Noh Minkyun, Gruber Wolfgang, Trumper David L
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
Institute of Electrical Drives and Power Electronics, Johannes Kepler University, 4040 Linz, Austria.
IEEE ASME Trans Mechatron. 2017 Oct;22(5):2308-2318. doi: 10.1109/TMECH.2017.2740429. Epub 2017 Aug 17.
We present a new concept of bearingless slice motor that levitates and rotates a ring-shaped solid rotor. The rotor is made of a semi-hard magnetic material exhibiting magnetic hysteresis, such as D2 steel. The rotor is radially biased with a homopolar permanent-magnetic flux, on which the stator can superimpose 2-pole flux to generate suspension forces. By regulating the suspension forces based on position feedback, the two radial rotor degrees of freedom are actively stabilized. The two tilting degrees of freedom and the axial translation are passively stable due to the reluctance forces from the bias flux. In addition, the stator can generate a torque by superimposing 6- pole rotating flux, which drags the rotor via hysteresis coupling. This 6-pole flux does not generate radial forces in conjunction with the homopolar flux or 2-pole flux, and therefore the suspension force generation is in principle decoupled from the driving torque generation. We have developed a prototype system as a proof of concept. The stator has twelve teeth, each of which has a single phase winding that is individually driven by a linear transconductance power amplifier. The system has four reflective-type optical sensors to differentially measure the two radial degrees of freedom of the rotor. The suspension control loop is implemented such that the phase margin is 25 degrees at the cross-over frequency of 110 Hz. The prototype system can levitate the rotor and drive it up to about 1730 rpm. The maximum driving torque is about 2.7 mNm.
我们提出了一种无轴承薄片电机的新概念，该电机可使环形实心转子悬浮并旋转。转子由具有磁滞现象的半硬磁材料制成，如D2钢。转子由单极永久磁通量进行径向偏置，定子可在其上叠加两极磁通以产生悬浮力。通过基于位置反馈调节悬浮力，可有效稳定转子的两个径向自由度。由于偏置磁通产生的磁阻力，两个倾斜自由度和轴向平移是被动稳定的。此外，定子可通过叠加六极旋转磁通来产生转矩，该磁通通过磁滞耦合拖动转子。这种六极磁通与单极磁通或两极磁通不会共同产生径向力，因此悬浮力的产生原则上与驱动转矩的产生是解耦的。我们已开发出一个原型系统作为概念验证。定子有十二个齿，每个齿都有一个单相绕组，由线性跨导功率放大器单独驱动。该系统有四个反射型光学传感器，用于差分测量转子的两个径向自由度。悬浮控制回路的实现方式是，在110Hz的交叉频率下相位裕度为25度。该原型系统可使转子悬浮并驱动其转速达到约1730转/分钟。最大驱动转矩约为2.7毫牛米。
