Research On Direct Torque Control Strategy Of Helicopter Electric Main Rotor Based On Active Disturbance Rejection Control

Compared with the oil-fired aeroengine,the electric main rotor helicopter has the advantages of low noise,high reliability,low maintenance cost,environmental protection,high efficiency and relatively simple operation.In this thesis,the permanent magnet synchronous motor is used as the power source to replace the traditional aviation fuel engine.The traditional PMSM control strategy is optimized by using the space vector modulation technology.The final simulation analysis shows that the improved direct torque control reduces the flux and torque ripple,reduces the overshoot,shortens the recovery and tracking time of constant speed,improves the tracking performance of constant speed,and improves the anti-interference performance and robustness of flight.Firstly,the blade aerodynamic model,natural swing model and shimmy model of the helicopter main rotor are established.The pull of the main rotor is calculated by using the blade element theory,and the required power is calculated and analyzed.Then the optimal constant speed of the permanent magnet synchronous motor based on the constant speed and variable distance control theory is determined.On this basis,the basic original parameters and selection of the permanent magnet synchronous motor are determined.Secondly,according to the characteristics of PMSM constant speed and variable distance control,the direct torque control with torque and flux as direct control variables,simple calculation and rapid change of electromagnetic torque is selected,and the flux ripple and torque ripple of direct torque control are optimized.PI regulator is used to replace the lag comparison link,Park inverse transformation and zero voltage vector are introduced,and space pulse width vector modulation technology is used,The circular stator flux control is used to replace the hexagonal flux trajectory control,which solves the pulsation problem of direct torque control itself.Then,based on the active disturbance rejection control theory,the speed loop in direct torque control is improved.The traditional PI control is a passive disturbance rejection method,with obvious lag effect and limited disturbance rejection ability.It can not meet the disturbance rejection needs in complex high-altitude environment and the stability requirements of constant speed in constant speed and variable distance control,and the speed is not stable enough.Aiming at one of the shortcomings,the extended state observer,tracking differentiator and nonlinear error feedback control law are designed,and the nonlinear Active Disturbance Rejection Control is built to replace the traditional PI regulator,which further improves the tracking ability and disturbance rejection ability of speed.Finally,in order to further simplify the calculation and improve the rapidity,the ADRC of the speed loop is linearized,the error function is used to replace the nonlinear function,the nonlinear state observer and error state feedback control law are designed,and the linear Active Disturbance Rejection Control is built,which simplifies the parameter tuning and further improves the rapidity.At the same time,aiming at the flux and torque ripple caused by high-altitude interference,the nonlinear Active Disturbance Rejection Control of flux loop and torque loop is built to form a three loop Active Disturbance Rejection Control main rotor control system to ensure the stability and safety of flight.