Modeling And Control Design For Maglev Blood Pump

Heart failure,as a pathophysiological syndrome which damages ability of filling ventricle and ejecting blood,has threatened seriously human health.At present,artificial heart,as a substitute for heart transplant,takes the fancy of researchers,and has become an effective medical device of alleviating ventricular failure.Especially,the third-generation artificial heart characterized by magnetic suspension owns many advantages,such as frictionless,lubrication-free support.Thus,maglev blood pump has been viewed as ideal objects by researchers.In general,magnetic levitation is controlled and designed well based on linearization models,which achieves good performance.As for maglev blood pump,however,it requires compact structure,low power consumption.Compared with maglev blood pumps in air,dynamic characteristics of magnetic levitation in the liquid will vary constantly,which makes the design and optimization of the control system complicated.CHVAD Demo V,the centrifugal blood pump developed by Suzhou Tongxin Medical Equipment Company,was served as the subject investigated.The project included mainly two aspects:the study on dynamic characteristics of the maglev blood pump in different environments and the optimization of controllers applied in the magnetic levitation.The detailed work is as follows:1.According to the maglev blood pump,sub-blocks and series of parameters of the magnetic suspension system have been analyzed and measured,which were then used to obtain the mathematical model;2.The model structures of the magnetic suspension was constructed based on Adams/Simulink after analyzing the actual open loop in different fluids during different rotational speeds;3.Considering the characteristics of maglev system,the parameter-varying PD controller was designed under different working conditions;4.The microcontroller STM32 has been used to realize the control based on design methods to the digital control,and then levitation and rotation tests were performed on the magnetic levitation.The following main progress can be brought based on the work above:first,the simulation by Adams/Simulink provided the reference for study on the magnetic levitation system under different environments;Second,According to the experimental results,the dynamic characteristics of maglev blood pump varied in the air,water and glycerol solution,and also changed at different speeds,the phenomenon became more obvious especially in the liquid;Third,the variable-parameter controller made the suspension performance optimized under different working conditions.These researches may not only reduce design phases of modeling and controller design,but also improve the performanceof magnetic suspension system under different working conditions.