Switched mode power converter with peak current control
In accordance with an embodiment, a method, includes operating a power converter that comprises an electronic switch connected in series with an inductor in one of a first operation mode and a second operation mode. Operating the power converter in each of the first operation mode and the second operation mode includes driving the electronic switch in a plurality of successive drive cycles based on drive parameter. Each of the plurality of drive cycles includes an on-time in which the electronic switch is switched on and an off-time in which the electronic switch is switched off.
1. A method, comprising:
operating a power converter that comprises an electronic switch connected in series with an inductor in one of a first operation mode and a second operation mode,
wherein operating the power converter in each of the first operation mode and the second operation mode comprises driving the electronic switch in a plurality of successive drive cycles based on a drive parameter,
wherein each of the plurality of successive drive cycles comprises an on-time in which the electronic switch is switched on and an off-time in which the electronic switch is switched off,
wherein the drive parameter is one of a duration of the drive cycle or a duration of the off-time,
wherein the drive parameter is predefined in the first operation mode, and
wherein the drive parameter is increased in the second operation mode as compared to the first operation mode such that a duration of the on-time in the second operation mode is above a predefined duration threshold.
2. The method of claim 1 , wherein driving the electronic switch in the on-time comprises:
switching on the electronic switch in accordance with the drive parameter;
monitoring a current flowing through the inductor; and
switching off the electronic switch when the current reaches a current threshold.
3. The method of claim 2 , wherein the current threshold is dependent on at least one control parameter.
4. The method of claim 3 , wherein the at least one control parameter is selected from the group consisting of:
an input voltage received by the power converter; and
an output voltage supplied by the power converter.
5. The method of claim 4 , wherein the control parameter defines a level of the current threshold.
6. The method of claim 4 ,
wherein the current threshold varies in accordance with a sawtooth signal, and
wherein the control parameter defines a start level and a slope of the sawtooth signal.
7. The method of claim 1 , wherein operating the power converter in one of the first operation mode and the second operation mode comprises:
monitoring an operation state of the power converter; and
operating the power converter in one of the first operation mode and the second operation mode dependent on the operation state.
8. The method of claim 7 , wherein monitoring the operation state comprises monitoring at least one operation parameter selected from the group consisting of:
an input voltage of the power converter;
an output voltage of the power converter; and
a feedback signal.
9. The method of claim 1 , wherein operating the power converter in the second operation mode comprises calculating the drive parameter based on at least one operation parameter.
10. The method of claim 9 , wherein the at least one operation parameter is selected from the group consisting of:
an input voltage of the power converter;
an output voltage of the power converter; and
a feedback signal.
11. The method of claim 9 , wherein calculating the drive parameter comprises calculating the drive parameter based on a piecewise linear approximation.
12. The method of claim 1 , wherein operating the power converter in one of the first operation mode and the second operation mode comprises:
monitoring a duration of the on-time; and
adapting the drive parameter dependent on the on-time.
13. The method of claim 12 , wherein adapting the drive parameter comprises:
one of increasing and decreasing the drive parameter each time the duration of the on-time falls below a first threshold; and
the other one of increasing and decreasing the drive parameter each time the duration of the on-time rises above a second threshold.
14. The method of claim 13 , further comprising:
limiting the drive parameter to a nominal value.
15. The method of claim 1 , wherein the drive parameter being predefined in the first operation mode comprises that the drive parameter is fixed.
16. The method of claim 1 , wherein the drive parameter being predefined in the first operation mode comprises that the drive parameter varies in accordance with a predefined time scheme.
17. A power converter, comprising:
an electronic switch connected in series with an inductor; and
a controller configured to operate the power converter in one of a first operation mode and a second operation mode and, in each of the first operation mode and the second operation mode, to drive the electronic switch in a plurality of successive drive cycles based on a drive parameter such that each of the plurality of successive drive cycles comprises an on-time in which the electronic switch is switched on and an off-time in which the electronic switch is switched off,
wherein the drive parameter is one of a duration of the drive cycle or a duration of the off-time,
wherein the drive parameter is predefined in the first operation mode, and
wherein the controller is configured to increase the drive parameter in the second operation mode as compared to the first operation mode such that a duration of the on-time in the second operation mode is above a predefined duration threshold.
18. The power converter of claim 17 , wherein the controller is configured to monitor an operation state of the power converter, and
operate the power converter in one of the first operation mode and the second operation mode dependent on the operation state.
19. The power converter of claim 17 , wherein the controller is configured, in the second operation mode, to calculate the drive parameter based on at least one operation parameter.
20. The power converter of claim 17 , wherein the controller is configured, in the first operation mode and the second operation mode, to monitor a duration of the on-time and adapt the drive parameter dependent on the on-time.
21. A power converter, comprising:
a controller configured to operate the power converter in one of a first operation mode and a second operation mode and, in each of the first operation mode and the second operation mode, to drive an electronic switch in a plurality of successive drive cycles based on a drive parameter such that each of the plurality of successive drive cycles comprises an on-time in which the electronic switch is switched on and an off-time in which the electronic switch is switched off,
wherein the drive parameter is one of a duration of the drive cycle or a duration of the off-time,
wherein the drive parameter is predefined in the first operation mode, and
wherein the controller is configured to increase the drive parameter in the second operation mode as compared to the first operation mode such that a duration of the on-time in the second operation mode is above a predefined duration threshold.
22. The power converter of claim 21 , wherein the controller is configured to
monitor an operation state of the power converter, and
operate the power converter in one of the first operation mode and the second operation mode dependent on the operation state.
23. The power converter of claim 21 , wherein the controller is configured, in the second operation mode, to calculate the drive parameter based on at least one operation parameter.
24. The power converter of claim 21 , wherein the controller is configured, in the first operation mode and the second operation mode, to monitor a duration of the on-time and adapt the drive parameter dependent on the on-time.