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 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:
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 power delivery system of claim 1 , wherein:
the power source is a battery, and the control circuitry is configured to select the constraint factor based on a voltage level available from the battery.
3. The power delivery system 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 power delivery system 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 power delivery system 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 power delivery system of claim 5 , wherein the first constraint region commences at a critical end-of-discharge voltage for the battery.
7. The power delivery system of claim 5 , wherein the first constraint factor sets a maximum current limit for the power converter defined by:
I
CELL
-
MAX
=
V
C
E
L
L
-
E
F
F
-
V
CELL
-
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 power delivery system 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 power delivery system of claim 8 , wherein the second constraint factor sets a maximum current limit for the power converter defined by:
I
PMAX
=
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 power delivery system 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 power delivery system 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 power delivery system of claim 11 , wherein the third constraint factor sets a maximum current limit for the power converter defined by:
I
CELL
-
LIM
=
I
PMAX
-
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 power delivery system 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 power delivery system 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 power delivery system 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 power delivery system 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
the fourth constraint region is located between the second constraint region and the third constraint region.
17. The power delivery system 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 power delivery system of claim 1 , wherein the constraint factor defines a current limit to be drawn from the power source.
19. A power converter configured to:
receive an input voltage from a voltage source and to generate an output voltage; and
operate in a plurality of operating regions wherein a maximum current drawn by the power converter in each operating region of the plurality of operating regions is defined by a constraint factor corresponding to such operating region.
20. A power delivery system, comprising:
a power converter configured to receive an input voltage from a power source and to generate an output voltage; and
control circuitry configured to:
calculate a plurality of current limit values, each current limit value of the plurality of current limit values corresponding to a constraint factor; and
control the power converter based on a current limit selected as a lowest of the plurality of current limit values.
21. The power delivery system of claim 20 , wherein the constraint factors comprise one or more of:
a power-source-imposed limitation on maximum current;
a maximum-stable-power imposed limitation on maximum current;
a practical-power-limit-imposed limitation on maximum current; and
a practical-current-limit-imposed limitation on maximum current.
22. 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:
selecting 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
controlling the power converter in accordance with the constraint factor.
23. The method of claim 22 , wherein:
the power source is a battery, and the control circuitry is configured to select the constraint factor based on a voltage level available from the battery.
24. The method of claim 23 , wherein the control circuitry models the voltage level available from the battery as a time-varying voltage source in series with an equivalent resistance.
25. The method of claim 23 , 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.
26. The method of claim 25 , 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.
27. The method of claim 26 , wherein the first constraint region commences at a critical end-of-discharge voltage for the battery.
28. The method of claim 26 , wherein the first constraint factor sets a maximum current limit for the power converter defined by:
I
C
ELL
-
MAX
=
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.
29. The method of claim 25 , 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.
30. The method of claim 29 , wherein the second constraint factor sets a maximum current limit for the power converter defined by:
I
PMAX
=
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.
31. The method of claim 29 , 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.
32. The method of claim 25 , 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.
33. The method of claim 32 , wherein the third constraint factor sets a maximum current limit for the power converter defined by:
I
C
ELL
-
LIM
=
I
PMAX
-
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.
34. The method of claim 33 , 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.
35. The method of claim 32 , 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.
36. The method of claim 25 , 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.
37. The method of claim 25 , 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
the fourth constraint region is located between the second constraint region and the third constraint region.
38. The method of claim 25 , 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.
39. The method of claim 22 , wherein the constraint factor defines a current limit to be drawn from the power source.
40. A method comprising:
receiving an input voltage from a voltage source and generating an output voltage; and
operating in a plurality of operating regions wherein a maximum current drawn by the power converter in each operating region of the plurality of operating regions is defined by a constraint factor corresponding to such operating region.
41. A method, in a system having a power converter configured to receive an input voltage from a power source and to generate an output voltage, the method comprising:
calculating a plurality of current limit values, each current limit value of the plurality of current limit values corresponding to a constraint factor; and
controlling the power converter based on a current limit selected as a lowest of the plurality of current limit values.
42. The method of claim 41 , wherein the constraint factors comprise one or more of:
a power-source-imposed limitation on maximum current;
a maximum-stable-power imposed limitation on maximum current;
a practical-power-limit-imposed limitation on maximum current; and
a practical-current-limit-imposed limitation on maximum current.
43. A device comprising:
one or more components;
a power converter configured to deliver electrical energy to the one or more components; and
a control circuit for controlling a current associated with the power converter, the control circuit comprising:
threshold-based control circuitry configured to control the current based on at least a peak current threshold level for the current and a valley current threshold level for the current; and
timer-based control circuitry configured to control the current based on a duration of time that the power converter spends in a switching state of the power converter.