Research On Power Transmission And Carrier System Of Ventricular Assist Device

Ventricular Assist Device(VAD)is a kind of medical device used for the treatment of heart failure,which can be applied in the treatment for patients suffering from short and medium term heart failure.Its working principle is that,the mechanical centrifugal blood pump partially substitutes for the heart function to reduce the pressure of the left atrium and left ventricle via delivering the oxygenated blood contained in ventricle to the aorta directly.At present,the major VADs in the world exist many problems,such as excessive number of conductors inside the percutaneous cable,complex operation of doctors,high infection rate and etc.Power-line Carrier Communication(PLCC)is one type of the signal transmission modes to adopt the power transmission line as the transmission channel.This research on the power-line carrier system of VAD is mainly aiming at the decrease in the number of percutaneous intra-cable wires between VAD and external controller,the reduction in the difficult of operation and the rate of infection after operation.In order to design a VAD system with fewer internal wires of percutaneous cable,more stable operation and lower error rate.The magnetic suspension centrifugal blood pump developed by CH Biomedical Inc.was used to research and analyze the basic theory and implementation scheme of Quadrature Phase Shift Keying(QPSK),and the BER characteristics under Gaussian noise.Then,the special QPSK modulation and demodulation chip is used to build the hardware circuit of the power line carrier system,and the upper computer and the lower computer software of the power line carrier communication system are constructed.This paper firstly analyzes the basic principle and implementation method of power line carrier implementation from the realization of power line carrier function.The basic principle of QPSK modulation and demodulation is analyzed.The scheme of QPSK system modulation and demodulation process,and the error of QPSK system are also introduced.After that,the code rate is theoretically analyzed.The QPSK modulation and demodulation code is written by Matlab,and the BER performance of QPSK under Gaussian channel is analyzed.Secondly,the hardware requirements of the power line carrier communication system are analyzed.Using the Cadence software,the hardware of the system is redesigned,which includes the power line carrier module,button system module,OLED display module and USB communication module.Thirdly,on the Visual Studio 2015 software platform,the upper computer system for blood pump control was developed using C#language.The main functions needed in the upper computer system includes serial communication,command generation.,data recording and saving,waveform display,etc.Finally,the experimental verification of the upper computer part and the lower computer part of the system is carried out.The experimental contents mainly include pre-system function test,power line carrier test,controller function test and host computer function experiment.