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Modeling, Identification, & Fault Diagnostics of Batteries Scott Moura Assistant Professor | eCAL Director University of California, Berkeley Nuclear Engineering Colloquium Download:


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SLIDE 1

Modeling, Identification, & Fault Diagnostics of Batteries

Scott Moura

Assistant Professor | eCAL Director University of California, Berkeley

Nuclear Engineering Colloquium

Download: https://ecal.berkeley.edu/pubs/slides/Moura-NE-Batts-Slides.pdf

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 1

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SLIDE 2

eCAL Battery Controls Team @ UC Berkeley

Current Researchers

  • Prof. Scott Moura | Dr. Satadru Dey | Leo Camacho-Solorio | Saehong Park | Dong ZHANG | Zach Gima

Supporting Researchers

  • Prof. Xiaosong Hu | Dr. Hector Perez | Defne Gun | Preet Gill

| Reve Ching | Zane Liu | Dylan Kato

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 2

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SLIDE 3

A Golden Era

1985 1990 1995 2000 2005 2010 2015

Year

1000 2000 3000

  • No. of Publications

Keyword Search: Battery Systems and Control

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 3

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SLIDE 4

Challenges

Samsung Galaxy Note Boeing 787 Dreamliner

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 4

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SLIDE 5

The Battery Problem

Needs: Cheap, high energy/power, fast charge, long life Reality: Expensive, conservatively design/operated, die too quickly

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 5

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SLIDE 6

The Battery Problem

Needs: Cheap, high energy/power, fast charge, long life Reality: Expensive, conservatively design/operated, die too quickly Some Motivating Facts EV Batts 1000 USD / kWh (2010)∗ 485 USD / kWh (2012)∗ 350 USD / kWh (2015)∗∗ 125 USD / kWh for parity to IC engine Only 50-80% of available capacity is used Range anxiety inhibits adoption Lifetime risks caused by fast charging

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 5

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SLIDE 7

The Battery Problem

Needs: Cheap, high energy/power, fast charge, long life Reality: Expensive, conservatively design/operated, die too quickly

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 5

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SLIDE 8

The Battery Problem

Needs: Cheap, high energy/power, fast charge, long life Reality: Expensive, conservatively design/operated, die too quickly

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 5

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SLIDE 9

The Battery Problem

Needs: Cheap, high energy/power, fast charge, long life Reality: Expensive, conservatively design/operated, die too quickly Some Motivating Facts EV Batts 1000 USD / kWh (2010)∗ 485 USD / kWh (2012)∗ 350 USD / kWh (2015)∗∗ 125 USD / kWh for parity to IC engine Only 50-80% of available capacity is used Range anxiety inhibits adoption Lifetime risks caused by fast charging Two Solutions Design better batteries Make current batteries better (materials science & chemistry) (estimation and control)

∗Source: MIT Technology Review, “The Electric Car is Here to Stay.” (2013) ∗∗Source: Tesla Powerwall. (2015) Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 5

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SLIDE 10

On-Going Research Goals

Increase usable energy capacity by 20% Decrease charge times by factor of 5X Increase battery life time by 50% Decrease fault detection time by factor of 10X

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 6

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SLIDE 11

Outline

1

BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS

2

ESTIMATION AND CONTROL PROBLEM STATEMENTS

3

ELECTROCHEMICAL MODEL

4

MODEL IDENTIFICATION

5

FAULT DIAGNOSTICS

6

SUMMARY AND OPPORTUNITIES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 7

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SLIDE 12

History

Luigi Galvani, 1737-1798, Physicist, Bologna, Italy “Animal electricity” Dubbed “galvanism” First foray into electrophysiology Experiments on frog legs Alessandro Volta, 1745-1827 Physicist, Como, Italy Voltaic Pile Monument to Volta in Como

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 8

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SLIDE 13

Comparison of Lithium Ion (Cathode) Chemistries

Lithium Cobalt Oxide (LiCO2) Lithium Manganese Oxide (LiMn2O4) Lithium Iron Phosphate (LiFePO4) Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) Lithium Titanate (Li4Ti5O12)

Source: http://batteryuniversity.com/learn/article/types_of_lithium_ion Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 9

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SLIDE 14

Outline

1

BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS

2

ESTIMATION AND CONTROL PROBLEM STATEMENTS

3

ELECTROCHEMICAL MODEL

4

MODEL IDENTIFICATION

5

FAULT DIAGNOSTICS

6

SUMMARY AND OPPORTUNITIES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 10

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SLIDE 15

Battery Models

Equivalent Circuit Model

(a) OCV-R

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 11

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SLIDE 16

Battery Models

Equivalent Circuit Model

(a) (b) (c) OCV-R OCV-R-RC Impedance

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 11

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SLIDE 17

Battery Models

Equivalent Circuit Model

(a) (b) (c) OCV-R OCV-R-RC Impedance

Electrochemical Model

Separator Cathode Anode LixC6 Li1-xMO2 Li+ cs

  • (r)

cs

+(r)

css

  • css

+

Electrolyte e- e- ce(x)

  • L
  • L

+ + sep

L

sep

r r x

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 11

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SLIDE 18

Safely Operate Batteries at their Physical Limits

Cell Current Surface concentration Terminal Voltage Overpotential

ECM-based limits of operation ECM-based limits of operation Electrochemical model-based limits of operation

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 12

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SLIDE 19

ElectroChemical Controller (ECC)

EChem-based State/Param Estimator I(t) V(t), T(t) Battery Cell EChem-based Controller Ir(t) V(t), T(t) ^ ^ + _

Innovations Estimated States & Params

ElectroChemical Controller (ECC)

Measurements

^ x(t), θ(t) ^

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 13

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SLIDE 20

Outline

1

BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS

2

ESTIMATION AND CONTROL PROBLEM STATEMENTS

3

ELECTROCHEMICAL MODEL

4

MODEL IDENTIFICATION

5

FAULT DIAGNOSTICS

6

SUMMARY AND OPPORTUNITIES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 14

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SLIDE 21

Battery Electrochemistry Model

The Doyle-Fuller-Newman (DFN) Model

Separator Cathode Anode LixC6 Li1-xMO2 Li+ cs

  • (r)

cs

+(r)

css

  • css

+

Electrolyte e- e- ce(x)

  • L
  • L

+ + sep

L

sep

r r x

Key References:

  • K. Thomas, J. Newman, and R. Darling, Advances in Lithium-Ion Batteries. New York, NY USA: Kluwer Academic/Plenum Publishers, 2002, ch. 12: Mathematical modeling of lithium

batteries, pp. 345-392.

  • N. A. Chaturvedi, R. Klein, J. Christensen, J. Ahmed, and A. Kojic, “Algorithms for advanced battery-management systems,” IEEE Control Systems Magazine, vol. 30, no. 3, pp. 49-68,

2010.

  • J. Newman. (2008) Fortran programs for the simulation of electrochemical systems. [Online]. Available: http://www.cchem.berkeley.edu/jsngrp/fortran.html

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 15

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Electrochemical Model Equations

well, some of them | Open Source Matlab CODE: github.com/scott-moura/fastDFN Description Equation Solid phase Li concentration

∂c±

s

∂t (x, r, t) =

1 r2

∂ ∂r

s (c± s ) · r2 ∂c±

s

∂r (x, r, t)

  • Electrolyte Li

concentration

εe ∂ce

∂t (x, t) = ∂ ∂x

  • Deff

e (ce) ∂ce

∂x (x, t) +

1−t0

c

F

e (x, t)

  • Solid

potential

σeff,± ∂φ±

s

∂x (x, t) = i±

e (x, t) − I(t)

Electrolyte potential

κeff(ce) ∂φe

∂x (x, t) = −ie±(x, t) +

2RT(1−t0

c )κeff(ce)

F

  • 1 +

d ln fc/a d ln ce

  • ∂ ln ce

∂x

(x, t)

Electrolyte ionic current

∂ie± ∂x (x, t) = a±

s Fjn±(x, t)

Molar flux btw phases j±

n (x, t) = 1 F i± 0 (x, t)

  • e

αaF RT η±(x,t) − e− αcF RT η±(x,t)

Temperature

ρcP

dT dt (t) = h

  • T0(t) − T(t)
  • + I(t)V(t) −

0+

0− asFjn(x, t)∆T(x, t)dx

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 16

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SLIDE 23

Electrochemical Model Equations

well, some of them | Open Source Matlab CODE: github.com/scott-moura/fastDFN Description Equation Solid phase Li concentration

∂c±

s

∂t (x, r, t) =

1 r2

∂ ∂r

s (c± s ) · r2 ∂c±

s

∂r (x, r, t)

  • (PDE in r, t)

Electrolyte Li concentration

εe ∂ce

∂t (x, t) = ∂ ∂x

  • Deff

e (ce) ∂ce

∂x (x, t) +

1−t0

c

F

e (x, t)

  • (PDE in r, t)

Solid potential

σeff,± ∂φ±

s

∂x (x, t) = i±

e (x, t) − I(t)

Electrolyte potential

κeff(ce) ∂φe

∂x (x, t) = −ie±(x, t) +

2RT(1−t0

c )κeff(ce)

F

  • 1 +

d ln fc/a d ln ce

  • ∂ ln ce

∂x

(x, t)

Electrolyte ionic current

∂ie± ∂x (x, t) = a±

s Fjn±(x, t)

Molar flux btw phases j±

n (x, t) = 1 F i± 0 (x, t)

  • e

αaF RT η±(x,t) − e− αcF RT η±(x,t)

Temperature

ρcP

dT dt (t) = h

  • T0(t) − T(t)
  • + I(t)V(t) −

0+

0− asFjn(x, t)∆T(x, t)dx

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 16

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SLIDE 24

Electrochemical Model Equations

well, some of them | Open Source Matlab CODE: github.com/scott-moura/fastDFN Description Equation Solid phase Li concentration

∂c±

s

∂t (x, r, t) =

1 r2

∂ ∂r

s (c± s ) · r2 ∂c±

s

∂r (x, r, t)

  • Electrolyte Li

concentration

εe ∂ce

∂t (x, t) = ∂ ∂x

  • Deff

e (ce) ∂ce

∂x (x, t) +

1−t0

c

F

e (x, t)

  • Solid

potential

σeff,± ∂φ±

s

∂x (x, t) = i±

e (x, t) − I(t) (ODE in x)

Electrolyte potential

κeff(ce) ∂φe

∂x (x, t) = −ie±(x, t) +

2RT(1−t0

c )κeff(ce)

F

  • 1 +

d ln fc/a d ln ce

  • ∂ ln ce

∂x

(x, t) (ODE in x)

Electrolyte ionic current

∂ie± ∂x (x, t) = a±

s Fjn±(x, t) (ODE in x)

Molar flux btw phases j±

n (x, t) = 1 F i± 0 (x, t)

  • e

αaF RT η±(x,t) − e− αcF RT η±(x,t)

Temperature

ρcP

dT dt (t) = h

  • T0(t) − T(t)
  • + I(t)V(t) −

0+

0− asFjn(x, t)∆T(x, t)dx

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 16

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SLIDE 25

Electrochemical Model Equations

well, some of them | Open Source Matlab CODE: github.com/scott-moura/fastDFN Description Equation Solid phase Li concentration

∂c±

s

∂t (x, r, t) =

1 r2

∂ ∂r

s (c± s ) · r2 ∂c±

s

∂r (x, r, t)

  • Electrolyte Li

concentration

εe ∂ce

∂t (x, t) = ∂ ∂x

  • Deff

e (ce) ∂ce

∂x (x, t) +

1−t0

c

F

e (x, t)

  • Solid

potential

σeff,± ∂φ±

s

∂x (x, t) = i±

e (x, t) − I(t)

Electrolyte potential

κeff(ce) ∂φe

∂x (x, t) = −ie±(x, t) +

2RT(1−t0

c )κeff(ce)

F

  • 1 +

d ln fc/a d ln ce

  • ∂ ln ce

∂x

(x, t)

Electrolyte ionic current

∂ie± ∂x (x, t) = a±

s Fjn±(x, t)

Molar flux btw phases j±

n (x, t) = 1 F i± 0 (x, t)

  • e

αaF RT η±(x,t) − e− αcF RT η±(x,t)

(nonlinear AE) Temperature

ρcP

dT dt (t) = h

  • T0(t) − T(t)
  • + I(t)V(t) −

0+

0− asFjn(x, t)∆T(x, t)dx

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 16

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SLIDE 26

Electrochemical Model Equations

well, some of them | Open Source Matlab CODE: github.com/scott-moura/fastDFN Description Equation Solid phase Li concentration

∂c±

s

∂t (x, r, t) =

1 r2

∂ ∂r

s (c± s ) · r2 ∂c±

s

∂r (x, r, t)

  • Electrolyte Li

concentration

εe ∂ce

∂t (x, t) = ∂ ∂x

  • Deff

e (ce) ∂ce

∂x (x, t) +

1−t0

c

F

e (x, t)

  • Solid

potential

σeff,± ∂φ±

s

∂x (x, t) = i±

e (x, t) − I(t)

Electrolyte potential

κeff(ce) ∂φe

∂x (x, t) = −ie±(x, t) +

2RT(1−t0

c )κeff(ce)

F

  • 1 +

d ln fc/a d ln ce

  • ∂ ln ce

∂x

(x, t)

Electrolyte ionic current

∂ie± ∂x (x, t) = a±

s Fjn±(x, t)

Molar flux btw phases j±

n (x, t) = 1 F i± 0 (x, t)

  • e

αaF RT η±(x,t) − e− αcF RT η±(x,t)

Temperature

ρcP

dT dt (t) = h

  • T0(t) − T(t)
  • + I(t)V(t) −

0+

0− asFjn(x, t)∆T(x, t)dx (ODE in t)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 16

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SLIDE 27

Simulations : LiCoO2-C cell | 5C discharge after 30sec

Space, r

c−

s (x, r, t)/c− s,max

Center Surface Space, r

c+

s (x, r, t)/c+ s,max 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.5 1 1.5 2

Space, x/L

ce(x, t)

0.45 0.5 0.55 0.6 0.65 0.7 0.75

Cathode Separator Anode

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 17

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SLIDE 28

Outline

1

BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS

2

ESTIMATION AND CONTROL PROBLEM STATEMENTS

3

ELECTROCHEMICAL MODEL

4

MODEL IDENTIFICATION

5

FAULT DIAGNOSTICS

6

SUMMARY AND OPPORTUNITIES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 18

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SLIDE 29

Model Identification from Experiments

Model Identification Problem

Given measurements of current I(t), voltage V(t), and temperature T(t), identify unknown/uncertain parameters. Challenges: How to design the experiments? How to optimally fit the parameters?

Space, r

c−

s (x, r, t)/c− s,max Center Surface Space, r

c+

s (x, r, t)/c+ s,max 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.5 1 1.5 2 Space, x/L

ce(x, t)

0.45 0.5 0.55 0.6 0.65 0.7 0.75 Cathode Separator Anode

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 19

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SLIDE 30

Current State-of-Art

Literature Review (Schmidt 2010) Fisher info, param grouping (Forman 2012) Fisher info, genetic algorithm (Marcicki 2013) SPMe, heuristic approach (Arenas 2014) ANOVA confidence intervals (Zhang 2015) Multi-obj GA (voltage & temp) (Alavi 2015) identifiability analysis (Rothenberger 2015) ECM, sinusoidal input (Liu 2016) ECM & SPM, sinusoidal input and more?

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 20

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Current State-of-Art

Literature Review (Schmidt 2010) Fisher info, param grouping (Forman 2012) Fisher info, genetic algorithm (Marcicki 2013) SPMe, heuristic approach (Arenas 2014) ANOVA confidence intervals (Zhang 2015) Multi-obj GA (voltage & temp) (Alavi 2015) identifiability analysis (Rothenberger 2015) ECM, sinusoidal input (Liu 2016) ECM & SPM, sinusoidal input and more?

Key Takeaway

Experiments are not optimized for parameter identifiability

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 20

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Optimal Control Approach

Canonical Optimal Control Problem (OCP)

minimize

tf

t=t0

L(x, u)dt + Φ(x(tf)) (1) subject to: d dt x(t) = f(x, u); x(t0) = x0 (2) xmin ≤ x(t) ≤ xmax (3) umin ≤ u(t) ≤ umax (4) x(t): state; u(t): controlled input

d dt x(t) = f(x, u);

x(t0) = x0

Numerical Solution Methods

Dynamic programming Quasilinearization Direct shooting Spectral methods Collocation methods many more...

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 21

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SLIDE 33

Optimal Control Problem for Maximizing Parameter Identifiability

minimize

tf

t=t0

det

  • ST

3(t)Q−1S3(t)

  • dt

(5) subject to: d dt x(t) = f(x, z, u; θ); x(t0) = x0(θ) d dt S1(t) = ∂f

∂xS1 + ∂f ∂z S2 + ∂f ∂θ

(6) 0 = g(x, z, u; θ) 0 = ∂g

∂x S1 + ∂g ∂z S2 + ∂g ∂θ

(7) y = h(x, z, u; θ) S3(t) = ∂h

∂x S1 + ∂h ∂z S2 + ∂h ∂θ

(8)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 22

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SLIDE 34

Optimal Control Problem for Maximizing Parameter Identifiability

minimize

tf

t=t0

det

  • ST

3(t)Q−1S3(t)

  • dt

(5) subject to: d dt x(t) = f(x, z, u; θ); x(t0) = x0(θ) d dt S1(t) = ∂f

∂xS1 + ∂f ∂z S2 + ∂f ∂θ

(6) 0 = g(x, z, u; θ) 0 = ∂g

∂x S1 + ∂g ∂z S2 + ∂g ∂θ

(7) y = h(x, z, u; θ) S3(t) = ∂h

∂x S1 + ∂h ∂z S2 + ∂h ∂θ

(8) Elegant formulation! However, the OCP proved to be computationally intractable: 2 weeks to generate 100 sec of optimized input signals

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 22

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SLIDE 35

Optimal Control Problem for Maximizing Parameter Identifiability

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 23

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SLIDE 36

Optimal Control Problem for Maximizing Parameter Identifiability

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 23

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SLIDE 37

A different idea!

Figure: Fixed menu of L inputs, index by j

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 24

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SLIDE 38

A different idea!

Figure: Fixed menu of L inputs, index by j

Convex OED

Pre-compute all sensitivities Sj on menu minimizeη log det

 

L

  • j=0

ηjSjQ−1ST

j

 

−1

subject to:

ηj ≥ 0,

L

  • j=0

ηj = 1

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 24

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SLIDE 39

A different idea!

Figure: Fixed menu of L inputs, index by j

Convex OED

Pre-compute all sensitivities Sj on menu minimizeη log det

 

L

  • j=0

ηjSjQ−1ST

j

 

−1

subject to:

ηj ≥ 0,

L

  • j=0

ηj = 1

Convex program → polynomial complexity Optimize 750 input profiles in 20 seconds

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 24

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SLIDE 40

Model Identification from Experiments

Generate Feasible Parameter Set Run Test Optimized for Model ID Optimize Parameters Validate on different test

Note: 10-bit A/D converter + 10V ref ⇒ 10mV resolution

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 25

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SLIDE 41

Outline

1

BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS

2

ESTIMATION AND CONTROL PROBLEM STATEMENTS

3

ELECTROCHEMICAL MODEL

4

MODEL IDENTIFICATION

5

FAULT DIAGNOSTICS

6

SUMMARY AND OPPORTUNITIES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 26

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SLIDE 42

Battery Safety Problem

Samsung Galaxy Note Boeing 787 Dreamliner

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 27

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SLIDE 43

Battery Faults

Sensor Faults Thermal Faults Electrochemical Faults Voltage sensor Thermal Runaway Mechanical deformation Current sensor Convective cooling failure Current collector corrosion

  • Temp. sensor

Internal thermal failure Gassing Separator failure Electrode fracture

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 28

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SLIDE 44

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 29

slide-45
SLIDE 45

Battery Fault Diagnostics Problem

Objectives

Detect fault Estimate fault size Boeing 787 Dreamliner

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 30

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SLIDE 46

Battery Fault Diagnostics Problem

Objectives

Detect fault Estimate fault size

Challenges

Few measurements Uncertainty Boeing 787 Dreamliner

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 30

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SLIDE 47

Battery Fault Diagnostics Problem

Objectives

Detect fault Estimate fault size

Challenges

Few measurements Uncertainty

State-of-Art

Industry: Limit check measurements Published Literature: Sensor faults,

  • ver charge/discharge

Boeing 787 Dreamliner

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 30

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SLIDE 48

Real-time Diagnosis of Thermal Failures

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 31

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SLIDE 49

Battery Thermal Model

Figure: Radial heat transfer model of cylindrical cell

β ∂T ∂t (r, t) = ∂2T ∂r2 (r, t) +

  • 1

r

∂T ∂r (r, t) + 1

k

˙

Q(t) (9)

∂T ∂r (0, t) =

(10)

∂T ∂r (R, t) =

h k [T∞ − T(R, t)] (11)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 32

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SLIDE 50

Battery Thermal Model

Figure: Radial heat transfer model of cylindrical cell

β ∂T ∂t (r, t) = ∂2T ∂r2 (r, t) +

  • 1

r

∂T ∂r (r, t) + 1

k

˙

Q(t)+∆Q (9)

∂T ∂r (0, t) =

(10)

∂T ∂r (R, t) =

h k [T∞ − T(R, t)] (11)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 32

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SLIDE 51

Diagnostic Scheme

Objective

Detect and estimate thermal fault size Robust Observer: Estimates dis- tributed temperature, under faulty & healthy conditions Diagnostic Observer: Detects and es- timates fault size

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 33

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SLIDE 52

Observer Structure: Copy of the System + Feedback

System Model:

∂T ∂t (x, t) = ∂2T ∂x2 (x, t) + 1

k

˙

Q(t) + θ · ψ(x, t) Thermal Fault (12)

∂T ∂x (0, t) =

0;

∂T ∂x (1, t) = h

k [T∞ − T(1, t)] (13)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 34

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SLIDE 53

Observer Structure: Copy of the System + Feedback

System Model:

∂T ∂t (x, t) = ∂2T ∂x2 (x, t) + 1

k

˙

Q(t) + θ · ψ(x, t) Thermal Fault (12)

∂T ∂x (0, t) =

0;

∂T ∂x (1, t) = h

k [T∞ − T(1, t)] (13) Robust Observer:

∂ˆ

T1

∂t (x, t) = ∂2ˆ

T1

∂x2 (x, t) + 1

k

˙

Q(t) + p1(x)

  • T(1, t) − ˆ

T1(1, t)

  • (14)

∂ˆ

T1

∂x (0, t) =

0;

∂ˆ

T1

∂x (1, t) = h

k [T∞ − T(1, t)] + p10

  • T(1, t) − ˆ

T1(1, t)

  • (15)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 34

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SLIDE 54

Observer Structure: Copy of the System + Feedback

System Model:

∂T ∂t (x, t) = ∂2T ∂x2 (x, t) + 1

k

˙

Q(t) + θ · ψ(x, t) Thermal Fault (12)

∂T ∂x (0, t) =

0;

∂T ∂x (1, t) = h

k [T∞ − T(1, t)] (13) Robust Observer:

∂ˆ

T1

∂t (x, t) = ∂2ˆ

T1

∂x2 (x, t) + 1

k

˙

Q(t) + p1(x)

  • T(1, t) − ˆ

T1(1, t)

  • (14)

∂ˆ

T1

∂x (0, t) =

0;

∂ˆ

T1

∂x (1, t) = h

k [T∞ − T(1, t)] + p10

  • T(1, t) − ˆ

T1(1, t)

  • (15)

Diagnostic Observer:

∂ˆ

T2

∂t (x, t) = ∂2ˆ

T2

∂x2 (x, t) + 1

k

˙

Q(t) + ˆ

θ(t)ψ(x, t) + p2 ˆ

T1(x, t) − ˆ T2(x, t)

  • (16)

∂ˆ

T2

∂x (0, t) =

0;

∂ˆ

T2

∂x (1, t) = h

k [T∞ − T(1, t)] (17) d dt

ˆ θ(t) =

p3

1 ψ(x, t) ˆ

T1(x, t) − ˆ T2(x, t)

  • dx

(18)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 34

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SLIDE 55

Diagnostic Scheme: Design and Theoretical Convergence Analysis

Key Design Steps

1

Backstepping transformation to get target error system

2

Analyze the target error system using Lyapunov stability theory

3

Utilize Lyapunov-based adaptive observer design to estimate θ

Theoretical Convergence Analysis

Asymptotically, estimation errors T(x, t) − ˆ T1(x, t)H1 → ǫ1,

  • θ − ˆ

θ(t)

  • → ǫ2 as t → ∞

Bounds ǫ1, ǫ2 can be made arbitrarily small by choosing p1(x), p10, p2, p3 appropriately

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 35

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SLIDE 56

Experimental Tests

Commercial LiFeO4 battery cell (A123 26650)

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 36

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SLIDE 57

Experimental Tests

Robust Observer estimates surface temperature under all conditions [estimation error within 0.2 deg C] Diagnostic Observer detects and estimates the fault [estimation error within 15%] Fault detection time 5 sec

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 37

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SLIDE 58

Outline

1

BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS

2

ESTIMATION AND CONTROL PROBLEM STATEMENTS

3

ELECTROCHEMICAL MODEL

4

MODEL IDENTIFICATION

5

FAULT DIAGNOSTICS

6

SUMMARY AND OPPORTUNITIES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 38

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SLIDE 59

Summary

Background & Electrochemistry Fundamentals Electrochemical-based models can enhance monitoring & performance! Optimal Experiment Design for Parameter Identifiability (Dim Sum) Thermal Fault Diagnostics

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 39

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SLIDE 60

Summary

Background & Electrochemistry Fundamentals Electrochemical-based models can enhance monitoring & performance! Optimal Experiment Design for Parameter Identifiability (Dim Sum) Thermal Fault Diagnostics Applicable control theoretic tools: PDE Control State estimation System identification Nonlinear and adaptive systems Optimal & constrained control

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 39

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SLIDE 61

Summary

Background & Electrochemistry Fundamentals Prob Defns: SOC Estimation, SOH Estimation, Charge/Discharge Control Electrochemical Modeling SOC Estimation Optimally Fast-Safe Charging

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 40

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SLIDE 62

Summary

Background & Electrochemistry Fundamentals Prob Defns: SOC Estimation, SOH Estimation, Charge/Discharge Control Electrochemical Modeling SOC Estimation Optimally Fast-Safe Charging Research Topics NOT discussed: Model Reduction State-of-Charge Estimation State-of-Health Estimation Optimal Fast-Safe Charging

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 40

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SLIDE 63

Reading Materials

SJM and H. Perez, “Better Batteries through Electrochemistry and Controls,” ASME Dynamic Systems and Control Magazine, July 2014.

  • N. A. Chaturvedi, R. Klein, J. Christensen, J. Ahmed, and A. Kojic, “Algorithms for advanced

battery-management systems,” IEEE Control Systems Magazine, 2010.

  • H. E. Perez, N. Shahmohammadhamedani, SJM, “Enhanced Performance of Li-ion Batteries via Modified

Reference Governors & Electrochemical Models,” IEEE/ASME Transactions on Mechatronics, Aug 2015. SJM, N. A. Chaturvedi, M. Krstic, “Adaptive PDE Observer for Battery SOC/SOH Estimation via an Electrochemical Model,” ASME Journal of Dynamic Systems, Measurement, and Control, Oct 2013.

  • H. Perez, SJM, “Sensitivity-Based Interval PDE Observer for Battery SOC Estimation,” 2015 American

Control Conference, Chicago, IL, 2015. O. Hugo Schuck Best Paper & ACC Best Student Paper. SJM, F . Bribiesca Argomedo, R. Klein, A. Mirtabatabaei, M. Krstic, “Battery State Estimation for a Single Particle Model with Electrolyte Dynamics,” IEEE Transactions on Control Systems Technology, Mar 2017

  • H. Perez, X. Hu, SJM, “Optimal Charging of Li-Ion Batteries via a Single Particle Model with Electrolyte

and Thermal Dynamics,” Journal of the Electrochemical Society. DOI: 10.1149/2.1301707jes

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 41

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SLIDE 64

VISIT US!

Energy, Controls, and Applications Lab (eCAL) ecal.berkeley.edu smoura@berkeley.edu

Download: https://ecal.berkeley.edu/pubs/slides/Moura-NE-Batts-Slides.pdf

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 42

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SLIDE 65

APPENDIX SLIDES

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 43

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SLIDE 66

Model Reduction

Methods in literature: Spectral methods Residue grouping Quasilinearization & Padé approx. Principle orthogonal decomposition Single particle model variants and much, much more Very popular and saturated topic Will not discuss further

ACCURACY SIMPLICITY Integrator Atomistic ECT SPMeT SPMe SPM ECM

Anode Separator Cathode

I(t) cs

  • (r,t)

r Li+ Rs

  • cs
+(r,t)

r Li+ I(t) Rs

+ Electrolyte Solid Li+ Solid Electrolyte

V(t) x ce(x,t) I(t) I(t) Li+ Li+ Li+ 0+ 0- L- 0sepLsepL+ T(t)

Cell 𝑊(𝑢) = ℎ(𝑑𝑡 − (𝑆𝑡 −, 𝑢), 𝑑𝑡 +(𝑆𝑡 +, 𝑢), 𝑑𝑓 −(𝑦, 𝑢), 𝑑𝑓 𝑡𝑓𝑞(𝑦, 𝑢), 𝑑𝑓 +(𝑦, 𝑢), 𝑈(𝑢), 𝐽(𝑢))

V(t) cs

  • (r,t)

r cs

+(r,t)

r Li+ Li+ Anode Separator Cathode Li

+

I(t) I(t) Rs

  • Rs

+

  • --Single Particle Model---

Solid Electrolyte

(b) OCV-R-RC

1/s

Power Energy

Atomistic ECT SPMe SPM ECM Integrator

Scott Moura | UC Berkeley Battery Modeling, ID, Fault Diagnostics September 18, 2017 | Slide 44