ramana k.vinjamuri 08/25/2004 under direction of dr. pritpal singh
DESCRIPTION
Design and Implementation of a State-of-charge meter for Lithium ion batteries to be used in Portable Defibrillators. Ramana K.Vinjamuri 08/25/2004 Under direction of Dr. Pritpal Singh. Outline. BACKGROUND PROCEDURE (experimental setup) - PowerPoint PPT PresentationTRANSCRIPT
Design Design andand Implementation of a Implementation of a State-of-charge meter State-of-charge meter for Lithium ion batteries to be for Lithium ion batteries to be
used in Portable Defibrillatorsused in Portable Defibrillators
Ramana K.VinjamuriRamana K.Vinjamuri
08/25/200408/25/2004
Under direction of Under direction of
Dr. Pritpal SinghDr. Pritpal Singh
OutlineOutline
BACKGROUNDBACKGROUND PROCEDURE (experimental setup)PROCEDURE (experimental setup) MEASUREMENTS AND ANALYSISMEASUREMENTS AND ANALYSIS FUZZY LOGIC MODELINGFUZZY LOGIC MODELING IMPLEMENTATION IN MC68HC12 (micro controller)IMPLEMENTATION IN MC68HC12 (micro controller) CONCLUSIONSCONCLUSIONS FUTURE SCOPEFUTURE SCOPE
BACKGROUNDBACKGROUND
Portable defibrillatorsPortable defibrillators
Today portable defibrillators are Today portable defibrillators are considered as sophisticated devices by considered as sophisticated devices by FDA (Food and Drug Administration). As a FDA (Food and Drug Administration). As a trend towards the widespread deployment trend towards the widespread deployment of portable defibrillators in the hands of of portable defibrillators in the hands of non-medical or non-technical personnel non-medical or non-technical personnel increases, there exists a need for a simple increases, there exists a need for a simple procedure to ensure that it will operate procedure to ensure that it will operate properly when needed.properly when needed.
Portable defibrillatorsPortable defibrillators
According to the FDA the major According to the FDA the major cause of defibrillator failure was cause of defibrillator failure was improper care of the rechargeable improper care of the rechargeable battery . The effective operation of a battery . The effective operation of a portable defibrillator depends portable defibrillator depends critically on the condition of the critically on the condition of the battery which are defined by State-battery which are defined by State-of-Charge and State-of-Health.of-Charge and State-of-Health.
Chemistry of Li ion batteriesChemistry of Li ion batteries
Reactions that occur at ElectrodesReactions that occur at Electrodes
Positive LiMO2 → Li Positive LiMO2 → Li 1-x1-xMO2 + x Li MO2 + x Li ++ + + xexe
Negative C + x Li Negative C + x Li ++ +xe → Li +xe → Li xx C C
Overall LiMO2 + C → Li Overall LiMO2 + C → Li xx C + Li C + Li 1-x1-x MO2MO2
Features of Li-ion batteries Features of Li-ion batteries
Higher Energy densityHigher Energy density Higher voltageHigher voltage Long operating timeLong operating time Compact Compact
DefinitionsDefinitions
SOC denotes the remaining pulses in a SOC denotes the remaining pulses in a battery pack in one discharge cycle battery pack in one discharge cycle
SOH represents the remaining number of SOH represents the remaining number of cycles (charge-discharge) that can be cycles (charge-discharge) that can be obtained from a battery pack in its obtained from a battery pack in its entire life. When the battery pack is new entire life. When the battery pack is new it is said to have 100% SOH. As the it is said to have 100% SOH. As the battery ages SOH eventually decreases. battery ages SOH eventually decreases.
Battery Interrogation TechniquesBattery Interrogation Techniques
Efficient battery interrogation Efficient battery interrogation techniques are required for techniques are required for determining the state-of-charge (SOC) determining the state-of-charge (SOC) of a battery.of a battery.
The three basic methods are:The three basic methods are:
1) Coulomb counting1) Coulomb counting
2) Voltage delay and 2) Voltage delay and
3) Impedance method3) Impedance method
Z’
Z”inductive tail
Rs
0
Diffusion
Anode
Cathode1kHz
100Hz
10 mHzCap
acit
ive
beha
vior
Indu
ctiv
e be
havi
orTYPICAL NYQUIST PLOT OF ELECTRO
CHEMICAL CELL
Equivalent Circuit for this CellEquivalent Circuit for this Cell
RS
RanodeRcathode
Canode Ccathode
L
Using AC impedance for Using AC impedance for
determination of SOCdetermination of SOC
Research by J. P.FellnerResearch by J. P.FellnerAt Air force laboratory, OH [1]At Air force laboratory, OH [1]
Using AC impedance for Using AC impedance for determination of SOCdetermination of SOC
Research by J. P.FellnerResearch by J. P.Fellner At Air force laboratory, OH [2]At Air force laboratory, OH [2]
Using AC impedance for Using AC impedance for determination of SOCdetermination of SOC
Research by Dr. Pritpal Singh [3]
Using AC impedance for Using AC impedance for determination of SOCdetermination of SOC
Research by J. P.FellnerResearch by J. P.Fellner At Air force laboratory, OH [2]At Air force laboratory, OH [2]
200
60
400
60
Introduction to Fuzzy LogicIntroduction to Fuzzy Logic
In fuzzy logic, a quantity may be a member In fuzzy logic, a quantity may be a member of a set to some degree or not be a member of a set to some degree or not be a member of a set to some degree. The boundaries of of a set to some degree. The boundaries of the set are fuzzy rather than crisp.the set are fuzzy rather than crisp.
A fuzzy system is a rule-based mapping of A fuzzy system is a rule-based mapping of inputs to outputs for a system.inputs to outputs for a system.
Two approaches in Fuzzy LogicTwo approaches in Fuzzy Logic
Mamdani Approach: Uses membership Mamdani Approach: Uses membership functions for both input and output functions for both input and output variablesvariables
Sugeno Approach: Sugeno Approach: Output Output membership functions are membership functions are “singletons” (zero order) or “singletons” (zero order) or polynomials (first order). polynomials (first order).
Example: Two input, two rule Fuzzy Model
m1
n1
F1
m2
n2 F2
S1
S2
Rule1
Rule2
Sugeno type of inferenceSugeno type of inference
PROCEDUREPROCEDURE
Li-ion battery packLi-ion battery pack
This Li ion battery pack consists of 12 This Li ion battery pack consists of 12 cells connected in series parallel cells connected in series parallel (4s3p configuration) (4s3p configuration)
Effective voltage of the battery pack Effective voltage of the battery pack is 16.8 volts(4.2 volts per cell)is 16.8 volts(4.2 volts per cell)
ChargeCharge profileprofile
The profile that we have adopted is The profile that we have adopted is
A constant current charging of 2.5 A A constant current charging of 2.5 A till the battery voltage is 16.6172 vtill the battery voltage is 16.6172 v
A constant voltage charging of 16.6 v A constant voltage charging of 16.6 v till the charge current drops below till the charge current drops below 100mA100mA
Discharge profileDischarge profile
The profile suggested by The profile suggested by
Medtronic/ Physio Control was Medtronic/ Physio Control was
Continuous discharge of 1.4 A and a Continuous discharge of 1.4 A and a discharge of 10 A for every 5 minutes discharge of 10 A for every 5 minutes for a period of 5 sfor a period of 5 s
DischargeDischarge profileprofile
Load current profile Voltage recovery profile
ApparatusApparatus
For discharge -- Electronic load 6063B from For discharge -- Electronic load 6063B from Agilent TechnologiesAgilent Technologies
For the impedance and the voltage recovery For the impedance and the voltage recovery measurements--Solartron 1280B,which is measurements--Solartron 1280B,which is Potentiostat /Galvanostat /FRAPotentiostat /Galvanostat /FRA
For charge --Centronix BMS2000, The Battery For charge --Centronix BMS2000, The Battery Management SystemManagement System
For different temperatures Tenney For different temperatures Tenney EnvironmentalEnvironmental oven oven
Battery pack, EC Load and Battery pack, EC Load and SolartronSolartron
EC-Load and OvenEC-Load and Oven
SoftwareSoftware
To control the Electronic Load the To control the Electronic Load the software is HP VEEsoftware is HP VEE
To view and plot the impedance data To view and plot the impedance data its Zview and Zplot respectivelyits Zview and Zplot respectively
To view and plot the voltage To view and plot the voltage recovery profiles data its Corr view recovery profiles data its Corr view and Corr wareand Corr ware
SoftwareSoftware controlcontrol
Test processTest process
Constant current discharge at 1.4A for 5 minutes, Constant current discharge at 1.4A for 5 minutes, monitoring the voltage of the battery pack monitoring the voltage of the battery pack
Constant current discharge at 10 A for 5 seconds, Constant current discharge at 10 A for 5 seconds, monitoring the voltage of the battery pack monitoring the voltage of the battery pack
Repeat this process for a total of 1100 seconds Repeat this process for a total of 1100 seconds which includes three 10 A dischargeswhich includes three 10 A discharges
EIS (Electro chemical Impedance spectroscopy) EIS (Electro chemical Impedance spectroscopy) measurement over frequency range of 1Hz-1KHzmeasurement over frequency range of 1Hz-1KHz
Repeat above four steps until end of discharge is Repeat above four steps until end of discharge is reached (2.5V/cell)reached (2.5V/cell)
Test processTest process
MEASUREMENTSMEASUREMENTS ANDAND ANALYSISANALYSIS
ImpedanceImpedance measurementsmeasurements
Nyquist plot
ImpedanceImpedance measurementsmeasurements
Bode plots
Monotonic variation of the voltage Monotonic variation of the voltage
recovery profilesrecovery profiles withwith SOCSOC
Comparing the First and the Last Comparing the First and the Last pulsepulse
AnalysisAnalysis
Minimum voltage curvesMinimum voltage curves Difference voltage curvesDifference voltage curves
Minimum voltage curvesMinimum voltage curves
The locus of the minimum voltages of The locus of the minimum voltages of every pulse in one cycle forms one every pulse in one cycle forms one curve corresponding to Cxx in the curve corresponding to Cxx in the graphgraph
One PulseOne Pulse
Minimum voltage curvesMinimum voltage curves
The locus of the minimum voltages of The locus of the minimum voltages of every pulse in one cycle forms one every pulse in one cycle forms one curve corresponding to Cxx in the curve corresponding to Cxx in the graphgraph
The above means the set of all As in The above means the set of all As in figure shownfigure shown
For battery pack at room For battery pack at room temperaturetemperature
Difference voltage curvesDifference voltage curves
The locus of the difference between The locus of the difference between the maximum and minimum voltages the maximum and minimum voltages of every pulse in a cycle forms a of every pulse in a cycle forms a curve Cxx in the figure.curve Cxx in the figure.
OneOne pulsepulse
Difference voltage curvesDifference voltage curves
Voltage Difference=B-AVoltage Difference=B-A The locus of the difference between The locus of the difference between
the maximum and minimum voltages the maximum and minimum voltages of every pulse (B-A) in a cycle forms of every pulse (B-A) in a cycle forms a curve Cxx in the figure.a curve Cxx in the figure.
For battery pack at room For battery pack at room temperaturetemperature
FUZZY LOGIC MODELINGFUZZY LOGIC MODELING
Two models1. To predict SOC –Remaining pulses (implemented)2. To predict SOH –Cycle number (theoretical model)
Fuzzy Logic ModelingFuzzy Logic Modeling
Inputs: Maximum voltage and Minimum Inputs: Maximum voltage and Minimum voltagevoltage
Output: Output: Pulses remainingPulses remaining Type of mem. functions: TrapezoidalType of mem. functions: Trapezoidal Type of inference : SugenoType of inference : Sugeno No. of rules : 12No. of rules : 12 4 mem. Functions for Max. voltage4 mem. Functions for Max. voltage 3 mem. Functions for Min. voltage3 mem. Functions for Min. voltage
Membership Functions for Membership Functions for Input1Input1
Membership Functions for Membership Functions for input2input2
Training error (0.95425)Training error (0.95425)
Testing error (0.99126)Testing error (0.99126)
Surface plotSurface plot
Fuzzy Logic ModelingFuzzy Logic Modeling
Inputs: Maximum voltage and Minimum Inputs: Maximum voltage and Minimum voltagevoltage
Output: Output: Cycle NumberCycle Number Type of mem. functions: TrapezoidalType of mem. functions: Trapezoidal Type of inference : SugenoType of inference : Sugeno No. of rules : 12No. of rules : 12 2 mem. Functions for Max. voltage2 mem. Functions for Max. voltage 6 mem. Functions for Min. voltage6 mem. Functions for Min. voltage
Testing error (2.6554)Testing error (2.6554)
Training error (2.565)Training error (2.565)
Surface plotSurface plot
IMPLEMENTATION IN MC68HC12 IMPLEMENTATION IN MC68HC12 (micro controller)(micro controller)
Implementation in Implementation in MC68HC12 (micro controller)MC68HC12 (micro controller)
Features of HC12:Features of HC12: On-Chip A/D conversion (any voltage On-Chip A/D conversion (any voltage
between 0-5 volts;0-00H and 5-FFH )between 0-5 volts;0-00H and 5-FFH ) Instruction Set with Fuzzy Logic Instruction Set with Fuzzy Logic
instructions (ability to implement instructions (ability to implement trapezoidal and triangular mem. trapezoidal and triangular mem. functions)functions)
Step down circuitStep down circuit
Voltage of the battery pack is stepped down Voltage of the battery pack is stepped down to be given as input to HC12to be given as input to HC12
R=511 K OhmsR=511 K Ohms
Op Amp=LMC60 42 AIN Op Amp=LMC60 42 AIN
Flow chart of the main programFlow chart of the main program
Timing DiagramTiming Diagram
Experimental setupExperimental setup
ResultsResultsDisplay showing 21 pulses remaining Average error=+/-2 pulses
LCD display Stem Plot
SummarySummary
Impedance and Voltage recovery profiles Impedance and Voltage recovery profiles collected for battery packs at room temperature collected for battery packs at room temperature and 0and 000CC
Battery characteristics were analyzed and Battery characteristics were analyzed and Minimum voltage curves and Difference voltage Minimum voltage curves and Difference voltage curves were developedcurves were developed
Based on the voltage recovery profiles a good Based on the voltage recovery profiles a good Fuzzy Logic Model was obtained to predict the Fuzzy Logic Model was obtained to predict the SOC of the battery pack at room temperature SOC of the battery pack at room temperature with a minimum error as low as 0.9with a minimum error as low as 0.9
Implemented on Micro Controller HC12 with a Implemented on Micro Controller HC12 with a very low error of +/-2 pulsesvery low error of +/-2 pulses
FutureFuture scopescope
This model can be extended to This model can be extended to estimate the SOC of the battery estimate the SOC of the battery packs at different temperaturespacks at different temperatures
An SOH meter that can predict the An SOH meter that can predict the cycle number can also be developed cycle number can also be developed provided, sufficient data is collected provided, sufficient data is collected for the battery packs at different for the battery packs at different temperaturestemperatures
PublicationsPublications1. 1. Pritpal Singh and Ramana Vinjamuri, Xiquan Wang and Pritpal Singh and Ramana Vinjamuri, Xiquan Wang and
David Reisner “David Reisner “FUZZY LOGIC MODELING OF EIS FUZZY LOGIC MODELING OF EIS MEASUREMENTS ON LITHIUM-ION BATTERIES”. MEASUREMENTS ON LITHIUM-ION BATTERIES”. EIS’04EIS’04
2. 2. Pritpal Singh and Ramana Vinjamuri, Xiquan Wang and Pritpal Singh and Ramana Vinjamuri, Xiquan Wang and
David Reisner.”David Reisner.” Analysis on Voltage recovery Analysis on Voltage recovery profiles and Impedance measurements of High profiles and Impedance measurements of High Power Li ion batteries”.Power Li ion batteries”.
41 st Power sources conference,2004 41 st Power sources conference,2004
ReferencesReferences
1.1. J.P.Fellner and R.A. Marsh “Use of the pulse current and AC J.P.Fellner and R.A. Marsh “Use of the pulse current and AC impedance characterization to enhance Lithium ion battery impedance characterization to enhance Lithium ion battery maintenance”, Electrochemical society proceedings volume 99-maintenance”, Electrochemical society proceedings volume 99-2525
2.2. J.P.Fellner, G.J.Loeber, S.S.Sadhu “Testing of lithium ion 18650 J.P.Fellner, G.J.Loeber, S.S.Sadhu “Testing of lithium ion 18650 cells and characterizing/predicting cell performance” Journal of cells and characterizing/predicting cell performance” Journal of Power sources conference 81-82(1999)Power sources conference 81-82(1999)
3.3. P. Singh, Y.S. Damodar, C. Fennie, and D.E. Reisner, “Fuzzy Logic-P. Singh, Y.S. Damodar, C. Fennie, and D.E. Reisner, “Fuzzy Logic-Based Determination of Lead Acid Battery State-of-Charge by Based Determination of Lead Acid Battery State-of-Charge by Impedance Interrogation Methods”Impedance Interrogation Methods”Procs. EVS-17Procs. EVS-17, Montreal, , Montreal,
Canada, Oct 15-18, 2000Canada, Oct 15-18, 2000