Research On Drive And Control Of Electric Passive Torque Servo System

Electric passive torque servo system is used under hardware-in-loop conditions to simulate load torque for transmission equipment,which plays a key role for ensuring production,research and development.And the increasing accuracy and maneuverability of transmission equipment request electric passive torque servo system having higher loading performance.However,the mathematical model of system is a resonant term,and its load torque reference and strong external disturbance caused by the active motion of bearing system have complicated forms,which make the dynamic performance,loading precision,stability and loading bandwidth of system being difficult to be effectively ensured.To settle these problems,this paper thoroughly studies electric passive torque servo system from its loading motor driver,current control strategy,speed control strategy and load torque control strategy.The researches aim on seeking the effective method to further improve the dynamic performance,loading precision,stability and loading bandwidth of electric passive torque servo system,and providing the theory and technical reference for the realization of higher loading performance.The loading of electric passive torque servo system is intrinsically the energy transmission.Therefore,the energy transmission speed of loading motor dirver directly affects the dynamic response of system.This paper firstly combines the energy transmission process of the loading motor driver with the mathematical model of current loop of system,and analyzes the influence of the energy transmission speed of loading motor dirver on the dynamic response of system.On this basis,the matrix converter and back-to-back dual PWM converter are analyzed and compared,which indicates that the matrix converter can effectively improve the dynamic response of system.For the application of matrix converter,its input filter is designed,which further ensures its dynamic response and the efficiency of power and voltage transmission.Finally,the effectiveness of applying matrix converter is validated by the waveforms of current and speed response of system.Applying matrix converter effectively improves the energy transmission speed of system,but it also provides much difficulty for the realization of high precision current control.Therefore,the modulation strategy and commutation strategy of matrix converter and the current control strategy of permanent magnet synchronous motor are studied.By optimizing the vector sequence of indirect space vector modulation strategy and improving the voltage-based commutation strategy,the influences of narrow pulses and commutation delays are effectively suppressed,and the loading performance of system under low speed operation state of loading motor is ensured.And the extended state observer is added into the current control strategy of permanent magnet synchronous motor by being combined with the “PI control + current cross decoupling”,to compensate the external disturbances of d-q axis of permanent magnet synchronous motor and the uncertainties of system caused by the changes of the motor parameters,which further improves the current control precision of system under different loading conditions.Finally,the effectiveness of the modulation strategy and commutation strategy of matrix converter and the current control strategy of permanent magnet synchronous motor are validated by simulations and experiments.The speed control strategy also has significant influence on the dynamic response,stability and loading bandwidth of system.The output,external disturbance and mathematical model of electric passive torque servo system are load torque,active motion of bearing system and resonant term,respectively.And all of them are obviously different from those of traditional electrical drive systems.To settle this problem,the two-degree-of-freedom state space speed control strategy applicable to electric passive torque servo system is proposed by combination of a proportional term,a speed reference feedforward term and a load torque compensation term,which effectively improves the tracking performance and surplus torque suppression performance of system,and ensures the stability and robust of system.On this basis,the extended state observer is applied to avoid the detrimental effects of speed detection error caused by encoder and friction,further ensuring the loading precision of system.Finally,the experimental results validate the effectiveness of the two-degree-of-freedom state space speed control strategy.Based on the researches mentioned above,the load torque control strategy based on proportional resonant control is studied according to the spectrum loading.The discrete mathematical model of system is built firstly,which provides effective theoretical basis for the design and analysis of the load torque control strategy.On this basis,a phase compensation term is added into the proportional resonant controller.And the load torque control strategies for both the sinusoidal gradient loading and nonsinusoidal loading conditions are designed and analyzed based on the Nyquist diagrams and pole-zero plots of the discrete mathematical model of system.Finally,the experimental results indicate that by applying the loading control strategy based on proportional resonant control,the loading bandwidth of system is increased to 20 Hz when the loading gradient is only 0.3N·m/°,effectively improving the dynamic performance,loading precision,stability and loading bandwidth of system...