The Development of a Pulsed Power Supply for μECM

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• 作者：Tobias Mole^a ; Brian McDonald^b ; Seá ; n Mullery^a ; Carl Diver^c ; David Tormey^a ; ^{Tormey.David@itsligo.ie" class="auth_mail" title="E-mail the corresponding author}
• 关键词：μECM ; Switch Mode Power Supply (SMPS) ; micro-Controller ; Inter Electrode Gap (IEG) ; Field Effect Transistors (FETs) ; High Frequency Pulse Width Generation
• 刊名：Procedia CIRP
• 出版年：2016
• 出版时间：2016
• 年：2016
• 卷：42
• 期：Complete
• 页码：809-814
• 全文大小：577 K

文摘

Electrochemical Machining (ECM) is a well-established process in areas such as the aviation and automobile industries but the further commercial development and use of the μECM process has been prohibited by several issues, the main one being the lack of a suitable power supply unit (PSU) that can deliver the high-current pulses required while maintaining a minimal form factor, physical geometry, and realistic cost. The work presented in the paper is based on research that was carried out during the development of a novel switch mode power supply (SMPS) that is capable of delivering nano-second pulses at the MHz frequency range to the machine tool with minimal inductance. Preliminary experimental work was conducted to obtain initial design parameters and specifications required for the power supply. This included analysis of load characterisation followed by an investigation into the power switching using gallium nitrate based field effect transistors (FETs) as a novel switching technology and an investigation of the effects of the Inter Electrode Gap (IEG) loop. A Pulse Width Modulator (PWM) Frequency generator was constructed that was tested and shown to produce a modulated frequency of up to 45 MHz with a minimum pulse on time of 14 ns. Methods were investigated and deployed for monitoring the current and voltage sensing feedback for optimising process performance and control. Control system requirements were defined and implemented by adapting a Texas Instrument Piccolo microcontroller specifically for interfacing with the PSU that was then integrated with the higher-level Delta Tau control system deployed for the controlling the overall machining process of the μECM demonstrator machine. The PSU was tested, validated and integrated with the demonstrator machine for a number of machining trials that were conducted on copper and 18CrNi8, with material removal observed. This paper will outline the development work that was undertaken for the PSU and present findings from the PSU control tests. In addition, findings will also be discussed and presented from the analysis of a novel multi-probe IEG connection concept which was shown to be correctly transmitting pulses to the IEG with a total loop inductance of just 50 nH with pulse-on times as short as 50 ns without any issue.