Method and apparatus for generating an adaptive switching frequency for operating power factor correction circuit

• US 8,971,075 B2
• Filed: 02/03/2012
• Issued: 03/03/2015
• Est. Priority Date: 02/07/2011
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ye, Zhong, Sun, Bosheng
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US13/365,528
• Publication Number:
  US 20120200268A1
• Time in Patent Office: 1,124 Days
• Field of Search: 363/89
• US Class Current: 363/89
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 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 Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

A method of operating a power factor correction (PFC) circuit and a corresponding power factor correction circuit include determining an adaptive switching frequency of the PFC circuit related to a current of the boost inductor of the PFC circuit, and operating the PFC circuit at a light load based on the adaptive switching frequency.

Claims

1. A method of operating a PFC (power factor correction) circuit having a main PFC FET and a boost inductor, the method comprising:

determining an adaptive switching frequency of the PFC circuit related to a current of the boost inductor; and

operating the PFC circuit at a light load based on the adaptive switching frequency, wherein determining the adaptive switching frequency of the PFC circuit comprises determining a time that the current of the boost inductor resonates from a negative value to a zero value, and generating the adaptive switching frequency based on the determined time.

2. The method of claim 1, wherein operating the PFC circuit at a light load is operating the PFC circuit at DCM (discontinuous-conduction mode).

3. The method of claim 1, wherein determining the adaptive switching frequency of the PFC circuit further comprises generating a Syn signal based on the time that the current of the boost inductor resonates from a negative value to a zero value, and turning on the main PFC FET based on the Syn signal.

4. The method of claim 3, wherein the main PFC FET is turned on when a voltage Vds of the main PFC FET is substantially equal to zero or at its lowest point, and a current flowing through the inductor is substantially equal to zero.

5. The method of claim 1, further comprising operating the PFC circuit at the adaptive switching frequency when the PFC circuit is operating in a first mode, and operating the PFC circuit at a switching frequency other than the adaptive switching frequency when the PFC circuit is operating in a mode other than the first mode.

6. The method of claim 5, wherein the first mode is a light load operating mode.

7. A method of operating a PFC (power factor correction) circuit having a main PFC FET and a boost inductor, the method comprising:

determining if the PFC circuit is operating in a first mode or in another mode;

if the PFC circuit is operating in the first mode, determining an adaptive switching frequency of the PFC circuit related to a current of the boost inductor; and

operating the PFC circuit at a light load based on the adaptive switching frequency, wherein determining the adaptive switching frequency of the PFC circuit further comprises generating a Syn signal based on a time that the current of the boost inductor resonates from a negative value to a zero value, and turning on the main PFC FET based on the Syn signal.

8. The method of claim 7, wherein operating the PFC circuit at a light load is operating the PFC circuit at DCM (discontinuous-conduction mode).

9. The method of claim 7, further comprising operating the PFC circuit at a switching frequency other than the adaptive switching frequency when the PFC circuit is operating in a mode other than the first mode.

10. The method of claim 7, wherein the main PFC FET is turned on when a voltage Vds of the main PFC FET is substantially equal to zero or at its lowest point, and a current flowing through the inductor is substantially equal to zero.

11. The method of claim 7, wherein the first mode is a light load operating mode.

12. A PFC (power factor correction) circuit having a main PFC FET and a boost inductor, comprising:

a Syn signal generator that detects a current of the boost inductor; and

a controller that determines an adaptive switching frequency based on the current of the boost inductor and controls operation of the PFC circuit at a light load based on the adaptive switching frequency, wherein the controller determines the adaptive switching frequency of the PFC circuit by determining a time that the current of the boost inductor resonates from a negative value to a zero value, and generates the adaptive switching frequency based on the determined time.

13. The PFC circuit of claim 12, wherein the controller operates the PFC circuit at the adaptive switching frequency when the PFC circuit is operating in a first mode, and operates the PFC circuit at another frequency when the PFC circuit is operating in a mode other than the first mode.

14. The PFC circuit of claim 13, wherein the first mode is a light load operating mode.

15. The PFC circuit of claim 12, wherein operating the PFC circuit at a light load is operating the PFC circuit at DCM (discontinuous-conduction mode).

16. The PFC circuit of claim 12, wherein the Syn signal generator generates a Syn signal based on the time that the current of the boost inductor resonates from a negative value to a zero value, and causes turning on of the main PFC FET based on the Syn signal.

17. The PFC circuit of claim 16, wherein the main PFC FET is turned on when a voltage Vds of the main PFC FET is substantially equal to zero or at its lowest point, and a current flowing through the inductor is substantially equal to zero.