Torque control of IPMSM drives using direct flux control for wide speed operation

Although the interior permanent magnet synchronous motor (IPMSM) is more capable of an extended speed range than EPMSM, control objectives are difficult to achieve in the transient period and flux-weakening regime because of the limited DC bus voltage and de-tuning of the current regulator in the overmodulation region and extended speed range. A new, fast response torque control strategy based on the stator flux control is proposed in this paper to cope with this situation. Compared with past work, the new control scheme not only improves the torque production over the entire speed range but also extends the speed range of constant power operation. Current regulator saturation, the worst degrading factor of torque production in the extended flux-weakening range, is eliminated.