Current-mode control for multistage interleaved resonant converters

1. A method for operating an interleaved resonant power converter, the method comprising:

generating a first pair of complementary signals to drive a first stage of the interleaved resonant power converter;

generating a second pair of complementary signals to drive a second stage of the interleaved resonant power converter;

generating a current-mode control signal based on a current sense signal of the first stage;

adjusting a switching frequency of the first pair of complementary signals based on the current-mode control signal; and

adjusting a switching frequency of the second pair of complementary signals to match the switching frequency of the first pair of complementary signals,

wherein adjusting the switching frequency of the first pair of complementary signals based on the current-mode control signal includes:

switching values of the first pair of complementary signals when the current-mode control signal pulses.

2. The method of claim 1 , wherein adjusting the switching frequency of the first pair of complementary signals based on the current-mode control signal further includes:

starting to increment a counter when the counter is equal to zero,

starting to decrement the counter when the current-mode control signal pulses, and

switching the values of the first pair of complementary signals when the counter is equal to zero.

3. The method of claim 2 , wherein adjusting the switching frequency of the second pair of complementary signals to match the switching frequency of the first pair of complementary signals further includes:

setting a counter threshold based on a value of the counter when the current-mode control signal pulses, and

switching values of the second pair of complementary signals when the value of the counter is equal to the counter threshold.

4. The method of claim 3 , wherein setting the counter threshold further includes setting the counter threshold based on a number of stages included in the interleaved resonant power converter.

5. The method of claim 3 , wherein setting the counter threshold further includes setting the counter threshold to one-half of the value of the counter when the current-mode control signal pulses.

6. The method of claim 3 , wherein the counter threshold is a first counter threshold, and wherein the method further comprises:

generating a third pair of complementary signals to drive a third stage of the interleaved resonant power converter;

setting a second counter threshold based on the value of the counter when the current-mode control signal pulses; and

switching the third pair of complementary signals when the value of the counter is equal to the second counter threshold.

7. The method of claim 6 ,

wherein setting the first counter threshold further includes setting the first counter threshold to one-third of the value of the counter when the current mode control signal pulses, and

wherein setting the second counter threshold further comprises setting the second counter threshold to two-thirds of the value of the counter when the current-mode control signal pulses.

8. The method of claim 1 , wherein generating the current-mode control signal based on a current sense signal of the first stage further includes:

generating a feedback voltage based on an output voltage produced by the interleaved resonant power converter, and

pulsing the current-mode control signal when a voltage of the current sense signal is equal to the feedback voltage.

9. A system for power conversion, comprising:

an interleaved resonant power converter including at least a first stage and a second stage; and

a controller configured to:

generate a first pair of complementary signals to drive the first stage,

generate a second pair of complementary signals to drive the second stage,

generate a current-mode control signal based on a current sense signal of the first stage,

adjust a switching frequency of the first pair of complementary signals based on the current-mode control signal, and

adjust a switching frequency of the second pair of complementary signals to match the switching frequency of the first pair of complementary signals,

wherein, to generate a current-mode control signal based on the current sense signal of the first stage, the controller is further configured to:

generate a feedback voltage based on an output voltage produced by the interleaved resonant power converter, and

pulse the current-mode control signal when a voltage of the current sense signal is equal to the feedback voltage.

10. The system of claim 9 , wherein, to adjust the switching frequency of the first pair of complementary signals based on the current-mode control signal, the controller is further configured to:

start to increment a counter when the counter is equal to zero,

switch values of the first pair of complementary signals when the current-mode control signal pulses,

start to decrement the counter when the current-mode control signal pulses, and switch the values of the first pair of complementary signals when the counter is equal to zero.

11. The system of claim 10 , wherein, to adjust the switching frequency of the second pair of complementary signals to match the switching frequency of the first pair of complementary signals, the controller is further configured to:

set a counter threshold based on a value of the counter when the current-mode control signal pulses, and

switch values of the second pair of complementary signals when the value of the counter is equal to the counter threshold.

12. The system of claim 11 , wherein the controller is further configured to set the counter threshold based on a number of stages included in the interleaved resonant power converter.

13. The system of claim 11 , wherein, to set the counter threshold, the controller is further configured to set the counter threshold to one-half of the value of the counter when the current-mode control signal pulses.

14. The system of claim 11 , wherein the counter threshold is a first counter threshold, and wherein the controller is further configured to:

generate a third pair of complementary signals to drive a third stage of the interleaved resonant power converter,

set a second counter threshold based on the value of the counter when the current-mode control signal pulses, and

switch the third pair of complementary signals when the value of the counter is equal to the second counter threshold.

15. The system of claim 14 , wherein, to set the first counter threshold, the controller is further configured to set the first counter threshold to one-third of the value of the counter when the current-mode control signal pulses, and wherein, to set the second counter threshold, the controller is further configured to set the second counter threshold to two-thirds of the value of the counter when the current-mode control signal pulses.

16. An apparatus for power conversion, comprising:

a controller configured to:

generate a first pair of complementary signals to drive a first stage of an interleaved resonant power converter;

generate a second pair of complementary signals to drive a second stage of an interleaved resonant power converter;

generate a current-mode control signal based on a current sense signal of the first stage;

adjust a switching frequency of the first pair of complementary signals based on the current-mode control signal; and

adjust a switching frequency of the second pair of complementary signals to match the switching frequency of the first pair of complementary signals,

wherein generating the current mode control signal comprises:

generating a feedback voltage based on an output voltage produced by the interleaved resonant power converter, and

pulsing the current-mode control signal when a voltage of the current sense signal is equal to the feedback voltage.

17. The apparatus of claim 16 , wherein the current-mode control signal pulses when the current sense signal is at a peak level.

18. The apparatus of claim 16 , wherein the controller comprises a comparator that is configured to output the current-mode control signal in response to the current sense signal.

19. The apparatus of claim 16 , the current-mode control signal is non-sinusoidal and the current sense signal is sinusoidal.

20. An apparatus for power conversion, comprising:

a controller configured to:

generate a first pair of complementary signals to drive a first stage of an interleaved resonant power converter;

generate a second pair of complementary signals to drive a second stage of an interleaved resonant power converter;

generate a current-mode control signal based on a current sense signal of the first stage;

adjust a switching frequency of the first pair of complementary signals based on the current-mode control signal; and

adjust a switching frequency of the second pair of complementary signals to match the switching frequency of the first pair of complementary signals,

wherein adjusting the switching frequency of the first pair of complementary signals comprises:

starting to increment a counter when the counter is equal to zero,

switching values of the first pair of complementary signals when the current-mode control signal pulses,

starting to decrement the counter when the current-mode control signal pulses, and

switching the values of the first pair of complementary signals when the counter is equal to zero.

21. The apparatus of claim 20 , wherein adjusting the switching frequency of the second pair of complementary signals comprises:

setting a counter threshold based on a value of the counter when the current-mode control signal pulses, and

switching values of the second pair of complementary signals when the value of the counter is equal to the counter threshold.