| Compared with asynchronous traction motor,permanent magnet synchronous traction motor has the advantages of large starting torque,high power density and high efficiency.In order to ensure high performance control of PMSM,closed-loop vector control strategy is usually adopted,which requires accurate rotor position and speed information.Mechanical sensors are usually used to measure angles.However,the addition of mechanical sensors will increase the space and cost of the system,and introduce unreliable factors such as mechanical faults.Therefore,how to realize sensorless control has become a hot issue in the industry.In this paper,the sliding-mode observation algorithm of permanent magnet synchronous motor is analyzed.In order to avoid the phase shift problem caused by the traditional low-pass filter,a complex coefficient filter is designed,which can realize the non-error extraction of the electric signal in the two-phase stationary coordinate system.At the same time,in order to keep the bandwidth of the PLL constant,the reverse potential normalization is used.In the application of urban rail transit,the motor parameters are variable.In order to ensure the stability of the sliding mode observer,this paper analyzes the stability condition and parameter robustness of the sliding mode observation algorithm.Permanent magnet synchronous motor control strategy is divided into flux-weaking area and the other area,generally use the MTPA combined with negative direct axis flux-weakening control strategy,but in sensorless control applications,because of the angle error,the traditional flux-weakening control strategy with current loop have the risk of losing control,therefore,in order to guarantee the stability of the weak magnetic control algorithm,this paper adopts a voltage phase angle control strategy,in which torque observation algorithm based on the static coordinate system of the,after reaching maximum voltage,torque closed loop is used to adjust the voltage phase angle,to realize the accurate torque output of the flux-weakening area,and good torque response speed.In sensorless control algorithm,the angle error is inevitable,this thesis analyzes the error sources and the corresponding influencing factors.To analyzes the influence of angle error of control,this thesis analyzes the influence of angle error on MTPA torque output,as well as the range of acceptable angle error of voltage phase angle control strategy.Finally,based on the d SPACE semi-physical simulation platform and the 210 k W high-power experimental platform,the corresponding algorithm is verified.The experimental results show that the sensorless control strategy based on the sliding mode observation algorithm has good stability and dynamic performance,which verifies the strong robustness of the sliding mode observation algorithm.The control scheme designed in this thesis has good engineering practice. |
