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Energy Storage by Means of Supercapacitors:Components, Power Electronics Interfaces
and Applications
Dr. P. Barrade
Laboratoire dElectronique Industrielle
EPFL - STI ISE - LEIELD 136, Station 11
Ch-1015 Lausanne / Switzerland
Phone : +41 (0)21 693 2651
Fax : +41 (0)21 693 2600
Seminar on Supercapacitors
Dr. P. Barrade
Summary
Generalities on Supercapacitors Principle, technology and construction
Electric-based model
Sizing of a supercapacitive tank
Energy requirements, Power availability
Thermal considerations
Limitations
Power electronics converters
Voltage equalization, Power electronics interfaces
Applications for supercapacitors
energy storage/energy buffer
elevators
hybrid vehicle
tramways/trolley-buses
UPS applications
Aeronautic application
Conclusion
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Energy storage devices
Capacitors Dielectric (Film-Foil, Metallized film) Electrostatic
Oxide electrolytic (Al, ta) Electrostatic
Electrochemical capacitor
Pseudocapacitor Faradaic
Double layer capacitor (ECDL) Electrostatic
Battery
Pb
NiCa NiMH
Li+ Faradaic
Fuel cell
H2, Methanol (reforming) Energy conversion
Flywheel Mechanical
Superconducting Magnetic Energy Storage (SMES) Magnetic
Seminar on Supercapacitors
Dr. P. Barrade
Energy storage devices
Ragone diagram : Energy Density versus Power Density
Generalities on Supercapacitors
Courtesy from Montena Component SA
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Energy storage devices
Energy density
Seminar on Supercapacitors
Dr. P. Barrade
Principle, Technology and Construction
Generalities on Supercapacitors
+++++++
-------
-------
+++++++
1 - 3 V
2 - 10
discharged
charged
Dielectric Electrolyte Separator
Electrodes
Current Collectors
C = r A/d
W = 1/2 CU2
A : up to 3000 m2(porous film)D : fix, ~10 er: fix, ~10U : 1 - 3 V, electrolyte decomposition voltageR : low, electrolyte
Conventional capacitor ELCD capacitor
Courtesy from Montena Component SA
-+
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+-
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Principle, Technology and Construction
Materials : Electrolyte :
"Acqueous : high ionic conductance, high power density (1V, 1.2S*cm) KOH, H2SO4
"Organic : high voltage, high energy density (2.5-3V, 50mS*cm) (Ex : 40mS*cm)
Electrode"Carbon: activated carbon
Separator"Organic: polymer (ex : 25m microporous polyolefin), paper
"Inorganic: glas fibers, ceramics
Current collector"Metal foil (Al, Ti, Fe)
Courtesy from Montena Component SA
Seminar on Supercapacitors
Dr. P. Barrade
Principle, Technology and Construction
Construction
Generalities on Supercapacitors
Courtesy from Montena Component SA
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Main properties
Life time : ageing mechanisms Type of aging
"Electrical solicitations
"Environmental (temperature, corrosive atmosphere)
"Mechanical (vibrations, shocks)
Electrical aging mechanisms"Ionic saturation of electrode surface
"Increased contact resistance in the electrodes
"Water diffusion
"
Impurities redox reaction"
Electrolyte decomposition
Life time : long life time thanks to
Reversible physical electrostatic charging cycles
No chemical redox reactions unlike batteries
Low voltage solicitation
Courtesy from Montena Component SA
Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Main properties
Cell behaviour under crushing conditions:
Strong resistance for axial crushing
Weak resistance for transverse crushing
Temperature / fire
Opening of cells in 6 min (600C without fire)
Opening of cells in 4 min in case of direct fire exposure
Flammable gaz emission in case of opening celle if T>500C
gaz emission in case of opening (HCn)
90 cells 3000F / for a 2m3 closed volume: risk of death
Courtesy from Montena Component SA
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Supercapacitors today:
Maximum voltage : 2.7V
1 Million charge/discharge cycles
~0.01Euro/F
From few farads to few thousand farads
From the single component to the modules
Courtesy from Maxwell Technologies SA
Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
The main parameters of a supercapacitor (from the power electronicians pointof view) :
The energy that can be stored :"
Capacitance : from 1F to 3000F (and more !)
"Maximum voltage : typically 2.5V -> 2.7V (and more ?)
The energy efficiency :"
Series resistor : limitation of the charging/discharging current
The self discharge"Leakage resistor : self discharging of the component
The classical model for a capacitor contains
an ideal capacitor
a series resistor
a leakage resistor
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
The main parameters of a supercapacitor : an ideal capacitor
"Defined by the surface of electrodes, width on ions
a series resistor"
Defined by the quality of carbon deposition on the aluminium current collectors
"Defined by the electrical conductivity of the carbon
"Defined by the ionic mobility of the electrolyte
a leakage resistor"
Overcharge beyond the decomposition limit of the electrolyte
"
Impurities redox reaction
"Redox reaction of functional groups on the edge of carbon particles
"Electronic conductance through the separator
Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
Capacitance and series resistance (ESR) Example of the BCAP0010 (Montena Component SA)
Courtesy from Montena Component SA
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
Additional parameters (specificity of supercapacitors)
Non-constant capacitance and relaxation phenomena
Voltage dependant capacitance Relaxation phenomena are not leakage
Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
Additional parameters (specificity of supercapacitors)
Voltage dependant capacitance (due to the width of the double layer)
How to consider?"Current capacitance
"Energetic capacitance
C =Co+Ku
Cu
!
Q =Cu! ic =
dQ
dt! i
c = C
o+ 2Ku( )Ci
! "# $#
du
dt
P = icu = C
o+ Ku( )u
du
dt!W
c=1
2C
o+4
3Ku
"
#$
%
&'
Cw
! "# $#
u2
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
Additional parameters (specificity of supercapacitors)
Voltage dependant capacitance. Example of the BCAP0008 (MontenaComponent SA) : C=1800F, Co=1800F and K=150F/V, U=2.5V
Really difficult to identify clearly the energy stored in a cell, depending ondefinitions
"Only real possibility: measures!
C 1800F 5625J
Co+K*u 2175F 6796J +20.8%
Ci 2550F 7968J +41.6%
Cv 2300F 7187J +27.7%
Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
Additional parameters (specificity of supercapacitors)
Relaxation phenomena
"Due to porosity of electrodes (misopores, mesopores, macropores)
"During a fast charge (discharge), ions will first enter (leave) into macropores,then in mesopores
"
Diffusion of ions in misopores is characterized by long constant times
"During ageing process, relaxation phenomena is re-inforced by impuritiesaffecting the dimension of the pores
"After a fast charge (discharge), non homogeneous repartition of loads on theelectrodes
"Diffusion of the loads to reach a homogenous distribution (depends on size ofthe pores and size of the ions)
Voltage decrease (after charge)
Voltage increase (after discharge)
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Seminar on Supercapacitors
Dr. P. Barrade
Generalities on Supercapacitors
Modelling supercapacitors :
Additional parameters (specificity of supercapacitors)
Voltage dependent capacitance Cu(width variation of the double layers)
rc sub-circuits (relaxation phenomena, poreousity of electrodes)
Seminar on Supercapacitors
Dr. P. Barrade
The energy stored in one single component is generally not sufficient
Sizing of a supercapacitive tank
For a given application, it must be found :
the number of needed supercapacitors
for that number, it must be defined the arrangement for the supercapacitors :"
how many supercapacitors will be series connected in an elementary branch
" the number of elementary branches
The two last parameters define the maximum voltage and current that a
supercapacitors tank can provide
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Seminar on Supercapacitors
Dr. P. Barrade
To identify the number of supercapacitors, energy requirements have to be known.
In various applications, energy requirements are not defined.
Power requirements are often described : this is the instantaneous power that thesupercapacitors bank has to store/provide.
Sizing of a supercapacitive tank
Energy requirements have to be identified thanks to the instantaneous
power requirements
The needed energy can be obtained thanks to the link equation between theenergy Wcand the power Pc:
Wc =
Z Pcdt
Seminar on Supercapacitors
Dr. P. Barrade
Identifying the needed energy :
example
Sizing of a supercapacitive tank
For a given power profile,
it is easy to identify by
numerical calculation theassociated energy profile.
The value of energy that
must be retained is not the
value at the end of a
complete cycle, but the
maximum value reached
during the cycle (220kJ in
the example).
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitors bank
From the needed energy to the number of supercapacitors : the total amount of energy in a supercapacitor is defined by the equation :
External behaviour and environment
To use to total stored energy :
the voltage across the component should be decreased from its maximum allowedvalue U
Mto 0V. But that is not possible :
" Because of the maximum current a supercapacitor can provide
" During a discharge with a constant current, the power follows the voltage profile
It is not possible to use the total amount of energy stored into a supercapacitor : a
residual voltage has to be taken into account to consider that the component is
discharged
Wc =1
2CUc
2
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Energy requirements Energy stored in a supercapacitor
Voltage discharge ratio: the minimum voltage during the discharge has to belimited for efficiency reasons
The usable energy is then only part ofthe maximum stored energy
Number of supercapacitors for a givenusable energy
WM =1
2CUM
2
d = 100
Um
UM
Wu = WM
1
d2
1002
Ns =2 u
CUM2
1
d2
1002
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Energy requirements
Using a 2600F/2.7V/0.4m#supercapacitor
Example: 220kJ to store
2600F, 2.5VTotal stored
energy
d=50% N=31 W=293.8kJ
d=60%
N=37 W=350.6kJ
d=70%
N=46 W=438kJ
Ns =2Wu
CUM2
1
d2
1002
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Power availability
Due to the series resistor of supercapacitors, energy efficiency ofsupercapacitors has to be taken into account during the sizing of thesupercapacitive tank
Energy efficiency has an influence on the power availability
Must be identified
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Procedure for the Exponential Charge
Initial charge : uci=UM.di/100
Charging voltage: Ue=UM.
Charge is finished when: ucf=UM.df/100
Main equations:
c = UM
1
1
di
100
e
t
RsC
Tch = RsCln
100 df
100 di
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Procedure for the Exponential Charge
Power in the series resistors
Energy lost in the series resistors
Taking into account Tch
Energy stored in the supercapacitor
Pr =1
Rs
UM uc
2= Pr =
1
RsUM
2
1
di
100
2e
t
RsC
Wr =Z t0
Prdt = Wr = 12CUM2
1 di
100
21 e2t
RsC
Wr = 1
2CUM
2
1
100
2df(200 df) di(200 di)
Wc =1
2Cucf
2
1
2Cuci
2= Wc =
1
2CUM
2
"df
100
2
di
100
2#
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Procedure for the Exponential Charge
Efficiency
For a high efficiency
dfand dimust be as high as possible
Not compatible with a large range of voltage variation
"It is mandatory to strictly control the charging/discharging current
= Wc
Wc+ Wr= =
1
200(df+ di)
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Efficiency for the charge/discharge with controlled current
Main equation
Charge/discharge time
Energy lost
Energy stored/provided
uc = UMdi
100+
1
C
Icct
Tch = CUM
Icc
df di
100
Wr = RsCIccUMdf di
100
Wc =1
2CUM
2
"df
100
2
di
100
2#
c = UMdi
100+
1
C
Icdt
Tch = CUM
Icd
f i
100
Wr = RsCIcdUMdf di
100
ChargeIcc>0 and df>di
DischargeIcd
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Efficiency for the charge/discharge with controlled current
Efficiency
ChargeIcc>0 and df>di
DischargeIcd
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Energy efficiency and power availability
Using a 2600F/2.7V/0.4m#
Example: 220kJ to store, +/- 40kW, with a 90% energy efficiency
For this special application, the power availability is the main sizing criterion
Seminar on Supercapacitors
Dr. P. Barrade
Example
Energy requirements : 220kJ (61Wh)
Power needs: +/- 40kW, with a 90% energy efficiency
Number of needed supercapacitors (theoretical) :
31 Scaps 2600F/2.7V
Energy available : 220kJ (61Wh) if the voltage is kept over 50% of the maximum Total stored energy : 293.8kJ (81.6Wh)
For practical reasons (energy efficiency, power availability) :
36 Scaps 2600F/2.7V are chosen" to obtain a 90% energy efficiency
" to assume the power demand
Available energy :220kJ (61Wh) if the voltage is kept over 60.36% of the maximum
Total stored energy : 341kJ (95Wh)
Final choice : 1x36 series connected Scaps (2600F/2.7V) (16.9kg, 12.9l)
Sizing of a supercapacitive tank
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
A supercapacitive tank is sized as an answer to Energy requirements
Power requirements"Available power is limited by the series resistor of the cells
"Available power is linked to the charge/discharge efficiency
Efficiency means internal losses into the cells"Internal losses act mainly as a joule effect
"Increase of temperature of the component
Temperature of a supercapacitive tank must be taken into account for a completesizing:
Natural cooling
Forced cooling
If no forced cooling possible, then increase the number of cells to maximise poweravailabilty (efficiency) and minimize losses
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Temperature of a supercapacitive tank must be taken into account for a completesizing
Main parameters to study thermal behavior of a supercapacitor
Density"
Easy to identify
Thermal conductivity"Generaly given by manufacturer, but deduced from experimental protocol that gives quite
vague datas
Thermal capacitance"Generaly not given by manufacturer
A way to obtain this data is to consider that supercapacitors are made of 60% ofaluminium, 25% of carbon, and 15% of water (from a thermal point of view)
Status at LEI: a complete evaluation will be made next summer
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Example: 3 cells (D-cells), mounted on a board, inside carbon fiber box.
2D finite element simulation software"Coupling of heat transfer / fluid mechanics solvers
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Example: Stand-by mode, 15mn warming under sunning conditions (1000w/m2)
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Example: stand-by mode, inrush air speed is 0.5m/s
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Example: power provided per cell is 110W, losses per cell are 11.3W (90.6%), during2400s (40mn), inrush air speed is 0.5m/s
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Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Example: power provided per cell is 110W, losses per cell are 11.3W (90.6%), during2400s (40mn), inrush air speed is 0.5m/s
Horizontal gradiant temperature
For this application, forced cooling is needed, even if temperature is not stabilised
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Thermal aspects
Example: power provided per cell is 110W, losses per cell are 11.3W (90.6%), during2400s (40mn), inrush air speed is 0.5m/s
Horizontal gradiant temperature
For this application, forced cooling is needed, even if temperature is not stabilised
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Seminar on Supercapacitors
Dr. P. Barrade
Limitation:
Example of a hybrid elevator
Supercapacitive tank plugged on the DC bus
Sizing of a supercapacitive tank
Grid
AC
DC
Braking resistors
DC
AC
DC
DC
Supercapacitive
accumulator
Permanent Magnet
Synchronous Motor
C
L
me
mpmc
mw1 mw2
Shaft
Ls
u1, u2, u3
i1, i2, i3
IlUd Uc
IsUs
Ia
It
S
Ib
um1, um2, um3
im1, im2, im3
Seminar on Supercapacitors
Dr. P. Barrade
Limitation:
Example of a hybrid elevator
Shaft length: 18m, 5 floors
Cabin mass: 800kg
Up to 8 passengers
Accumulator capacity: 20Wh
Sizing of a supercapacitive tank
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Seminar on Supercapacitors
Dr. P. Barrade
Limitation:
Example of a hybrid elevator
Tests on strategies for energy management"
Rule Based vs. Dynamic Programming
Sizing of a supercapacitive tank
0 20 40 60 800
25
50
75Scaps Energy Profile
Energy[kJ]
Rules
0 20 40 60 800
25
50
75
Energy[kJ]
Mission
DP
Seminar on Supercapacitors
Dr. P. Barrade
Sizing of a supercapacitive tank
Limitation:
Example of a hybrid vehicle: Power requirements are easy to clearly identify
Energy requirements are not so easy to identify"Need a deep knowledge on the system
"Strongly affected by strategies for storing/supplying
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Seminar on Supercapacitors
Dr. P. Barrade
Series connection of supercapacitors :
Power Electronics Converters
Power losses in the associated power converter are related to thecharging/discharging current of the supercapacitors.
The operating voltage (Scaps voltage) must be much more higher thanthe forward voltage caused by conduction in the needed converter
To increase the efficiency for a given power
Decrease the charging/discharging current in the supercapsIncreasing the total voltage of the supercaps
A series connection of supercapacitors is required
Seminar on Supercapacitors
Dr. P. Barrade
Unbalanced voltages: consequences
There are differences between the Scaps values
Power Electronics Converters
Uc1
I
Uc2
C1
C2
U
Voltages across C1and C2will not be the same at the end of a
charging process
3 cases have to be considered : Ideal case : C1=C2
Real case : C1$C2, but the supercapsmaximum voltage may not be reached
Ideal Real case : C1$C2, but a deviceensures the voltages sharing
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Seminar on Supercapacitors
Dr. P. Barrade
Unbalanced voltages: consequences
The charging process is stopped as soon as one Scap reaches its maximumvoltage
Power Electronics Converters
C1=C2C2=80% of C1
No sharing
C2=80% of C1Sharing
Uf (V) 5 4.5 5
Uc1f (V) 2.5 2 2.5
Uc2f (V) 2.5 2.5 2.5
E (J) 6250 4500 5625
Seminar on Supercapacitors
Dr. P. Barrade
Unbalanced voltages in the series connection of supercapacitors
Because of differences between the various capacitances
Consequences after various charge/discharge cycles
Risks of over-voltages on several cells (those of lowest capacitance)
As the charge must be stopped as soon as one cell reaches its maximumvoltage (that one of lowest capacitance)
"The cell of high capacitance are far away from the full state of charge
"The totat amount of stored energy can not be obtained
"Needs in circuits for the voltage equalization
Power Electronics Converters
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Seminar on Supercapacitors
Dr. P. Barrade
Power Electronics Converters
Voltage equalization
Voltage sharing solution, using power electronics solutions to offer a highefficiency.
C1
C2
C3
L1
L2
T1
D1
T2
D2
T'2
D'2
T'3
D'3
I
i1
i2
il1
il2
i'2
i3
C1
C2
C3
T1
T2
T3
D2
D3
D1
Np1
Np2
Np3
Df
Nf
I
i1
i2
i3Centralized flyback dc-dc
converter with distributed
secondary
association of buck-boost
dc-dc converters
forward dc-dc converterwith distributed primary
Seminar on Supercapacitors
Dr. P. Barrade
Power Electronics Converters
Voltage Equalization
Voltage sharing solution, using dissipativeelements offer also a high efficiency.
High performances obtained thanks to anefficient control and management of voltageequalization processes
Supercapacitor manufacturers are able topropose ready-to-use solutions, directlyintegrated into a modular supercapacitivetank
Cell balancing
Module to module balancing
Integration of protection against short-circuits
Voltage monitoring for external control
"
Up to 1kV!!!!!
Courtesy from Maxwell Technologies SA
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Seminar on Supercapacitors
Dr. P. Barrade
Power Electronics Converters
Power electronics interfaces :
During charging and discharging, the voltage across a supercapacitors bank isvarying :
A power interface between the Scaps bank and its load has to be defined :
Example : interface between a Scaps bank and a DC bus
Scaps
bank
Power
Converter
DC bus
Which topology ?
Wc =
1
2CU
c
2I
c = C c
dt
Seminar on Supercapacitors
Dr. P. Barrade
Power Electronics Converters
Power electronics interfaces :
Two solutions : using a buck or a boost topology
Scapsbank
BuckConverter
DC bus
Scaps
bank
Boost
Converter
DC bus
Buck converter Boost converter
The current provided by the Scaps is
strongly discontinuous
A maximum number of series
connected Scaps is needed
The current provided by the Scaps iscontinuous
The number of series connected Scapscan be minimised
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Seminar on Supercapacitors
Dr. P. Barrade
Power Electronics Converters
Power electronics interfaces :
Two solutions : using a buck or a boost topology
Huge number
of series connected
Scaps :
Large number ofactive components
Safety problems
High cost
High efficiency
Reduced number
of series connected
Scaps :
reduced number of
active components
Low cost
easier symetrizingprocess
Low efficiency
The boost topology offers more advantages
Seminar on Supercapacitors
Dr. P. Barrade
Power Electronics Converters
Power electronics interfaces :
using a boost topology : association of a Boost and a buck converter
Scaps
bank
DC bus
Scaps
bank
DC bus
When the DC voltage is nearly
constant and can not be lower
than that one of the Scaps
When the DC voltage varies
strongly and can become much
lower than that one of the Scaps
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Seminar on Supercapacitors
Dr. P. Barrade
Power electronics interfaces :
Adapting the voltage-level with transformers Voltage adaptation with an intermediary AC-link with MF-transformer
topology with resonant mode
Power Electronics Converters
Seminar on Supercapacitors
Dr. P. Barrade
Power electronics interfaces :
Increasing efficiency with ZVT/ZCS Technology Topology : MF-AC-link with ZVT/ZCS converters
Power Electronics Converters
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Seminar on Supercapacitors
Dr. P. Barrade
Energy Storage / Energy Buffer
Are supercapacitors able to store enough energy for a powering a bus ?
0 100 200 300 400 500 600 700 800 900 1000-1
0
1
2
3
4
5
6
7
8
9x 10
7
t (s)
Energie
(J)
0 100 200 300 400 500 600 700 800 900 1 0000
10
20
30
40
50
60
70
80
90
100
t (s)
Vitesse
(km/h)
From Bellerive to St Franois5km / 120m
The needed energy is 84MJ (23.3kWh)
19900 Scaps (1800F) / 7.46m3/ 7.96T
Applications for supercapacitors
Seminar on Supercapacitors
Dr. P. Barrade
Energy Storage / Energy Buffer
Supercapacitors are not able tostore enough energy for acomplete run
Some intermediary re-loadingstages have to be defined
Bus
Supercondensateurs
DEPART
STATION 1
STATION 2
STATION n
ARRIVEE
Applications for supercapacitors
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Dr. P. Barrade
Energy Storage / Energy Buffer
7 loading stations
4160 supercapacitors1800F/2.5V
26x160 series connected
total energy : 23.4MJ(6.5kWh)
operational energy :
17MJ (4.75kWh) Time for loading : 20s
Current for loading :2.6kA
1.6m3 / 1.7T
Applications for supercapacitors
Seminar on Supercapacitors
Dr. P. Barrade
Energy Storage / Energy Buffer
The power absorbed bythe bus is the mirror of the
power provided by thesupercapacitors
The loading of thesupercapacitors needs toabsorb high magnitudepower on the network :
1MW x 7 times x 20s
Applications for supercapacitors
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Seminar on Supercapacitors
Dr. P. Barrade
Energy Storage / EnergyBuffer
when loading the mainsupercapacitors, theenergy is taken on fixsupercapacitors
to prepare the coming ofthe next bus, the fixsupercapacitors have tobe re-loaded :
10mn instead of 20s
the power absorbed onthe network is low
Bus Supercondensateur
DEPART
STATION 1
STATION 2
STATION n
ARRIVEE
Supercondensateursintermdiaires
s1 s2
Supercondensateursintermdiaires
s1 s2
Applications for supercapacitors
Seminar on Supercapacitors
Dr. P. Barrade
Energy Storage / Energy Buffer
The power provided bythe network is the sum ofthe low power absorbedby each loading station
The power provided bythe network is the realmean power needed by thebus
The power provided bythe network is less than100kW
Applications for supercapacitors
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Seminar on Supercapacitors
Dr. P. Barrade
Energy Storage / Energy Buffer
The energy density of supercapacitors is too low for most of the applications It is often impossible to use supercapacitors are single energy storage devices to give
the complete autonomy of a system
Thanks to their power availability, supercapacitors are mainly used as energy buffers"To minimize power constraints on a main energy source
"To allow an efficient energy management
"To allow the recovery of energy when possible
Applications for supercapacitors
Supercapacitors are mainly used:
- as energy buffers (hybrid systems)
- as main energy sources for applications with reduced energy needs
Seminar on Supercapacitors
Dr. P. Barrade
Applications for supercapacitors: elevators
Variable frequency drives for elevators
Elevators are intrinsically reversible systems
3
!"
#"
$"
Conventional feeding
Non-Reversible
Efficiency increase
Reversible front-end
Efficiency increase
Local accumulator
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Seminar on Supercapacitors
Dr. P. Barrade
Applications for supercapacitors: elevators
Solutions for allowing an efficiency increase
Recovering of energy
Reversible front-end
"Solve the problem of energy recovering
"Does not solve the problem of power fluctuations on the grid
It is reinforced
Local accumulator
"Solve the problem of energy recovering
Depends on the size of the accumulator
Depends on the control
"Can solve the problem of power fluctuations on the grid
Depends on the size of the accumulator
Seminar on Supercapacitors
Dr. P. Barrade
Applications for supercapacitors: elevators
Structure and objectives
Structure
Objectives
Increase of the global efficiency
Limitation of power fluctuations on the grid
GridAC
DC
Braking resistors
DC
AC
DC
DCSupercapacitive
accumulator
Permanent Magnet
Synchronous Motor
C
L
me
mpmc
mw1 mw2
Shaft
Ls
u1, u2, u3
i1, i2, i3
IlUd Uc
IsUs
Ia
It
S
Ib
um1, um2, um3
im1, im2, im3
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Seminar on Supercapacitors
Dr. P. Barrade
Applications for supercapacitors: elevators
Tests on an elevator
Considered elevator
Shaft length: 18m, 5 floors
Cabin mass: 800kg
Up to 8 passengers
Accumulator capacity: 20Wh
Seminar on Supercapacitors
Dr. P. Barrade
Applications for supercapacitors: elevators
Tests on an elevator
Experimental results
0 20 40 60 800
2
4
6
Grid Power Profile
Power[kW]
Elevator
0 20 40 60 800
2
4
6
Power[kW]
Rules
0 20 40 60 800
2
4
6
Power[kW]
Mission
DP
0 20 40 60 800
100
200
300Braking Resistor Energy Profile
Energy[kJ]
Mission
Elevator
Rules
DP
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Dr. P. Barrade
Applications for supercapacitors: elevators
Test on strategies
Experimental results
0 20 40 60 800
25
50
75Scaps Energy Profile
Energy
[kJ]
Rules
0 20 40 60 800
25
50
75
Energy
[kJ]
Mission
DP
Seminar on Supercapacitors
Dr. P. Barrade
Diesel-electric trains
Well-established technology on railways systems
Lines of low traffic potential
Reduced costs compared to the infrastructure costs of a line-powered trains
Principle:
Applications for supercapacitors: hybrid vehicle
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Seminar on Supercapacitors
Dr. P. Barrade
Diesel-electric trains
Main disadvantage Diesel engine has to assume all power and energy needs
"Strong speed/torque fluctuations
Efficiency, Emissions
Losses into the energy transfer chain"
Efficiency of asynchronous generator, power converters, asynchronous motors
Use of resistors during braking modes
Applications for supercapacitors: hybrid vehicle
Seminar on Supercapacitors
Dr. P. Barrade
Diesel-electric trains
How to increase efficiency Use of an energy storage tank
"To minimize power constraints on diesel engine (decoupling of energy and power needs)
"To allow the control of the diesel engine at its maximum efficiency, or switch it off
"To enable energy recovering during braking phases
technology ofsupercapacitors
They are powercompatible
Life time / number ofcycles compatibles
It has to be checked ifthey are energycompatible!
Applications for supercapacitors: hybrid vehicle
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Seminar on Supercapacitors
Dr. P. Barrade
Case of study
GTW train (Stadler Rail AG, CH) Total weight (w/o load): 67t
Total weigth: 84t
Diesel engine power: 2x380kW
Max. power at the wheels: 620kW
Max. speed: 140km/h
Applications for supercapacitors: hybrid vehicle
Seminar on Supercapacitors
Dr. P. Barrade
Case of study
Track: Merano-Malles (north of Italia)
Power profile
Altitude variation
0 2000 4000 6000 8000 10000 12000 14000 16000 18000-2000
-1500
-1000
-500
0
500
1000
Wheel power for typical itinerary
Time (s)
Power(kW)
InstantaneousMean
0 2000 4000 6000 8000 10000 12000 14000 16000 180001000
1100
1200
1300
1400
1500
1600
1700
1800
Altitude variation for a typical itinerary
Time (s)
Altitude(m)
Applications for supercapacitors: hybrid vehicle
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Seminar on Supercapacitors
Dr. P. Barrade
On-board stored energy versus diesel-engines power constraints
Main results Reduction of required diesel generator power as a function of stored energy
0 100 200 300 400 500 6000
100
200
300
400
500
600
700
Downsizing the maximal power of the diesel motor
Stocked energy in the supercapcitive tank (MJ)
Dieselmotorpowerneeded(kW)
Applications for supercapacitors: hybrid vehicle
Seminar on Supercapacitors
Dr. P. Barrade
In hybrid vehicle, supercapacitors enable
To lower the sizing of thermal engines/batteries
To increase efficiency
Control of the thermal engine on its maximum efficiency map
Energy saving during braking
For catenary- fed vehicles
Increased efficiency
Limitation of power constraints on the grid
"More vehicles on a line without modifying the infrastructures
Applications for supercapacitors: hybrid vehicle
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Seminar on Supercapacitors
Dr. P. Barrade
Uninterruptible Power Supplies (UPS applications)
Compared with application with batteries, supercapacitors cannot propose anequivalent autonomy
Thanks to their power density, Supercapacitors can offer:
A reduced charging time (to reconfigure faster the UPS)
A larger lifetime
A maintenance free UPS
Applications for supercapacitors
IN
AC
DC
DC
AC
DC
DC
OUT
Switch
Rectifier Inverter
dc/dc interface
ScapsTank
Seminar on Supercapacitors
Dr. P. Barrade
Uninterruptible Power Supplies (UPS applications)
Experimental results on a 500W UPS Batteries have been replaced by supercapacitors and their power converter
5 Scaps 1800F, series connected
Autonomy: 60sec for a 300W load
0.2 0.25 0.3 0.35 0.4 0.45 0.5-400
-200
0
200
400
Uin
(V)
0.2 0.25 0.3 0.35 0.4 0.45 0.5
0
5
10
15
20
Icap
(A)
0.2 0.25 0.3 0.35 0.4 0.45 0.5-400
-200
0
200
400
t (s)
Uout
(V)
0.05 0.1 0.15 0.2 0.25-400
-200
0
200
400
t (s)
Uout
(V)
0.05 0.1 0.15 0.2 0.25-40
-30
-20
-10
0
10
20
t (s)
Icap
(A)
Network failure Reconfiguration
Applications for supercapacitors
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Seminar on Supercapacitors
Dr. P. Barrade
Wind turbines
Wind Turbine Pitch Control Systems
Voltage Regulation and VARS Support
Short term energy storage
Applications for supercapacitors
Seminar on Supercapacitors
Dr. P. Barrade
Application for airplanes
New airbus A380
16 doors per Aircraft (Basicversion)
Electrically operated
2 main doors in permanent use forboarding
14 rescue doors for emergency use
local door controller integratedwithin each passenger door
Applications for supercapacitors
Courtesy from Maxwell Technologies SA
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Dr. P. Barrade
Application for airplanes
New airbus A380
Requirements on AC level
Operational requirements
Doors Operation independent from AC electrical system
Emergency opening even after transversal break of the fuselage
Local energy storage
High reliability
Extremely high availability
A/C System Requirements
Minimum burden to the A/C Electrical System (max. 130VA, no peak loads)
Minimum radiated and conducted distortion
Maximum radiated and conducted susceptibility
Robustness for primary power interrupts and transients
Applications for supercapacitors
Courtesy from Maxwell Technologies SA
Seminar on Supercapacitors
Dr. P. Barrade
Application for airplanes
Environmental and operating conditions
Normal (severe) operating temperature -40 +60oC (+70oC)
Average operating temperature +45 +55oC
Ground survival temperature -55 +85oC
Temperature gradients up to 5K per min.
Operational shock (crash) up to 20g
Operational vibrations (random sinus) with up to 4,1g
Vibration frequency 2kHz down to 10Hz
Application to water, fluids, sand and dust, fungus, fire, lightning etc.
Environmental requirements, equipment in aircraft doors:
Power supply with nominal 115VAC, variation range 96 130VAC
Wild frequency network nominal 400Hz, variation range 360 800Hz
Therefore
HW and SW designed with assurance level A
Failure rate of critical blocks 10-7 10-8 per flight hour
Only achievable with overall double resp. triple redundancy
Useful life 25 years resp. 140.000 flight hours
No scheduled maintenance is allowed for the equipment
Applications for supercapacitors
Courtesy from Maxwell Technologies SA
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Seminar on Supercapacitors
Dr. P. Barrade
Application for airplanes
New airbus A380
Energy storage device used for the doors: supercapacitors Normal operation mode
Emergency operation mode
Consists of 56 UltraCaps PC100G (C = 100F each)
Arranged in 14 lines and 4 columns, connected by current rails
Ctotal = 28,5 F
Umatrixmax = 34 V
Ucelltyp = 2,2 V, Ucellmax = 2,5 V 13.500 Ws (typ), 16.500 Ws (max)
ESR < 50mOhm
Total weight of Capacitors 2.200g
Mechanical fixture with fixing grid
Applications for supercapacitors
Courtesy from Maxwell Technologies SA
Seminar on Supercapacitors
Dr. P. Barrade
Conclusion
For most of applications, supercapacitors are used to smooth power fluctuations on amain energy source
Reduced energy density
High power density
Long lifetime
Supercapacitive tank can be sized in a 2 steps process:
Energy requirements: this defines mainly the number of components
Power requirements: in order to match the required power availability
Supercapacitors technology seems to be now mature enough for large scaleapplications
Price
Performances
However: needs in strong developments in power electronics, competition withother technologies (flywheel)