This article proposes a robust deadbeat predictive current control (DPCC) method for the interior permanent magnet synchronous motor (IPMSM) based on a full parameter identification method. The DPCC method is innovatively combined with the high frequency currents injection method, which can observe inductances, flux linkage, and resistance values of the IPMSM online. After the parameter identification results are obtained, the initial crude parameters are replaced by the identification values in the DPCC method to enhance the robustness of the IPMSM control system. Moreover, a novel online accuracy verification method for parameter identification results is proposed to judge the error estimation level. The proposed method extracts the high bandwidth and the high parameter sensitivity characteristic of the DPCC method. The online identification and verification of IPMSM parameters are proceeded subsequently while achieving robust control of the IPMSM with the DPCC method. Finally, the proposed method is experimentally demonstrated with a 1.5 kW motor. The experimental results show that the IPMSM with the proposed method can still work well even in the situation of severe initial parameters mismatch.

An adaptive droop-based hierarchical optimal voltage control (DHOVC) scheme is proposed for voltage-source converter high-voltage-direct-current (VSC-HVdc) connected offshore wind farms (WFs). The wind turbines (WTs) and WF side VSC (WFVSC) are coordinated to minimize the voltage deviations of buses inside the WF from the nominal voltage and mitigate reactive power (Var) fluctuations of WTs. The model predictive control is used to improve the performance of the DHOVC scheme during a certain predictive horizon. A hierarchical solution method based on the alternating direction method of multipliers is developed to reduce the calculation burden of the central controller while improving the information privacy protection. During the predictive horizon, the WTs and WFVSC are coordinated to achieve the near global optimal performance without global information. A WF with 32 × 5MW WTs was used in the MATLAB/Simulink to test the proposed DHOVC scheme.

The permanent magnet synchronous motor (PMSM) has become a core component of electromechanical energy conversion in the modern industrial field. In order to expand the application of the PMSM in the field of high power traction, a robust predictive torque control (R-PTC) strategy for the N-segment three-phase PMSM (N*3-phase PMSM) is proposed in this paper. Firstly, the output characteristics of the N*3-phase PMSM are illustrated with the finite element analysis method, and the mathematical model is established. Then, the six-segment three-phase PMSM predictive control system driven by six parallel inverters is designed to generate the required torque. Further, the influence of the parameter mismatch on the predicted torque and stator flux is taken into consideration based on the conventional predictive torque control (PTC). Finally, a novel R-PTC method with the proportional controller is developed for the N*3-phase PMSM, which can effectively improve accuracy and robustness of predictive control performance under parameters mismatch. Simulation and experimental results verify that, compared with the conventional PTC, the proposed R-PTC method can make the predicted stator flux and torque value accurately track its reference values while achieving lower stator flux and torque ripple.

In a high-power traction system, the stator current of the dual three-phase permanent magnet synchronous motor (DTP-PMSM) suffers from a large number of current harmonics due to the limitation of the switching frequency of the inverter. Thus, this article proposes a novel current harmonic distortion minimization pulsewidth modulation (PWM) method under a low carrier ratio to suppress current harmonics for the DTP-PMSM, which takes the salient pole ratio, the leakage inductance, and the load angle of DTP-PMSM into consideration. The mathematical model of current harmonics of DTP-PMSM using synchronous PWM is established under a low carrier ratio. The established model demonstrates that the current harmonics of the DTP-PMSM are not only affected by the inverter output voltage but also affected by the salient pole ratio, the leakage inductance, and the load angle of DTP-PMSM. To achieve better control performance on harmonics suppression of the DTP-PMSM, an optimization problem considered characteristics of the DTP-PMSM is formulated to minimize the current harmonics by regulating the switching angles of each phase. The total harmonic distortion of stator current can be reduced effectively by solving the optimization problem. The effectiveness and robustness of the proposed method are verified and compared with three other methods under the same switching frequency.

The conventional model predictive torque control (MPTC) used for dual three-phase permanent magnet synchronous motors (DTP-PMSMs) faces several challenges, such as significant computational burden, large current harmonics, and large torque and flux ripples due to the application of imprecise voltage vectors. To address these issues, a novel three-vector-based MPTC strategy was introduced in this study for DTP-PMSMs. First, virtual vectors were adopted to reduce the current harmonic components. Second, four candidate vector groups were determined based on torque deviation and flux position. Each candidate vector group comprised two virtual vectors and one zero vector, which enabled the precise control of torque and flux through the duty-ratio modulation strategy. Third, the switching sequence was optimized to facilitate implementation in digital controllers. Then, a cost function was defined to evaluate the average torque and flux ripples of each candidate vector group in a sampling period, and the one with the minimum cost function was applied in the next sampling period. This approach effectively reduced the current harmonics, torque ripple, and flux ripple while avoiding large computational burden. Finally, experiments were conducted to demonstrate the effectiveness of the proposed method.

This paper proposes a decentralized Volt/Var control method based on variable gradient projection (VGP) for the permanent magnet synchronous generator (PMSG)-based wind farm (WF). The aim is to achieve a fast Var response of each wind turbine (WT) to depress voltage fluctuations inside the WF caused by the stochastic wind and voltage disturbance of external girds. The gradient projection (GP) method is used in the PMSG-based WF to regulate terminal bus voltage within a feasible range in a fully decentralized manner while the dynamic characteristics of the PMSGs and grid side converters (GSCs) are taken into consideration. Moreover, according to the difference of the available power distribution among the WTs inside the WF, the adaptive and variable gain method is designed for the GP method, which can achieve maximum Var margin of each local WTs during the real-time operation of the WF. With the proposed control method, the PMSG-based WTs are coordinated to achieve near-global optimal performance only with local measurements. The voltage fluctuations of buses are reduced while the Var margin of WT converters is maximized. The WF with $24 \times 5$ MW WTs is tested in Matlab/Simulink with the real-time fully nonlinear AC power flow environment.