Dynamic optimization of efficiency using dead time and FET drive control

• US 20050281058A1
• Filed: 12/02/2004
• Published: 12/22/2005
• Est. Priority Date: 06/21/2004
• Status: Abandoned Application

• Current Assignee: Astec International Limited (Emerson Electric Company)
• Original Assignee: Astec International Limited (Emerson Electric Company)
• Inventors: Qahouq, Jaber Abu, Mao, Hong, Batarseh, Issa
• Application Number:
  US11/003,013
• Publication Number:
  US 20050281058A1
• Time in Patent Office: Days
• US Class Current: 363/16
• CPC Class Codes: H02M 1/38 Means for preventing simultaneous conduction of switches
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer

Abstract

A power converter uses a control method to optimize efficiency by dynamically optimizing a controlled parameter. A change in efficiency of the converter after changing at least one controlled parameter is determined. The direction of change in efficiency of the converter is compared to a direction of the change in the controlled parameter. The controlled parameter is changed in a positive direction when the direction in the change in the efficiency of the converter and the direction of the change in the controlled parameter are the same and changed in a negative direction when the direction in the change in the efficiency of the converter and the direction of the change in the controlled parameter are opposite. The controlled parameters may include dead time between turn-on and turn-off and between turn-off and turn-on of the primary and corresponding secondary side switches of the controller, drive voltage(s) for the switches, and intermediate bus voltages.

Claims

1. A method of controlling a power converter to optimize efficiency, comprising:

a. determining a direction of change in efficiency of the converter after changing at least one controlled parameter;

b. comparing the direction of change in efficiency of the converter to a direction of the change in the controlled parameter; and

c. changing the controlled parameter in a positive direction when the direction in the change in the efficiency of the converter and the direction of the change in the controlled parameter are the same and changing the controlled parameter in a negative direction when the direction in the change in the efficiency of the converter and the direction of the change in the controlled parameter are opposite.

2. The method of claim 1 wherein the power converter is a DC-DC converter and the controlled parameter is dead time between turn-on of at least one primary side switch of the converter and turn-off of a corresponding secondary side switch of the converter and between turn-off of the primary side switch and turn-on of the corresponding secondary side switch, and changing the controlled parameter in the positive direction includes adjusting a switching signal for at least one of the primary and secondary side switches to increase the dead time and changing the controlled parameter in the negative direction includes adjusting the switching signal for at least one of the primary and secondary side switches to decrease the dead time.

3. The method of claim 1 wherein the power converter is a DC-DC converter and the controlled parameter includes dead time between turn-on of primary side switches of the converter and turn-off of corresponding secondary side switches of the converter and between turn-off of the primary side switches and turn-on of the corresponding secondary side switches, and changing the controlled parameter in the positive direction includes adjusting switching of the primary and secondary side switches to increase dead time and changing the controlled parameter in the negative direction includes adjusting switching of the primary and secondary side switches to decrease dead time.

4. The method of claim 1 wherein the power converter is a DC-DC converter and the controlled parameter includes a drive voltage for at least one of an input and output side switch and changing the controlled parameter in the positive direction includes increasing the drive voltage and changing the controlled parameter in the negative direction includes decreasing the drive voltage.

5. The method of claim 1 wherein the power converter is a DC-DC converter and the controlled parameter includes drive voltages for input and output side switches and changing the controlled parameter in the positive direction includes increasing the drive voltages and changing the controlled parameter in the negative direction includes decreasing the drive voltages.

6. The method of claim 1 wherein the controlled parameter includes a plurality of controlled parameters including dead time between turn-on of primary side switches of the converter and turn-off of corresponding secondary side switches of the converter and between turn-off of the primary side switches and turn-on of the corresponding secondary side switches and drive voltages for the primary and secondary side switches.

7. The method of claim 6 wherein the converted is a cascaded converter and the plurality of controlled parameters also includes intermediate bus voltages.

8. The method of claim 1 wherein the power converter is a cascaded power converter and the controlled parameter includes intermediate bus voltages.

9. A method of controlling a DC-DC converter to optimize efficiency, comprising:

a. determining a direction of change in efficiency of the converter after changing dead time between turn-on of primary side switches of the converter and turn-off of corresponding secondary side switches of the converter and between turn-off of the primary side switches and turn-on of the corresponding secondary side switches,

b. comparing the direction of change in efficiency of the converter to a direction of the change in the dead time;

c. increasing the dead time when the direction in the change in the efficiency of the converter and the direction of the change in the dead time are the same and decreasing the dead time in a when the direction in the change in the efficiency of the converter and the direction of the change in the dead time are opposite;

d. determining a direction of change in efficiency of the converter after changing a drive voltage for at least one of the primary and secondary side switches;

e. comparing the direction of change in efficiency of the converter to a direction of the change in the driving voltage;

f. increasing the driving voltage when the direction in the change in the efficiency of the converter and the direction of the change in driving voltage are the same and decreasing the driving voltage when the direction in the change in the efficiency of the converter and the direction of the change in the dead time are opposite.

10. The method of claim 9 wherein the drive voltage includes drive voltages for the primary and secondary side switches.

11. A power converter, comprising:

a. a power converter circuit;

b. a controller coupled to power converter circuit that determines a direction of change in efficiency of the converter after changing at least one controlled parameter, compares the direction of change in efficiency of the converter to a direction of the change in the controlled parameter, and changes the controlled parameter in a positive direction when the direction in the change in the efficiency of the converter and the direction of the change in the controlled parameter are the same and changes the controlled parameter in a negative direction when the direction in the change in the efficiency of the converter and the direction of the change in the controlled parameter are opposite.

12. The power converter of claim 11 wherein the power converter is a DC-DC converter and the controlled parameter is dead time between turn-on of the primary side switch of the converter and turn-off of a corresponding secondary side switch of the converter and between turn-off of the primary side switch and turn-on of the corresponding secondary side switch, the controller adjusting a switching signal for at least one of the primary and secondary side switches to increase the dead time to change the controlled parameter in the positive direction and adjusts the switching signal for at least one of the primary and secondary side switches to decrease the dead time to change the controlled parameter in the negative direction.

13. The power converter of claim 11 wherein the power converter is a DC-DC converter having primary and secondary side switches and the controlled parameter includes a drive voltage for at least one of the primary and secondary side switches, the controller increasing the drive voltage to change the controlled parameter in the positive direction and decreasing the drive voltage to change the controlled parameter in the negative direction.

14. The power converter of claim 11 wherein the power converter is a DC-DC converter having primary and secondary side switches and the controlled parameter includes drive voltages for the primary and secondary side switches, the controller increasing the drive voltages to change the controlled parameter in the positive direction and decreasing the drive voltage to change the controlled parameter in the negative direction.

15. The power converter of claim 11 wherein the power converter is a DC-DC converter and the controlled parameter includes a plurality of controlled parameters including dead time between turn-on of primary side switches of the converter and turn-off of corresponding secondary side switches of the converter and between turn-off of the primary side switches and turn-on of the corresponding secondary side switches and drive voltages for the primary and secondary side switches.

16. The power converter of claim 11 wherein the power converter is a cascaded converter and the controlled parameter includes a plurality of controlled parameters including dead time between turn-on of primary side switches of the converter and turn-off of corresponding secondary side switches of the converter and between turn-off of the primary side switches and turn-on of the corresponding secondary side switches, drive voltages for the primary and secondary side switches, and intermediate bus voltages.

17. A DC-DC converter, comprising:

a. a primary side having a plurality of primary side switches and a secondary side having a plurality of secondary side switches; and

b. a controller coupled to the primary side and secondary side that determines a direction of change in efficiency of the converter after changing dead time between turn-on of the primary side switches and turn-off of corresponding secondary side switches and between turn-off of the primary side switches and turn-on of the secondary side switches, compares the direction of change in efficiency of the converter to a direction of the change in the dead time, increases the dead time when the direction in the change in the efficiency of the converter and the direction of the change in the dead time are the same and decreases the dead time when the direction in the change in the efficiency of the converter and the direction of the change in the dead time are opposite.

18. A DC-DC converter, comprising:

a. an input side having at least one input side switch and an output side having at least one output side switch; and

b. a controller coupled to the input and output sides that determines a direction of change in efficiency of the converter after changing a drive voltage for at least one of the input and output side switches, compares the direction of change in efficiency of the converter to a direction of the change in the drive voltage, increases the drive voltage when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltage are the same and decreases the drive voltage when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltage are opposite.

19. A DC-DC converter, comprising:

a. an input side having at least one input side switch and an output side having at least one output side switch; and

b. a controller coupled to the input and output sides that determines a direction of change in efficiency of the converter after changing drive voltages for the input and output side switches, compares the direction of change in efficiency of the converter to a direction of the change in the drive voltages, increases the drive voltages when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltage are the same and decreases the drive voltages when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltages are opposite.

20. A DC-DC converter, comprising:

a. input and output side switches; and

b. a controller coupled to the input and output sides that determines a direction of change in efficiency of the converter after changing drive voltages for the input and output side switches, compares the direction of change in efficiency of the converter to a direction of the change in the drive voltages, increases the drive voltages when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltages are the same and decreases the drive voltages when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltages are opposite.

22. The converter of claim 20 wherein the drive voltage includes drive voltages for the primary and secondary side switches.

21. A DC-DC converter, comprising:

a. primary and secondary side switches;

b. a controller coupled to the primary side and secondary side switches;

c. the controller determining a direction of change in efficiency of the converter after changing dead time between turn-on of the primary side switches and turn-off of corresponding secondary side switches and turn-off of the primary side switches and turn-on of the corresponding secondary side switches, compares the direction of change in efficiency of the converter to a direction of the change in the dead time, and adjusts switching signals for the primary and secondary side switches to increase the dead time when the direction of change in converter efficiency is the same as the direction of change in dead time and adjust the switching signals to decrease dead time when the direction of change in converter efficiency is opposite the direction of change in dead time; and

d. the controller also determining a direction of change in efficiency of the converter after changing a drive voltage for at least one of the primary and secondary side switches, comparing the direction of change in efficiency of the converter to a direction of the change in the drive voltage, increasing the drive voltage when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltage are the same and decreasing the drive voltage when the direction in the change in the efficiency of the converter and the direction of the change in the drive voltage are opposite.