Power Supply for Electric Arc Gas Heater

Patent metadata

Field	Value
Publication number	US-2018235037-A1
Application number	US-201515516055-A
Country	US
Kind code	A1
Filing date	Sep 25, 2015
Priority date	Oct 1, 2014
Publication date	Aug 16, 2018
Grant date	—

Abstract

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U 0 ; a DC to DC switching converter having a switching frequency f S ; a current control loop having a latency Formula (I); and, a ballast inductor having an inductance L; characterized in that inductance L is such that Formula (II) and Formula (III). Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.

τ
;

(
I
)

L
>

(

U
0

1500

)


τ

,

(
II
)

L
<

1

f
s



(

U
0

200

)

.

(
III
)

First claim

1 - 6 . (canceled)

7 . A DC power supply for driving a non-transferred electric arc gas heater, comprising:
an AC to DC rectifier providing a potential U 0 ; a DC to DC switching converter having a switching frequency f S ; a current control loop latency τ; and, a ballast inductor having an inductance L; wherein

L
>

(

U



0

1500

)


τ

,

and



L

<

1

f
s



(

U



0

200

)

.

8 . A DC power supply according to claim 7 , wherein the DC to DC converter is a buck converter.

9 . A DC power supply according to claim 7 , wherein U 0 >3000 V.

10 . A DC power supply according to claim 7 , wherein the power delivered to the gas heater is between 1 and 10 MW.

11 . A DC power supply according to claim 7 , wherein the electric gas heater is a non-transferred segmented plasma torch with hollow electrodes.

12 . . A method of operating a non-transferred electric arc gas heater, characterized in that the heater is fed with a current of more than 500 A RMS, the current comprising a DC component and an AC component, the AC component having a peak to peak amplitude between 50 A and 20% of the DC component.

Assignees

• Umicore Nv

Inventors

• Ostermeyer John
• Heulens Jeroen

Classifications

• H05B7/185 Primary

  Heating gases for arc discharge (gas-filled discharge tubes H01J37/32) · CPC title

• H05H1/36

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

• H05B7/144

  Power supplies specially adapted for heating by electric discharge; Automatic control of power, e.g. by positioning of electrodes · CPC title

• B23K9/073

  Stabilising the arc · CPC title