Torque Control Strategy of Polyphase Permanent-Magnet Synchronous Machines With Minimal Controller Reconfiguration Under Open-Circuit Fault of One Phase

Comparison and analysis of post-fault operation modes in a five-phase PMSM considering thermal behavior

“…Then the M 2 strategy is 12% implicitly used before the adoption of a reconfiguration. The M 4 strategies have been studied for induction machine [6] and PM machines [7]- [8].…”

“…Two main families of FTC have been developed in previous works for the opened-phase fault. In the first family (called MT, as Maximum Torque), the copper losses and the current waveform in the healthy phases are imposed to be equal [6]- [7], inducing then also identical peak currents. The current constraints for the transistors of the Voltage Source Inverter are then easily defined by the peak value.…”

“…The current constraints for the transistors of the Voltage Source Inverter are then easily defined by the peak value. Moreover, when the electromotive forces (emf) are sinusoidal [7]- [8] or with only the first and third harmonics [9] , the torque ripples are also easily controlled and references of current are calculated in order to obtain the maximum torque. In the second family of FTC, the waveforms of the currents are free: for given waveforms of emf and required average torque, the Joule losses are minimized under the constraint of zero torque ripples.…”

“…In the second family of FTC, the waveforms of the currents are free: for given waveforms of emf and required average torque, the Joule losses are minimized under the constraint of zero torque ripples. The currents are calculated either by optimization approach (as Lagrangian multiplier) in case of sinusoidal [7] but also non-sinusoidal emf [10]- [11] or by a vectorial approach [12]- [13], this last one being more convenient for real-time control and non-sinusoidal emf. With this second family of FTC, the peak currents and voltages can be quite different in the healthy phases, leading to unequal Joule losses even if the global losses are the same as the normal operation.…”

Analytical optimal currents for multiphase PMSMs under fault conditions and saturation

“…If not, from the control point of view, new references of current are required to keep a reduced constant torque. Several works presented analytical formulas of optimal stator currents which lead to the desired electromagnetic torque while minimizing the ohmic losses under open-circuit fault [12][13][14][15][16][17][18]. In general, we need two independent phases to generate a rotation of the stator magnetic field.…”