Xiaoguang Zhang

In the drive system of nonsalient permanent magnet synchronous motors, sensorless control at low speed remains challenging, since the existing saliency-based and model-based methods may be ineffective. To address this issue, this article proposes a sensorless control method capable of full-speed-range operation. In the proposed method, an extended state observer estimates the back-electromotive force in the $\bm{\gamma}$ - $\bm{\delta}$ frame, while a phase-locked loop-type estimator extracts the rotor position and speed. Experimental results demonstrate that the motor can start up from any initial position under rated load and achieve reliable speed reversal. Moreover, the method maintains high estimation accuracy even when the motor runs at 2% rated speed. This indicates that a single-method full-speed-range sensorless solution is feasible.

This paper proposes a dual internal model (DIM) decoupling control method with delay compensation, in which the internal model principle is applied to both the voltage loop and the current loop to solve the high order and strong coupling problems of the permanent magnet synchronous motor (PMSM) system fed by the current source inverter (CSI). By means of deriving the complex-vector model of the CSI-fed PMSM system, the influence of cross-coupling caused by coordinate transformation is analyzed and the decoupling performance of the DIM decoupling control method is quantitatively evaluated. To overcome the influence of control delay and angle coupling, the model of the DIM decoupling control method in the discrete domain is derived. The codesign method of controller parameters and the delay compensation coefficient is introduced and compared with the traditional decoupling method. Finally, the experimental results show that the proposed decoupling method can improve the control performance in both dynamic and steady states.

This paper proposes a robust short-circuit fault diagnosis method based on dual-scale average current errors for the permanent magnet synchronous motor (PMSM) drive fed by the current source inverter (CSI). The method only employs the already exist motor currents and does not need additional sensors and circuits, which is simple and easy to implement. The current errors between the average values of the reference currents and that of the feedback currents in one cycle are calculated, and the ratios of the errors to the average absolute values of the reference currents are used as the diagnostic variables. In addition, two amplitude thresholds are set to determine the fault type by comparing the diagnostic variables with the amplitude thresholds. Then, the faulty switch is located according to the signs of the diagnostic variables. In order to avoid misdiagnosis in the transient processes, a time threshold as the second scale is set to enhance the robustness of the diagnostic algorithm. Finally, an experimental platform is built to verify the effectiveness and the robustness of the proposed diagnosis method.

Model predictive current control (MPCC) is recognized as a promising control method for permanent magnet synchronous motor (PMSM) drives. In conventional MPCC, only current tracking is considered while the switching transition term is neglected, which can reduce system efficiency and overall control performance. To balance the influence of current error and switching transition term, a dual objective MPCC (DOMPCC) method is put forward in this paper. First, the conventional MPCC method is introduced and the limitations are formulated. Then, the proposed method is presented where a new cost function including switching transition term is designed. In addition, the design process for the balance factor and weighting coefficient is developed, and the stability analysis is provided. Finally, comparative studies are conducted on a 1.25 kW experimental platform to demonstrate the effectiveness of the proposed DOMPCC method.

A permanent magnet synchronous motor (PMSM) must operate at a low-switching frequency under certain operating conditions. Although traditional model predictive current control (MPCC) can achieve relatively stable operation of PMSM at low-switching frequency, it can increase the content of specific order harmonics in the stator current. Therefore, this article proposes a novel method based on MPCC, called MPCC with specific harmonic suppression. This method predicts and suppresses the specific harmonic current obtained by using the proposed novel harmonic prediction model and synthetic cost function, to reduce the adverse effects of current harmonics. This method can significantly reduce the content of specific order harmonics and reduce the system's total harmonic distortion (THD). Finally, experiments were conducted on a 1.25 kW PMSM back-to-back testbench, and the effectiveness of the proposed harmonic suppression strategy was confirmed from both steady-state and dynamic perspectives.

Unfortunately, we found that the references of the above article are almost completely irrelevant to what is mentioned in the introduction section of this article. This causes difficulties for the reader. For this reason, we have provided the correct version of the references and the corresponding introduction to remedy this problem in a timely manner.