ENERGY TRANSMISSION SYSTEM FOR ARTIFICIAL

HEART

Contents

Introduction Artificial Heart Energy Transference Scheme Determination of Control Region System Design Input Voltage and Converter Type Control of the System Conclusion Reference

Introduction

Electrical circulatory assist devices use brushless dc motor as its pump

Electrical energy is transferred to these devices transcutaneously using a transcutaneous transformer

Transcutaneous transformer has large leakage inductance which reduce its efficiency

Dc-dc converter employing secondary side resonance can be employed to alleviate this problem but the transfer gain of voltage varies widely with coupling coefficient

Converter employing compensation of leakage inductance on both sides of the transformer offers stable gain and high efficiency

Artificial Heart

Mechanical heart which completely substitutes the natural heart anatomically and physiologically

Extra pumping chamber that can pump blood throughout the body

Can be used either temporarily or permanently Made up of metal and plastic Has 5 major parts

Energy Source

Control and driving system

Energy conversion system

Pump actuator

Blood handling parts

Energy Transference Scheme

Use method of compensation of leakage inductance on both sides of the transcutaneous transformer

In this scheme capacitors are added in series to compensate the leakage inductance

Voltage gain of the converter is:

Determination of Control region

Gv curve is divided into 3 regions: low frequency, middle frequency and high frequency regions

Region II provides maximum transfer gain but is very sensitive to changes in load and coupling coefficient, hence not used

Region I and III can control output voltage Region III is desirable because the unity gain

frequencies is much less sensitive than for region I

System Design

Output requirements: V0 = 24V Iomax =2.0A I0min =0.5A Size, geometry and core material of the

transformer and range of air gap and misalignment between them are already defined

For transformer windings the same cores used in series converter are used

System Design

Transformer Core: Ferroxcube Pot Core 6656 3C8 Ferrite OD=2.6in Thickness=1.1in Air gap=10-20mm Misalignment=0-10mm Region III of gain characteristics is selected for control Low value of Q is selected to reduce sensitivity if

variation Compensating resonant frequency is chosen at 120kHz

Input Voltage and Converter Type

Control of the System

Conclusion

Converter employing leakage inductance compensation of transcutaneous transformer provides high voltage gain and reduced circulating current

A control region of operating frequency is determined

The converter offers high efficiency Minimized configuration of the devices in the

thorax is experimented

Reference

www.ieee.org www.wikipedia.org www.medscimonit.com www.ferroxcube.com www.sciencedaily.com www.synchardia.com www.essortment.com