Radial force control for triple three-phase sectored SPM machines. Part I: Machine model

Abstract

Access from the University of Nottingham repository:http://eprints.nottingham.ac.uk/45288/1/Radial%20Force%20Control%20for%20tripe %20three-phase%20sectored%20SPM%20machines.%20Part%201%20Model %20machine.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk  Abstract -The radial force control technique for a triple three-phase Surface Permanent Magnet (SPM) machine is investigated in this paper. The machine has a nine-phase winding arranged in three sectors and supplied by three different Voltage Source Inverters (VSI). A machine model is developed, based on the multi space vector approach. The multi space vector current control technique is exploited to control the torque and the radial force. The radial force control can be useful to compensate for a bearing fault or for a rotor eccentricity. Finite element simulations are used to validate the model and the control technique. Finally, criticalities of the control and modelling aspects are discussed.Index Terms-Analytical models, brushless machines, fault tolerance, fault tolerant systems, force, force control, machine vector control, permanent magnet machines. I. INTRODUCTIONULTIPHASE machines have a series of benefits, when compared to conventional three-phase ones, in terms of performance and fault tolerant behaviour. Owing to the higher number of phases, the degrees of freedom increase allows controlling more harmonics of the air-gap field. The multiphase current control can be exploited to reduce the torque ripple related to the higher harmonic fields, to levitate the rotor in a bearingless configuration, to define a sensorless machine control, to detect machine faults and implement fault tolerant controls, and for other purposes related to the various machine topologies [1]- [3].The radial force can be controlled with two motor topologies according to their winding configuration: dual set and single set winding. While in the first category the radial force is produced by the design of a specific winding with a different pole pair number, in the latter one it is generated by the multiphase machine control. Indeed, in multiphase machines it is possible to inject current sequences in order to control both even and odd field harmonics, and so both the radial force and the torque [4].In critical systems or when high reliability is required, a...

Power-Sharing Control in Bearingless Multi-Sector and Multi-Three-Phase Permanent Magnet Machines

“…The reluctance and higher order contributions to the radial force are the cause of the discrepancy between the FE calculated force and the analytically estimated one. A more complex model could be developed to consider in detail all the contributions to the radial force production, including also the reluctance component [45]. However, this would further increase the control algorithm complexity.…”

Radial force control for triple three-phase sectored SPM machines. Part II: Open winding fault tolerant control

“…Modeling the machine in mechanical angles and with the time dependence implicit, it is possible to approximately define a torque control independent from the radial force one [15]. The resulting torque equation is  , …”

“…This paper is the second part of a work on the radial force control for triple three-phase sectored SPM machines. In the first part (Part I [15] The machine model developed in [15] …”

Space Vectors and Pseudoinverse Matrix Methods for the Radial Force Control in Bearingless Multisector Permanent Magnet Machines

“…The multi-sector winding design of a permanent magnet machine, where independent three-phase windings are located in different stator areas (sectors), is a possible multiphase solution to allow a radial force control. The complexity of the control of such a system emerges when a detailed analysis is carried out to allow a radial force control, as in this work, or if asymmetries and faults are taken into account in order to avoid performance deterioration [18]- [21]. The main objective of this paper is the validation of two different radial force and torque control techniques applied to a MSPM machine.…”

“…The first one exploits the Moore-Penrose pseudo inverse of the machine model matrix formulation to obtain those α − β reference currents that generate the required force and torque minimizing the Joule losses [22], [23]. Instead, the second method exploits the SV technique to generate appropriate magnetic field harmonics in the airgap responsible for both torque and radial force generation [18], [19]. Both the methods are employed to achieve a two DOF bearingless operation.…”