Control method for zero voltage switching buck-boost power converters

Patent metadata

Field	Value
Publication number	US-9793810-B2
Application number	US-201514850125-A
Country	US
Kind code	B2
Filing date	Sep 10, 2015
Priority date	Sep 10, 2015
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A method comprises providing a buck-boost converter comprising a first high-side switch and a first low-side switch connected in series across an input capacitor, a second high-side switch and a second low-side switch connected in series across an output capacitor and an inductor coupled between a common node of the first high-side switch and the first low-side switch, and a common node of the second high-side switch and the second low-side switch, detecting a first voltage resonance waveform across a switch of the buck-boost converter and turning on the switch of the buck-boost converter when the first voltage resonance waveform falls to zero.

First claim

What is claimed is:

1. A method comprising:
detecting one or more voltage resonance waveforms across a switch of a buck-boost converter, wherein the buck-boost converter comprises a first high-side switch and a first low-side switch connected in series across an input capacitor, a second high-side switch and a second low-side switch connected in series across an output capacitor and an inductor coupled between a common node of the first high-side switch and the first low-side switch, and a common node of the second high-side switch and the second low-side switch; and
turning on the switch of the buck-boost converter after the one or more voltage resonance waveforms fall to a voltage approximately equal to zero, wherein, prior to turning on the switch, a voltage across the switch falls to a first voltage approximately equal to zero and increases from the first voltage to a second voltage greater than zero.

2. The method of claim 1 , wherein:
the inductor resonates with a drain-to-source capacitor to generate the one or more voltage resonance waveforms.

3. The method of claim 1 , wherein:
turning on the switch of the buck-boost converter after the one or more voltage resonance waveforms fall to a voltage approximately equal to zero includes turning on the switch of the buck-boost converter after a first voltage resonance waveform falls to zero.

4. The method of claim 1 , wherein:
turning on the switch of the buck-boost converter after the one or more voltage resonance waveforms fall to a voltage approximately equal to zero includes turning on the switch of the buck-boost converter when a last voltage resonance waveform of the one or more voltage resonance waveforms falls to zero.

5. The method of claim 4 , further comprising:
configuring the buck-boost converter to operate at a fixed switching frequency by selecting a number of the voltage resonance waveforms between a first voltage resonance waveform and a turn-on time of the switch of the buck-boost converter.

6. The method of claim 4 , further comprising:
under a light load operating condition, limiting a maximum switching frequency of the buck-boost converter by selecting a number of the voltage resonance waveforms between a first voltage resonance waveform and a turn-on time of the switch of the buck-boost converter.

7. The method of claim 1 , wherein:
during a buck operating mode, the switch is the first high-side switch.

8. The method of claim 1 , wherein:
during a boost operating mode, the switch is the second low-side switch.

9. The method of claim 1 , further comprising:
configuring the buck-boost converter to operate in a buck operating mode, wherein the switch is the first high-side switch.

10. The method of claim 1 , further comprising:
configuring the buck-boost converter to operate in a boost operating mode, wherein the switch is the second low-side switch.

11. An apparatus comprising:
a buck converter portion comprising a first high-side switch and a first low-side switch connected in series across an input capacitor;
a boost converter portion comprising a second high-side switch and a second low-side switch connected in series across an output capacitor;
an inductor coupled between the buck converter portion and the boost converter portion, wherein the buck converter portion, the boost converter portion and the inductor form a buck-boost converter; and
a controller configured to:
detect a first voltage resonance waveform across a switch of the buck-boost converter, wherein the first voltage resonance waveform includes a peak and two valleys; and
turn on the switch of the buck-boost converter after the first voltage resonance waveform falls to zero.

12. The apparatus of claim 11 , wherein the controller is configured to:
operate the buck-boost converter in a buck operating mode and turn on the first high-side switch of the buck-boost converter when a first voltage resonance waveform across the first high-side switch falls to a voltage approximately equal to zero.

13. The apparatus of claim 11 , wherein the controller is configured to:
operate the buck-boost converter in a boost operating mode and turn on the second low-side switch of the buck-boost converter when a first voltage resonance waveform across the second low-side switch falls to a voltage approximately equal to zero.

14. The apparatus of claim 11 , wherein the controller is configured to:
operate the buck-boost converter in a buck operating mode and turn on the first high-side switch of the buck-boost converter when a last resonance waveform of a plurality of voltage resonance waveforms across the first high-side switch falls to a voltage approximately equal to zero.

15. The apparatus of claim 11 , wherein the controller is configured to:
operate the buck-boost converter in a boost operating mode and turn on the second low-side switch of the buck-boost converter when a last resonance waveform of a plurality of voltage resonance waveforms across the second low-side switch falls to a voltage approximately equal to zero.

16. The apparatus of claim 11 , wherein the controller is configured to:
detect the first voltage resonance waveform across the switch of the buck-boost converter, and wherein the first voltage resonance waveform is generated by a resonance process between the inductor and a drain-to-source capacitor of the switch.

17. The apparatus of claim 11 , wherein the controller is configured to:
operate the buck-boost converter in a fixed switching frequency mode by selecting a number of voltage resonance waveforms between the first voltage resonance waveform and a turn-on time of the switch of the buck-boost converter.

18. The apparatus of claim 17 , wherein:
at least one voltage resonance waveform is between the first voltage resonance waveform and the turn-on time of the switch of the buck-boost converter.

19. The apparatus of claim 11 , wherein the controller is configured to:
under a light load operating condition, limit a maximum switching frequency of the buck-boost converter by selecting a number of voltage resonance waveforms between the first voltage resonance waveform and a turn-on time of the switch of the buck-boost converter.

20. The apparatus of claim 19 , wherein:
at least one voltage resonance waveform is between the first voltage resonance waveform and the turn-on time of the switch of the buck-boost converter.

Assignees

• Futurewei Technologies Inc

Inventors

• Fu Dianbo
• Huang Jinbo
• Liu Ce
• Ye Liming
• Dai Heping
• Chen Daoshen

Classifications

• H02M3/1582 Primary

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title

• H02M1/0058

  by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826) · CPC title

• Y02B70/10

  Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes · CPC title