1

Chris Mi, Ph.D, Fellow IEEE

Professor, Department of Electrical and Computer Engineering

Director, DOE GATE Center for Electric Drive Transportation

San Diego State University

5500 Campanile Drive, San Diego, CA 92182 USA,

Tel: (619)594-3741; email: mi@ieee.org

Battery Management Systems for

Electric and Plug-in Hybrid Electric

Vehicles

First Prepared on Jan 2009. Last Revised on October 20, 2015

OEM and Suppliers are committed to the electrification of the Automobile

Range, cost, charging time is of major concerns, and……………….…..

EVs provide opportunity for fuel savings and GHG emissions.

2

A after market conversion of a Prius has caught fire in June 2008

Fire Damaged PHEV, conversion by a Colorado company

Saturday, June 7, 2008

Before After

Chevy Volt Battery Fires Threaten All Electric Vehicle Makers, Not Just GM,

by Forbes

Statement of the National Highway Traffic Safety Administration On Formal Safety Defect Investigation of Post-Crash Fire Risk in Chevy Volts

- http://www.nhtsa.gov/PR/Volt

GM Announces Fix for

Chevrolet Volt Fire Risk:

http://www.foxnews.com/leisure/2012/

01/05/gm-announces-fix-for-

chevrolet-volt-fire-

risk/#ixzz20QrKboWQ

http://www.forbes.com/sites/jimhenry/2011/12/12/chevy-volt-battery-fires-threaten-all-electric-ve/

3

BYD e6 taxi catches fire in China after crash caused by drunk Nissan GT-R

driver- http://www.shenzhenparty.com/byd-electric-taxi-explosion-fire

- http://green.autoblog.com/2012/05/28/byd-e6-taxi-catches-fire-in-china-after-crash-caused-by-drunk-ni/

- http://www.nytimes.com/2012/05/30/business/global/byd-releases-details-about-electric-taxi-fire.html

Tutorial Outline

1. Introduction to energy storage systems2. Functions of battery management systems3. Current, voltage, and temperature

monitoring 4. State of charge (SOC) calculation5. Battery cell balancing 6. Thermal Management7. State of health (SOH) 8. Lithium ion Battery Safety

9. High Voltage System Safety

10. Battery Modeling

4

1. Introduction to Energy Storage Systems for EV, HEV, and PHEV

Energy Storage Options

Batteries Flywheels Ultracapacitors Compressed air Hydraulic energy storage Superconducting magnetic energy storage Integrated energy storage using lithium ion

battery and ultracapacitor Lithium ion battery is considered the only viable

energy storage solution for EV and PHEV at the present time

5

Battery Types, History, and Evolvement

Primary Battery- non-rechargeable battery- Cannot be recharged. Designed for a

single use

Secondary Battery – rechargeable battery- Lead-acid (Pb-acid)- Nickel-cadmium (NiCd)- Nickel-metal-hydride (NiMH)- Lithium-ion (Li-ion)- Lithium-polymer (Li-poly)- Sodium-sulfur- Zinc-air (Zn-Air)

Secondary batteries are still evolving- Some metal-air batteries are under

development, high energy density (500+Wh/kg+, but low cycle life (25+)

1946 Neumann: sealed NiCd

1960 Alkaline, rechargeable NiCd

1970 Lithium, sealed lead acid

1990 Nickel metal hydride (NiMH)

1991 Lithium ion

1992 Rechargeable alkaline

1999 Lithium ion polymer

6

Battery Power and Energy

BM

PSP

Specific Energy

Specific Power

Discharge Energy

Total Battery Mass B

ESE

M

(units: Wh/kg)

(units: W/kg)

Energy Density

Power Density

Discharge EnergyTotal Battery Volume

EPower Density

V

PPower Density

V

(units: W/m3)

(units: Wh/m3)

Lithium Battery Schematics

7

Advantages of Li-Ion Batteries

Lithium battery are considered the only viable solution for PHEV

Li ion batteries offer high energy density: - 1.5 times NiMH; 3 times lead acid

High power density

Long life cycles - 1000 vs. 300 lead acid;

Low memory effect; deep discharge cycles

High cell voltage (3.2V vs. 1.2V)

Low self discharge, long shelf life – only 5% discharge loss per month; 10% for NiMH, 20% for NiCd

model 18650, energy 3.2V*1.5Ah=4.8Wh;

Lithium:

228Wh/L;

120-200Wh/kg

Lead Acid:

85Wh/L; 39Wh/kg

Disadvantages of Li-Ion

Expensive -- 40% more than NiCd.

Delicate -- battery temp must be monitored from within (which raises the price), and sealed particularly well.

Regulations -- when shipping Li-Ion batteries in bulk (which also raises the price).

Class 9 miscellaneous hazardous material

8

Major Lithium Ion Battery PlayersCompany Cathode Anode Electrolyte Packaging Structure Shape

Toyota NCA Graphite Liquid Metal Spiral Elliptic

Panasonic NMC Blend Liquid Metal Spiral Elliptic

JCS NCA Graphite Liquid Metal Spiral Cylindrical

Hitachi LMO/NMC Hard Carbon Liquid Metal Spiral Cylindrical/Elliptic

AESC LMO/NMC Hard Carbon Liquid Pouch Stacked Prismatic

Sanyo LMO//NMC Blend Liquid Metal Spiral Cylindrical

GS Yuasa LMO/NMC Hard Carbon Liquid Metal Spiral Elliptic

A123 LFP Graphite Liquid Metal Spiral Cylindrical/Elliptic

LG Chem LMO Brend Carbob Gel Pouch Stacked Prismatic

Samsung LMO/NMC Graphite Liquid Metal Spiral Cylindrical

SK LMO Graphite Liquid Pouch Spiral Prismatic

Toshba LMO LTO Liquid Pouch/metal Spiral Prismatic

AltairNano LMO LTO Liquid Pouch Stacked Prismatic

BYD LFP NA Liquid Metal Spiral Cylindrical/Elliptic

Electrovaya LMP NA NA NA NA NA

Valence LFP NA Polymer pouch Stacked Prismatic

Major CollaborationsFord Toyota Honda GM Mercede

sNissa

nVW Mitsubis

hiHyunda

iBosc

hContinenta

l

Sanyo X X X X Develop

Panasonic

JV

NEC JV

JC-Saft X

Bak-A123 X

A123-Cobsys

X

MRI X

LG X X

GYS JV JV

Samsung JV

Enax JV

9

Ultra-Capacitors

Electrochemical energy storage systems

Devices that store energy as an electrostatic charge

Higher specific energy and power versions of electrolytic capacitors

Stores energy in polarized liquid layer at the interface between ionically conducting electrolyte and electrode

2

2

1CVEnergy

Current aim is to develop ultra capacitors

with capabilities of 4000 W/kg and

15Whr/kg.

Functions of Capacitors

Energy Storage: for smoothing the DC bus voltage, absorbing surge

Snubber circuits to limit voltages applied to devices during turn off transients (usually use in combination with resistance); limit currents during turn-on transients; as well as limit di/dt and dv/dt values

This is what ultracapacitors do though

10

Flywheels

Electromechanical energy storage device

Stores kinetic energy in a rapidly spinning wheel-like rotor or disk

Has potential to store energies comparable to batteries

All IC Engine vehicles use flywheels to deliver smooth power from power pulses of the engine

Modern flywheels use high-strength composite rotor that rotates in vacuum

2

2

1 JEnergy

Flywheel Vehicle wheel

Jv ,

Generator Motor

JFW , ωFW

Converter / Inverter

Generator Motor

Motion transfer direction

Hydraulic Energy Storage

Gasoline, diesel etc.

IC Engine Hydraulic pump

Reservoir with fluid at high pressure

Reservoir with fluid at low pressure

Hydraulic motor

Mechanical load

Compressible fluid for energy storage

11

Superconducting magnetic energy storage

Energy Storage Efficiency

Energy Storage Options Efficiency

Battery 60% - 80%

ultracapacitor 90% - 98%

Flywheel 80%-90%

Compressed air 75% - 85%

Hydraulic 70% - 85%

Hydrogen 60% - 85%

Super Conducting Magnetic 98%

12

Hybridization of Energy Storage

High specific

energy storage

High specificpower storage

Powerconverter

Load

Low power demand

High specific

Energy storage

High specificpower storage

Powerconverter

Load

Negative power

Primary power flow

Secondary power flow

High specificEnergy storage

High specificpower storage

Powerconverter

Load

High power demand

(a)

(b)

(c)

Fig. 10.18

Use multiple sources of storage

Tackle high demand and rapid charging capability

One typical example is to combine battery and ultracap in parallel

Topologies of Hybridization

. . .

. . .

Bat

teri

es

+

-

Ultr

acap

acit

or

Direct parallel connection - passive Or through two quadrant chopper for better

power management – semi-active or active

PEMFC

Battery

Buck or Boost DC-DC

Converter

Buck –BoostBidirectional

DC-DC Converter

Ultracapacitor

DCLink Load

• Longer service life due to peaks are only from ultracap

• Smaller size, volume, and weight possible

• More fuel savings due to increased regen capture

• Better performance due to power capabilities

13

Hybrid Energy Storage Example

For PHEV 40 miles

60kW power requirement,

Battery 11kWh; at 2C discharge gives 22kW, so 38kW from ultra cap discharging

C/2 charging (braking) battery is 5.5kW; at 60kW will need ultracap to absorb 54.5kW

At 4.3kW/kg, need minimum 54.5/4.3=13kg

At 13kg, energy is 13kg*(4.3Wh/kg)= 54Wh

54Wh/54.5kW=10 seconds

Battery 11kWh, 110kg, 5.5kW (CC), 22kW (2C, DC)

Ultracap: 54Wh, 13kg, 55 kW (CC), 55kW (DC)

Total: 11kWh, 123kg, 60kW CC and DC

2. Functions of Battery Management Systems (BMS)

14

Functions of BMS

Cell monitoring- Voltage, current, temperature, state of charge (SOC), SOH

Cell protection and safety- Avoid over charge or over discharge and over temperature

Cell balancing- Dynamic balancing

- Charge balancing

Thermal management

Charge control

Safety, life and capacity of lithium batteries can be effectively addressed by a battery management system - Protect the cells from damage, and prolong the life

3. Current, Voltage, and Temperature Monitoring

15

LEM Current Measurement

DHAB S/25 Dual Channel 200A for discharge measurement, 25A for charging measurement, 5V supply

V=constant * I

16

Current Measurement Circuit

Channel 1: 10mV/A, offset 2.5V with 5V supply- -200A 0.5V; 0A 2.5V; 200A 4.5V

Channel 2: 80mV/A, offset 2.5V with 5V supply- -25A 0.5V; 0A 2.5V; 25A 4.5V

-250A 0 250A

2.5V

Vo

I

5V

Isolated High Voltage Sensor

LEM AV 100: The linearity errors are within 0.1 % while the overall accuracy is 1.7 % of VPN between –40 and 85 °C.

Range 50V to 1500V, for pack voltage measurement

Configuration with single

power supply

http://www.lem.com/images/stories/files/Products/1-3_applications/CH24101.pdf

17

HV Measurement and Floating Ground

0

;12 12 24

1relative to battery negativeterminal

21

100 * ; relative to analog ground240

; *100100 120

bat batbat

bat

bat bat

batbat o bat

V VI

Meg Meg Meg

V V V

V k I V V

V V VI so V V I k

k

If Vbat = 400V

Vo = 3.33V

Op-amp is able to handle 2000V ESD

The up and bottom 12M separates the op-amp from HV

1% resistors provide accurate measurement

Careful about band width

Bypass cap necessary

Floating ground is generated at Vbat/2; this is relative to the analog ground (the op-amp ground)

C=2200pF

Current from battery + go through R8 to

analog ground

Current of R9 goes through 12Meg to battery

negative

LTC6803-2

Cell voltages, maximum 5V per cell, resolution near 1mV (12-bit ADC), measurement error < 0.25%

Cell or module temperature (2 temperature sensors per module)

Low standby mode supply current (12uA)

SPI communication with Packet Error Checking

A 48-cell monitoring and management unit Proprietary, Gannon Motors and Controls, LLC

18

Temperature Monitoring

Thermal couples or thermistors can be directly connected to MCU A/D channel; or through a op-amp follower to the A/D Channel

A table is needed inside the MCU to look up the temperature

RTDs

A platinum resistance temperature detector (RTD) is a device with a typical resistance of 100 Ω at 0C. It consists of a thin film of platinum on a plastic film. Its resistance varies with temperature and it can typically measure temperatures up to 850 C. The relationship between resistance and temperature is relatively linear.

http://www.omega.com/rtd.html

19

Thermistors

• Thermistors are made from certain metal oxides whose resistance decreases with increasing temperature. Because the resistance characteristic falls off with increasing temperature

• They are called negative temperature coefficient (NTC) sensors.

• Popular for Battery temperature measurement

http://www.omega.com

Thermocouples

Thermocouples are based on the effect that the junction between two different metals produces a voltage which increases with temperature.

Compared with resistance thermometers they offer the clear advantage of a higher upper temperature limit, up to several thousand degrees Celsius.

Their long-term stability is somewhat worse (a few degrees after one year), the measuring accuracy is slightly poorer

Has polarity in wiring

20

4. Calculation of State of Charge

If the battery original SOC is given, then the new SOC is

SOC is in percentage

Ts is the sampling time

Therefore, initial SOC or (Ah) of the battery needs to be known

Sampling frequency needs to be accurate

Integration of Current

*( ) ( )

( )s

total

I TSoC new SoC old

Ah

21

Self Discharge

Self discharge inside the battery can not be counted for by the BMS for SOC calculations

Small current draw from the HV when vehicle is at rest (BMS sleeping mode) can also be monitored by the BMS

Therefore, initial calibration is also important during vehicle start up

Impact of Current Harmonics

Modern electric machines and power electronics operating from the battery generates harmonics. Therefore it is difficult to measure accurately the current

22

Measurement Error and Process Noise

Current sensor has certain error (resolution, accuracy, etc.)

Timing may cause error too

Noise in the measurement loop and in the amplification circuits

Capacity fade over time

Internal loss due to internal impedance - Different at different discharge rate

Aging of Battery etc.

Aging of battery will alter the base of nominal capacity hence cause error in the calculated percentage SOC

In consistency (could be small) but can cause error over time in the accumulated SOC calculations

Furthermore, initial SOC may not be known or may not be accurate

Temperature can cause nominal capacity to change

23

5. Cell Balancing

Batteries without Charge Balancing

A balanced system can be charged without cell monitoring

Battery cells deteriorate differently- Chemistry

- Temperature

Once the highest cell is charged, continued charge will cause potential damage and hazard due to over charge of some cells

potential damage

24

Batteries without Management

Unmanaged system start to deteriorate over time

ID V1 V2 V3 V4 T1 T2 T3 T4 V1 3.67 3.64 3.68 3.69 26 27 27 28 14.692 3.31 3.29 3.31 3.33 26 26 9 23 13.233 3.34 3.31 3.34 3.36 27 26 27 26 13.354 3.31 3.29 3.32 3.33 26 27 26 27 13.265 3.30 3.28 3.30 3.32 27 26 28 0 13.206 3.34 3.30 3.35 3.35 26 26 27 26 13.347 3.33 3.31 3.33 3.35 27 27 27 27 13.328 3.32 3.30 3.32 3.34 25 26 23 27 13.279 3.34 3.32 3.34 3.35 28 27 27 26 13.36

10 3.32 3.30 3.33 3.35 27 28 27 27 13.3111 3.33 3.31 3.34 3.35 28 28 28 28 13.3412 3.34 3.32 3.35 3.36 27 27 28 27 13.3613 3.33 3.31 3.33 3.35 27 28 27 29 13.3214 3.32 3.29 3.32 3.33 28 28 28 28 13.2615 3.66 3.64 3.64 3.67 28 28 28 31 14.62

Prius PHEV

Passive Resistor Balancing

Energy of high cells is consumed by resistors

Loss of energy due to balance

Hard to manage heat

N. H. Kutkut, “Life cycle testing of series battery strings with individual battery equalizers,” white paper, Power Designers, Inc., 2000. Available: http://t2rerc.buffalo.edu/products/2003_powercheq%20testing.pdf

25

Capacitive Balancing

Slow speed balancing: up to 20 hours

Large size Capacitor

Lack of enable/disable feature

P. T. Krein, R. Balog, “Life Extension Through Charge Equalization of Lead-Acid Batteries,” ITELEC02, 2002

Inductive Balancing

Large size transformer

Difficult to package

Werner Rößler, Boost battery performance with active charge-balancing, Infineon, EE Times India, 2008. http://www.powerdesignindia.co.in/STATIC/PDF/200807/PDIOL_2008JUL24_PMNG_TA_01.pdf?SOURCES=DOWNLOAD

26

Dynamic Balance

BidirectionalDC-DC

Converter

6+

6-

5+

5-

4+

4-

3+

3-

2+

2-

1+

1-

The lowest row/cell is charged by the DC-DC converter using the pack voltage

The highest cell is discharged to the whole pack

Difficulty is the small duty ratio for large packs- Rows are divided into groups

- Balance within and between groups

Ziling Nie, and Chunting Mi, “Ziling Nie, and Chunting Mi, “Fast Battery Equalization with Isolated Bidirectional DC-DC Converter for PHEV Applications,” the Fifth IEEE International Vehicle Power and Propulsion Conference (VPPC), Dearborn, Michigan, USA, September 7-11, 2009.

Advanced Active Balancing Technology

Multi-winding transformer, one per cell

Balance up to 4 A

Efficiency up to 94%

One control signal for all switches (on and off at the same time)

Soft switching

27

Balancing Example

Chevy Volt Battery Pack- Resistive passive balancing; at very low current

- Accumulated balancing duration over 10 month

- On average, the balancing resistors are switched on in only 0.55% of time

http://files.evbatteryforum.com/battery2/2_12Adam%20Opel_Horst%20Mettlach_Cell%20Balanci

ng%20Techniques%20Using%20The%20Example%20Of%20The%20Li-

ion%20Battery%20System%20For%20The%20Opel%20Ampera.pdf

Balancing Algorithms

Based on when to balance- Balance during charging

- Balance during discharging

- Balance during idle

Based on balance current- Fast balancing (> 4A)

- Slow balancing (< 1A)

Based on balance activation- Voltage based – most popular

- SOC based – very difficult due to the need of SOC of individual cells

28

6. Battery Thermal Management

Battery Cooling

Measurement of individual cell temperature- Max (T)

Ambient temperature- Ta

Fun turn on when T>Tset- Fan speed (if possible) proportional to (T-Ta)

Typical lithium ion battery temperature- 0 to 60oC (high self discharge at high T)

29

Battery Heating

Battery does not perform very well below 0oC

A heater may be added and controlled by BMS

Thermally insulated pack may help the battery to stay warm

Cycling the battery at very low charge/discharge rate may also help to keep the battery warm

Heating the battery while also heat up the catalyst; start engine after the catalyst is hot can help reduce cold emissions.

7. Battery State of Health (SOH)

30

What Parameters in SOH

Internal impedance- Increase over time and aging of battery

Individual cell voltage- Become too high too quickly during charge

- Become too low too quickly during discharge

Individual cell temperature - Hotter that other cells during charge/discharge

Cell capacity - Needed to be balanced first during charge or

discharge (repeatedly)

Cell Impedance Measurement

Cell impedance can be measured by impose a AC excitation and measure the response.

Measure DC voltage and current during charge or discharge to estimate the DC resistance of the battery

R=(Vo-VB)/IB, where Vo is open circuit voltage, and VB is the battery voltage during discharge at rate IB

31

Measured DC Resistance and Cell Capacity

Compare the internal resistance to determine whether the battery has deteriorated.

If monitored charge or discharge capacity has dropped, then the health condition has deteriorated

%100ResistanceurrentC

ResistanceNominalConditionHealth

%100CapacityNominal

CapacityAvailableConditionHealth

10. Battery Modeling

It is extremely difficult, if not impossible, to follow all the complex interactions of individual cell phenomena in an electrochemical system that is on the order of the size of a human hair using a strictly experimental approach.

Modeling supports battery research efforts - Interpreting experimental results

- Identifying performance limiting phenomena

- Predicting the impact of new materials and components

- Assisting in cost and performance optimization

- Suggesting advanced designs for specialized applications

Modeling methods- Electrochemical Modeling

- Equivalent circuit

- Thermal modelingReference: http://www.transportation.anl.gov/batteries/modeling_batteries.html

32

Electrochemical Modeling

Utilizes a set of coupled non-linear differential equations to describe the pertinent transport, thermodynamic, and kinetic phenomena occurring in the cell

Reference: http://www.transportation.anl.gov/batteries/modeling_batteries.html

Equivalent Circuit

Use an equivalent circuit to represent the characteristics of the battery

One example is shown below

+_

+_

1 2o o ov E v v IR

1 1 2 21 2

1 2

v dv v dvi C C

R dt R dt

0 0.2 0.4 0.6 0.8 13.4

3.6

3.8

4

4.2

Battery SOC

Vo

ltag

e(V

)

OCV at charge processAverage valueOCV at discharge process

33

Thermal Modeling

At pack level and cell level

Gradients' in a pack or within a cell

5 10 15 20 25 30 35 40

1

2

3

4

5

6

7

8

9

10

11

12

Group

1Group

2

Cooling air

We conduct research to help improve performance and safety of PHEVs

34

Advanced Battery Management System Incorporating Real-Time Diagnosis and Data-Driven Prognostic Health Management with Joint SOC, SOH and Parameter

EstimationContributors: Yuhong Fu, Le Yi Wang, Chris Mi, Zhimin Xi et al

Funding Agency/Collaborations: DOE, Chrysler, Ford, ARPA-e

• Real-time battery diagnosis with joint SOC and parameter

estimation and large deviation principles

• Prognostic health management of battery systems through

data-driven algorithms

Technology Summary

Technology Impact

• Increase effectiveness of fault diagnostics

• Increase accuracy of residual life predictions

• Reduce sensor count by incorporating advanced algorithms

• Preventing catastrophic failures through fast, real time, and

accurate battery cell parameter estimations

Metric State of the Art Proposed

Diag response time Seconds Milliseconds

Prog response time minutes 3 seconds

Accuracy 90% 99%

Real time No Yes

Need of sensor Large number Reduced count

Proposed Targets

Gannon

BMS

Joint

parameter

estimation

with error less

than 1%

Life

prediction

with high

accuracy

Patent pending

Integrated Battery Management System Incorporating Modular, Reconfigurable Charger, Active Balancer, PFC and Sensorless Voltage Monitoring

Contributor: Siqi Li, Chris Mi, et al

Funding Agency/Collaborations: DOE, GATE, ARPA-e, Chrysler

• Modular,, high efficiency, and low cost charger with

integrated active balance and power factor correction (PFC)

• High efficiency, low cost active cell balancing

• Sensorless cell parameter monitoring

Technology Summary

Technology Impact

• Modular design reduce BMS/Charger/Balancer cost by 80%

• Increase charge efficiency by 3~5%

• Increase balance efficiency by 5~10%

Patent Pending

Metric State of the Art Proposed

6kW PHEV Charger

<90%; cost>$1000 >96%; cost<$200

Active cell balancer

<70%;cost>$10/cell max 2A/cell

>93%;cost<$0.15/cell; max 8A/cell

Sensorless monitoring

$1/cell No additional cost

PFC Separate circuitPart of charger/balancer

Proposed Targets

BCU:

Sensorless voltage monitoring, SOC,

SOH, and im

pedance estimate Module #1

Module #n

Novel Packaging Concepts

Module #2

Charger Balancer Monitoring

Gannon

BMS

Modular

concept to

reduce cost

and

increase

efficiency

Individual

cell based

charger/bala

ncer/PFC

35

A High Efficiency Active Battery Balancing Circuit Using Multi-Winding Transformer

Funding Agency/Collaborations: DOE, Chrysler

Disadvantages:

1. Two stage Energy Transfer:

a. Energy flows out of all cells

b. Energy distribute to different cells

2. Diode voltage drop effect:

a. Inconsistency

b. energy loss

c. Temperature dependent

Hard to achieve good balance results

Low efficiency : ~ 75% by simulation

Conventional balancer using multi-winding transformer

Advanced balancer using multi-winding transformer

Advantages:

1. Direct energy transfer:

High efficiency

2. No Diode voltage drop involved:

Ideal balance & high efficiency

3. Simple control:

Only one MOSFET signal needed

4. Low cost:

All low voltage components

Final Results:

Up to 93% energy transfer efficiency

Prototype test

•Dimension: 10cm x 9.5cm

•Support 12 cells per board

•Maximum current :1.5A

•Simple control interfaceSoft-switching

waveforms

Vgs Vds

Test platform

(4-cell version)

Efficiency vs. voltage difference

Bi-directional PFC converter with reduced passive components size and low electro-magnetic interference for electric vehicle on-board charger

Contributors: Siqi Li, Chris Mi, et al

Funding Agency/Collaborations: DOE, Chrysler

• High order input filter for low weight and compact size

• Model based control method for good dynamic characteristics

• Bi-directional capability for future V2G technology

Technology Summary

Technology Impact

Compared with traditional bridgeless PFC:

• 1/10 of the input inductor value with same current ripple

• Total size and weight reduced by 20%~40%

• Total cost almost the same

• No EMI issue

• Bi-directional capability and good dynamic characteristics,

get ready for V2G

Patent Pending

Proposed bi-directional PFC topology

0

200

400

600

800

1000

1200

Volume Price

Traditional PFC

Proposed PFC

Passive components size and cost comparison

Model base control schematic

50 100 150 200 250 300 350 400

-50

0

50

50 100 150 200 250 300 350 400300

350

400

450

t / ms t / ms

Step response from no load to full load

Output DC voltageInput AC current

36

Wireless Charging of EV Wireless changing is different from inductive

charging, and information transmission, such as radio signal

Wireless means transferring power and energy in a great distance.

It is typically done through electromagnetic resonance

MIT, KIAST, and University of Tokyo, some of the leaders in this area.

MIT Lab

University of TokyoUS DOE

Funding Agency/Collaborations: Chrysler, DENSO, Oakridge National Laboratory

High Efficiency Lithium-Ion Battery Charger for Plug-in Hybrid Electric VehicleContributors: Sideng Hu, Junjun Deng, Chris Mi, et al

• Bridgeless PFC boost converter performs the front end AC-

DC conversion with high efficiency by eliminating the input

rectifier diodes

• Full bridge multi-resonant LLC converter offers very high

efficiency and low EMI at high power by providing ZVS of

MOSFETs and ZCS of output diodes

Technology Summary

Technology Impact

• Increase power rating for different P-HEV application

• Increase efficiency by soft-switching technology

• Increase power factor by advanced algorithms

Metric State of the Art Proposed

Power rating 3.3kW 6kW

EMI/noise fair good

Power factor medium high

Efficiency fair good

Cost medium low

Proposed Targets

Fig.1 System Diagram Overview

Funding Agency/Collaborations: Chrysler, DOE