L Study Of The Phase Angle Of The Magnetic Moment Of The Large Gap Magnetic Drive System And The Electromagnetic Body Temperature Of The Blood Pump

Taking the large gap magnetic driving system as the way of energy supply for permanent magnet axial flow blood pump can conquer engineering and medical problems such as wear and infection and rejection brought by traditional driven approach effectively. However, the driving torque will decrease rapidly with the gap between poles increasing and can't be utilized fully with equal phase angle, the temperature rise will be very high with magnetic working and the human body may not adapt and the reliability of the system may be affected. So phase angle of magnetic torque of the system must be controlled reasonably and temperature rise must be ensured to be lower than the permission.Two switching modes of poles for generating driving magnetic field were presented, single pole and double pole switching. The coupling mechanism and driving torque and the energy transfer efficiency and loss of the electromagnets of the system were compared. Choose double pole switching mode as the generating method at last. The driving torque of the system was simulated based on ANSYS software. The concept and solution of the best phase angle for magnetic field was presented through analyzing the relationship between the driving torque and phase angle for four pole-states of the electromagnets. The approximate formula for the best phase angle was drawn through analyzing the influence of the position of magnetic poles on the best phase angle of the system. The temperature rise was calculated using ANSYS software based on the analysis of heat exchange mechanism and determining thermal properties. It shows that the maximum temperature of the electromagnets is very high and measures to reduce temperature rise were studied through reducing loss and improving thermal conductivity and cooling conditions.The results show that the obtained best phase angles can get the largest driving torque, temperature rise of electromagnets can be reduced by minimizing loss and improving cooling conditions, When the electric current of a single coil is less than 0.56A, the air velocity is more than 3.5 m/s and the air temperature is less than 10℃, the maximum temperature of the electromagnets will be less than 50℃. The study conclusions have important theoretical significance for improving driving torque of the system and reducing temperature rise of electromagnets and improving large gap magnetic driving system of blood pump to ensure reliability of the system.