Research On Model Predictive Control Of Permanent Magnet Synchronous Motor Driven By NPC Three-level Inverter

Permanent magnet synchronous motor(PMSM)has the advantages of small size,light weight,high power density and reliable operation.In recent years,it is widely used in new energy vehicles,petrochemical industry,aerospace and many other fields.In the control system of PMSM,vector control and direct torque control are two traditional mainstream control strategies.With the rapid and robust requirements of PMSM control system,these two traditional control technologies are difficult to meet the complex control requirements.In recent years,finite control set model predictive control(FCS-MPC)has become a research hotspot in the field of motor control due to its simple structure design,good dynamic performance and easy handling of nonlinear and multi-constraint problems.With the rapid development in the field of power electronics and power transmission,the application of traditional two-level inverters is subject to many restrictions in large-capacity AC speed control systems.Multi-level inverter is very suitable for using in large-capacity AC speed control systems because of its good output waveforms,low harmonic content,low voltage jumps and switching losses.Among the diversified topological structures of multi-level inverters,the neutral point clamped(NPC)three-level inverter has been widely used in many fields due to the advantages of moderate number of levels and simple control.Therefore,the NPC three-level inverter is used to research the PMSM model predictive control system in this thesis.The main research contents are divided into the following aspects:(1)The basic structure of PMSM and mathematical model of PMSM are introduced,which is established in different coordinate systems based on coordinate transformation theory.And the basic principles of NPC three-level inverter and model predictive control is analyzed to provide a theoretical basis for the research of this thesis.(2)Aiming at the problem of large calculation amount in the model predictive torque control(MPTC)system of the PMSM model driven by the NPC three-level inverter,an improved MPTC strategy based on deadbeat control is proposed.The deadbeat method of electromagnetic torque and stator flux linkage is used to directly estimate the required voltage vector in a single control cycle and optimized the vector selection with sector subdivision to reduce the amount of system calculation.At the same time,the neutral point voltage constraint term is introduced into the objective function to realize the neutral point voltage balance control.(3)A super-twisting algorithm(STA)sliding mode observer of PMSM model predictive current control(MPCC)system based on phase locked loop(PLL)technology is designed to realize sensorless control of PMSM system,so as to further improve the control performance of the system.