Study On Flux Weakening Control System Of Vehicle PMSM

With the oil energy crisis and urban environmental pollution problems become more and more serious,many major automobile producing countries(such as Germany,Britain and France,etc)have announced the the deadline of suspension of production of fuel vehicles,China is also actively promoting the stduy and promotion of electric vehicles in recent years.From January to August 2018,China's permanent magnet synchronous motor(PMSM)installed capacity reached 551,000 units,accounting for 78.3% of the total installed motor capacity of vehicles.Therefore,stduy on the control technology of PMSM for vehicles has become one of the hot spots in the automotive industry.The characteristics of frequent starting and accelerating conditions of the car require the motor to have a higher output torque at the base speed(rated speed),the traditional id=0 control algorithm is simple to implement,but it's torque output capability is insufficient.In addition,the high speed working condition of the car requires the motor to have a wide speed range,when the inverter output voltage reaches the maximum value,the motor cannot continue to increase speed by increasing the voltage.Therefore,it is necessary to use the flux weakening control algorithm to widen the speed range of the motor,however,during the flux weakening process,the torque output capability decreases rapidly with the increase of the rotational speed,and the current integral saturation problem during deep flux weakening causes serious current oscillation.This thesis studies the control algorithm of PMSM for vehicles based on the above requirements and existing problems,it contains the following main contents:1.Firstly,Take the interior PMSM which has good speed expansion ability as the object,simplify the control algorithm by establishing a mathematical model under dq coordinates by Clark coordinate transformation and Park coordinate transformation,stduy on space vector pulse width modulation(SVPWM)based on vector control model.2.Secondly,study the maximum torque per ampere(MTPA)control algorithm in the base speed range,with the same current to output maximum torque.Stduy on the current lead angle flux weakening control algorithm based on voltage feedback in high speed range,but its output torque drops fast.To solve this problem,study SVPWM overmodulation algorithm to improve voltage utilization,thereby improving torque output capability.For current integral saturation problems,study improved algorithm for anti-integral saturation PI regulation to improve the response speed and the speed following ability.Build simulink simulation model to test and verification the above algorithms.3.Finally,Designed State scheduling function subroutine,CAN communication subroutine and PWM output subroutine based on the motor control development platform.Take test with the 10 Kw PMSM on motor hardware in loop(HIL)test platform.In the base speed range,take constant torque load start and acceleration test,in the high speed range,take speed regulation and anti-load interference capability test.The test results show that MTPA's maximum output torque increased by 9.5% compared to id=0,the maximum speed range under flux weakening reaches 2.22 times the base speed,increases output torque under flux weakening by 10% with SVPWM overmodulation,increased speed response speed by 50% with improved anti-integration saturation.