Research Of Model Predictive Current Control For Five Phase Permanent Megnet Synchronous Machines

Multi-phase machines have received widespread attentation in low voltage and high current applications.Compared with traditional three phase machine system,the multi-phase machine drive system has a series of advantages such as high power density,low torque ripple and strong fault tolerance.However,the increase of phase number also makes control methods complicated.Therefore,it is of great importance to study the control algorithms applicable to multi-phase drive system.In this paper,five-phase permanent magnet synchronous machine(PMSM)is taken as the research object.On the basis of fundamental principles of finite control set model predictive current control(FCS-MPCC)method,some optimized predictive current control schemes are studied.Firstly,the coordinate transformation matrix in five-phase system is introduced,and the mathematical models of five-phase PMSM in stationary coordinate system and rotating coordinate system are deduced.In addition,the distribution characteristics of voltage vectors in ?1-?1subapace and ?3-?3 subspace are analyzed in detail.Secondly,this paper has studied the implementation process of FCS-MPCC algorithm and analyzed the impact of calculation delay.Then,the delay compensation strategy is provided.And a simplified FCS-MPCC scheme is proposed in order to overcome the drawback of large calculation burden in traditional scheme.Based on the corresponding relationship between voltage vectors in ?1-?1 subapace and ?3-?3 subspace,synthetic voltage vectors are utilized to suppress the third harmonic current.According to the different effects of synthectic voltage vectors on torque and stator flux,two hysteresis compactors are introduced to filter redundant voltage vectors.With the use of hysteresis compactors,only two synthetic voltage vectors need to be predicted and calculated in each control cycle,which can reduce calculation burden greatly.In addition,in order to improve the performance of torque,the duty ratio is calculated according to the principle of minimum torque ripple.Thirdly,this paper has studied the FCS-MPCC scheme with low switching frequency for high power applications.Firstly,the change trend of predictive current trajectory is analyzed in detail.And then,with the use of given current region,the candicante voltage vectors can be selected.The liner extrapolation is introduced after the current prediction,and a cost function containing the extrapolation number and switching number is given.The proposed method can not only keep the merit of fast dynamic response but also reduce the switching frequency effectively.Finally,the traditional FCS-MPCC scheme and the proposed schemes are implemented on a scale-down experimental platform with TMS320F28335 controller.After experimental verification and comparative analysis,the correctness and effectiveness of these proposed shcemes are verified.