Research On High Performance Permanent Magnet Synchronous Motor System Based On Model Predictive Torque Control

Permanent magnet synchronous motor(PMSM)has many advantages,such as simple structure,high power density,small size and good control performance.It has been widely used in new energy fields such as electric vehicles in recent years.In this thesis,a PMSM drive system is deeply and systematically investigated,including motor features,direct torque control(DTC),model predictive control,maximum torque per ampere(MTPA),flux weakening(FW)and multi-level technology,providing theoretical guidance and practical value in the PMSM drive system.The fruits of this thesis are as follows:1.The basic work principle are introduced.On the basis of PMSM mathematical model,DTC,model predictive torque control(MPTC)and model predictive flux control(MPFC)algorithms are studied.The advantages and disadvantages of the three control algorithms are analysed and compared both in the simulation and experiment environment.2.Based on MPTC algorithm,the MTPA control above base speed and FW control below base speed in the PMSM control system is studied.Furthermore,in order to implement the low switch frequency during the full speed range,a switch frequency restriction is also constructed.Then,the control algorithm is developed in both the constant-torque operation and constant-power operation conditions,when the MTPA and FW control methods are employed,respectively.Finally,simulation results are presented,verifying the effectiveness of the proposed control strategy.3.To overcome the difficulty of adjusting the weight factors in the MPTC for PMSM supplied by three-level inverters,a weightless MPFC for PMSM is proposed.The proposed control algorithm transforms the control of motor torque and stator flux amplitude in MPTC into the control of stator flux vector,and thus constructs a cost function,which includes the differences between dq component of predictive stator flux and its value.Then,by estimating the relationship between the direction of neutral point current and neutral point voltage,a pair of redundant small vectors are used to adjust the neutral point voltage to achieve neutral point voltage balance.Furthermore,the duty cycle MPFC strategy based on q-axis flux linkage deadbeat is adopted to improve the steady-state performance of the motor,and the vector space is divided into 12 sectors.Then,four non-zero vectors in the sector where the reference voltage vector is located are optimized and evaluated to reduce the computational complexity of multi-vector selection.Finally,the simulation and experimental results verify the feasibility and superiority of the control algorithm.4.In order to solve the problems such as massive switching devices,fluctuant neutral-point voltage and high system cost in the three-level inverters,a MPFC strategy for semicontrolled open-winding permanent magnet synchronous generator based on zero-sequence circulating current suppression is proposed.The simulation and experimental verification of open-winding generator with the common dc bus are carried out in the field of power generation,so as to realize the switch from a single field of drive to the field of power generation and ensure the integrity of control strategy of the permanent magnet synchronous motor.5.Based on hardware driver circuit,software implementation plan and real-time d SPACE1104,a digital drive and control experimental platform of PMSM drive system is built.Experimental results verify the effectiveness of the proposed control algorithms and the correctness of theoretical analysis and simulation.