Actually, the literature on the subject has grown exponentially during the last years. Accordingly, multiphase drives are becoming remarkable contenders for applications where high reliability is required, such as electric vehicles and standalone/off-shore generation. That is the case of failures in the dc link, resolver/encoder, control unit, cooling system, etc. Moreover, their greater number of degrees of freedom permits improving diagnosis and performance not only under faults affecting individual phases, but also under those affecting the machine/drive as a whole. Their phase redundancy makes them able to continue running in the event of faults (e.g., open/short-circuits) in certain phases. Multiphase drives offer enhanced fault-tolerant capability compared with conventional three-phase ones. The standard vehicle driving cycle test result shows that this optimisation brings a nearly 11% reduction of the overall estimation error. The speed‐dependent convective thermal resistances are formulaically parameterised and then used to replace the related constant thermal resistances in the thermal model. It is found that the changing trend of the airflow presents a multi‐stage characteristic in the speed range of 0–12,000 rpm. Aiming at eliminating this error and improving the accuracy, this paper explores the variation of the airflow's aerodynamics characteristics and the heat convection with the rotational speed through a syncretic study of theoretical, experimental, and numerical methods. However, in practical situations, the thermal convection intensities on the surfaces of the air gap and the end‐cavity vary significantly with the rotational speed, producing a non‐negligible influence on the estimation accuracy of the onboard thermal model. The onboard thermal model is generally in an analytical form with constant thermal resistances. Using the embedded onboard digital thermal model is an economical and effective way to monitor the rotor temperatures of the electric vehicle (EV) propulsion Permanent Magnet Synchronous Motor (PMSM) in real‐time. The experiment results show that the proposed scheme achieves better control performance than the conventional PI controller based thermal control and can effectively reduce peak rotor temperature and hence thermal stress of the machine for improving its lifetime. The proposed control scheme was assessed by simulations and experiments on laboratory machine drive systems and compared with a PI controller based rotor temperature control. Compared with the existing multi-node thermal model based MPC thermal control scheme, the parameters of the proposed one-node thermal model can be easily obtained from a set of experiments while the computation burden of the proposed MPC control was decreased significantly. The proposed MPC control scheme can adaptively set a current limit according to the thermal state of machines to limit the rotor temperature. Since the capability of overload operation is closely related to rotor temperature for some types of motors, in this paper, a novel one-node lumped-parameter thermal model is proposed and adopted by the model predictive control (MPC) to achieve the active rotor temperature management. However, the extent and the time of the overload operation are difficult to determine. In order to exploit the torque capability of electrical motors, overload operations are appreciated.
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