Interior permanent magnet synchronous motor (IPMSM) drives have been widely employed in sustainable transport such as electric vehicles (EV). However, the traditional vector control (VC) strategies cannot achieve optimal control due to the intrinsic property of the IPMSMs, which is strong coupling. To solve the issue, this paper proposes an improved decoupling VC strategy to improve the steady-state performance of the IPMSMs with reduced parameter mismatch impacts. First, a deviation decoupling strategy is developed, and meanwhile, the parameters that influence the decoupling method are clearly illustrated. This enriches the theory concerning decoupling control and lays the ground for the development of effective solutions to the parameter mismatch issue. Second, the Luenberger observer theory is discussed, based on which the reason why the Luenberger inductance observers are not widely employed is explained for the first time. Third, with the aid of intermediate variables, which are the disturbances caused by the mismatched inductances, a new inductance identification method based on the Luenberger observer is proposed. Finally, the simulation and experimental results prove that the proposed decoupling methods, as well as the parameter identification method, are effective.

Reluctance machines with DC field coil in stator are a competitive candidate for starter generation application, due to the elimination of rare-earth permanent magnet (PM), robust structures, and controllable excitation. However, due to the poor excitation ability of DC field coils, the torque density is disadvantageous. Moreover, with the increase in the DC field current, it is exposed to the risk of extra DC saturation in stator teeth. As a consequence, the torque density and efficiency are both constrained. To solve the aforementioned problems, based on the comprehensive consideration of production cost and torque performance, this study proposed a novel type of hybrid reluctance machine with dual-ferrite–assisted in stator slots. The inner-layer ferrite PM is magnetized tangentially, which can effectively achieve the DC-saturation–relieving effect, while the outer-layer ferrite PM is magnetized radially to increase the machine torque density through the flux modulation effect. Based on finite element analysis, the machine torque density and efficiency can be improved by 20 and 5%, respectively. Furthermore, to simplify the excitation system of the DC terminal, a two-stage excitation method is proposed by splitting some turns of armature winding to feed DC field winding with passive rectifier. No power switching devices are needed for the excitation system in this way, making the system highly robust. The effectiveness of the proposed design is verified by time-stepping finite element analysis.