Over voltage protection control method and circuit for four-switch buck-boost converter

• US 10,003,263 B2
• Filed: 11/11/2016
• Issued: 06/19/2018
• Est. Priority Date: 11/07/2013
• Status: Active Grant

• Current Assignee: Silergy Semiconductor Technology (Hangzhou) Ltd. (Silergy Corporation)
• Original Assignee: Silergy Semiconductor Technology (Hangzhou) Ltd. (Silergy Corporation)
• Inventors: Hang, Kailang, Sun, Liangwei
• Primary Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US15/349,108
• Publication Number:
  US 20170063238A1
• Time in Patent Office: 585 Days
• Field of Search: 323222, 323225, 323235, 323237, 323266, 323267, 323272-276, 323279, 323282-288, 363 1215, 363 2116, 363 89, 363 95
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence

Abstract

In one embodiment, a method of over voltage protection control can include: (i) determining whether an output voltage of a buck-boost converter is in an over voltage condition, where the buck-boost converter includes a first switch coupled to an input terminal and an inductor, a second switch coupled to ground and a common node of the first switch and the inductor, a third switch coupled to ground and a common node of a fourth switch and the inductor, where the fourth switch is coupled to an output terminal of the buck-boost converter; and (ii) simultaneously controlling the first, second, third, and fourth switches in the buck-boost converter by turning on the second and third switches, and turning off the first and fourth switches, in response to the over voltage condition.

Claims

1. A controlling method for over voltage protection control, the method comprising:

a) determining whether an output voltage of a buck-boost converter is in an over voltage condition, wherein said buck-boost converter comprises a first switch coupled to an input terminal and an inductor, a second switch coupled to ground and a common node of said first switch and said inductor, a third switch coupled to ground and a common node of a fourth switch and said inductor, wherein said fourth switch is coupled to an output terminal of said buck-boost converter; and

b) turning on said second and third switches, and turning off said first and fourth switches, in direct response to said over voltage condition.

2. The method of claim 1, wherein when said converter operates in a buck mode, the method further comprises:

a) during a first time period when said first and fourth switches are on, and said output voltage is in said over voltage condition, turning off said first and fourth switches, and turning on said second and third switches; and

b) during a second time period when said second and fourth switches are on, and said output voltage is in said over voltage condition, turning on said third switch, and turning off said fourth switch.

3. The method of claim 1, wherein when said buck-boost converter operates in a boost mode, the method further comprises:

a) during a first time period when said first and third switches are on, and said output voltage is in said over voltage condition, turning off said first switch, and turning on said second switch; and

b) during a second time period when said first and fourth switches are on, and said output voltage is in said over voltage condition, turning off said first and fourth switches, turning on said second and third switches.

4. The method of claim 1, wherein when said buck-boost converter operates in a buck-boost mode, the method further comprises:

a) during a first time period when said first and third switches are on, and said output voltage is in said over voltage condition, turning off said first switch, and turning on said second switch;

b) during a second time period when said first and fourth switches are on, and said output voltage is in said over voltage condition, turning off said first and fourth switches, and turning on said second and third switches; and

c) during a third time period when said second and fourth switches are on, and said output voltage is in said over voltage condition, turning on said third switch, and turning off said fourth switch.

12. The method of claim 1, wherein said determining whether said output voltage of said buck-boost converter is in said over voltage condition comprises using a comparator.

13. The method of claim 12, wherein said comparator is configured as a hysteresis comparator.

14. The method of claim 1, wherein said determining whether said output voltage of said buck-boost converter is in said over voltage condition comprises determining if a voltage feedback signal indicative of said output voltage is greater than an over voltage threshold signal.

15. The method of claim 14, wherein said second and third switches are controlled to be on, and said first and fourth switches are controlled to be off, when said voltage feedback signal is greater than said over voltage threshold signal.

16. The method of claim 1, wherein said turning on said second and third switches, and turning off said first and fourth switches, in direct response to said over voltage condition, is independent of a previous state of said first, second, third, and fourth switches.

5. An apparatus, comprising:

a) a buck-boost converter comprising a first switch coupled to an input terminal and an inductor, a second switch coupled to ground and a common node of said first switch and said inductor, a third switch coupled to ground and a common node of a fourth switch and said inductor, wherein said fourth switch is coupled to an output terminal of said buck-boost converter;

b) an over voltage detection circuit configured to receive a voltage feedback signal indicative of an output voltage of said buck-boost converter, and an over voltage threshold signal, and to generate an over voltage signal;

c) a first control circuit configured to generate a first PWM control signal according to an operation mode of said buck-boost converter;

d) a first logic circuit configured to receive said first PWM control signal and said over voltage signal, and to directly control said first and second switches when said over voltage signal is activated;

e) a second control circuit configured to generate a second PWM control signal according to said operation mode of said buck-boost converter; and

f) a second logic circuit configured to receive said second PWM control signal and said over voltage signal, and to directly control said third and fourth switches when said over voltage signal is activated.

6. The apparatus of claim 5, wherein said over voltage detection circuit comprises:

a) a voltage feedback circuit configured to receive said output voltage of said buck-boost converter, and to generate said voltage feedback signal; and

b) a comparator configured to compare said voltage feedback signal against said over voltage threshold signal, and to activate said over voltage signal when said voltage feedback signal is greater than said over voltage threshold signal.

7. The apparatus of claim 5, wherein said first logic circuit comprises:

a) an inverter configured to receive said over voltage signal; and

b) an AND-gate configured to receive an output of said inverter and said first PWM control signal, and to provide a first logic control signal to a first driving circuit for controlling said first and second switches.

8. The apparatus of claim 5, wherein said second logic circuit comprises an OR-gate configured to receive said over voltage signal and said second PWM control signal, and to provide a second logic control signal to a second driving circuit for controlling said third and fourth switches.

9. The apparatus of claim 5, wherein said over voltage detection circuit comprises a comparator.

10. The apparatus of claim 9, wherein said comparator is configured as a hysteresis comparator.

11. The apparatus of claim 5, wherein said second and third switches are controlled to be on, and said first and fourth switches are controlled to be off, when said voltage feedback signal is greater than said over voltage threshold signal.