| Summary: | 碩士 === 國立臺灣海洋大學 === 電機工程學系 === 106 === In recent years, the medical equipment has been developed rapidly to help patients to continue their lives or promote health. The left ventricular assist device (LVAD) is a kind of technological product that assists patients with heart disease by diverting blood from the atria or ventricles to the pump and then back into the artery to relieve the workload of the heart. For patients of no matter whether sudden acute myocardial infarction or chronic heart failure after cardiac surgery, without any improvement on them with the help of drugs or intra-aortic balloon pump (IABP), then LVAD can be used instead of cardiac function to increase longevity or increase heart transplant opportunities. At the same time, it also greatly improves the life quality of patients.
There are two kinds of left ventricular assist devices, in which one is external and the other is long-term implantable. Using electricity to drive the LVAD pump is a more convenient type in the two devices. However, how to avoid frequent operations and continuous power supply becomes a major issue. The long-term implantable LVAD contains a chargeable battery that can be continuously powered by electronic technology to reduce the hospital's medical resources and the patient's inconvenience of life. The wireless charging technology for battery leads to the motivation of this study.
The aim of this thesis is to study non-contact electromagnetic induction charging technologies for the power of medical equipment. Different from the traditional charging mode directly connected to the power supply, the non-contact inductive charging technology uses the principle of transmitting energy through radio waves which can inductively charge the rechargeable batteries without wires.
This study first analyzes the system architecture of the charging circuit, and designs a circuit whose frequency is in accordance with the human body frequency band by means of the voltage doubler circuit. The positive and negative values of the voltage at the input terminal of the Zener diode are used to control the switching and achieve the effect of voltage growth. Then, NI Multisim simulation software is applied in the frequency band of 800 MHz to 1500 MHz. The capacitance values are chosen in 0.001 pF, 0.002 pF, 0.01 pF, 0.1 pF, 1 pF, 10 pF and 100 pF, therefore voltage is multiplied by 6 to 12 stages (times) with the Zener diode and capacitors circuit.
After analyzing the result of simulation, the best circuit parameters are: 11-stage circuit, capacitance of 0.001 pF, and voltage amplification rate of 0.001 pF up to 343%.Which are in line with the goal of the most simplified and optimized performance of the circuit.
This study discusses the circuit parameters of human-appropriate medical devices by the analysis of voltage doubler circuits. Finally, the research results are in line with the circuit specifications for the wireless charging requirements of left ventricular assistive device (LVAD). The LVAD is an expensive medical device (for example: the price of a HeartMate type 2 (Abbott Inc. USA) LVAD is about 5.5 million NTD). Our laboratory lacks the entity of the LVAD, so this study only bases on the theory of electrical engineering. Research on the improvement of electronic medical equipment is conducted and practical conclusion is also obtained as a design reference of wireless charging circuits in the future.
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