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

Abstract

This paper deals with the power-sharing control of bearingless multi-sector and multi-three-phase permanent magnet machines. The proposed control strategy allows to distribute the power flows among the three-phase inverters supplying the machine during bearingless operation of the drive. The control technique is based on the extension of the vector space decomposition modeling approach. The components producing the electromagnetic torque, i.e. the q-axis currents, are controlled independently from the d-axis ones, also with the aim of managing the power flows among the three-phase systems. Conversely, the d-axis currents are exploited for the generation of the radial forces needed to levitate the rotor, while considering the compensation of the forces caused by the q-axis currents in case of unbalanced power sharing strategy. The validity of the proposed method is confirmed by simulations and experimental tests on a prototyped bearingless multisector permanent magnet synchronous machine. The proposed approach is a contribution to the development of advanced control systems employing multiphase drives in the field of bearingless and multiport applications. Index Terms-Bearingless machines, force control, machine vector control, magnetic levitation, multiphase drives, permanent magnet machines, power-sharing, variable speed drives. NOMENCLATURE Pole pair number. Subscript used to identify the sub-windings under the same P th sector (= 1,2, … ,). Number of three-phase star connected windings located under each pole pair (sector). T Subscript used to distinguish the sub-windings under the same P th sector (= 1,2, … ,). ̅ , Current space vector of each T th three-phase sub-winding under the P th sector.

Electric Traction Chain with Segmented Power Supply

“…The phase windings of an electric machine can be split to add redundancy to the electric drive [25] or to adapt the voltage ratings of the machine and of the power electronics [14]. Alternatively, multi threephase machines can be obtained by splitting the different sectors of a three-phase machine [26] or by grouping the phases of multi-phase drives [27].…”

Control of a Segmented Three-Phase Synchronous Motor With Highly Coupled Subwindings

“…For a given three-phase motor and a given current rating, it is possible to reduce the voltage rating by using several independently supplied winding sets [5]. These structures, often referred to as segmented drives, are also relevant approaches in ensuring continuity of service and enhancing drive energy efficiency since each phase is made of several sub-windings [6]. Improvements in connector technology [7], [8] as well as the attractive benefit of integrating power converters close to the motor end windings [3], [9], [10] highly mitigate the drawback of modular structures, namely the increased number of terminals.…”

“…Multi-Sector Segmentation (MSS) layout is the standard approach in segmenting the windings of a three-phase motor. Each elementary three-phase winding set is housed in a distinct stator sector [6], [21], [25]- [27]. As any other segmentation process, the MSS approach induces no change in the motor Matrix with MDQF, Scalar with the proposed CDM method low harmonic torque ripple distribution [21] while enabling the parallelization of low voltage DC sources [3].…”

“…As any other segmentation process, the MSS approach induces no change in the motor Matrix with MDQF, Scalar with the proposed CDM method low harmonic torque ripple distribution [21] while enabling the parallelization of low voltage DC sources [3]. However, an additional radial force control is required in the MSS structure in order to take advantage of its power sharing capability [6] or to implement a fault-tolerant scheme [22]. Moreover, the MSS approach is limited by the number of poles per phase N p .…”

Modular Power Sharing Control for Bearingless Multithree Phase Permanent Magnet Synchronous Machine

“…This conclusion makes the modular multi-m phase winding a serious contender in fault tolerant bearingless applications. This particular drive architecture has already been investigated in [23] for a bearingless application with power sharing capability among modules. However, the presented control strategy was based on the vector space decomposition approach.…”