Characteristics of public quick chargers
to support EV users
December 8 , 2010
TEPCO
Takafumi Anegawa
1. Why public chargers are necessary?
2. How much kW is optimal output power?
3. Does quick charger degrade battery?
4. Is there negative impact on power grid?
1. How can we deploy quick chargers?
EV drivers can not use full battery capacity
25
Typical distribution of daily driving range
Comfort
Discomfort
Fearfulness
% of drivers
20
15
Driving range
Driving range
10
5
Driving range
0
<10 <20 <30 <40 <50 <60 <70 <80 <90 <100 <110 <120 <130 <140 <150
Driving Range (km)
Driver knew that EV could but didn’t use it
(October 2007)
15km
March 2008
8km
Drive mileage was 203km before quick charger installation.
Driver understood EV performance but they were reluctant to use it.
Quick charger removed range anxiety
(July 2008)
15km
8km
Drive mileage was drastically increase to 1472km
after quick charger installation.
Why public chargers are necessary?
• Daily base driving distance is less than 100km in most
cases then current EV can cover it easily.
• However, drivers are uncomfortable if remaining driving
range become less than 50km.
• Public quick chargers relieve drivers’ range anxiety,
and drivers use quick chargers only few times.
1. Why public chargers are necessary?
2. How much kW is optimal output power?
1. Does quick charger degrade battery?
2. Is there negative impact on power grid?
1. How can we deploy quick chargers?
Public charging stations in California
- 129 in San Francisco and Bay Area
- 186 in Los Angels County
- Inductive and conductive are mixed
- Output power is around 5kW
- Charging time is around 2hrs for 70km
- Price is about $3,000 without installation cost.
- Private charger design is same of public one.
Inductive
700km
Conductive
Optimal output of public charger
200
Cost is high.
Charging time isn’t so short.
90
Waiting time
is too long.
80
180
160
70
140
60
120
50
100
40
80
Optimal
power
30
60
20
40
10
20
0
0
0
20
40
60
80
100
Charger Output Power (ｋＷ)
120
140
160
Charger cost (k$)
Charging time for 80km range (min)
100
Specification of developed quick charger
Specifications
-Type: Switching type
constant current power supply
- Input: 3-phase 400V
- Output power: 50kW (10~100kW)
- Maximum DC output Voltage: 500V
- Output current: 125A (20~200A)
Target charging time
5 minutes for 40km driving range
10 minutes for 60km driving range
Unit price €20,000~30,000
Installation cost ~€20,000
Cost for one user
€250 = €50,000 ÷ 200 users
How much kW is optimal power?
• Waiting time should be less than 15min.
• Additional driving range is 30km~60km which is
equivalent of 5~8kWh.
• 50kW power can meet 10~15min recharging time.
• Less than 20kW is too slow.
• More than 80kW is too costly and charging time doesn’t
become so short.
1. Why public chargers are necessary?
2. How much kW is optimal output power?
1. Does quick charger degrade battery?
2. Is there negative impact on power grid?
1. How can we deploy quick chargers?
Optimal charging speed is different in each batteries
• Battery degradation is caused by over voltage and high temperature.
• Limit voltage and temperature depend on battery characteristics.
• On-board battery management system is watching the voltage and
the temperature in real time.
BMS: Battery Management System
Observing parameters
• Battery total voltage
• Cell voltage
• Battery temperature
• Input Current etc.
Charging process is controlled by EV in CHAdeMO
Problems:
• Battery improvement is so fast that it’s difficult to catch up every batteries’ data.
• Standardization to meet lowest speed battery disturbs battery improvement.
How CHAdeMO charger works:
• EV computer unit decides charging speed based on BMS observation.
• Charging current signal is sent to charger using CAN bus.
• Charger supplies DC current following the request from EV.
signal
Current
Communication
Protocol
Connector
Does quick charger degrade battery?
• CHAdeMO quick charger can change charging speed to
meet each batteries characteristics and condition.
• There is no negative impact on battery system by quick
charging if charging speed is well controlled.
• Advanced battery which can absorb higher current can
get higher power.
1. Why public chargers are necessary?
2. How much kW is optimal output power?
1. Does quick charger degrade battery?
2. Is there negative impact on power grid?
1. How can we deploy quick chargers?
Location of quick chargers on power grid
Ultra High Voltage
Substation
>270 ｋV
High Voltage
Low Voltage
Substation
66kV
Power
Station
6.6kV
66kV
5000kVA
Trans
200kVA
Trans
Trans
３φ200V
Mall
Office
Building
50kVA
Trans
1φ200V
Commercial Area Condo
Residential Area
×
Normal charging
50kVA Quick Charger
Slow AC for private and quick DC for public
Fast
Charging
Speed
EV users share quick chargers.
Necessary number is ~100s
Private/Office
Location
All EVs need their own outlets
Charging speed is most important.
Public
Necessary number is ~100,000s
Low unit cost is most important.
Slow
×
People cannot wait for hours.
1. Why public chargers are necessary?
2. How much kW is optimal output power?
1. Does quick charger degrade battery?
2. Is there negative impact on power grid?
3. How can we deploy quick chargers?
Quick charger location in Japan
For public use
For private use
Greater Tokyo Area
25ｋｍ
50ｋｍ
~300 chargers are in service
Locations are on Google Map
Search keyword is “CHAdeMo”
TEPCO branch office
64 quick chargers are installed.
310 EVs are already deployed.
It will be 100 by the end of 2010.
210 EVs will be deployed in 2010.
Kanagawa prefecture office
Operation started on
June 2008
Office Building
Operation started
on September 2008
Operation started
on April 2009
Operation started
on September 2009
Metropolitan highway parking area
Operation started on
October 2008
Tokyo University of Marine Science and Technology
Operation started on March 2009
Gas station
Operation started on
Operation started on
March 2009
July 2009
Shopping mall
Operation started on
September 2008
Convenience store
Operation started on
December 2009
Mitsubishi Motors & Nissan Headquarter
Operation started on
Operation started on
June 2009
August 2009
CHAdeMO Association
Activities:
1.Establish technical specification of
DC fast charger
2.Deploy DC fast chargers by sharing
installation and operation experience
among the members.
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Thank you
Why don’t you have a cup of tea？