Research On Model Predictive Control Of Dual Three-phase Pmsm Drives

In this paper,the dual three-phase permanent magnetic synchronous motor(PMSM)drive system is chosen as the research object.The finite control set model predictive current control strategies for two-level voltage-source inverters and t-type three-level inverters fed this drive system are deeply analyzed and demonstrated.Based on the configuration of the dual three-phase PMSM,this paper builds the mathematical model of the motor in the six-phase stationary coordinate system.For the convenience of the implementation of the control schemes,the vector space decomposition(VSD)technique is used to build the mathematical model of the motor under the synchronous reference frame coordinate system.After analyzing the principles of the finite control set model predictive current control strategies and combining with the mathematical model of the motor under the synchronous reference frame coordinate system,the predictive model of the dual three-phase PMSM is built.To reduce the negative impact of one-step delay in the digital implementation when the model predictive control(MPC)applied,a delay compensation method is also considered.The drive system of two-level voltage-source inverters fed dual three-phase PMSM is firstly studied.This paper presents a novel two-step MPC method for this drive system,aiming at reducing the switching frequency and computation burden of the system.This proposed method offers similar good operation performance under dynamic response and steady-state operation when compared to conventional model predictive current control.What’s more,the proposed method has remarkable advantages on the reduced switching frequency and low-computation burden.The drive system with even number of phase legs has the advantages of eliminating common-mode voltage.By utilizing this advantage,a zero common-mode voltage predictive current control is proposed for two-level voltage-source-inverter fed the asymmetric six-phase motor drive system,where the two three-phase windings share a common neutral point which can eliminate the common-mode voltage effectively.Compared to two-level inverters,three-level inverters have the merits of low equivalent switching frequency,redundant voltage vectors,easy to eliminate common-mode voltage with the neutrals of dual three-phase isolated and the dimension of the current control is reduced as well reducing the difficulty of the control and increasing the stability of the drive system.Considering the research on the MPC for the mutilevel inverters and mutiphase PMSMs is rare,the MPC for ttype three-level voltage-source inverters fed dual three-phase PMSM is studied.Utilizing the space voltage vector synthesis method to synthesize a group of harmonic-free voltage vectors,this paper proposes a new MPC strategy for the drive system to suppress the current harmonics.This strategy can effectively reduce the current harmonics in the motor resulting from small harmonic impedance in harmonic subspace and take measures to alleviate the computation burden.Because of the redundant voltage vectors of this drive system,a predictive current control for this system utilizing a group of zero common-mode voltage vectors is proposed which can eliminate the common-mode voltage of the system as well as alleviate the operation burden and improve the operation speed.Finally,the experiments are conducted to verify the correctness and effectiveness of the relevant researches in this paper.