Analysis, design, and control of a transcutaneous power regulator for artificial hearts

Qianhong Chen, Siu Chung Wong, Chi Kong Tse, Xinbo Ruan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

176 Citations (Scopus)

Abstract

Based on a generic transcutaneous transformer model, a remote power supply using a resonant topology for use in artificial hearts is analyzed and designed for easy controllability and high efficiency. The primary and secondary windings of the transcutaneous transformer are positioned outside and inside the human body, respectively. In such a transformer, the alignment and gap may change with external positioning. As a result, the coupling coefficient of the transcutaneous transformer is also varying, and so are the two large leakage inductances and the mutual inductance. Resonant-tank circuits with varying resonant-frequency are formed from the transformer inductors and external capacitors. For a given range of coupling coefficients, an operating frequency corresponding to a particular coupling coefficient can be found, for which the voltage transfer function is insensitive to load. Prior works have used frequency modulation to regulate the output voltage under varying load and transformer coupling. The use of frequency modulation may require a wide control frequency range which may extend well above the load insensitive frequency. In this paper, study of the input-to-output voltage transfer function is carried out, and a control method is proposed to lock the switching frequency at just above the load insensitive frequency for optimized efficiency at heavy loads. Specifically, operation at above resonant of the resonant circuits is maintained under varying coupling-coefficient. Using a digital-phase-lock-loop (PLL), zero-voltage switching is achieved in a full-bridge converter which is also programmed to provide output voltage regulation via pulsewidth modulation (PWM). A prototype transcutaneous power regulator is built and found to to perform excellently with high efficiency and tight regulation under variations of the alignment or gap of the transcutaneous transformer, load and input voltage.
Original languageEnglish
Pages (from-to)23-31
Number of pages9
JournalIEEE Transactions on Biomedical Circuits and Systems
Volume3
Issue number1
DOIs
Publication statusPublished - 19 Feb 2009

Keywords

  • Phase-locked loop (PLL)
  • Pulsewidth modulation (PWM) control
  • Resonant converter
  • Transcutaneous power regulator

ASJC Scopus subject areas

  • Biomedical Engineering
  • Electrical and Electronic Engineering

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