e. f. piene, "grid connected vehicles capabilities and characteristics," in electric...
TRANSCRIPT
Egil Falch PieneTHINK Global AS
Norway
Grid connected vehicles
Capabilities and characteristics
EES-UETP Course title
Course date 22 September 2010
Course place DTU Lyngby, Copenhagen
History
• Founded 19 years ago in Norway
• The first prototype predecessor to today’s modern
THINK City was developed in 1991
• The first generation THINK City was produced
from 1999-2003
• Ford Motor Company owned and invested heavily
in THINK between 1999-2003
• In 2006 Norwegian investors bought THINK and
have invested over $120 million to further develop
the latest generation THINK City
• Production moved to THINK’s strategic partner
and shareholder, Valmet Automotive of Finland,
in late 2009
EV design requirements
1. Optimize for energy efficiency and range
2. Optimize for cost and driving performance
3. Optimize for basic and sneaky design
4. Optimize for grid conditions and battery life
Think is doing "practical innovation"
Scope of this presentation
• Description of system in an electric car
conductively connected to the grid, with
AC transferred to an on-board charger
• Highlight some specifics for systems
integration, with focus on the modules
involved in the charging process
• Briefly discuss regulation services from a
user and vehicle perspective
Questions in mind
• What will be needed to prepare for the
charging infrastructure, so the grids can
supply many simultaneously connected
EVs?
• Are the vehicles being designed well
enough, so when many connected they do
not aggravate conditions in the grids?
Block diagram of modules
COML1L2L3N
PE
BMS
ChargingStation
Vehicle CANCOM
On-boardCharger
TractionBattery
VehicleController
DCACAC
Grid side Vehicle side
AC-charging from a 1-phase or 3-phase source
• Typical for plug-ins today, is that they
charge with the power available, without
taking care of other loads or even any
other grid condition
• The vehicle charger system and the user
takes for granted that there are energy
and grid capacity available
Plug-in vehicles today
Courtesy of BRUSA www.brusa.biz
Gain of 80% State of Charge
Battery size: 25 kWh
Total efficiency: 80%
Charging time versus interface
km/charge-hourSource Transfer EV * PIHV Th!nk City
• 230V 1ph 16A 3.6kW 18 7 17 (3,2kW)
• 400V 3ph+N 16A 11kW 55 - 51 (9,6kW)
• 400V 3ph+N 32A 22kW 110 - -
• 400V 3ph+N 63A 44kW 220 - -
• 690/400VAC ** DC 50kW 250 - TBD
* Example: General EV with ca 200 Wh/km consumption, "Plug-to-Wheel"
** CHAdeMO
Power x time = km
>400 Wh/km 190 Wh/km
On-boardCharger
DC
Block diagram of modules
COML1L2L3N
PE
BMS
DC
Off-board
ChargingStation
Vehicle CANCOM
Power relaycontrol unit
TractionBattery
VehicleController
DCAC
Grid side Vehicle side
DC-connected from an off-board charger, bypasses the AC on-board charger
Front - end
• Charging station
– Provide energy
– Electrical safety
– Forward available
maximum current
– Link communication
– Metering energy
– Payment
– IEC/EN 61851-1
with sub standards
• Today's Li-ION
traction batteries
– 90 - 130 Wh/kg
– 150 - 200 Wh/l
– 450 - 600 $kWh
• Battery pack size for
an usable EV
– 15 - 40 kWh
– 150 - 400 kg
EV battery monitoring system
• BMS is a highly integrated module with
specific software
• Protection for overload, overcurrents,
overheat, overcharge
• Doing measurements and calculations
• Taking care of cell balancing
• HV isolation monitoring towards chassis
• Diagnostics and communication
On-board Charger
• The input voltage range shall without any
configuration, cover the voltages available
in all domestic power systems
Input voltage range
• Japan = 100 V to UK = 240 V ±10%
• which give 90 - 264 V + margin
• which give ≈ 85 - 275 V
• @ 50 - 60 Hz
Output voltage range
• The output voltage range need to match
the on board traction battery system
• Li-ION cells may have voltages varying
from 2.5 to 4.2V - depending its state of
charge (SOC)
• A modern EV will typically have (ca) 100
cells in series, which gives an operating
voltage range of 250 to 420V
- further properties
• Efficiency as high as possible
• Power output as linear as possible
• Conducted noise as low as possible
• Galvanic isolation (grid to traction battery)
• Power factor correcting
• Must respond to a control signal
• Light weight
• Automotive requirements *
HE rectifier circuits
Primary side
DSPSecondary side DSP
SPICAN
Transistor
drive signals
AC in
DC out
Transistor
drive signals
Courtesy of ELTEK VALERE www.eltekvalere.com
HE rectifier efficiency
82%
84%
86%
88%
90%
92%
94%
96%
98%
100%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Eff
icie
nc
y
Load
HE rectifier
Standardrectifier
Courtesy of ELTEK VALERE www.eltekvalere.com
Energy consumption and loss
• Assumptions– 25 kWh battery with 5% internal system loss
– 3 kW on-board charger
– Average daily depth of discharge 60%
– 240 commute days pr year
• Energy delivered to battery– Per day: 25 kWh x 0.6 x 1.05 = 15.75 kWh
– Per year: 15.75 kWh x 240 = 5 749 kWh
• On-board charger conversion losses– 90% efficiency: 420 kWh per year
– 95% efficiency: 199 kWh per year
• Energy saved pr year: = 221 kWh
Power factor correction & noise
• Power supplies sold and used in Europe must be compliant to the below standard, which sets the limits for grid current harmonics (up to 2 kHz)
• For power supplies larger than ca 250 W, active power factor correction is necessary to reduce feedback of harmonic currents
EN 61000-3-2
Grid current harmonics
0
2
4
6
8
10
12
14
16
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Harmonic number
Am
pere Measured harmonics
EN61000-3-2 limits
Courtesy of ELTEK VALERE www.eltekvalere.com
1. Harmonic (50 Hz)
Measurements from a 3 kW unit @ 230 V
Automotive requirements
• Vibration resistive
and mechanical
stability
• Wide temperature
range
• Efficient cooling
• Sealed enclosures
and connectors
• High voltage
isolation
Single loop charging regulation
• In a traditional battery charger circuit, the
regulation is based on the battery's need
COML1L2L3N
PE
BMS
ChargingStation
Vehicle CANCOM
On-boardCharger
TractionBattery
VehicleController
Effects of negative impedance
• If the grid voltage drops, a connected
charger with single loop regulation would
increase the input current to maintain a
constant current or power output
• The increased input current will represent
a heavier load that may even drop the
voltage further down
• The max current allowed from the charging
station, must be registered by vehicle
AC current regulation loop
• An EV prepared for Smart Charging would
need one additional regulation loop
COML1L2L3N
PE
BMS
ChargingStation
Vehicle CANCOM
On-boardCharger
TractionBattery
VehicleController
Coincidence factor
• If standardization for protection against
charger’s negative impedance is not
solved in the vehicle systems, a smart grid
signal could make control of distributed
power
• When dimensioning charging facilities for
fleets or many vehicles, the coincidence
factor would need to be carefully assessed
Balancing 3-phase
• Phase individual loads can by achieved
by the use of three single charger units
• Separate voltage measurement and
control
• Power 10 kW
• Redundancy
• Single phase
configurable
~ / =
~ / =
~ / =
L1
L2
L3
N
CAN
DC
Statement
Ph.D. Lars Henrik Hansen
Questions in mind 2
• How can plug-in
vehicles develop from
only being a load and
become a medium for
regulation services?
• What alternatives are
here now?
Regulation capable or not
• Dumb chargingPlugging in whenever
and wherever
• Timer chargingPlug in, but no charge
until assumed valley
hours
• V2GIn control from the
grid operator
• Smart ChargingIn control from the
grid operator or other
source
The sceptics response to V2G
• Uncertainty regarding the market for regulation
• New regulation technologies are emerging
• Which user incentives, "cash-back" only and
how will it be influenced by the volume of cars?
• User applicability, hence adaption, how combine
grid regulation with the need for driving range?
Smart charging scheduler
• Smart phone apps,
plan for the next drive
• Not only as the
control instrument for
the user,
• but as well a way of
spreading the
information towards
modern times for
greater concerns
about energy
consumption
Automakers V2G response
• Culture of designing machines for
transportation, not for storing electricity
• New technology, few standards
• Long time for development and validation
• Which battery life impact?
• Warranty aspects with battery system
• Safety for electrical hazards, liability issues
• Extra cost on the vehicle
• Different and new business models
Capacity retention
General impacts on Li-ION life
• High temperatures (> ≈ 55 C)
• Too heavy charge or discharge at low temp
• Too heavy charge or discharge at low SOC
• Too heavy charge or discharges
• Full or deep discharge cycles
• Storage empty (self discharge)
• Time
Charging efficiency, vehicle
Full V2G, not yet...
• Imperative that the owner of vehicle doesn’t
suffer an economic loss due to accelerated
retention of the battery
• Economic incentive must cover battery
system wear and degradation
• Warranty and legal aspects must be
transparent
• Comprehensive ‘Cash Back’ model is
needed for EVs and PHEVs
For realisation now is V2G light
• Providing regulation
up and down
according to a
scheduled middle
charge rate
• Vehicle should be in
daily use, as
regulation service
would be possible only
while charging up
• The battery will not be
worn more than in a
regular operation
• Less losses in both
LV-grid and vehicle
• Setup will probably
require more vehicles
in the pool, to provide
the same grade of
regulation compared
to real V2G
Control through infrastructure
• Control signal from
grid operator through
a fixed line
• Wireless not regarded
suitable for faster
response demands
• Local fleet servers for
power or time share
depending the local
capacity and number
of vehicles connected
and counting energy
metering data
• Aggregation server to
collect load data and
provide control signal
• Standardized protocol
- more "V2G light"
• Target for charge rate
response time
less than 3 sec
• Aggregator to control
charging rate within
predefined limits
• Not only for fleets, the
system can possible
be general available
• The vehicles would
need a small extra
communication unit
• The charging station
would need to be
connected "on-line"
• The user would need
a scheduler via web
or in a phone-app
Added autonomous regulation
• In case the communication is lost,
– the vehicle charger system could enter an
autonomous mode, by providing regulation
with a fraction of the scheduled charge rate
with response to the line frequency
– a preset charge rate according to the
average daily/hourly load profile could work
as a back up and make the control
– The user would be notified via the phone-app
scheduler and still have the option to override
Local storage, regulation, solar, wind,
and fast EV-charging
Main battery10 x Na-NiCl, Z36
U-nominal = 370V DC
P-nominal = 250 - 500kWh
P-peak = 500 - 1000kW
AC
DC
Grid inverter4 x,150kWpeak, bidirctional
Frequency 50Hz
Switching frequency 24kHz
with external prefilters
LV Grid
3 x 400 VAC+N
350 V DCDirect connection to the vehicle
2 to 3 charging spots
250A capability (87W)
DCDC-converterBidirectional, no isolation
Switching frequency 48kHz
50kVA
Photovoltaic panelMPP-Voltage up to 300V
20kWpeak
DC
DC
AC
DC
AC
DC
AC
DC
Courtesy of BRUSA www.brusa.biz
2nd life EV batteries