Research On Torque Control And Distribution Strategy Of Double Reaction Flywheel Motors

The attitude control system of spacecraft is the core of the attitude task that the spacecraft can complete according to the instruction.The attitude control system directly determines the anti-interference and attitude control accuracy of the spacecraft.The reaction flywheel has low consumption,high precision,simple mechanism and high reliability,is a commonly used execution mechanism in spacecraft attitude control system.In order to control the attitude change of the spacecraft through the reaction torque provided by the reaction flywheel variable speed rotation,it is necessary to adopt a reasonable flywheel configuration and its control system.We also need to design its control law and motor control distribution algorithm,realize the motor torque command distribution to improve the control effect.Since the flywheel motor is a small-inductance brushless DC motor,the circuit structure needs to be improved to solve the phase current discontinuity.And the control parameters need to be designed to improve the reliability of the system.In this paper,the orthogonal double-reaction flywheel configuration is selected,and the problem of single-axis double flywheel set is analyzed and studied by deconstructing the three-axis attitude control system into a single-axis double flywheel group.This paper analyzes the characteristics,working principles and advantages of the double-reaction flywheel configuration,and selects the orthogonal double reaction flywheel configuration as the attitude control system flywheel configuration.The three-axis double-flywheel attitude control problem is deconstructed into the single-axis double-reaction flywheel torque control problem,and double-reaction flywheel attitude control system frame diagram is obtained.An attitude control law of the flywheel group is designed for the single-axis double flywheel group.The traditional PD control principle and sliding mode variable structure control principle are analyzed.Two control laws are designed to control the double reaction flywheel motor group.In this paper,I analyze and compare the influence of each control law parameter on the system,and compare the attitude control effects of the two control laws.According to the position control and parameter adaptability requirements,the sliding mode variable structure control is selected as the control law of the double reaction flywheel control system.In this paper,a reasonable motor control torque allocation algorithm is designed to solve the problem of control distribution of single-axis double-flywheel group configuration with redundant configuration.In view of the problem of zeroing and saturation of the flywheel attitude control system,the control distribution strategy design is carried out in combination with the dynamic distribution theory.At the same time,the torque change is flat and the precision is high,and the command torque is output within the ideal speed range.By increasing the feedback link to optimize the closed-loop torque control distribution strategy,the torque instructions of each flywheel are assigned to the executing mechanism to ensure the execution effect,improve the stability,control accuracy and reliability of the system,and reduce the impact of installation deviation.The reaction flywheel motor is a small inductive brushless DC motor,and this paper proposes a new three-level DC voltage regulation circuit and a three-phase inverter circuit combined circuit structure to avoid the phenomenon of intermittent current and reduce torque pulsation.The control system structure used by the design motor for the torque command is designed,and the rate feedback torque mode control scheme of the outer ring is the rate circuit and the inner ring is the current circuit.Realize the real-time tracking of the desired torque and the suppression of the internal interference torque.In order to verify the double reaction flywheel configuration and attitude control law,control distribution algorithm,drive circuit rationality and feasibility,an experimental platform is set up to carry out verification experiments.The single-axis double reaction flywheel motor experimental platform is designed to achieve position control,ensuring that there is no speed over zero and saturation of each flywheel.The effectiveness of the proposed configuration,control law,control distribution algorithm and drive circuit is verified by the experimental platform motor speed and system response.