Burst mode control in resonant converters

Patent metadata

Field	Value
Publication number	US-10186948-B2
Application number	US-201715668983-A
Country	US
Kind code	B2
Filing date	Aug 4, 2017
Priority date	Aug 19, 2016
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

According to an implementation, a resonant converter for burst mode control includes an oscillator configured to control switching operations of at least one power switch, and a burst mode controller configured to control a burst mode by determining a start of a burst pulse of the burst mode using a first internal signal and determining an end of the burst pulse of the burst mode using a second internal signal. The burst mode controller is configured to stop the switching operations during the burst pulse.

First claim

What is claimed is:

1. A resonant converter for burst mode control, the resonant converter comprising:
an oscillator configured to control switching operations of at least one power switch; and
a burst mode controller configured to control a burst mode by determining a start of a burst pulse of the burst mode using a first internal signal and determining an end of the burst pulse of the burst mode using a second internal signal, the burst mode controller configured to stop the switching operations during the burst pulse,
the burst mode controller configured to compare a voltage of the first internal signal with a first voltage threshold to determine the start of the burst pulse, and to compare a voltage of the second internal signal with a second voltage threshold to determine the end of the burst pulse.

2. The resonant converter of claim 1 , wherein the first internal signal represents an output load condition of the resonant converter.

3. The resonant converter of claim 1 , wherein the first internal signal includes a power estimation signal.

4. The resonant converter of claim 1 , wherein the second internal signal includes a frequency control signal.

5. The resonant converter of claim 1 , wherein the burst mode controller is configured to determine the start of the burst pulse in response to the voltage of the first internal signal being less than the first voltage threshold.

6. The resonant converter of claim 1 , wherein the burst mode controller is configured to determine the end of the burst pulse in response to the voltage of the second internal signal being less than the second voltage threshold.

7. The resonant converter of claim 1 , further comprising:
a soft burst circuit configured to control the oscillator in a soft burst mode in response to the end of the burst pulse, the oscillator, when in the soft burst mode, configured to resume switching operations of the at least one power switch.

8. The resonant converter of claim 7 , wherein the oscillator, when in the soft burst mode, is configured to switch the at least one power switch at a first frequency for a first duration, and switch the at least one power switch at a second frequency for a second duration after the first duration, the second frequency being lower than the first frequency.

9. The resonant converter of claim 1 , wherein the burst mode controller includes a first voltage comparator to compare the voltage of the first internal signal with the first voltage threshold, and a second voltage comparator to compare the voltage of the second internal signal with the second voltage threshold.

10. A resonant converter for burst mode control, the resonant converter comprising:
an oscillator configured to control switching operations of at least one power switch; and
a burst mode controller configured to control a burst mode by determining a start of a burst pulse of the burst mode in response to a voltage of a power estimation signal being less than a first voltage threshold, and determining an end of the burst pulse of the burst mode in response to a voltage of a frequency control signal being less than a second voltage threshold, the burst mode controller configured to stop the switching operations during the burst pulse,
the burst mode controller including a first voltage comparator configured to compare the voltage of the power estimation signal with the first voltage threshold, and a second voltage comparator configured to compare the voltage of the frequency control signal with the second voltage threshold.

11. The resonant converter of claim 10 , wherein the burst mode controller includes:
a power estimator configured to generate the power estimation signal based on an integrated current sense signal sensed on a primary side of a transformer of the resonant converter.

12. The resonant converter of claim 10 , further comprising:
a soft burst circuit configured to control the oscillator in a soft burst mode by sending a soft burst control signal to the oscillator in response to the end of the burst pulse, the oscillator, when in the soft burst mode, configured to resume switching operations of the at least one power switch based on the soft burst control signal.

13. The resonant converter of claim 12 , wherein the soft burst control signal includes a first voltage step and a second voltage step, a voltage of the second voltage step being less than a voltage of the first voltage step, wherein the oscillator, when in the soft burst mode, is configured to switch the at least one power switch at a first frequency based on the first voltage step, and decrease the first frequency to a second frequency based on the second voltage step.

14. A resonant converter for burst mode control, the resonant converter comprising:
an oscillator configured to control switching operations of at least one power switch;
a burst mode controller configured to control a burst mode by determining a start of a burst pulse of the burst mode and determining an end of the burst pulse of the burst mode, the burst mode controller configured to stop the switching operations during the burst pulse; and
a soft burst circuit configured to control the oscillator in a soft burst mode, the soft burst circuit configured to send a soft burst control signal to the oscillator in response to the end of the burst pulse, the oscillator configured to resume switching operations of the at least one power switch in response to the soft burst control signal, the soft burst circuit including a down counter configured to generate the soft burst control signal as a voltage signal with a first voltage step and a second voltage step, the second voltage step being less than the first voltage step,
the oscillator configured to switch the at least one power switch at a first frequency in response to the first voltage step,
the oscillator configured to switch the at least one power switch at a second frequency in response to the second voltage step, the second frequency being less than the first frequency.

15. The resonant converter of claim 14 , wherein the start of the burst pulse of the burst mode is determined using a power estimation signal.

16. The resonant converter of claim 14 , wherein the end of the burst pulse of the burst mode is determined using a frequency control signal.

17. The resonant converter of claim 14 , wherein the burst mode controller is configured to determine the start of the burst pulse in response to a voltage of a first internal signal being less than a voltage threshold.

18. The resonant converter of claim 14 , wherein the burst mode controller is configured to determine the end of the burst pulse in response to a voltage of a second internal signal being less than a voltage threshold.

19. The resonant converter of claim 14 , wherein the start of the burst pulse of the burst mode is determined using a power estimation signal, and the end of the burst pulse of the burst mode is determined using a frequency control signal, the burst mode controller including:
a power estimator configured to generate the power estimation signal based on an integrated current sense signal sensed on a resonant network of the resonant converter;
a first voltage comparator configured to compare a voltage of the power estimation signal with a first voltage threshold, the start of the burst pulse being determined in response to the voltage of the power estimation signal being less than the first voltage threshold; and
a second voltage comparator configured to compare a voltage of the frequency control signal wi

Assignees

• Fairchild Korea Semiconductor Ltd
• Semiconductor Components Ind Llc

Inventors

• Moon Sangcheol
• Kim Jintae
• Choi Hangseok

Classifications

• H02M3/3385

  with automatic control of output voltage or current (H02M3/33561 takes precedence) · CPC title

• H02M3/3381 Primary

  using a single commutation path · CPC title

• H02M3/33523

  with galvanic isolation between input and output of both the power stage and the feedback loop · CPC title

• G01R31/00

  Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere ({measuring superconductive properties G01R33/1238;} testing line transmission systems H04B3/46; testing or measuring semiconductors or solid state devices during manufacture {H10P74/00}) · CPC title

• G01R19/14

  Indicating direction of current; Indicating polarity of voltage · CPC title