EMI Modeling And Flux Weakening Algorithm For Permanent Magnet Synchronous Motor In Electric Vehicle

Power-train in electric vehicle(EV)usually composes of a battery pack,inverter and permanent magnet synchronous motor(PMSM).The power-train system in electric vehicle may cause broadband electromagnetic emission due to high switching frequency behavior of power semiconductor device.Permanent magnet synchronous motor provides propagation paths for electromagnetic interference(EMI)noise and enhances EMI,it's an important part of EMI model for power-train system.Permanent magnet provides magnetic field,and induction voltage on the stator winding is proportional to the motor speed when motor rotates.Motor speed is limited due to the limited DC input voltage of inverter.Flux weakening algorithm weakes the magnetic field provided by permanent magnet and lifts the upper limit of motor speed.Chapter 1 introduces basic concepts of electromagnetic compatibility and EMC standards for electric vehicles.Then,three types of motor EMI modeling method are introduced.At same time,different motor control methods are compared with each other.Chapter 2 studies extration method of parasitic parameters of motor.Firstly,a lumped parameter model of PMSM is introduced.By analyzing the PMSM structure,circuit components of the lumped model are associated with its parasitic parameters.Secondly,a method combining theoretical calculation and finite element analysis is proposed to obtain parasitic parameters of motor,and experiments are conducted to verify the method.Basing on this method,lumped model is obtained.Finally,common mode(CM)and differential mode(DM)impedance of a PMSM are measured by impedance analyzer,and comparisons between experiment results and predicted results are made.Chapter 3 is based on the mathematic model of PMSM,MTPA Control and flux weakening algorithm are deduced.Control block diagram of PMSM is introduced,and retardation comparator is used.MTPA control and flux weakening algorithm are verifivated by experiment.Chapter 4 makes the summary of the current research work,and looks forward to the future work.