Research On Dual Three-Phase PMSM Sensorless Compound Control And Smooth Switching Strategy

By comparing with traditional three-phase motor adjustable speed drive,multiphase motor adjustable speed drive is characterized by high power density,high reliability,high adaptability and high precision.Recently,power electronic technology and modern control theory have made continuous improvement with a lot of researches by scholars in various countries.It is an inevitable trend to develop and apply high-power AC drives.Nowadays,with wide applications,multiphase motor is mainly used in the high-power situations with high requirements for system reliability and complex working conditions such as e-automobile,all-electric ship propulsion system,industrial and agricultural production,water cycle of nuclear power station,aerospace and other fields.It is necessary to acquire the accurate position of motor and speed information in the alternating current governor system,and mechanical sensor also faces the problems such as hardware costs taking up system volume.Therefore,for the settlement of these problems,this thesis makes an in-depth research with the sensorless vector control within the full-speed range by taking the dual three-phase PMSM with double Y-shift of 30° winding which is similar to the three-phase permanent magnet synchronous motor as the research object.This thesis firstly introduces the merits,demerits and development situation of multi-phase motor and analyzes the stator winding structure of dual three-phase PMSM.In the meantime,assuming that dual three-phase PMSM is the ideal motor,the mathematic model of dual three-phase PMSM is given.For simplifying the analysis,the reduced decoupling is conducted for the mathematic model of PMSM with two common modelling methods: vector space decoupling and double d-q modelling.Besides,this thesis analyzes the corresponding PWM strategies of two modelling methods,establishes the simulation model and verifies the correctness of the model.Then,this thesis selects,analyzes and compares high-frequency signal injection in the low-speed section of motor and model reference adaptive system among different sensorless control methods of PMSM and verifies the effectiveness of the schemes selected through simulation.At the end,through setting the switching module in the simulation software,the smooth switching between two sensorless vector control methods is realized during the process of operating the double three-phase PMSM within the full speed range.Through analyzing the error curves of the motor speed and the rotor position of the compound control system,the feasibility and effectiveness of the theories researched in this thesis are verified.