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Electromagnetic torque and stator flux of a permanent magnet synchronous motor (PMSM) can be controlled indirectly with model predictive current control (MPCC). In MPCC, a predefined cost function is minimised by selecting and applying appropriate voltage vectors to stator terminals. Since MPCC employs machine model to predict stator currents, it requires accurate knowledge of its parameters. Furthermore, MPCC results in high torque and current ripples at normal sampling rates. In this study, torque and current ripples of a surface-mounted PMSM are effectively reduced by incorporating the concept of duty cycle and applying two voltage vectors, instead of one voltage vector as in conventional MPCC, during a control period. A fuzzy logic modulator is designed and utilised to determine the duty cycles of voltage vectors. Furthermore, sensitivity of the proposed control strategy against parameter variations is alleviated by employing a full-order Luenberger observer. Various case studies are carried out on a hardware-in-the-loop setup and performance of the proposed method is compared with conventional and a recently introduced duty cycle-based predictive control. The obtained results verify the superiority of the proposed MPCC and its effectiveness in reducing the PMSM torque and current ripples with accurate and erroneous knowledge of motor parameters.

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Rapid development of high-speed trains confronts the power grid with serious power quality problems. In this study, to compensate power quality, an improved grid voltage sensorless control method for the railway power conditioner (RPC) is proposed. The proposed control strategy utilises a moving average filter to better detect the compensating currents and a proportional-resonant controller to control the compensating currents. Moreover, a sensorless virtual flux method based on second order low-pass filters is presented to replace the AC voltage sensors. Using the proposed strategy, the dynamic and steady-state characteristic of the RPC is significantly enhanced. Through simulation tests, the effectiveness of the proposed methods is confirmed.

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In this study, the potential of the space vector modulation (SVM) to control the matrix converter beyond its intrinsic voltage transfer ratio (VTR) limitation (0.866) is investigated. Afterwards, a simple space vector overmodulation method to increase the VTR of matrix converter is proposed. Depending on the desired VTR, the method is divided into two modes. In the first mode, besides improving the VTR, the quality of the reference quantities is of main concern. In the second mode, the main goal is to reach the maximum achievable VTR at the expense of increased harmonic ripples in the converter waveforms. It is demonstrated that the maximum achievable VTR in both modes depends on the ratio of the desired output frequency to the input frequency. Experimental results confirm the feasibility and appropriate performance of the proposed method.

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