Temperature regulation for thermoplastic micro-forming of bulk metallic glass: Robust control design using buck converter

Nattasit Dancholvichit, Shiv G. Kapoor, Srinivasa M. Salapaka

Research output: Contribution to journalArticle

Abstract

This article presents the design, identification, simulation, and control of a buck converter implemented for bulk metallic glass thermoplastic micro-forming. In manufacturing of multi-faceted bulk metallic glass knife edge, the temperature of the micro-forming sample is critical to the thermoplastic deformation, which determines the quality of the blade edge shape. We propose a nested inner-current outer-temperature control system for high-fidelity temperature regulation. The inner-current control loop is implemented on a modified buck converter, which allows high-power rectified AC input and outputs current that can be regulated with a precision of 2 % over a bandwidth of 5 Hz. We use switch-averaged electrical model together with feedback linearization to address complex nonlinear dynamics that describe a buck converter, and to enable it using linear control design methods. The outer-temperature control design ensures temperature regulation of a heater by prescribing real-time reference power that the current-control loop should provide. The challenge of nonlinear relationship between the required reference power and the regulated current is addressed by exploiting the high-bandwidth of the inner-current loop. The control objectives of regulation performance and robustness to modelling uncertainties are posed and solved in an optimal control (H) framework. Experimental results demonstrate that our control design achieved the required temperature regulation at 673 K within 0.03 K. An improvement of over 5000 % is demonstrated when compared with previously implemented control designs. Moreover, the buck converter-based system enables regulation accuracies that were not possible with other popular existing methods such as TRIAC and traditional relay switches.

Original languageEnglish (US)
Pages (from-to)1294-1303
Number of pages10
JournalJournal of Manufacturing Processes
Volume56
DOIs
StatePublished - Aug 2020

Keywords

  • Buck converter
  • Manufacturing process
  • Micro-forming
  • Process control
  • Robust control
  • Temperature control

ASJC Scopus subject areas

  • Strategy and Management
  • Management Science and Operations Research
  • Industrial and Manufacturing Engineering

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