is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Abstract-This paper deals with the generation of optimal current references for Multiphase Permanent Magnet Synchronous Machines in normal or fault mode (open-circuited phases). Current references are computed in order to keep a constant torque while minimizing instantaneous Joule losses. In comparison with commonly used scalar methods, a vectorial approach makes it possible to reduce the number of computations in order to generate optimal current references, in real-time. In addition to this, since current references are expressed in terms of physical parameters of the machine, this approach can be used to evaluate the influence of the machine parameters over the control performances. Finally, experimental results of a surface mounted permanent magnet five-phase synchronous machine are provided in order to demonstrate the proposed strategy.

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication.

an alternative to traditional field-oriented control (FOC) methods for three-phase drives. The conventional DTC scheme has been successfully extended to multiphase drives in recent times, using hysteresis regulators to independently track the desired torque and flux in symmetrical five-phase induction machines (IM). The fault-tolerant capability of multiphase drives is an interesting intrinsic advantage for safety-critical applications, where recent research has demonstrated the effectiveness of FOC schemes to perform ripple-free post-fault operation. In spite of the utility of DTC methods in normal operation of the multiphase machine, no extension to manage the post-fault operation of the drive is found in the literature. In this paper, a novel fault-tolerant DTC scheme is presented. The performance of the proposed method is experimentally validated in a five-phase IM drive considering an open-phase fault condition. Provided tests analyze steady and transient states, including the transition from pre-to post-fault operation. Obtained results prove the interest of the proposal, which ensures the open-phase fault-tolerant capability of DTC controlled five-phase IM drives. Index Terms-Direct torque control (DTC), fault-tolerant capability, multiphase induction motor (IM) drives, open-phase fault operation.

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. This is an author-deposited version published in: https://sam.ensam.eu Handle ID

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Direct torque control (DTC) has been recently used for the development of high performance five-phase induction motor (IM) drives, where normal operation of the system has been usually considered and the ability of DTC to manage the situation has been analyzed in comparison with different rotor field-oriented control (RFOC) strategies. The exploitation of fault-tolerant capabilities is also an interesting issue in multiphase machines, where the utility of RFOC controllers has been stated when the open-phase fault operation is considered. In this paper, the performance of DTC and RFOC controllers based on proportional resonant regulators and predictive control techniques is compared when an open-phase fault appears in a five-phase IM drive. Experimental tests are provided to compare the performance of the system using these control alternatives. Index Terms-Direct torque control, multiphase induction motor drives, rotor field-oriented control, open-phase fault operation. NOMENCLATURE DSP Digital Signal Processor. DTC Direct torque control. EMF Electromotive force. IM Induction machine. MCL Minimum copper loss. MMF Magnetomotive force. PCC Predictive current control. PI Proportional integral. PR Proportional resonant. PWM Pulse width modulation. RFOC Rotor field-oriented control. THD Total harmonic distortion. VSD Vector space decomposition. VSI Voltage source inverter. VV-DTC Virtual vector based DTC ed,q Direct and quadrature feedforward terms. In Nominal stator current value. iα,βr Rotor currents in the α-β subspace. ia,b,c,d,es Stator phase currents. id,qs Direct and quadrature stator currents. iα,βs Stator currents in the α-β subspace. ix,ys Stator currents in the x-y subspace. izs Stator current in the z subspace. i * α,βs,max Maximum reference currents in the α-β subspace. J Cost function for PCC. Llr Rotor leakage inductance. Lls Stator leakage inductance. Lm Magnetizing inductance. Lr Rotor inductance. Ls Stator inductance. p Number of pole pairs. Rr Rotor resistance. Rs Stator resistance. Si Switching signals of every VSI leg. Te Electrical torque. TL Load torque. Tn Nominal torque. T0 Generalized Clarke transformation matrix. TPOST Modified VSD transformation matrix. Vdc DC-link voltage. VVi Virtual voltage vectors. va,b,c,d,es Stator phase voltages. vd,qs Direct and quadrature stator voltages. vα,βs Stator voltages in the α-β subspace. vx,ys Stator voltages in the x-y subspace. ϑ Fixed spatial displacement between windings. λα,βs Stator fluxes in the α-β subspace. ωe Electrical speed. ωm Mechanical speed. ωr Rotor electrical speed (defined as p•ωm). * (superscript) Reference variables. ^ (superscript) Estimated variables.

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