500W
linear amplifier
And base driver
- +
Vref
Use of a SPDT switch
+ -
+
-
V(t)
50V
R
I
10A
Vg
100V
+
-
Vs(t)
Vs(t) Vg
switch position:
Vs=DVg
DTs
(1-D)Ts
0
1
1
2
t
1
2
The switch changes the dc voltage level
Vs(t) Vg
switch position:
Vs=DVg
DTs
(1-D)Ts
0
1
1
2
t
D=switch duty cycle
0<D<1
-
- Ts=switching period
fs=switching frequency
=1/ Ts DC component of Vs(t)=average value:
Vs
=
∫ 0
Ts Vs(t)
dt
=DVg
Addition of low pass filterAddition of (ideally lossless) L- C low- pass filter, for removal of
switching harmonics:
Choose filter cutoff frequency f0 much smaller than switching frequency fs.
This circuit is known as the “buck converter”.
+ -
+
-
V(t)
50V
R
I
10A
Vg
100V
+
-
Vs(t)
1
2
L C
Pin≈ 500W Ploss small
Pout=500W
Addition of control system for regulation of output voltage
+ -
+
-
V
i
Vg
H(s)
Pulse-width modulator
sensor gain
Gc(s)
-
+
transistor gate driver
Power input
Load Switching converter
error signal
Ve
Vc
Vref
Reference input
compensator
δ
δ (t)
t
dTs
Ts
Major issues in power electronicsHow to meet the requirement of the load or gain better control of the loadHow to improve the efficiency -- for reliable operation of power semiconductor devices -- for energy savingHow to realize power conversion with less volume, less weight, and less
cost.How to reduce negative influence to other equipment in the electric power
system and to the electromagnetic environment.
V. About this course
Three parts of the content
Power electronic devices: Chapter 1 Power electronic circuits: Chapter 2, 3, 4, 5, 8 Control techniques: Chapter 6 and 7
top related