Research On Permanent Magnet Synchronous Motor And Its Feedback Braking Control Strategy Based On Inductance Online

With the continuous development of power electronics technology,the permanent magnet synchronous motor and its inverter power supply system are widely used in new energy power generation,new energy electric and servo drive systems that require high control accuracy.However,at present,the motor parameters in the permanent magnet synchronous motor control system are processed according to the constant parameters,and the influence of the magnetic circuit saturation,temperature change and ferromagnetic material nonlinearity on the motor parameters is not considered,that is,when different control strategies and different operating conditions are not considered.The change of motor parameters makes the control precision of the permanent magnet synchronous motor drive system not high.For example,the derivation of the optimal operating point in the MTPA control strategy of a permanent magnet synchronous motor depends very much on the accuracy of the motor inductance parameters.If the inductance parameters are not accurate,the derivation of the optimal operating point will deviate from the actual optimal operating point of the motor.Therefore,real-time and accurate inductance parameters are the prerequisite for precise control of the motor.Aiming at the problems of permanent magnet synchronous motor inductance parameter identification,curve fitting MTPA parameter immutability and braking energy feedback,this paper expands the following research:1.Based on the derivation of the mathematical model of the motor and related theories,using the transient voltage model of the permanent magnet synchronous motor,a method for real-time online identification of the motor inductance parameters using the least squares method with forgetting factors is proposed,and through simulation and experiment The feasibility of this method is verified,and accurate motor parameters can be identified under various working conditions,which provides an important basis for precise control of permanent magnet synchronous motors.2.In the past the curve fitting of the MTPA(Maximum Torque current ratio-the Maximum Torque Per Ampere)control strategy,because the two problems of the parameters of the immutable and large error of fitting results in case of negative torque are not good for control.According to the motor mathematics model the MTPA control strategy based on iterative method is obtained by theoretical derivation.Through the simulation and experiment the practical feasibility and effectiveness of this method is verified;In addition,by combining this method with the inductance identification method proposed,it can precisely determine the best operation state of the motor under various working conditions,which significantly improves the starting performance and carrying capacity of the motor.3.Theoretically the models of maximum energy feedback,maximum efficiency feedback and maximum feedback speed of IPMSM in energy feedback are derived,and its effectiveness and feasibility is verified through simulation,laying a theoretical foundation for further research on IPMSM energy feedback in the laboratory.4.Based on 2.2 k W d SPACE control platform of permanent magnet synchronous motor in the laboratory,hardware,new energy feedback to threephase controlled rectifier power supply is added to replace the original nocontrolled rectifier power supply,it ensure energy bi-directional flow,in order to simulate the electric car energy feedback,and finally on this platform the permanent magnet synchronous motor with parameter identification MTPA control and energy bi-directional flow is realized.