Research On Extracorporeal Magnetic Field Drive And Control System For Axial Flow Blood Pump

Blood pump circulatory support is an effective method to rescue severe heart failure. However, there still exist some technical problems in most blood pumps, such as energy transmitted, transcutenous line, and blood pump control based on physiological mechanism, which restrict their clinic application to improve recipient's quality of life. The drive system and control system are important components of blood pump, and also a key to solve the problems as mentioned above. The extracorporeal magnetic drive axial flow blood pump, which is a left ventricular assist device, utilizes magnetic field to transcutenous energy transmit, by which the post-operation infection from transcutenous line can be avoided. This type of blood pump is significant for academic research and clinic application. In this paper, the extracorporeal magnetic drive axial flow blood pump is used as the research target and ventricular work as its control objective, the whole blood pump driving and control system based on physiological mechanism is constructed through modeling, simulation and experiments. The research contents are introduced as following.Based on drive method of non contact transcutenous energy transmit and control strategy of multi-physiological signal, the drive and control system of blood pump are designed to solve the problems of device-related line (pump) and control strategy. The dive and control system are proposed for axial flow blood pump based on extracorporeal magnetic drive and physiological mechanism control.The magnetic diving system is investigated for blood pump. The mathematical model of magnetic driving model is built up based on the theory of electromagnetics. The variation regularity of magnetic line distribution and torque with different parameters of angle, distance and pole number are investigated according to the finite theory and Maxwell stress method. The parameters for matching optimum system performance of magnetic drive system are concluded form simulation results. The method to solve following performance and hang for magnetic driving system is proposed.The power source for diving blood pump is constructed. The mathematical model of the electromagnetic actuator (EMA) is constructed under the condition of using extracorporeal permanent magnet as the rotor and armature as stator. The work principle is introduced, and start performance is investigated for blood pump based on the constructed EMA mathematical model.The control system with double feedback and PI regulating structure is constructed for blood pump. These models of current regulator, rotation speed regulator PWM controller, soft sensor and EMA to blood pump are built up. The hardware configuration and software structure are designed based on DSP (Digital Signal Processing). The control system is developed based on DSP to realize the design thought of physiological mechanism control blood pump and without hardware sensor in the system.The control strategy based on ventricular work is proposed. Based on the Windkessl's model of analog systemic circulation, the blood pressure and flow equations, which includes such hemodynamical parameters as cardiac cycle, ventricular systole interval, vessel impedance, property impedance, compliance and stroke volume, are constructed and used as control model for blood pump outputs. Using hemodynamical parameters of health and morbidity as design variables, the simulation is done to the control objective model with single-factor method. According to simulation results, the influence of hemodynamical parameters to blood pump output is studied. A modify rule for control objective model is proposed comparing clinical symptom.The simulation model of control system performance is constructed to simulate system control characteristic, mechanical and dynamic property. The experiment platforms of drive system and EMA controlled performance are developed to study their performances.