Dynamic characteristics of a large gap magnetic driving blood pump during start-up process

Tan Jianping¹ - Liu Yunlong¹ - Xu Yan^1,2 - Liu Zhijian¹ - Zhu Zhongyan¹ - Jiang Tingting¹

¹ School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
² Department of Mechanical and Electrical Engineering, Changsha University, Changsha 410003, China

Abstract
In order to obtain the dynamic law of blood pump under a large gap and achieve optimal control of pulse frequency during the start-up process, dynamic characteristics of the blood pump were studied. First, the driving torque of the large gap magnetic drive system was solved. Second, the dynamic equilibrium equation, the continuity equation of water flow and the net head-flow equation of the pump during the start-up process were deduced. Then a mathematical model of dynamic characteristics of the pump was established. Taking the start-up process under a coupling distance of 60~mm between the driving electromagnet and the driven permanent magnet as an example, the mathematical model was solved using MATLAB, and the relation between various important parameters such as speed, flow with regard to time were obtained. Then the optimal driver was designed according to the discretization of the acceleration curve and used for blood pump experimental research. By comparing the curves resulted from the numerical solution of the dynamic mathematical model with the experimental characteristic curves, the correctness of the model was demonstrated. The experimental results also confirm that, compared to the driver based on the linear acceleration curve, the optimal driver can significantly shorten the acceleration time, and the efficiency of energy transfer of the driving system is comparatively higher. Figs 12, Refs 23.