Analysis, Design, and Control of a Transcutaneous Power Regulator for Artificial Hearts

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.

Series-series compensated wireless power transfer at two different resonant frequencies

“…For this reason, the analysis of the resonant tanl<-at various resonant frequencies is required to understand WPT system more easily. Furthermore, in various research areas, the preferred resonant frequency is divided into two: one resonant frequency by self-inductance and resonant capacitor [I ]- [18] and the other resonant frequency by leakage inductance and resonant capacitor [19], [20]. Therefore, the difference between two resonant frequencies is needed to be clarified.…”

“…The equivalent circuit at the second resonant frequency W02 consists of the equivalent load resistance Reg and the magnetizing inductance Lm from (20), as shown in Fig. 3(b).…”

“…Note that the input impedances ZlN at the second resonant frequencies W02 in (20) are about the same with the equivalent load resistance Reg and the phase differences e02 in (21) become almost zero when the terms w02KLp is much more than the equivalent load resistance Reg (the load quality factor QL is very high).…”

Secondary Side Output Voltage Stabilization of an IPT System by Tuning/Detuning through a Serial Tuned DC Voltage-controlled Variable Capacitor

“…Since a separate communication channel is normally needed for primary side control [3]- [10], it is more straightforward to directly regulate the output voltage at the secondary side [11]- [18]. In [11]- [13], an active switch is used to short the secondary side circuit to regulate the power flow and to stabilize the output voltage.…”

Design and Optimization of Inductive Power Link for Biomedical Applications

“…Powering biomedical devices is a major issue in the design of wearable and implantable electronics Chaimanonart et al (2006); Chen et al (2009); Kendir et al (2004); Smith et al (2002). Often, there is not space available for a battery that will last for the lifetime of the device, as batteries are limited both by total charge storage ability and number of recharge cycles Heller (2006).…”