Investigation Of Asynchronous Motor Control System With On-line Parameter Identification

For the field of new energy vehicle research,with the breakthrough of new energy storage technology,which has entered a stage of rapid development.As one of the three major systems of new energy vehicles,the electric drive system needs to provide sufficient driving force for the whole vehicle,which is also the main part of the vehicle’s energy consumption.Therefore,in order to improve energy utilization ratio and ensure the reliability and power performance of new energy vehicles,research on electric drive systems has important significance.This paper discusses the influence of motor parameter on the stability of motor control system and proved.The necessity of using line parameter identification in high performance asynchronous motor control system is proved.The recursive least squares method is chosen as the basic method for the parameter identification process of asynchronous motors.According to the recursive least squares method,the mathematical model of asynchronous motor in two-phase stationary coordinate frame is processed and improved.The mathematical model of integral form is proposed to eliminate the error introduced by the second derivative in the identification process.The mathematical model of asynchronous motor and the simulation model of asynchronous motor drive system based on vector control are built by Simulink.The effectiveness of the algorithm is verified.The number of subdivisions about the flux angle in the hardware system is determined according to the analysis of the simulation results.The online parameter identification simulation model of asynchronous motor is built and the effectiveness of the improved identification model was verified.The simulation results are used to determine the reference values of the forgetting factor and sampling time in the hardware system.According to the requirements of the new energy vehicle’s asynchronous motor drive system,the hardware circuit of the motor controller is designed.In order to improve the safety of the drive system,various protection measures are added.In addition,part of the vehicle controller function is reserved to meet the basic driving requirements of the low-profile models.The devices used in the controller are determined according to the automobile chip standard and the components are modularly arranged.The motor controller software was designed according to the embedded software development standard.Besides,the communication protocol based on Modbus standard was developed.The program has strong functionality,reliability,easily use and portability.The hardware circuit,function and online parameter identification algorithm ofthe motor controller are tested and verified on the special test bed of the electric drive system.The test results show that the electric drive system can run stably and the parameter identification for asynchronous motor results a good repeatability,which can meet the requirements for real-time correction of asynchronous motor parameters.