Design And Control Of A Novel Bearlingless Switched Reluctance Motor With Double Stator

Bearingless switched reluctance motor (BLSRM) is a new type of motor whichdeveloped on the basis of traditional switched reluctance motor (SRM). It not only hassuperior performance of SRM, but also has a good feature of bearingless motors, such asno abrasion and no friction. It will be widely used in high speed motor, aerospace and soon. BLSRM have two kinds of stator windings composed of motor main windings andradial force windings in the same stator in order to produce the radial force that can realizerotor shaft suspension. However, the radial force of BLSRM is coupled with the rotationaltorque, and the control of radial force is very difficult.In this paper, a novel BLSRM with double stator is proposed. Inside stator generatesradial force to suspend the rotor. Outside stator produces rotational torque. Compared withthe previous BLSRM, decoupling control between torque and radial force can be realizedin double stator BLSRM, at the same time, a wide and almost constant radial force can beachieved at any rotor position with a given current, so a simpler control algorithm ispossible to be applied to implement suspend the rotor.To verify the proposed structure, a novel structure and operating principle arepresented. Based on the existing work of previous researches for BLSRM, mathematicalmodels of the radial force in x-axis and y-axis direction are deduced. Through finiteelement method (FEM) analysis, the characteristics such as inductance, torque and radialforce profiles of two stator windings are analyzed with the cases of non-eccentric andeccentric rotor. From the analysis, the proposed BLSRM has linear characteristic of radialforce and independence from torque current, decoupling control between torque and radialforce can be realized. Meanwhile in order to realize steady suspension, control scheme ofdesired radial force is proposed. Some simulation results are shown to verify the validity ofcontrol strategy. The experiment system is constructed. From experiment results, it can beseen that the motor can operate steadily, the torque current has almost no effect on thesuspending force and the suspending force current also has almost no effect on the output torque, which further verifies the validity of the double stator BLSRM and its controlscheme.