Variable switching frequency power supply plasma cutters

Patent metadata

Field	Value
Publication number	US-9908196-B2
Application number	US-201414786871-A
Country	US
Kind code	B2
Filing date	Apr 10, 2014
Priority date	Apr 24, 2013
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A power supply, for a plasma cutter or a plasma arc welder, having a variable switching frequency and method of operating the power supply is generally disclosed. The power supply includes a switch for setting the switching frequency and a chopper control circuit for determining current output from the power supply, determining an operating frequency based on the determined current output and setting the switching frequency based on the determined operating frequency.

First claim

The invention claimed is:

1. A power supply for forming a plasma arc in a plasma tool, the power supply comprising:
a direct current (DC) power source;
a chopper circuit configured to modulate a switching frequency of the DC power source; and
a chopper control module configured to vary the switching frequency, the chopper control module including:
a processor configured to identify a type of a plasma tool coupled to the power supply and determine a first switching frequency based on the type of the plasma tool; and
a switch controller configured to cause the switching frequency of the DC power source to be substantially equal to the determined first switching frequency.

2. The power supply of claim 1 , wherein the type of the plasma tool includes a plasma cutter or a plasma arc welder.

3. The power supply of claim 1 , wherein:
the processor is further configured to identify an ampere operating range of the type of the plasma tool coupled to the power supply; and
the chopper control module is configured to vary the switching frequency of the chopper circuit further based on the ampere operating range of the type of the plasma tool coupled to the power supply.

4. The power supply of claim 1 , wherein:
the chopper control circuit further includes a measurement module configured to measure an output current value of the power supply; and
the processor of the chopper control module is configured to determine the first switching frequency as a fixed switching frequency when the output current value from the power supply is smaller than or equal to a predetermined current value, and determine the first switching frequency as a variable switching frequency when the output current value from the power supply is greater than the predetermined current value.

5. The power supply of claim 1 , wherein the chopper control module is further configured to monitor a ripple current of the chopper circuit and vary the switching frequency of the chopper circuit based on the monitored ripple current.

6. The power supply of claim 1 , wherein the chopper control module is further configured to monitor a temperature of the chopper circuit and vary the switching frequency of the chopper circuit based on the monitored temperature.

7. The power supply of claim 1 , wherein the processor of the chopper control module is further configured to select the first switching frequency from a look-up table that stores a plurality of switching frequencies.

8. A method for varying a switching frequency of a power supply for forming a plasma arc used in a plasma tool, comprising:
identifying, by a processor, a type of a plasma tool coupled to the power supply;
determining, by the processor, a first switching frequency based on at least the type of the plasma tool coupled to the power supply; and
setting the switching frequency of the power supply to be substantially equal to the determined first switching frequency.

9. The method of claim 8 , further comprising:
identifying, by the processor, an ampere operating range of the type of the plasma tool coupled to the power supply; and
determining, by the processor, the first switching frequency further based on the ampere operating range of the type of the plasma tool coupled to the power supply.

10. The method of claim 8 , wherein the type of the plasma tool includes a plasma cutter or a plasma arc welder.

11. The method of claim 8 , further comprising:
measuring, by a current measurement module, an output current value of the power supply;
determining, by the processor, the first switching frequency as a fixed switching frequency when the output current value from the power supply is smaller than or equal to a predetermined current value; and
determining, by the processor, the first switching frequency as a variable switching frequency when the output current value from the power supply is greater than the predetermined current value.

12. The method of claim 8 , further comprising:
monitoring, by a controller circuit, a ripple current of an output of the power supply; and
varying the switching frequency of the power supply based on the monitored ripple current.

13. The method of claim 8 , further comprising:
monitoring, by a controller circuit, a temperature of the power supply; and
varying the switching frequency of the power supply based on the monitored temperature.

14. The method of claim 8 , further comprising selecting the first switching frequency from a look-up table that stores a plurality of switching frequencies.

15. A non-transitory computer readable medium containing instructions which, when executed by a processor, cause the processor to perform a method comprising:
identifying a type of a plasma tool coupled to a power supply;
determining a first switching frequency based at least the type of the plasma tool coupled to the power supply; and
setting a switching frequency of the power supply to be substantially equal to the determined first switching frequency.

16. The non-transitory computer readable medium of claim 15 , wherein the instructions which, when executed by the processor, cause the processor to further perform:
identifying an ampere operating range of the type of the plasma tool coupled to the power supply; and
determining the first switching frequency is further based on the ampere operating range of the type of the plasma tool coupled to the power supply.

17. The non-transitory computer readable medium of claim 15 , wherein the instructions which, when executed by the processor, cause the processor to further perform:
receiving, from a current measurement module, an output current value of the power supply;
determining the first switching frequency as a fixed switching frequency when an output current value from the power supply is smaller than or equal to a predetermined current value; and
determining the first switching frequency as a variable switching frequency when the output current value from the power supply is greater than the predetermined current value.

18. The non-transitory computer readable medium of claim 15 , wherein the instructions which, when executed by the processor, cause the processor to further perform:
monitoring a ripple current of an output of the power supply; and
varying the switching frequency of the power supply based on the monitored ripple current.

19. The non-transitory computer readable medium of claim 15 , wherein the instructions which, when executed by the processor, cause the processor to further perform:
monitoring a temperature of the power supply; and
varying the switching frequency of the power supply based on the monitored temperature.

20. The non-transitory computer readable medium of claim 15 , wherein the type of the plasma tool includes a plasma cutter or a plasma arc welder.

Assignees

• Esab Group Inc
• Esab Group Inc

Inventors

• Higgins Philip K
• Gujja Karunakar
• Hamer Iii John W

Classifications

• B23K10/006 Primary

  Control circuits therefor · CPC title

• H05H1/36

  Circuit arrangements (H05H1/38, H05H1/40 take precedence) · CPC title

• H02M3/156

  with automatic control of output voltage or current, e.g. switching regulators · CPC title