Apparatus and method for accurate energy device state-of-charge (SoC) monitoring and control using real-time state-of-health (SoH) data
View Patent ↗A device and associated testing method for empirically determining the state-of-charge of an electrochemical energy device, comprising: applying electrical excitations to the energy device at a predetermined electrical excitation frequency ω e ; applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency ω m ; measuring an electrically-induced phase difference Δθ e (ω e ) between voltage (V) and current (I) within the energy device from applying the electrical excitations; measuring a mechanically-induced phase difference Δθ e (ω m ) between voltage (V) and current (I) within the energy device from applying the mechanical excitations; and deducing the empirical real-time state-of-health of the energy device by comparing the electrically-induced phase difference Δθ e (ω e ) with the mechanically-induced phase difference Δθ e (ω m ); and using the deduced state of health to determine the state of charge.
1. A method for empirically determining the state-of-charge of an electrochemical energy device, comprising:
applying electrical excitations to the energy device at a predetermined electrical excitation frequency ω e ;
applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency ω m ;
measuring an electrically-induced phase difference Δθ e (ω e ) between voltage (V) and current (I) within the energy device from applying said electrical excitations;
measuring a mechanically-induced phase difference Δθ e (ω m ) between voltage (V) and current (I) within the energy device from applying said mechanical excitations; and
deducing the empirical real-time state-of-health of said energy device by comparing said electrically-induced phase difference Δθ e (ω e ) with said mechanically-induced phase difference Δθ e (ω m ); and
using said deduced state of health to determine the state of charge.
2. The method of claim 1 , further comprising:
taking a difference Δθ=Δθ e (ω e )−Δθ e (ω m ) between said electrically-induced phase difference Δθ e and said mechanically-induced phase difference Δθ e (ω m ); and
using said difference as a basis to deduce said SoH.
3. The method of claim 2 , further comprising:
deducing the state-of-health of said energy device by determining a magnitude of Δθ=Δθ e (ω e )−Δθ e (ω m ) in relation to 0°, wherein better state-of-health is deduced from said magnitudes being larger and poorer state-of-health is deduced from said magnitudes being smaller.
4. The method of claim 2 , further comprising:
deducing that said energy device is approaching its end of life by determining that Δθ=Δθ e (ω e )−Δθ e (ω m )→0°.
5. The method of claim 1 , further comprising:
at a baseline time, determining baseline-time phase differences Δθ e (ω e ) and Δθ e (ω m ) between current and voltage of said energy device;
at a later time, determining later-time phase differences Δθ e (ω e ) and Δθ e (ω m ) between current and voltage of said energy device; and
deducing said state of health by comparing said later-time phase difference with said baseline-time phase difference.
6. The method of claim 5 , further comprising:
deducing said state of health by determining how much said later-time phase difference has diminished from said baseline time phase difference.
7. The method of claim 6 , further comprising deducing a magnitude of decline in said state of health substantially in proportion to said diminution.
8. The method of claim 1 , wherein:
a difference between measurements of internal impedance Z INT the energy device when said electrical excitation frequency ω e is applied versus when said mechanical excitation frequency ω m is applied, is determined according to:
Z
INT
e
(
ω
e
)
-
Z
INT
e
(
ω
m
)
=
(
1
R
el
(
ω
e
)
1
R
el
2
(
ω
e
)
+
(
ω
e
C
b
(
ω
e
)
)
2
-
1
R
el
(
ω
m
)
1
R
el
2
(
ω
m
)
+
(
ω
e
C
b
(
ω
m
)
)
2
)
-
j
(
ω
e
C
b
(
ω
e
)
1
R
el
2
(
ω
e
)
+
(
ω
e
C
b
(
ω
e
)
)
2
-
ω
e
C
b
(
ω
m
)
1
R
el
2
(
ω
m
)
+
(
ω
e
C
b
(
ω
m
)
)
2
)
,
where R el designates an electrochemical resistance of said energy device and c b designates a storage capacity of said energy device; further comprising:
deducing said electrically-induced phase difference Δθ e (ω e ) between said voltage V and
said current I according to
Z
INT
e
(
ω
e
)
=
V
√
θ
e
(
ω
e
)
I
;
and
deducing said mechanically-induced phase difference Δθ e (ω m ) between said voltage V and said current I according to
Z
INT
e
(
ω
m
)
=
V
√
θ
e
(
ω
m
)
I
.
9. The method of claim 1 , further comprising using said state of charge determination to display to a user the degree to which said electrochemical energy device is presently charged.
10. The method of claim 1 , further comprising using said state of charge determination to control and optimize the charging and/or discharging of said electrochemical energy device.
11. An apparatus for empirically determining the state-of-charge of an electrochemical energy device, comprising:
an electrical excitation source for applying electrical excitations to the energy device at a predetermined electrical excitation frequency ω e ;
a mechanical excitation source for applying mechanical excitations to the energy device at a predetermined mechanical excitation frequency ω m ;
a measurement device for measuring an electrically-induced phase difference Δθ e (ω e ) between voltage (V) and current (I) within the energy device from applying said electrical excitations; and
said measurement device for further measuring a mechanically-induced phase difference Δθ e (ω m ) between voltage (V) and current (I) within the energy device from applying said mechanical excitations; wherein
the empirical real-time state-of-health of said energy device is deduced by comparing said electrically-induced phase difference Δθ e (ω e ) with said mechanically-induced phase difference Δθ e (ω m ); and
said deduced state of health is used to determine the state of charge.
12. The apparatus of claim 11 , wherein:
the state-of-health of said energy device is deduced by taking a difference Δθ=Δθ e (ω e )−Δθ e (ω m ) between said electrically-induced phase difference Δθ e and said mechanically-induced phase difference Δθ e (ω m ).
13. The apparatus of claim 12 , wherein:
the state-of-health of said energy device is deduced by determining a magnitude of Δθ=Δθ e (ω e )−Δθ e (ω e ) in relation to 0°, and wherein better state-of-health is deduced from said magnitudes being larger and poorer state-of-health is deduced from said magnitudes being smaller.
14. The apparatus of claim 12 , wherein:
said energy device is approaching its end of life is deduced by determining that Δθ=Δθ e (ψ e )−Δθ e (ψ m )→0°.
15. The apparatus of claim 11 , wherein:
baseline-time phase differences Δθ e (ω e ) and Δθ e (ω m ) between current and voltage of said energy device are determined at a baseline time;
later-time phase differences Δθ e (ω e ) and Δθ e (ω m ) between current and voltage of said energy device are determined at a later time;
said baseline-time phase difference is compared with said later-time phase difference to deduce said state-of-health.
16. The apparatus of claim 15 , wherein:
said state of health is deduced by determining how much said later-time phase difference has diminished from said baseline time phase difference.
17. The apparatus of claim 16 , wherein a magnitude of decline in said state of health is deduced substantially in proportion to said diminution.
18. The apparatus of claim 11 , wherein:
a difference between measurements by said measurement device of internal impedance Z INT the energy device when said electrical excitation frequency ω e is applied versus when said mechanical excitation frequency ω m is applied, is determined according to:
Z
INT
e
(
ω
e
)
-
Z
INT
e
(
ω
m
)
=
(
1
R
el
(
ω
e
)
1
R
el
2
(
ω
e
)
+
(
ω
e
C
b
(
ω
e
)
)
2
-
1
R
el
(
ω
m
)
1
R
el
2
(
ω
m
)
+
(
ω
e
C
b
(
ω
m
)
)
2
)
-
j
(
ω
e
C
b
(
ω
e
)
1
R
el
2
(
ω
e
)
(
ω
e
C
b
(
ω
e
)
)
2
-
ω
e
C
b
(
ω
m
)
1
R
el
2
(
ω
m
)
+
(
ω
e
C
b
(
ω
m
)
)
2
)
,
where R el designates an electrochemical resistance of said energy device and c b designates a storage capacity of said energy device;
said electrically-induced phase difference Δθ e (ω e ) between said voltage V and said current I is deduced according to
Z
INT
e
(
ω
e
)
=
V
√
θ
e
(
ω
e
)
I
;
and
said mechanically-induced phase difference Δθ e (ω m ) between said voltage V and said current I is deduced according to
Z
INT
e
(
ω
m
)
=
V
√
θ
e
(
ω
m
)
I
.
19. The apparatus of claim 11 , wherein said state of charge determination is used to display to a user the degree to which said electrochemical energy device is presently charged.
20. The apparatus of claim 11 , wherein said state of charge determination is used to control and optimize the charging and/or discharging of said electrochemical energy device.