Equivalent two-phase mutual inductance model and measurement algorithm of three-phase bearingless motor

Abstract

For a bearingless motor that has two sets of stator windings, i.e. torque windings and suspension windings, the mutual inductance between the two sets of stator windings is a critical parameter; it is the basis of displacement sensorless control technology. Aiming at a three-phase bearingless motor, the equivalent two-phase mutual inductance model between two sets of stator windings is deduced. Then, based on the mutual inductance measurement method of a simple two-phase bearingless motor, a novel measurement algorithm of the equivalent two-phase mutual inductance is proposed, and the proposed measurement algorithm is applicable for a three-phase bearingless motor. Finally, based on a three-phase bearingless induction prototype motor, the experimental measurement of the equivalent two-phase mutual inductance is carried out. From the experimental results, it is clear that within the limited radial eccentricity of the rotor, the measured value of the equivalent two-phase mutual inductance is approximately proportional to the radial displacement of the rotor, and the correction coefficient kc of the equivalent two-phase mutual inductance model is derived; the consistency between measured and calculated values has verified the validities of the equivalent two-phase mutual inductance model and the proposed measurement algorithm from one instance. Thus, the theory foundation has been laid for research on the displacement sensorless vector control technology of a three-phase bearingless motor.

Research on the Speed Sliding Mode Observation Method of a Bearingless Induction Motor

“…[1,[6][7][8][9]. The bearingless motor (BLM) is a new AC motor [1,[10][11][12][13][14][15] proposed based on the similar structure between an ordinary AC motor stator and a magnetic bearing. Under normal circumstances, two sets of windings are embedded in the BLM stator, including a set of torque windings with pole-pair number p 1 and current frequency ω 1 , and a set of suspension windings with pole-pair number p 2 and current frequency ω 2 .…”

“…Compared with a magnetic bearing motor, the BLM has unique advantages, such as a shorter shaft and a higher critical speed, etc., giving it bright application prospects in the high-speed-drive field [1,10,11,[21][22][23][24][25]. In all kinds of BLMs, because of the robust structure and larger stiffness coefficient of magnetic suspension force, the bearingless induction motor (BL-IM) has aroused wide attention [1,[6][7][8][9]12,13,[26][27][28].…”

LS-SVM Inverse System Decoupling Control Strategy of a Bearingless Induction Motor Considering Stator Current Dynamics

“…The AC motor supported by magnetic bearing has been widely used in the high speed drive field [1]- [4], but it still has some disadvantages, such as the higher magnetic suspension power consumption, the difficulty to over speed, etc. [5]- [8]. The bearingless motor is a new type of AC motor that is proposed based on the similarity of stator structure between ordinary AC motor and magnetic bearing [9], [10].…”

“…The bearingless motor is a new type of AC motor that is proposed based on the similarity of stator structure between ordinary AC motor and magnetic bearing [9], [10]. Normally, there are two sets of windings in the stator slots of bearingless motor, one is the torque windings with current angular frequency ω 1 and pole-pair number p 1 , another is the suspension windings with current angular frequency ω 2 and pole-pair number p 2 [5], [10]. The magnetic field…”

Load disturbance rejection control of a bearingless induction motor based on fractional-order integral sliding mode

“…It is widely used in high-speed hard disk, aerospace, petrochemical industry, aseptic workshop, life science and other fields. [6][7][8][9] However, the BIM control system is a multivariable, nonlinear and strong coupling system. Especially when the internal parameters of the system are changed or the system is influenced by external disturbances, higher requirements for high-performance precision control are put forward.…”