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This paper proposes a multi-vector-based model predictive torque control with fixed switching frequency for a six-phase permanent-magnet synchronous machine to improve its steady-state performance. First, two active vectors are synthesized in each control period to suppress the stator current harmonics in x–y subspace. For the sake of easy implementation in the real-time system, the vectors are artfully synthesized in two different manners. Second, to achieve the fixed switching frequency, two null vectors are inserted along with the synthesized vector. The duty ratio of the null vectors is determined based on the principle of deadbeat torque control. In the meantime, the synthesized vector and its duty ratio are evaluated simultaneously by the cost function. In this way, the torque ripple can be reduced considerably. Thus, with the proposed method, both the current harmonics and the torque ripple are reduced effectively. Also, the proposed methodology can be readily implemented practically under the constant switching frequency. Finally, the experimentation is carried out to verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a novel deadbeat current control (DBCC)-based model predictive control for an asymmetrical six-phase permanent magnet synchronous machine. First, the solution of DBCC is adopted to obtain the expected reference voltage vector (RVV). Then, two groups of virtual vectors, in the total number of 24 with different magnitudes, are defined for the sake of current harmonics suppression. Subsequently, two in-phase virtual vectors which are closest to the RVV are selected as the prediction vectors. The next step is to define a cost function which is composed of the error between the RVV and the available prediction vectors. Then, the selected two virtual vectors are evaluated and the one that minimizes the cost function will be applied in the next instant. In this way, only two prediction vectors need to be evaluated and the computation burden is highly alleviated. In the meantime, the weighting factor involved in predictive torque control is avoided. In addition, to achieve the readily implementation with standard pulsewidth modulation switching sequence, 18 virtual vectors are artfully replaced by their corresponding equivalent virtual vectors. Finally, the proposed method is comparatively studied and compared with other benchmark methods. Simulation and experimental results are offered to confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a novel model predictive torque control with discrete duty ratio optimization for a six-phase PMSM machine with high robustness against weighting factor variation. First, a two-step lookup table is developed to initially select the optimal voltage vector, which is to regulate the torque and flux in the energy conversion related subspace, as well as suppress the harmonic currents in the x–y subspace. Then, a null vector is inserted along with the selected optimal voltage vector to adjust the duty ratio with a set of value to avoid the complicated derivation. Subsequently, the optimal duty ratio is determined by a cost function to minimize the torque and flux error. So by using the proposed method, the torque ripple is reduced and even applying an improper weighting factor will not deteriorate the machine performance severely. Finally, experimentations are carried out to verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a model predictive control scheme based remedial control for the single-phase open-circuit fault of an asymmetrical six-phase PMSM machine. The proposed strategy adopts the normal vector space decomposition transformation matrix without reconfiguring the controller topology. The key is to derive the perturbation term of the prediction vectors in α-β and x-y subspace, which is based on the difference of the faulty phase voltage under healthy and faulty condition. Through the compensation of the prediction vectors, the predictive model can be accurately described in the faulty condition. Thus, the current variables in the next instant is accurately predicted and the torque fluctuation is suppressed. Finally, the experimental results are provided to verify the validity of the proposed method on pre- and post-fault tolerant operation. [ABSTRACT FROM AUTHOR]