Active front end power converter with boost mode derating to protect filter inductor

Patent metadata

Field	Value
Publication number	US-9461559-B2
Application number	US-201313832214-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

Methods and apparatus are presented for controlling a power converter to protect input filter inductors from overheating, in which an active front end (AFE) rectifier is operated in a boost mode to provide a boosted DC voltage at a derated output current value selected according to the DC bus voltage boost amount corresponding to a maximum load condition for which the filter inductors will not overheat.

First claim

The following is claimed:

1. A method for operating a power conversion system, the method comprising:
operating a rectifier of the power conversion system in a boost mode to provide a DC bus voltage higher than a peak line to line AC input voltage value;
determining a derated output current value according to the line to line AC input voltage value and according to a DC bus voltage boost amount, the derated output current value being less than or equal to a maximum output current rating for the rectifier; and
operating the rectifier according to the derated output current value.

2. The method of claim 1 , wherein determining the derated output current value comprises:
obtaining the derated output current value corresponding to the DC bus voltage boost amount from a lookup table corresponding to the line to line AC input voltage value.

3. The method of claim 2 , wherein determining the derated output current value comprises:
selectively interpolating two derated output current values of the lookup table corresponding to DC bus voltage boost amounts above and below the DC bus voltage boost amount present in the power conversion system to derive the derated output current value.

4. The method of claim 2 , wherein determining the derated output current value comprises:
selecting a given one of a plurality of lookup tables corresponding to the line to line AC input voltage value; and
obtaining the derated output current value corresponding to the DC bus voltage boost amount from the given one of the plurality of lookup tables.

5. The method of claim 4 , wherein determining the derated output current value comprises:
selectively interpolating two derated output current values of the given one of the plurality of lookup tables corresponding to DC bus voltage boost amounts above and below the DC bus voltage boost amount present in the power conversion system to derive the derated output current value.

6. The method of claim 2 , wherein the DC bus voltage boost amounts and corresponding derated output current values of the lookup table correspond to maximum steady state load operating conditions of the power conversion system for which an input filter inductor is designed not to overheat.

7. The method of claim 1 , wherein determining the derated output current value comprises:
solving at least one derating formula according to the DC bus voltage boost amount.

8. The method of claim 7 , wherein determining the derated output current value comprises:
selecting a given one of a plurality of derating formulas corresponding to the line to line AC input voltage value; and
solving the given one of the plurality of the rating formulas according to the DC bus voltage boost amount.

9. The method of claim 1 , comprising operating an inverter of the power conversion system according to the derated output current value.

10. A non-transitory computer readable medium with computer executable instructions for operating a power conversion system, the computer readable medium comprising computer executable instructions for:
operating a rectifier of the power conversion system in a boost mode to provide a DC bus voltage higher than a peak line to line AC input voltage value;
determining a derated output current value according to the line to line AC input voltage value and according to a DC bus voltage boost amount, the derated output current value being less than or equal to a maximum output current rating for the rectifier; and
operating the rectifier according to the derated output current value.

11. The computer readable medium of claim 10 , wherein the computer executable instructions for determining the derated output current value comprise computer executable instructions for:
obtaining the derated output current value corresponding to the DC bus voltage boost amount from a lookup table corresponding to the line to line AC input voltage value.

12. The computer readable medium of claim 11 , wherein the computer executable instructions for determining the derated output current value comprise computer executable instructions for:
selectively interpolating two derated output current values of the lookup table corresponding to DC bus voltage boost amounts above and below the DC bus voltage boost amount present in the power conversion system to derive the derated output current value.

13. The computer readable medium of claim 11 , comprising at least one lookup table including a plurality of derated output current values and corresponding DC bus voltage boost amounts.

14. The computer readable medium of claim 11 , wherein the computer executable instructions for determining the derated output current value comprise computer executable instructions for:
solving at least one derating formula according to the DC bus voltage boost amount.

15. A power conversion system, comprising:
a filter circuit comprising at least one inductor;
an active rectifier comprising a plurality of rectifier switching devices coupled to receive AC input power from an external power source through the filter circuit and to provide a DC bus voltage at a DC bus; and
a controller providing rectifier control signals to the rectifier switching devices to selectively operate the rectifier in a boost mode to provide the DC bus voltage higher than a peak line to line AC input voltage value, the controller being operative to determine a derated output current value according to the line to line AC input voltage value and according to a DC bus voltage boost amount, the derated output current value being less than or equal to a maximum output current rating for the active rectifier, the controller being operative to selectively operate the rectifier according to the derated output current value.

16. The power conversion system of claim 15 , wherein the controller is operative to obtain the derated output current value corresponding to the DC bus voltage boost amount from a lookup table corresponding to the line to line AC input voltage value.

17. The power conversion system of claim 16 , wherein the controller is operative to selectively interpolate two derated output current values of the lookup table corresponding to DC bus voltage boost amounts above and below the DC bus voltage boost amount present in the power conversion system to derive the derated output current value.

18. The power conversion system of claim 16 , wherein the controller is operative to select a given one of a plurality of lookup tables corresponding to the line to line AC input voltage value, and to obtain the derated output current value corresponding to the DC bus voltage boost amount from the given one of the plurality of lookup tables.

19. The power conversion system of claim 18 , wherein the controller is operative to selectively interpolate two derated output current values of the given one of the plurality of lookup tables corresponding to DC bus voltage boost amounts above and below the DC bus voltage boost amount present in the power conversion system to derive the derated output current value.

20. The power conversion system of claim 15 , wherein the controller is operative to determine the derated output current value by solving at least one derating formula according to the DC bus voltage boost amount.

21. The power conversion system of claim 15 , wherein the derated output current value and the corresponding DC bus voltage boost amount correspond to a maximum steady state load operating condition of the power conversion system for which the at least

Assignees

• Patel Yogesh
• Wei Lixiang
• Rockwell Automation Tech Inc

Inventors

• Patel Yogesh
• Wei Lixiang

Classifications

• H02M2001/0022

  Electricity · mapped topic

• H02M1/4225

  using a non-isolated boost converter · CPC title

• H02M7/219

  in a bridge configuration · CPC title

• Y02B70/126

  Cross-Sectional Technologies · mapped topic

• H02M7/217 Primary

  using semiconductor devices only · CPC title