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Ultracapacitors ! Microelectronics ! High-Voltage Capacitors

Gateway to a New Thinking in Energy Management - Ultracapacitors


What is an Ultracapacitor?

Supercapacitor?

Electrochemical Double Layer Capacitor?

Energy Storage Capacitor?


Science of the Technology

C = εεεεr A/dMinimize (d)Maximize (A)

E = 1/2 CV2

Dielectric

Thin Film Electrode

Electrolyte

ECDL

Separator

" A 100-year-old technology, enhanced by modern materials

"Based on polarization of an electrolyte, high surface area electrodes and extremely small charge separation


Basic Equations

Definition of Capacitance: C = Q/V (1)

Charge = current * time: Q = I*t C = I*t/V (1a)

Solving for voltage: V = I*t/C (2)

Dynamic Voltage: dV/dt = I/C (3)

Stored Energy E = ½ C*V2(4)

At initial voltage Vo, Eo = ½ C*Vo2

At final voltage Vf, Ef = ½ C*Vf2

Delivered energy = Eo � Ef

∆E =½ C*(Vo2 � Vf

2) (5)


Voltage & Current vs. TimeC = 15 farad; Resr = 100 milliohm

Vo = 48V; I = 30A

-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Time (sec)

20

25

30

35

40

45

50

Vol

tage

(V)

0

5

10

15

20

25

30

35

40

45

50

Cur

rent

(A)

-

Resr

+

+C-

i

Voltage

Current

Vo

Vmin

Vf

V = Q/CdVesr = I*ResrdV/dt = I/C ; dV = I*dt/CdVtotal = I*dt/C + I*Resr∆E =½ C*(Vo2 � Vf

2)


Ultracapacitor Performance Characteristics

� Ultracapacitors perform mid-way between conventional capacitors and electrochemical cells (batteries).

� Fast charge/discharge capability� Highly reversible process: 100,000�s of cycles� Excellent low temperature performance� Low voltage, DC devices� Extremely long life


Technology Comparison

AvailablePerformance

Lead AcidBattery

Ultracapacitor ElectrolyticCapacitor

Charge Time 1 to 5 hrs 0.3 to 30 s 10-3 to 10-6 sDischarge Time 0.3 to 3 hrs 0.3 to 30 s 10-3 to 10-6 sEnergy (Wh/kg) 10 to 100 1 to 10 < 0.1Cycle Life 1,000 >500,000 >500,000Specific Power (W/kg) <1000 <10,000 <100,000Charge/discharge efficiency

0.7 to 0.85 0.85 to 0.98 >0.95


Technology Comparison (page 2)

0,01

0,1

1

10

100

1000

10 100 1000 10000

Power Density/[W/kg]

Ener

gy D

ensi

ty/[W

h/kg

]

Double-Layer Capacitors

10h 1h0.1h

36sec

3.6sec

0.36sec

Lead AcidBattery

Ni/Cd

Li-Battery

Electrolytics

Boostcap

Fuel Cells

36msec

10h


0

1

2

3

4Efficiency

Self Discharge

Availability

Cycle Stability

Energy Density

Power Density

Energy Cost

Power Cost

System Cost

Safety

Recycling

Environment

Temperature Range

Charge AcceptanceUltracapsPb-AGMNiMHLi Ion

Ultracapacitors vs Batteries


Ultracapacitor Performance vs. Temperature

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

-50 -30 -10 10 30 50 70

Temperature (C)

Rel

ativ

e Pe

rfor

man

ce

Capacitance Resistance


Capacitance, Frequency Response

0

0.2

0.4

0.6

0.8

1

1.2

0.1 1 10 100

Frequency (hz)

Rela

tive

Capa

cita

nce


Resistance, Frequency Response

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.1 1 10 100

Frequency (hz)

Rel

ativ

e R

esis

tanc

e


Ultracapacitor Aging

� Unlike batteries, Ultracapacitors do not have a hard end of life criteria.

� Ultracapacitors degradation is apparent by a gradual loss of capacitance and a gradual increase in resistance.

� End of life is when the capacitance and resistance is out of the application range and will differ depending on the application.

� Therefore life prediction is easily done.


Product Portfolio Range

PowerCache Modules" 50 V, 1.6 and 2.3 kWm

PC Series" 4 and 10 F" Modules rated at 5 and 15 V

BC Series (Power & Energy)" 120, 140, 310, 350 F" Modules and packs rated at 15 V

MC Series (Power & Energy)" 650, 1200, 1500, 2000, 2600, 3000 F" Modules rated at 16 V and 48 V


When should Ultracapacitors be considered?

� High reliability back-up power

� Momentary bridge power (1 - 60 seconds)

� Voltage sag compensation

� Buffering large momentary in-rush or power surges

Is there a need for?


Application Model


Peak Power Shaving� Ultracapacitors provide peak power ...

AvailablePower

Required PowerUltracapacitor Peak Power

Peak Power Shaving


Back-Up Power Support

� Ultracapacitors provide peak power�...and back-up power.

Required Power

Available Power Ultracapacitor Backup Power

Back-up Power


Ultracapacitor Market


Ultracapacitor Market

Ultracapacitor World Market

Consumer Products

Digital CameraPDA

Toys

Memory back-up

UPSWindmill

Industrial

Stationary Fuel Cell

Automation/Robotics

Transportation

Hybrid Bus/TruckEngine starting

Light Hybrid

Local Power

Rail



Energy saving and voltage stabilization

Today’s Leading Industrial Markets

Pitch control and back up power

High power transmission or last

gasp messaging

Train Stations Windmills AMR


Energy storage system:

Time t1Vehicle 1 is braking

Energy storage system stores thebraking energy

Time t2Vehicle 2 is accelerating

Energy storage system delivers the energy

Siemens SITRAS® SES - Solution

Advantage: Cost savings through reduced primary energy consumption and prevents critical voltage sag levels within immediate grid network


Nominal voltage 750 V DC# of Ultracapacitors 1,344Energy stored 2.3 kWh (8.2 MJ)Energy saving per h 65 kWh/hMax. power 1 MWCapacitor efficiency 0.95Operational temperature �20 to 40 °C

SITRAS® Energy Storage System

ESS rack composed of 42 2600F cells


SITRAS® Installation Examples DresdenHellerauFull-time service since September 2002

CologneSchlebuschFull-time service since July 2003

MadridSainz de Baranda

Full-time service since July 2003


Wind Turbine Pitch Systems

" Modern wind turbinesconsist of three-bladed variable speed turbines

" Independent electro-mechanical propulsion units control and adjust the rotor-blades

" Latest technology uses the wind not only to produce wind energy but also for its own safety


Pitch System Storage Systems

" Each pitch systems is equipped with an ultracapacitor emergency power supply

" Ultracapacitors represent an optimum emergency power supply system due to their� Enhanced level of

safety� High reliability� Efficiency� Scalability

75 V, 81 F ultracapacitor module

4 modules are put in series to power 300 V

pitch systems of 3-5 MW wind power plants

Switch box including 2600F ultracapacitors


S&C Electric, ESA Announcement

Newly Invented Electronic Shock Absorber Will Give Big Boost to Hawaii Wind Farm.

Hawaiian Electric Company, Inc. (HECO) and S&C Electric Company held on Jan. 17 a dedication at Lalamilo Wind Farm near Waikoloa on the Big Island of Hawaii to mark the installation of the first PureWave® Electronic Shock Absorber (ESA), an innovative grid stabilizing device for wind farms.

S&C, a leader in power electronic system design and delivery, received exclusive rights from HECO to design, build and commercialize the ESA. The device employs S&C�s trademarked DSTATCOM Distributed Static Shunt Compensator with the addition of ultracapacitor energy storage. Production of the first PureWave® ESA began in early 2005. Attendees at today�s dedication toured the inside of the 30-foot trailer that houses the ESA system.


S&C Electric, ESA


S&C Electric, ESA System

Nominal voltage 800 V DC# of Ultracapacitors 640Energy stored 3 MJMax. power 263 kWOperational temperature �25 to 50 °C

Initial System


On Site Installation

S&C Electric, ESA system will be on display at:

IEEE T&D, Dallas, TX � May, 2006Windpower, Pittsburgh, PA � June, 2006


Northern Power, Energy Bridge

CEC Awards Grant to Northern Power to Integrate Advanced Power Electronics TechnologyWAITSFIELD, Vt. -- Northern Power Systems, a subsidiary of Distributed Energy Systems Corp. (NASDAQ: DESC), has been contracted to design, engineer and install an advanced energy storage system for the Palmdale Water District's Southern California water treatment plant and adjacent pumping facility.

Northern's Power Technology Group (PTG) will integrate its advanced power conversion, switching and controls solutions with Maxwell Technologies ultracapacitor modules to create a system that will provide critical load support for the protected loads. In the event of a grid outage, the high- reliability system will be capable of creating short-term power as the transition is made to on-site or backup generation power. The system will be able to support 450 kW for 20 - 60 seconds depending on the loads, enough time to bring a generator on line and avoid any interruption in power at the Palmdale facility.


ClearwellProtected

Loads~400 kW

Diesel Back-up1000 kW

Diesel Back-up750 kW

Palmdale Water District Power System

SCE UtilityGrid

Wind Turbine950 kW

Static switch

Water TreatmentPlant Loads

~500 kW

PQM

PQM

ClearwellOther Loads

~350 kW

Hydro250 kWHydro

250 kW

MM

ATS

PQMMM

EnergyBridge™ EB 450

MM

PQM

ATS

Utility meter

Power quality meter

Automatic transfer switch

Circuit breaker

Legend

Ultracapacitors

Power conversion

450 kW

Energy Bridge, Palmdale


Energy Bridge Specifications

480 Vac, 3 Phase wye, 3 or 4 wireCircuit voltage & type

<2% per harmonic, <3% total THDCritical Bus Voltage THD

480 Vac +/- 2.5%Critical Bus Voltage

99% at rated loadSystem efficiency

30 sec.Back up time

450kW @ 0.8 pfRated power

IEEE 1547 & 519, UL1778, CBEMAApplicable Standards

0-40oC, de-rated above 40oCOperating temperature

3�x20�x7� (DxWxH)Enclosure Dimensions


One Line Diagram

SeriesInductance

Ls

FastSwitch

S1

BypassBreaker

CB3 (Optional)

IsolationBreaker

CB2

IsolationBreaker

CB1

BidirectionalInverter

BidirectionalDC to DCConverter

UltracapacitorBank

3

ToUtilityGrid

ToCriticalLoads

InductorL3

ElectrolyticCapacitor Bank

Sub-system 2: Shunt Power Conversion

Sub-system 1: Series Components

DSP Controller

EnergyBridgeTM UPS - One-line Diagram

Sub-system 3: Energy Storage


Sizing Your System


Basic Model

� Series/Parallel configurations� Changes capacitor size; profiles are the same� Series configurations

� Capacitance decreases, Series Resistance increases� Cs=Ccell/(#of cells in series) Rs=Rcell*(# of cells in series)

� Parallel configurations� Capacitance increases, Series Resistance decreases� CP=Ccell*(# of cells in parallel) RP=Rcell/(# cells in parallel)

� Current controlled� Use output current profile to determine dV/dt

dV = I * (dt/C + ESR)� Power controlled

� Several ways to look at this:Pterm = I*Vcap –I2*ESR (solve quadratic for I)I = [Vcap - sqrt(Vcap

2-4*ESR*Pterm)]/(2*ESR)� Solve for dV/dt as in current-controlled� J=W*s=1/2CV2 Solve for C.


Applications with a singleenergy storage component

� Applications in which little total energy is required (i.e. memory backup)

� Possibly used with other energy sources� Short duration, high power (i.e. pulse transmit)� Long duration, low power (i.e UPS backup)� Opportunities for high charge rates (i.e toys)


Applications with twoenergy storage components

� Power vs. Energy design tradewhen using two components� Single component vs. two components

� Engines/Fuel cells/Batteries/Solar Arrays are energy rich/power poor (or poor response)

� Size these components for enough energy, system may be limited in power

� Size these components for power, system may have surplus of energy� Ultracapacitors are power rich/energy poor

� Size an ultracapacitor for enough energy, system may have a surplus of power

� Size an ultracapacitor for power, system may be limited in energy

� Two components� A primary source for energy; Ultracapacitor for power� Requires appropriate definition of peak power vs. continuous power


Capacitance and ESR vs Frequency

ESR vs . Frequency

0,00E+00

1,00E-04

2,00E-04

3,00E-04

4,00E-04

5,00E-04

6,00E-04

7,00E-04

1,00E-02 1,00E-01 1,00E+00 1,00E+01 1,00E+02 1,00E+03Frequency [Hz]

ESR

[mO

hm]

Capacitance vs. Frequency

0,00E+00

5,00E+02

1,00E+03

1,50E+03

2,00E+03

2,50E+03

3,00E+03

3,50E+03

1,00E-02 1,00E-01 1,00E+00 1,00E+01 1,00E+02 1,00E+03

Frequency [Hz]

Cap

acita

nce

[F]


C and ESR Temperature Dependency

0,4

0,5

0,6

0,7

0,8

0,9

1

1,1

1,2

-60 -40 -20 0 20 40 60 80 100Temperature [°C]

ESR

[mO

hm]

1000

1200

1400

1600

1800

2000

Cap

acita

nce

[F]

ESR BCAP0008 (DC)Capacitance BCAP0008


BCAP Self Discharge

Self Discharge vs Temperature

30,0

40,0

50,0

60,0

70,0

80,0

90,0

100,0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Time [days]

% U

(t =

0)

- 35 °C

+ 5 °C

+ 25 °C

+ 65 °C


BCAP Cycling Capacity

90 A CC, 1.15-2.3 V, 25 s, RT

50.0

60.0

70.0

80.0

90.0

100.0

110.0

0 20000 40000 60000 80000 100000

Cycle Number

Cha

nge

in C

apac

itanc

e [%

]

0.0E+002.0E-044.0E-046.0E-048.0E-041.0E-031.2E-031.4E-031.6E-031.8E-032.0E-03

ESR

[Ohm

]

ESR

Capacitance


BCAP Cycling

500�000 cycles between 1.8 and 2.7 V, 100 AESR (1 Hz) increase 140 % (0.49 to 0.79 mOhmCapacitance decrease 38 % (2760 to 1780 F), 30% compared to rated capacitance


BCAP DC Life

Capacitance and ESR variation at U, T = 40 °C

50,0

55,0

60,0

65,0

70,0

75,0

80,0

85,0

90,0

95,0

100,0

105,0

0,0 100,0 200,0 300,0 400,0

duration [days]

% C

(t =

0)

2.5V 40°C

2.1V 40°C

2.3V 40°C

-40,0

-20,0

0,0

20,0

40,0

60,0

80,0

100,0

120,0

140,0

160,0

180,0

200,0

0,0 100,0 200,0 300,0 400,0duration [days]

% E

SR (t

= 0)

2.5V 40°C2.1V 40°C2.3V 40°C


BCAP DC Life

0,0

20,0

40,0

60,0

80,0

100,0

120,0

0 100 200 300 400

duration [days]

% C

(t =

0)

2.1V 65°C2.3V 65°C2.5V 65°C

-40,0

-20,0

0,0

20,0

40,0

60,0

80,0

100,0

120,0

0 100 200 300 400duration [days]

% E

SR (t

= 0)

2.5V 65°C2.1V 65°C2.3V 65°C

Capacitance and ESR variation at U, T = 65 °C


Sizing Examples


Example sizing

1) Define System Requirements15 W delivered for 10 seconds10V max; 5V min

2) Determine total energy needed: J=WS=10W*10sec=150Ja) Determine Capacitance based on: J=1/2CV2

b) Substitute the energy from above: 150J=1/2C(Vmax2-Vmin

2)c) Solve for C: C=300/(102-52)=4F

3) Add 20-40% safety margin to cover I2R losses Csystem = 4.8F4) Calculate number of cells in series (since maximum cell voltage = 2.5V)

10V/2.5V = 4 cells in series5) Calculate cell-level capacitance

C = Csys * # of series cells = 4.8F* 4 = 19.2F per 2.5V �cell�6) Calculate number of cells in parallel (we will assume a 10F cell)

# in parallel = 19.2/10F = 2 x 10F cells in parallel


Guidelines to Designing an Ultracapacitor System


Ultracapacitor Cell Balancing

Why Cell Balancing?

� Achieve cell to cell voltage balance

� Accounts for variations in capacitance and leakage current, initial charge and voltage dependent on capacitance, sustained voltage dependent on leakage current

� Reduces voltage stress on an individual cell

� Increase overall reliability of the individual cells



How to Cell Balance?

� Resistor method, resistor placed in parallel, resistor value calculated at 10x leakage current for slow balance, 100x for faster balance, good for low cycle when efficiency or stand by loss not an issue

Surface Mount Resistor for low

duty cycle application



� Active method, use semiconductors to limit or balance voltage between cells, best for high duty cycle or when efficiency and stand by loss from leakage current are important, highest cell reliability option

Active cell to cell balance

circuit


Cell Balancing

Low capacitance,high leakage cell

Note high and low points;

low capacitance cell

1.5 hours of Vehicle cycling (~ 200A)

� Low Cost� Scalable balance current

� 10mA, 300mA circuits� Very low quiescent current (<20µA)

� No on/off required� Modular installation

� N cells requires N-1 circuits� Voltage independent

2600F cells; 4 in Series

300mA balancer for high capacity cells

10mA balancer for low capacity cells


Cell Balancing

+

-

R3

R4

C2

C11M 1%

1M 1%

R1

R2

VPP

VNN

U1

499k 1%

475 1%Ultracapacitors

C1 Positiv e

C1-C2 Midpoint

C2 Negativ e

POS

NEG

+

-U1

VNN

VPP

R1100K 1%

R2100K 1%

R6

5.6 1% 1.5W

R549.9k 1%

C2

C1

Ultracapacitors

C1 Positive

C1-C2 Midpoint

C2 Negative

POS

NEG

Q1

Q2

TLV2211CDBV

R3

100

R4

100

MMBT2222AWT1

MMBT2907AWT1

10mA Balancer

300mA Balancer


Cell Balancing

Three cells with one cell balancing resistor removed:OCTA Cycles Max. Voltage Profiles

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0 1 2 3 4 5 6 7 8 9 10

Day #

Cel

l vol

tage

(V)

C1-VC2-V

C3-V


Ultracapacitor Packaging

Why Packaging?

� Ensure proper mechanical stress� Ensure robust low resistance interconnect� Ensure proper electrical isolation� Ensure proper thermal considerations� Ensure agency compliance� Increase overall cell reliability� Reduce or eliminate maintenance requirements



How to Package Cells?

� Care should be taken for the electrical interconnect, a few key guidelines to follow:

� Do not over torque. Over torque at the terminals may cause internal failure of contact points. For example, the Maxwell BCAP specification is 100 in.-lbs

� Use similar conductor metal interconnect bus bars to eliminate galvanic corrosion.

� Good surface to surface contact will reduce inter-cell resistance, reducing voltage drop and temperature stress


How to Package Cells?

� Cell to cell spacing should take into consideration two key points and can be accomplished by the design of the interconnect or the cell balancer:

� Depending on the cell some part of the outer case may be electrically the same as one of the terminals, ensure electricalisolation and watch for rubbing components that may wear through ultracapacitor insulation, do not remove the factory installed insulator sleeve

� Some air space between the cells allows convection cooling via air flow improving reliability, depends on cycle time, short duration high cycle applications may require forced air or othercooling method




ElectricalIsolation

Aluminum Interconnect

Proper Torqueand Hardware


Summary


Benefits Summary

Calendar Life� Function of average voltage and temperature

Cycle Life� Function of average voltage and temperature

Charge acceptance� Charge as fast as discharge, limited only by heating

Temperature� High temp; no thermal runaway� Low temp; -40°C


Benefits Summary

No fixed Voc� Control Flexibility; context-dependent voltage is permitted� Power Source voltage compatibility

� Examples; Fuel cells, Photovoltaic devices

No Vmin� Cell can be discharge to 0V.� Control Safety; No over-discharge� Service Safety

Cell voltage management� Only required to prevent individual cell over-voltage

State of Charge & State of Health� State of Charge equals Voc� Dynamic measurements for C and ESR = State of Health� No historical data required


About Maxwell

Capacitor Manufacturer since 1965

www.maxwell.com

Manufacturing facilities:US, Europe, Asia

Maxwell is a leading developer and manufacturer of innovative,cost-effective energy storageand power delivery solutions.

Certifications:ISO 9001:2000ISO/TS 16949

ISO 9002


Product Overview


HV Products

Booth at IEEE, T&D 2006


Useful Links

� Useful links on Maxwell Technologies Web-site:� White Papers� Technology Overview� Sizing worksheet� Application Notes� Data Sheets� Product Guide

www.maxwell.com


Contact Information

John Dispennette

Application Engineer

[email protected]

919 847 3073

Documents

Gateway to a New Thinking in Energy Management ... · " A 100-year-old technology, ... Ł Ultracapacitors perform mid-way between ... Sainz de Baranda Full-time service since July