Development of Small and High-Efficiency Self-Bearing Motor Using Self-Sensing Technique for Artificial Heart

本研究提出一种新的自感控制的IPM型自轴承电机具有高效率和高的永磁结构的设计可能性。IPM电机具有凸极特性，因为主磁通方向的磁阻大于正交磁通方向的磁阻。因此，当转子旋转时，电动机绕组的电感变化问题发生，并且由于变化而无法使用自感。为了克服这一问题，提出了d-q等效结构，并证实了电感的变化可以忽略不计。基于磁等效电路推导出近似方程，解释了差动输出的非线性特性。结果表明，旋转电流和悬浮电流对传感器的敏感特性有不利影响。分别对旋转电流和悬浮电流进行了非线性补偿。补偿实现了较好的位移估计。但是，即使个别补偿是有效的，两种补偿结果的叠加也不能有效地起作用。最后，提出了利用二元多项式方程的近似系数进行线性化的方法，实现了永磁轴承电机的稳定悬浮和旋转。

This research proposes new self-sensing control for the IPM type self-bearing motor possessing high efficiency and high design possibility of permanent magnet configuration. IPM motor has a magnetic salient pole property because of the magnetic reluctance of the main flux direction is bigger than the quadrature flux direction. Therefore, when the rotor rotates, the inductance variation problem of the motoring winding occurs and self-sensing could not use by the variation. To overcome this problem, d-q equivalent structure was proposed and confirmed the inductance variation was negligible. Then the approximate equation based on the magnetic equivalent circuit is derived to explain the nonlinear characteristics of the differential output. The result shows the rotation and levitation currents have an adverse effect of sensing property. The nonlinear compensation is introduced for rotation and levitation current individually. The compensation realized good displacement estimation. But, even the individual compensation is effective, the superposition of the two compensation results does not work effectively. Finally, linearization method using the approximate coefficients of polynomial equation with two unknowns is proposed for stable levitation and rotation of the IPM self-bearing motor.