Multiphysics thermal modeling and temperature characteristics analysis of a FPCB catheter pump motor

Abstract To address the potential thermal damage risk of the drive motor in percutaneous catheter pumps for cardiogenic shock interventional therapy, this study proposes a three-dimensional (3D) magneto-thermal-fluid multiphysics coupling modeling method for slotless brushless DC (BLDC) motors employing flexible printed circuit board (FPCB) windings. Firstly, a 3D anisotropic equivalent thermal conductivity model for the motor stator core and windings is established, achieving the equivalent thermal conductivity of its complex laminated structure through radial, axial, and tangential layered analytical approaches. Secondly, finite element electromagnetic field calculations are utilized to determine the iron losses, copper losses, and eddy current losses, establishing thermal source boundary conditions. A multiscale coupling approach, combining zero-dimensional lumped parameter modeling (LPM) with 3D transient computational fluid dynamics (CFD), is employed to dynamically obtain non-uniform convective heat transfer coefficients under cardiac cycle-driven conditions as thermal dissipation boundary conditions. Finally, a bidirectional fluid-solid coupling heat transfer model is established and solved, revealing the three-stage heat dissipation characteristics of the impeller flow field under rated speed conditions. The results of the simulation indicate that the proposed anisotropic equivalent model for windings reduces the equivalent error by 28%. Furthermore, under the influence of dynamic boundaries, the temperatures of both the motor housing and stator exhibit periodic fluctuations with a cycle of 0.8 s. Due to the limitations of the prototype, the experiments were conducted in air, and simulation parameters were adjusted to match the experimental conditions. The results showed that the maximum deviation between the simulation and measured data was 1.7 °C, verifying the model’s validity. This lays the foundation for further blood environment experiments.