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Transcript
ENERGY TRANSMISSION
SYSTEM FOR ARTIFICIAL
HEART
Contents
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Introduction
Artificial Heart
Energy Transference Scheme
Determination of Control Region
System Design
Input Voltage and Converter Type
Control of the System
Conclusion
Reference
Introduction
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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
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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
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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
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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
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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
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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
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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
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www.ieee.org
www.wikipedia.org
www.medscimonit.com
www.ferroxcube.com
www.sciencedaily.com
www.synchardia.com
www.essortment.com