US 10,856,373 B2 · Power supply for electric arc gas heater

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 U0; a DC to DC switching converter having a switching frequency fS; 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 )

Claims12

Dependent claims

A DC power supply for driving a non-transferred electric arc gas heater, comprising:

an electrode;
an AC to DC rectifier configured to provide a voltage potential U0;
and
a MW-level DC to DC switching converter coupled between the AC to DC rectifier and the electrode, wherein the MW-level DC to DC switching converter comprises:
a pulse-width modulated chopper configured to operate at a switching frequency fs;
and
a ballast inductor coupled between the pulse-width modulated chopper and the electrode, wherein:
the MW-level DC to DC switching converter is configured to have a current control loop latency τ;
the ballast inductor is configured to provide a minimum inductance greater than
(
U
⁢
0
1
⁢
5
⁢
0
⁢
0
)
⁢
τ
to maintain a loop stability criterion;
and
the ballast inductor is further configured to provide a maximum inductance less than
1
f
⁢
s
⁢
(
U
⁢
0
2
⁢
0
⁢
0
)
to produce a peak to peak current ripple to enhance wandering of electric arc roots on the electrode under operation.

39 more elements

Dependencies are inferred from the claim text.

Power supply for electric arc gas heater

Life of this patent

Power supply for electric arc gas heater

Life of this patent

Abstract

Claims12