Control of power converter based on dynamic constraint factors
A power delivery system may include a power converter configured to electrically couple to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter, and control circuitry configured to select a constraint factor from a plurality of different constraint factors based on at least one of an input voltage to the power converter and a power level available to the power converter, and control the power converter in accordance with the constraint factor.
1. A portable electronic device, comprising:
one or more components;
a battery;
a power converter configured to electrically couple to and receive power from the battery and further configured to supply electrical energy to the one or more components; and
control circuitry configured to:
select a constraint factor from a plurality of different constraint factors based on at least one of an input voltage to the power converter and a power level available to the power converter; and
control the power converter in accordance with the constraint factor.
2. The portable electronic device of claim 1 , wherein
the control circuitry is configured to select the constraint factor based on a voltage level available from the battery.
3. The portable electronic device of claim 2 , wherein the control circuitry models the voltage level available from the battery as a time-varying voltage source in series with an equivalent resistance.
4. The portable electronic device of claim 2 , wherein:
a plurality of constraint regions are defined for different ranges of the voltage level available from the battery; and
the control circuitry is configured to select the constraint factor based on a constraint region of the plurality of constraint regions corresponding to the voltage level available from the battery.
5. The portable electronic device of claim 4 , wherein a first constraint region of the plurality of constraint regions is associated with a first constraint factor which corresponds to a battery-imposed limitation on maximum current.
6. The portable electronic device of claim 5 , wherein the first constraint region commences at a critical end-of-discharge voltage for the battery.
7. The portable electronic device of claim 5 , wherein the first constraint factor sets a maximum current limit for the power converter defined by:
I
C
E
L
L
-
M
A
X
=
V
C
E
L
L
-
E
F
F
-
V
C
ELL
-
MIN
R
0
where V CELL-EFF is an effective battery voltage at a given instance, V CELL-MIN is the critical end-of-discharge voltage for the battery, and R 0 is an equivalent series resistance of the battery.
8. The portable electronic device of claim 4 , wherein a second constraint region of the plurality of constraint regions is associated with a second constraint factor which corresponds to a power converter stability-imposed limitation on maximum current.
9. The portable electronic device of claim 8 , wherein the second constraint factor sets a maximum current limit for the power converter defined by:
I
P
M
A
X
=
V
C
E
L
L
-
E
F
F
2
(
R
0
+
R
T
R
A
C
E
+
R
S
N
S
+
R
L
O
S
S
)
where R 0 is an equivalent series resistance of the battery, R TRACE is a resistance of a trace and/or connector resistance between the power source and the power converter, R SNS is a resistance of a current sense resistor, and R LOSS is a resistance modeling losses of the power converter.
10. The portable electronic device of claim 8 , wherein:
a first constraint region of the plurality of constraint regions is associated with a first constraint factor which corresponds to a battery-imposed limitation on maximum current; and
the second constraint region commences at an intersection of the first constraint factor and the second constraint factor.
11. The portable electronic device of claim 4 , wherein a third constraint region of the plurality of constraint regions is associated with a third constraint factor which corresponds to an output-power-based limitation on maximum current.
12. The portable electronic device of claim 11 , wherein the third constraint factor sets a maximum current limit for the power converter defined by:
I
C
ELL
-
LIM
=
I
P
M
A
X
-
P
MAX
-
P
LIM
R
0
+
R
TRACE
+
R
SNS
+
R
LOSS
where I pMAX is a maximum current limit as defined for a second constraint factor, P MAX is a maximum power delivery capability of the power converter, P LIM is an output power limit defined for the power converter, R 0 is an equivalent series resistance of the battery, R TRACE is a resistance of a trace and/or connector resistance between the power source and the power converter, R SNS is a resistance of a current sense resistor, and R LOSS is a resistance modeling losses of the power converter.
13. The portable electronic device of claim 12 , wherein a second constraint region of the plurality of constraint regions is associated with the second constraint factor which corresponds to a power converter stability-imposed limitation on maximum current.
14. The portable electronic device of claim 11 , wherein:
a second constraint region of the plurality of constraint regions is associated with a second constraint factor which corresponds to a power converter stability-imposed limitation on maximum current; and
the third constraint region commences at a breakpoint between the second constraint factor and the third constraint factor.
15. The portable electronic device of claim 4 , wherein a fourth constraint region of the plurality of constraint regions is associated with a fourth constraint factor which corresponds to a fixed current limit.
16. The portable electronic device of claim 4 , wherein:
a second constraint region of the plurality of constraint regions is associated with a second constraint factor which corresponds to a power converter stability-imposed limitation on maximum current;
a third constraint region of the plurality of constraint regions is associated with a third constraint factor which corresponds to an output-power-based limitation on maximum current; and
a fourth constraint region is located between the second constraint region and the third constraint region.
17. The portable electronic device of claim 4 , wherein the plurality of constraint regions includes:
a first constraint region associated with a first constraint factor which corresponds to a battery-imposed limitation on maximum current;
a second constraint region with a second constraint factor which corresponds to a power converter stability-imposed limitation on maximum current;
a third constraint region associated with a third constraint factor which corresponds to an output-power-based limitation on maximum current; and
a fourth constraint region associated with a fourth constraint factor which corresponds to a fixed current limit.
18. The portable electronic device of claim 1 , wherein the constraint factor defines a current limit to be drawn from the battery.
19. The portable electronic device of claim 1 , wherein the one or more components comprise at least one of the following: another power converter, a processor, an audio coder/decoder, an amplifier, and a display device.
20. The portable electronic device of claim 1 , wherein the battery comprises a lithium-ion battery.
21. The portable electronic device of claim 1 , wherein the power converter is implemented using at least one of a boost converter, buck converter, buck-boost converter, transformer, or charge pump.
22. The portable electronic device of claim 1 , wherein the portable electronic device comprises a smart phone, a tablet, or a game controller.
23. A portable electronic device comprising:
one or more components;
a battery;
a power converter configured to electrically couple to and receive power from the battery and further configured to supply electrical energy to the one or more components; and
control circuitry configured to:
calculate a plurality of current limit values based on at least one of an input voltage to the power converter and a power level available to the power converter; and
control the power converter based on a current limit selected as a lowest of the plurality of current limit values.
24. The portable electronic device of claim 23 , wherein the one or more components comprise at least one of the following: another power converter, a processor, an audio coder/decoder, an amplifier, a display device.
25. The portable electronic device of claim 23 , wherein the battery comprises a lithium-ion battery.
26. The portable electronic device of claim 23 , wherein the power converter is implemented using at least one of a boost converter, buck converter, buck-boost converter, transformer, or charge pump.
27. The portable electronic device of claim 23 , wherein the portable electronic device comprises a smart phone, a tablet, or a game controller.
28. A power delivery system comprising:
a power converter configured to electrically couple to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter; and
control circuitry configured to:
calculate a plurality of current limit values based on at least one of an input voltage to the power converter and a power level available to the power converter; and
control the power converter based on a current limit selected as a lowest of the plurality of current limit values.
29. The power delivery system of claim 28 , wherein the one or more loads comprise at least one of the following: another power converter, a processor, an audio coder/decoder, an amplifier, a display device.
30. The power delivery system of claim 28 , wherein the power source comprises a battery.
31. The power delivery system of claim 30 , wherein the battery comprises a lithium-ion battery.
32. The power delivery system of claim 28 , wherein the power converter is implemented using at least one of a boost converter, buck converter, buck-boost converter, transformer, or charge pump.
33. A method comprising, in a power converter configured to electrically couple to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter:
calculating a plurality of current limit values based on at least one of an input voltage to the power converter and a power level available to the power converter; and
controlling the power converter based on a current limit selected as a lowest of the plurality of current limit values.
34. The method of claim 33 , wherein the one or more loads comprise at least one of the following: another power converter, a processor, an audio coder/decoder, an amplifier, a display device.
35. The method of claim 33 , wherein the power source comprises a battery.
36. The method of claim 35 , wherein the battery comprises a lithium-ion battery.
37. The method of claim 33 , wherein the power converter is implemented using at least one of a boost converter, buck converter, buck-boost converter, transformer, or charge pump.