大间隙永磁轴流式血泵速度控制研究

发布时间：2018-06-14 17:48

本文选题：轴流式血泵 + 大间隙　；参考：《中南大学》2013年博士论文

【摘要】：血泵作为人工心脏的核心部件,最主要的功能是代替自然心脏完成泵血功能,因此血泵驱动系统与控制方法的研究,是人工心脏走向临床应用所要面临的首要问题。在血泵的大间隙磁力驱动技术应用研究方面,血泵的转速与机体的生理状态有着直接的对应关系,是系统首要的控制目标参数。而目前对血泵的速度控制策略缺乏较为深入的研究,血泵启动过程的稳定性、调速响应的快速性以及运行过程的平稳性等均有待提高。此外,系统还存在能量利用率低、发热严重及驱动装置笨重等问题,且对系统的控制参数(通电电流、脉冲频率、驱动程序)、性能参数(驱动力矩、负载功率)以及输出状态参数(血泵转速、流量、压力)等之间的相互作用规律缺乏较为系统的研究。本文以实现血泵快速、平稳的调速响应和可靠、安全的运行状态监控为目标,通过对系统电磁驱动性能、能量损耗以及矩频-矩角特性等基础科学问题的研究,提出血泵调速及稳定运行过程的速度控制方法,并实现了血泵输出状态的闭环控制,为血泵自适应控制系统的建立提供参考。论文的主要研究内容及结论： 1、设计血泵电磁驱动闭环控制系统根据人体生理模式基本调节机制,针对不同生理状况(不同血压)下所对应的不同心脏搏血量,设计轴流式血泵的磁力驱动闭环控制系统,以血泵输出流量为反馈控制参数,实现了满足不同血压(不同的血泵出口压力)下血泵出口流量的自动调节。 2、建立电磁驱动系统能量损耗计算模型针对系统中的涡流损耗、磁滞损耗和铜损等几种主要能量损耗形式,建立血泵电磁驱动系统能量损耗数学模型；仿真研究不同铁芯形状对电磁体铁损耗的影响规律,结果表面铁芯形状对磁滞损耗影响不大,而当铁芯形状不对称时,对涡流损耗影响约为5%。 3、基于矩角特性提出最大驱动力矩磁极状态控制方法根据驱动电路电压-电流方程,建立电磁驱动系统的矩频-矩角特性数学模型,研究通电电流随脉冲频率的变化规律,通过数值计算和实验,得出能使血泵获得最大磁驱动力矩的电磁体磁极状态切换偏移角计算公式,提出磁极状态控制方法。 4、基于矩频特性提出最小能耗血泵启动电流控制方法基于矩频特性和能量损耗模型,提出最小能耗血泵启动过程电流控制方法,实验验证了小电流递增启动方法的可行性；从启动响应的快速性出发,提出了基于血泵启动过程动力学模型的速度控制方法,通过实验,血泵能在2s内达到额定输出功率,验证了控制方法的有效性。 5、提出血泵恒功率输出控制方法针对血泵稳速运行过程,提出不同耦合距离下血泵恒功率输出控制方法,能根据磁极耦合距离的变化,实现稳定的血泵输出功率；基于磁极状态偏移角计算公式,提出血泵最大磁力矩控制方法,采用修正后的控制程序,使血泵的最大负载力矩提高了9.5%。
[Abstract]:As the core part of artificial heart , the main function of blood pump is to replace the natural heart to complete the pump blood function , so the research of the blood pump driving system and control method is the primary problem to be faced by the artificial heart to the clinical application .

In the application of the large - gap magnetic drive technology of blood pump , the rotational speed of blood pump is directly related to the physiological state of the body , which is the primary control target parameter of the system .

In order to realize the fast and stable speed regulation response and reliable and safe operation state monitoring of blood pump , this paper puts forward the speed control method of blood pump speed regulation and stable operation process by studying the basic science problems such as electromagnetic drive performance , energy loss and moment frequency - moment angle characteristic of the system , and realizes the closed - loop control of the output state of the blood pump , and provides reference for the establishment of the blood pump self - adaptive control system .

The main contents and conclusions of the thesis are as follows :

1 . Design blood pump electromagnetic drive closed - loop control system

according to the basic regulation mechanism of the physiological mode of the human body , the closed - loop control system of the magnetic force of the axial - flow blood pump is designed aiming at different heart beat blood volumes corresponding to different physiological conditions ( different blood pressure ) , the output flow of the blood pump is used as a feedback control parameter , and the automatic regulation of the outlet flow of the blood pump under different blood pressure ( different blood pump outlet pressure ) is realized .

2 . Establish an electromagnetic drive system energy loss calculation model

Aiming at the eddy current loss , hysteresis loss and copper loss in the system , the mathematical model of energy loss of the electromagnetic drive system of blood pump is established .
The influence of different core shape on iron loss of electromagnet is studied . The influence of surface iron core shape on hysteresis loss is not large , and when the shape of iron core is asymmetric , the influence of core shape on eddy current loss is about 5 % .

3 . Method for controlling state of pole state of maximum driving torque based on moment angle characteristic

According to the voltage - current equation of the drive circuit , a mathematical model of the moment frequency - moment angle characteristic of the electromagnetic drive system is established , and the change law of the electrified current with the pulse frequency is studied . Through the numerical calculation and experiment , the calculation formula of the magnetic pole state switching offset angle can be obtained which can make the blood pump obtain the maximum magnetic driving torque , and the magnetic pole state control method is proposed .

4 . Method for controlling starting current of blood pump with minimum energy consumption based on moment frequency characteristic

Based on the moment frequency characteristic and the energy loss model , the current control method of the minimum energy consumption blood pump starting process is put forward , and the feasibility of the small current incremental starting method is verified .
Based on the rapidity of starting response , the velocity control method based on the dynamic model of blood pump is put forward . Through experiments , the blood pump can reach the rated output power within 2s , and the effectiveness of the control method is verified .

5 . Method for controlling constant power output of blood pump

aiming at the steady - speed operation process of the blood pump , a constant power output control method of the blood pump at different coupling distances is proposed , and stable blood pump output power can be realized according to the change of the coupling distance of the magnetic pole ;
Based on the calculation formula of magnetic pole state deviation angle , the maximum torque control method of blood pump is put forward , and the maximum load torque of the blood pump is increased by 9.5 % by the modified control program .
【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R318.11;TP273

【参考文献】