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arXiv · 2610.07930

Adaptive Average Current-Mode Control of a Buck Converter Supplying Plasma Arc Loads

Lukas Ecker·Thomas Voglhuber-Brunnmaier
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Abstract

Reliable operation of plasma processes requires a power supply that can regulate and limit the arc current despite rapid changes of the electrical load. Gas-flow fluctuations, arc motion, changing attachment conditions, and electrode interactions can cause abrupt arc-voltage variations and may lead to arc interruption. The power supply must therefore provide fast current control and a suitable actuation layer for supervisory stabilization. This paper presents an adaptive average current-mode controller for a buck converter supplying a nonlinear plasma arc load. Based on an averaged model of the converter inductor dynamics, the controller combines current-error feedback with feedforward compensation of the measured arc voltage. Online adaptation of the inductance and its effective series resistance compensates for converter-parameter uncertainty without requiring an online nonlinear arc model. A Lyapunov analysis establishes bounded estimation errors and asymptotic current tracking for the averaged closed-loop system under bounded-reference assumptions. Experiments with an argon plasma arc demonstrate contact-opening ignition and current-reference tracking under varying arc- voltage conditions, supporting the controller as a fast current-control layer for plasma applications.

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Lukas Ecker, Thomas Voglhuber-Brunnmaier. 2026-10-06. Adaptive Average Current-Mode Control of a Buck Converter Supplying Plasma Arc Loads. https://arxiv.org/abs/2610.07930

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