Research On Motor Control System For On-line Tuning Of Speed PI Parameters Based On Positive Flow System

With the increasingly serious environmental pollution and energy shortages,green,energy saving,and emission reduction have aroused widespread concern from all mankind.The large volume and high pollution of construction machinery forces it to seek transformation and upgrading as soon as possible.Pure electric-driven technology adopts electric motors to replace traditional diesel engines,which can truly achieve zero emissions,low noise and high energy efficiency,which is inevitable choice for transformation and upgrading of construction machinery.However,the development of supporting equipment for pure electric-driven construction machinery is slow,especially for motor controllers.Most of the existing pure electric-driven construction machinery motor controllers are transplanted from other field,and cannot well fit the working condition characteristics of it.Therefore,it is of great significance to carry out analysis of the working conditions of construction machinery and to develop a targeted motor control system.Taking the pure electric-driven excavator as an example,the paper analyzes the characteristics of working conditions and summarizes the important performance indicators.At the same time,by analyzing the working features of the power motor,requirements are put forward for the motor output performance and motor control strategy of the motor controller,that are the most important,as well as waterproof and dustproof.The variable speed-quantitative pump positive flow system is selected as the application object.Through the analysis of the mathematical model of the positive flow system,the influence of the motor speed characteristics and torque characteristics on the performance of the positive flow system is obtained.The paper selects permanent magnet synchronous motor as the main power motor,and uses vector control as the control strategy to form a current-speed double PI closedloop control system.Since the motor control system of pure electric-driven construction machinery is a non-linear,variable load,and large disturbance multiparameter coupling system and the responsiveness and robustness of the motor control system need to improved,it is proposed to create a permanent magnet synchronous motor vector control system of the speed PI parameter online tuning based on fuzzy control,and the fuzzy PI regulator is designed.The simulation models of vector control system and positive flow system were built in Simulink and AMEsim respectively,and joint simulations were carried out.By comparing the performance under traditional PI control and fuzzy PI control,the simulation results show that when fuzzy PI is used,the motor speed and torque have better responsiveness and anti-load disturbance ability,and the hydraulic system has better maneuverability and the ability to resist load shock.In order to verify the feasibility of the proposed control strategy,the overall scheme of the motor control system was designed,and the motor controller hardware circuit design and software algorithm writing was completed,and then completed the construction of motor control system test platform.A comparison test of no-load,load,constant speed,and variable speed is carried out.The test results show that when fuzzy PI control is used,the motor control system has better responsiveness and robustness,and the system has stronger anti-load disturbance capability which is very suitable to be used in pure electric-driven construction machinery with severe load fluctuations.In order to further verify the performance of the designed motor controller,a variable speed-quantitative pump positive flow system test platform was built,and the motor controller was validated.The test results show that the output signal of the motor has good responsiveness and stability,the output of the controller can quickly follow the load change,and the hydraulic system runs smoothly and has good robustness.The designed motor control system can well adapt to the working conditions of pure electric drive construction machinery,and the scheme proposed in the thesis is feasible.