Control method for buck-boost power converters

Patent metadata

Field	Value
Publication number	US-10177661-B2
Application number	US-201514739827-A
Country	US
Kind code	B2
Filing date	Jun 15, 2015
Priority date	Jun 15, 2015
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A method comprises generating a first ramp signal and a second ramp signal for controlling a buck converter portion and a boost converter portion of a buck-boost converter respectively, comparing the first ramp signal and the second ramp signal to a control signal, controlling the buck converter portion using the comparing the first ramp signal to the control signal and the boost converter portion using the comparing the second ramp signal to the control signal, comparing a current flowing through the inductor to a current threshold and terminating a switching cycle based upon the comparing the current flowing through the inductor to the current threshold.

First claim

What is claimed is:

1. A method comprising:
generating a first ramp signal for controlling a buck converter portion of a buck-boost converter generating a second ramp signal for controlling a boost converter portion of the buck-boost converter;
comparing the first ramp signal and the second ramp signal to a control signal;
controlling a state of a high-side switch of the buck converter portion using the comparing the first ramp signal to the control signal and a state of a low-side switch of the boost converter portion using the comparing the second ramp signal to the control signal;
comparing a current flowing through an inductor of the buck-boost converter to a current threshold, wherein the current threshold is a negative value; and
terminating a switching cycle of the buck-boost converter based upon the comparing the current flowing through the inductor to the current threshold, wherein the current flowing through the inductor changes direction twice during the switching cycle.

2. The method of claim 1 , further comprising:
adding an offset into the second ramp signal;
in response to an output voltage greater than an input voltage of the buck-boost converter, turning off the low-side switch of the boost converter portion, turning on a high-side switch of the boost converter portion and resetting the second ramp signal when the second ramp signal is equal to the control signal; and
in response to the output voltage greater than the input voltage of the buck-boost converter, turning off the high-side switch of the boost converter portion and resetting the first ramp signal when the current flowing through the inductor is equal to the current threshold.

3. The method of claim 1 , further comprising:
adding a delay time at an end of a switching cycle.

4. The method of claim 3 , further comprising:
configuring the buck-boost converter to operate at a fixed switching frequency by adjusting the delay time.

5. The method of claim 1 , further comprising:
adding an offset into the second ramp signal;
in response to an output voltage approximately equal to an input voltage of the buck-boost converter, turning off the low-side switch of the boost converter portion, turning on a high-side switch of the boost converter portion and resetting the second ramp signal when the second ramp signal is equal to the control signal;
in response to the output voltage approximately equal to the input voltage of the buck-boost converter, turning off the high-side switch of the buck converter portion, turning on a low-side switch of the buck converter portion and resetting the first ramp signal when the first ramp signal is equal to the control signal; and
in response to the output voltage approximately equal to the input voltage of the buck-boost converter, turning off the low-side switch of the buck converter portion and the high-side switch of the boost converter portion, and turning on the high-side switch of the buck converter portion and the low-side switch of the boost converter portion when the current flowing through the inductor is equal to the current threshold.

6. The method of claim 1 , further comprising:
adding an offset into the second ramp signal;
in response to an input voltage greater than an output voltage of the buck-boost converter, turning off the high-side switch of the buck converter portion, turning on a low-side switch of the buck converter portion and resetting the first ramp signal when the first ramp signal is equal to the control signal; and
in response to the input voltage greater an output voltage of the buck-boost converter, turning off the low-side switch of the buck converter portion and turning on the high-side switch of the buck converter portion when the current flowing through the inductor is equal to the current threshold.

7. The method of claim 6 , wherein:
the offset is greater than the control signal.

8. The method of claim 1 , further comprising:
adding an offset into the first ramp signal;
in response to an output voltage greater than an input voltage of the buck-boost converter, turning off the low-side switch of the boost converter portion, turning on a high-side switch of the boost converter portion and resetting the second ramp signal when the second ramp signal is equal to the control signal;
in response to the output voltage greater than the input voltage of the buck-boost converter, turning off the high-side switch of the buck converter portion, turning on a low-side switch of the buck converter portion and resetting the first ramp signal when the first ramp signal is equal to the control signal; and
in response to the output voltage greater than the input voltage of the buck-boost converter, turning off the high-side switch of the boost converter portion and the low-side switch of the buck converter portion, and turning on the low-side switch of the boost converter portion and the high-side switch of the buck converter portion when the current flowing through the inductor is equal to the current threshold.

9. The method of claim 1 , further comprising:
adding an offset into the first ramp signal;
in response to an output voltage approximately equal to an input voltage of the buck-boost converter, turning off the low-side switch of the boost converter portion, turning on a high-side switch of the boost converter portion and resetting the second ramp signal when the second ramp signal is equal to the control signal;
in response to the output voltage approximately equal to the input voltage of the buck-boost converter, turning off the high-side switch of the buck converter portion, turning on a low-side switch of the buck converter portion and resetting the first ramp signal when the first ramp signal is equal to the control signal; and
in response to the output voltage approximately equal to the input voltage of the buck-boost converter, turning off the low-side switch of the buck converter portion and the high-side switch of the boost converter portion, and turning on the high-side switch of the buck converter portion and the low-side switch of the boost converter portion when the current flowing through the inductor is equal to the current threshold.

10. The method of claim 1 , further comprising:
adding an offset into the first ramp signal;
in response to an input voltage greater than an output voltage of the buck-boost converter, turning off the low-side switch of the boost converter portion, turning on a high-side switch of the boost converter portion and resetting the second ramp signal when the second ramp signal is equal to the control signal;
in response to the input voltage greater than the input voltage of the buck-boost converter, turning off the high-side switch of the buck converter portion, turning on a low-side switch of the buck converter portion and resetting the first ramp signal when the first ramp signal is equal to the control signal; and
in response to the input voltage greater than the input voltage of the buck-boost converter, turning off the low-side switch of the buck converter portion and the high-side switch of the boost converter portion, and turning on the high-side switch of the buck converter portion and the low-side switch of the boost converter portion when the current flowing through the inductor is equal to the current threshold.

11. A method comprising:
detecting an input voltage and an output voltage of a power converter comprising a buck converter portion and a boost converter portion;
comparing a first ramp signal and a second ramp signal to a control signal;
controlling a state of a high-side switch of the buck converter portion using the comparing the first ramp signal to the control sig

Assignees

• Futurewei Technologies Inc

Inventors

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

Classifications

• H02M3/1582 Primary

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

• H02M2001/0032

  Electricity · mapped topic

• Y02B70/16

  Cross-Sectional Technologies · mapped topic

• H02M2001/0058

  Electricity · mapped topic

• H02M2001/0025

  Electricity · mapped topic