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1
Power Electronics
1
Lecture 1 – Introduction & Basic Switching
Electric Drives Control 2
2
We want torque !
We are mainly interested in the mechanical torque on the
electrical machine shaft
But, the torque is the result of a complex interaction of
electric voltages and currents, magnetic fluxes and
mechanical layout
Our source is (usually) a DC Voltage, that ...
– we convert to AC with PWM and feed to the electrical
machine to ...
– control the machine currents such that the
mechanical torque becomes the one we want.
Against us we have:
– A machine that require voltages that increase with
speed
– A battery with limited and almost constant voltage
– A converter that needs to be controlled in a
microsecond time scale
Electric Drives Control 3
How we do it?
We start knowing:
– The desired torque
– Lots of system states, like speed,
DC link voltage, phase currents,
battery SOC, ...
We calculate:
– The traction machine currents
needed
– The voltages needed to set these
currents
– The modulation pattern needed to
set these voltages
We modulate the swithes accordingly
! Electric Drives Control 4
Torque
control
Current
Control
Modu-
lation PEC
Torque Ref
Current refs Voltage refs Switch states Output Voltage
Current, Speed and Position feedback
DC Link Voltage
feedback
This course
3
Why Power Electronics?
• The efficiency of a linear amplifier (converter) has a theoretical
upper limit of 78.5 %
• This is sufficient in many low power applications, such as home
audio
• In trains the rated power may be as high as 4-8 MW
• For an efficiency of 78.5 % the losses would be 0.86-1.72 MW
• This means that huge amounts of power and money would be
lost
... but the main problem would be thermal management, i.e. handling
the heat power
• Typically, the efficiency of a power electronic switch mode
converter is >98 %
Simple low power amplifiers
A B och AB
Eff = 20 – 25% Eff = 60 %
Electric Drives Control 6
4
Class D Audio Amplifiers
What is Power Electronics used for? • All kinds of electrical drives where electrical power is transfered to mechanical
and variable speed is required such as
• Traction applications such as trains, electrical vehicles and ship propulsion
• Pumps and fans
• All kinds of electrical drives where electrical power is transfered to mechanical
and position control (servo) is required such as
• Robots, cranes
• Power system applications such as
• HVDC (up to 3000 MW), Transistor based HVDC
• Feeding and priming power from renewable energy sources (solar, wind, ...)
• Active power filters, reactive power compensation, ...
• Power supplies
• Computers, tv-sets, ...
• Battery chargers for computers, mobile phones, hand-held tools, ...
- Back-up power, i.e. uninteruptable power supplies
• Many other applications
5
Electrical Motor Drives
http://www.irf.com
http://www.semikron.com
http://www.abb.com
Typical Motor Drive Applications - Except pumps, fans, cranes, …
Series Hybrid
http://www.hybridcenter.org/
http://www.toyota.com/
Prallel Hybrid
http://www.hybridcenter.org/
Series-Parallel Hybrid
http://www.hybridcenter.org/
Traction: for example trains and hybrid vehicles
http://www.abb.com
Robotics
6
Energy Conversion in Hybrid Vehicles
Electric Drives Control 11
12
EV Charging
Professor Mats Alaküla Industrial Electrical Engineering at Lund University
Senior Technology Advisor, AB Volvo
Scientific Leader, Swedish Electro Mobility Research Centre
7
13
Energy
Source
Energy
Transfer
Energy
Use
Conventional
Renewable
Inefficient
Dirty
14
The last Century
8
15
1912
The Charging Challenge is NOT new ...
16
Possibilities
9
It’s not easy...
0 5 10 15 20 25 >30 [x10 km]
Days with certain range
Example: 1:342
Norway: 1:40
18
Static Charging
10
19
On board Off board
On board / Off board = AC / DC
• ”AC Charging”
• Automation missing
• High power plug missing?
• 10...100 MW/m2
• ” DC Charging”
• Automation missing
• 10...100 MW/m2
• ”Wireless Charging”
• 10...100 kW/m2
20
Current
Control
a b c 0 pe
Current
Control
NO PE !
AC
DC1
DC2 DC/DC
2bl Isol
Current
Control
11
21
a b c 0 pe
Current
Control AC
• 3 phase plug limited to 63 A
• Max charging power 44 kW
• Available from all OEMs for night time
charging
• E.g. 200 kWh in 5 hours night time.
• NOT Enough for Opportunity Charging at
+100 kW
• New Plug Needed for higher power levels!
22
Current
Control
a b c 0 pe
AC
DC1
DC2
• OppCharge an open ”standard”, capable of up to 600 kW
• Expensive stations, not compatible with most truck applications
• CCS/DC normally limited to 200 A.
• @ 750 V this gives 150 kW, e.g 4x0.25h = 150 kWh
• NOT automatic
• Pushed towards 500 A with water cooling = 375 kW
@ 750 V
12
23
a b c 0 pe
NO PE !
DC2 DC/DC
2bl Isol
Current
Control
• Siemens eHighway is currently leading
• Others follow very soon
• Significant battery size reduction (-60%...-80%)
• 150 kWh instead of 600 kWh
• No protective earth – requires special safety
solutions
24
Dynamic Charging
13
25
Is automatic
Works with both small and BIG vehicles
Can be used both when
standing still and when moving
Can be used both
in the city and on the highway
The Perfect Charging Connection ...
Conductive ERS concepts
Honda Elways Alstom Elonroad Siemens
14
27
Siemens/Scania
Elways
Alstom/Volvo
Elonroad
-80 % battery size !
Elonroad
Siemens
28
Vision of one technology supplier ...
15
A technology example...
30
16
Tesla Semi Analysis ...
• GVW = 80000 lbs = 36 287 kg
• Drag Coefficient = Cd = 0.36
• Drivetrain: 4 PM motors from Model 3
• Acceleration 0-60 mph = 0-97 km/h
– Tractor only: 5 seconds
– Full load (80000 lbs): 20 seconds
• Hill climbing: 5 % slope @ 65 mph = 105 km/h
• Range: 300/500 miles = 483/805 km
• Charging time: 400 miles = 644 km in 30
minutes
Technical facts Given Facts Calculated Facts
• Energy consumption = about 1 kWh/km
• Tractor weight = 9 tons
• Traction motors = 4 x 137/192 kW (cont/peak)
• Battery Energy = 850 – 950 kWh (depends on DoD)
• Battery Weight = 4.2 – 4.7 tons (@ 0.2 kWh/kg)
• Charging power
= almost 1.3 Megawatt for Fast Charging
= 100 kW for Night Time Charging
• MEGA Charging Connector: Seems to be 4xSUPER
Charging Connector
X 4 =
17
Frequency Conversion
Japan East / West
50/60 Hz
600 MW
HVDC
Japan: Hokkaido to Honshu / 600 MW
18
HVDC and Transistor Based HVDC
http://swepollink.svk.se/ http://www.abb.com/
Camera with flash
19
Audio amplifiers
Electric Drives Control 37
Renewable Energy Systems
http://www.toshiba.com
Converters Suitable for Solar Cells
Without transformer
With transformer
20
Active Filters
-10
0
10
iLoad
[A]
-10
0
10
iLine
-10 0 10 20 30 40 50 60 70
-10
0
10
iAF
t [ms]
5 7 11 13 17 19 23 25 29 31 35 370
1
2
Ih
h
LoadLineAF
[Arms
]
iLoad
iLineiAF
Cdc
L2 L1
C
Vdc
Vbatt
3400 V50 Hz
Line sidefilter
Line sideconverter
DClink
Batterysidefilter
Batteryside
converter
Switch Mode Power Supplies - Forward Converter
http://www.irf.com
21
Thank You!
The Course 2018
Lectures 2 times a week
2…3 exercises a week
6 labs with home assignments / simulation exercises:
– The Flyback Converter
– The H-bridge
– Speed Control with a DC Machine
– Control of an Active Power Filter
– Control of PM Machines
– Control of Induction Machines
22
Teaching Plan
Week Who Date Time Lecture Content Who Date Time Lecture Content Who Date Time Lecture content Lab w ho
3 Mats 2017-01-15 13-17 Intro + Diode/Thyristor & Rectif ier Mats 2017-01-17 13-17 Buck converter, sw itch, snubbers Philip 2017-01-18 08-10 Lab Flyback converter preparation
4 Hans 2017-01-22 13-17 DC/DC conv +1 phase modulation Hans 2017-01-24 13-17 H-bridge + 2 phase modulation Philip 2017-01-25 08-10 Lab H-bridge preparation
5 Fran 2017-01-29 13-17 DC Current Control Mats 2017-01-31 13-17 Position and Speed Control Mats 2017-02-01 08-10 Torque Generation Lab Flyback Philip
6 Mats 2017-02-05 13-17 DC-machine theory Mats 2017-02-07 13-17 DC Machine Control Samuel/Max 2017-02-08 08-10 Lab DC-machine preparation Lab H-bridge Philip
7 Hans 2017-02-12 13-17 AC-pow er + 3 phase modulation Hans 2017-02-14 13-17 AC Current Control Samuel/Max 2017-02-15 08-10 Lab Active filter preparation
8 Mats 2017-02-19 13-17 Pow er Systems Applications Mats 2017-02-21 13-17 - Mats 2017-02-22 08-10 - Lab DC Samuel/Max
9 Mats 2017-02-26 13-17 Synchronous Machine and PMSM Mats 2017-02-28 13-17 Control of PMSM Mats 2017-03-01 08-10 Lab AF Samuel/Max
10
11
12 Hans 2017-03-20 13-17 IM Modelling and Control Hans 2017-03-22 13-17 Lab PMSM preparation
13 Mats 2017-03-27 13-17 Semiconductor PN junction Mats 2017-03-29 13-17 Semiconductor Mos IGBT
14
15
16 Hans 2017-04-17 13-17 New materials, Silicon Carbide Hans 2017-04-19 13-17 Lab Induction Machine preparation Lab PMSM Samuel/Max
17 Hans 2017-04-24 13-17 Passive components (Ind&Cap) Hans 2017-04-26 13-17 Losses, Temp, cooling
18 Mats 2017-05-03 13-17 Resonance and Multilevel converter Lab IM Gabriel
19 Mats 2017-05-08 13-17 EMC
20 Mats 2017-05-15 13-17 Guest Lecture - Hybrid Mats 2017-05-17 13-17 Guest Lecture - ERS
22 Hans 2017-05-22 13-17 Guest Lecture - Hybrid Hans 2017-05-24 13-17 Guest Lecture - ERS
22 Mats 2017-05-30 8-13 Tentamen
Ascension Day
Easter w eek !!!???!!!
Self studies
Exam w eek
Self-studies
Re-exam w eek?
Walpurgis Eve + Labour day
Home Assignments
Content as similar as possible to the labs
Prepares you for the lab
Diagnostic tests can be used before the labs – You must pass!
23
Teachers
Lectures:
– Mats Alaküla, professor, Senior Scientific Advisor Volvo Powertrain
– Hans Bängtsson, professor, Adjunct Professor Lund University, former
Senior Specialist Power Electronics and EMC at Bombardier
– Francisco Marquez
Course assistance, simulation exercises and Labs:
– Philip Abrahamsson, PhD student
– Max Collins, PhD student
– Samuel Estenlund, PhD Student
Components
24
Components 1 : The transistor
Works like a valve for electric current
Compare to a water tap
– Control a big flow with a small movement
– Flow x Pressure drop = Power
– Heats the water (a little)
A transistor
– Controls a big current with a small current
– The voltage drop across the transistor x the current = Power
– Heats the transistor (a lot)
Components 2: The Diode
Anod
Katod
+
-
i
u
Backriktning Framriktning
u
i
Spärrtillstånd
Ledtillstånd
25
Components 3: The IGBT – transistor
Symbol
Bottnad
Strypt Effektgräns
i
u
C
CE
i C
u CE +
+
- -
u GE
Gate
Kollektor
Emitter
u
u
u
GE2
GE3
GE1
Ökande u GE
Components 4: The Capacitor
Stores electric current with increasing
voltage like a hydrophore stores a fluid
or gas with increasing pressure
iCdt
duc 1
+ uc - ic
26
Components 5: The Inductor
Stores currrent into magnetic energy like
a flywheel stores torque into speed and
mechanical energy
LL u
Ldt
di
1
iL
+ uL -
Never break an inductive current Never short a capacitive voltage
LL u
Ldt
di
1c
c iCdt
du
1
cu
Lu
Lici
27
Basic Switching
Fundamentals of Switching
Analogue Switched
Ut
Uload
Ia
U0
0 Ploss = Ut*Ia
Pload = Uload*Ia
Ut ≈ Uload
On
Ut ≈ 0 Ut = U0
Ploss = 0 Ploss = 0
Off
Ia = Iload Is = 0 Ploss ≈ Pload
Ia
t t
Electric Drives Control 54
28
Never break an inductive current Never short a capacitive voltage
Electric Drives Control 55
BASIC turn on current step, capacitive load. No problem
C
i
dt
du
I u
i
t
u,i
Electric Drives Control 56
29
BASIC turn off current step, capacitive load. No problem
C
i
dt
du
I u
i
u,i
t
Electric Drives Control 57
BASIC turn on voltage step with capacitive load. Problem!
dt
duCi
Electric Drives Control 58
uU
+
U
-
u
i
u,i
t
30
BASIC turn off voltage step, capacitive load. No problem
dt
duCi
Electric Drives Control 59
uU
+
U
-
+
u
-
i
u,i
t
BASIC voltage ramp, capacitive load. No problem
dt
duCi
i
u,i
t
+
U
-
Electric Drives Control 60
31
BASIC turn on current step, inductive load. Problem
dt
diLu
I
+
u
-
i
t
u,i
Electric Drives Control 61
I > i
BASIC turn on current step, inductive load. Counter measure with capacitor
t
u,i
Electric Drives Control 62
dt
diLu
I
+
u
-
i
I > i
32
BASIC turn off current step, inductive load. Problem
t
u,i
Electric Drives Control 63
dt
diLu
I
+
u
-
i
BASIC turn off current step, inductive load. Counter measure with freewheeling diode
I +
u
-
i
t
u,i
Electric Drives Control 64
33
BASIC current ramp, inductive load. No problem
dt
diLu
I
+
u
-
i
u,i
t
Electric Drives Control 65
BASIC turn on voltage step with inductive load. No problem
dt
diLu
U u
i
u,i
t
U
Electric Drives Control 66
34
BASIC turn off voltage step, inductive load No problem
dt
duCi
+
U
-
+
u
-
i
u,i
t
Electric Drives Control 67
Summary An inductance keeps a current ”constant”
L
u
dt
di
u
i
Electric Drives Control 68
35
Summary A capacitance keeps a voltage ”constant”
C
i
dt
du
u
i
Electric Drives Control 69
Some fundamental topologies
36
Quadrants
Power Electronic
Converter
+
u
-
i
u u u u
i i i i
1-quadrant 2-quadrant 2-quadrant 4-quadrant
Electric Drives Control 71
Classification
DC Voltage
AC voltage
DC-voltage
conversion
AC voltage
conversion
Inversion
Rectification
Electric Drives Control 72
37
Single phase diode rectifier ideal
U0
-1
-0,5
0
0,5
1
0 50 100 150 200 250 300 350 400
Single phase diode rectifier ideal
-1
-0,5
0
0,5
1
0 50 100 150 200 250 300 350 400
Positive
Negaative
38
Single phase diode rectifier voltage
LNLNLN
TLNdc Eetdt
edtte
TV
22ˆ
2)()cos(
2
ˆ2)cos(ˆ
2
1 2
22
Line-to-neutral voltage and DC side voltage for a single-phase
diode rectifier
-1
-0,5
0
0,5
1
-4 -3 -2 -1 0 1 2 3 4
T/2
Diode rectifier with capacitive DC link
Figure 1.1: A single-phase diode rectifier
with a capacitive DC link.
Figure 1.2: Line-to-neutral voltage and DC side voltage
for a single-phase diode rectifier with a capacitive DC link.
LNLN
LN
TLNdc Eetdt
edtte
TV
22ˆ
2)()cos(
2
ˆ2)cos(ˆ
2
1 2
22
Figure 1.3: Line current (left) and its frequency spectrum (right),
for a single-phase diode rectifier with a capacitive DC link.
39
The Buck Converter (Step-Down Converter)
Figure 1.16: Buck converter.
Figure 1.17: Ideal waveforms of the
Buck converter.
S ”on”
swloaddc
LL
Lloaddc DTL
VVi
dt
diLvVV
S ”off”
swload
LL
Lload TDL
Vi
dt
diLvV 1
The Boost Converter (Step-Up Converter)
Figure 1.18: Boost converter.
Figure 1.17: Ideal waveforms of the
Boost converter. Replace
Vdc and Vload of the Buck
converter with Vout and Vin
S ”on”
S ”off”
swin
L DTL
Vi inSinL
L VvVvdt
diL
outinoutDinLL VVVvVv
dt
diL
swoutin
L TDL
VVi
1
40
The Buck-Boost Converter (Half-Bridge)
Figure 1.19: Buck-boost converter.
Figure 1.17: Ideal waveforms of the
Buck-boost converter.
S ”on”
swloaddc
LL
Lloaddc DTL
VVi
dt
diLvVV
S ”off”
swload
LL
Lload TDL
Vi
dt
diLvV 1
The Flyback Converter
Figure 1.23: Principal schematic of a flyback converter. Only the devices needed to
understand the operation are included.
41
The Laboratory Flyback Converter
Flyback converter with input filter, inrush current limitation, diode rectifier, dc link capacitors, power
MOSFET, transformer, output filter and three snubber circuits. The controller circuits are not included in the
circuit.
That’s all folks...
Electric Drives Control 82