Torque and controllable radial force production in a single winding bearingless switched reluctance motor with a speed controlled drive operation

Abstract

Summary Switched reluctance motors have an innate characteristic of producing significant amount of radial forces during its motoring operation owing to the nonuniformity in the air gap of the motor. This inherent radial force can be properly utilized, if produced using an external power source and controlled actively using a controlled algorithm for bearingless operation of the motor. This paper presents a single set of stator winding called bridge configured winding, which has the ability to generate both torque and radial force. The winding structure forms two sets of terminal connections in each phase's winding, one for the torque production and one for generating controllable radial force for suspension of the motor. The potential paths and commutation period for the winding currents to produce both torque and radial forces are identified, and an analytical model is developed for a 12/8 bearingless switched reluctance motor. The principle and insight of the proposed single winding scheme and its behaviour with the incorporation of the power converter circuits coupled with a speed‐current controlled drive system are analysed using a finite element model for both motoring and radial force production. The finite element–based results are validated with the analytical results obtained.

A decoupling control of composite cage rotor bearingless induction motor based on SA‐PSO support vector machine inverse

“…(2) Both the magnetic fields generated by torque winding and suspension winding are in the same direction. (3) The two windings have the same electric angular frequency of magnetic fields 23 …”

“…A bearingless induction motor (BIM) integrates the characteristics of induction motors and magnetic bearings, with several advantages, no friction, no wear, no lubrication required, a simple structure, low torque pulsation, high mechanical strength, strength and reliability and a wide range of weak magnetism. It can satisfy bearingless operation clean, corrosive, high speed, and ultra‐high‐speed environments, which are the most common applications 1‐4 . However, when the rotor is running at high speed, the lamination becomes loose.…”

Analytical representation and characteristics optimization for radial electromagnetic force of the switched reluctance motor under airgap eccentricity

“…3,4 On the other hand, the airgap eccentricity occurs due to the interference of external excitation in motor operating. 5,6 Consequently, the radial electromagnetic force will be out of balance in the symmetric direction, 7 resulting in residual unbalanced radial force that affects the electromagnetic response of the SRM as shown in Figure 1. For example, it serves as the in-wheel motor of electric vehicles, and the road excitation will cause the airgap eccentricity in the vertical direction, which seriously damage the vehicle ride comfort and handling stability.…”

Rotor vibration unbalance compensation control of a bearingless induction motor

“…Meanwhile, the unbalanced exciting force is at the same frequency as the rotational speed, and it causes unbalanced vibration of the rotor system. The unbalanced vibration force is proportional to the square of the rotational speed 11‐15 . When the motor runs at high speed, the rotor will not be able to suspend with stability and this case may even cause the friction between stator and rotor.…”