Research On Sensorless Control Of Underwater Thruster Based On Parameter Identification

With the development of marine resources in the world,there is a growing demand for high-performance marine vehicles and higher requirements for thrusters.Thruster is the core power component of ocean vehicle.Because of space limitation,it is difficult to install position sensor,so the control mode without position sensor is usually adopted.The model parameters of underwater thruster motor are easy to change under the influence of various non-ideal factors in actual working conditions,so the control performance of sensorless control algorithm is affected.In this thesis,according to the requirements of the underwater operation of the self-developed underwater operating robot,the electric propulsion system of the underwater operating robot is designed.According to the design requirements,a high-power and high-integration underwater thruster is developed.On this basis,a new control algorithm of the sensorless position of the underwater thruster is researched and applied in the electric propulsion system of the underwater operating robot.The main research contents of this thesis are as follows:Based on the overall scheme of underwater operating robot,the design of electric propulsion system for underwater operating robot is studied.The electric propulsion system is designed and developed,and the control system of the power module and the control module is designed.The structure and motor drive of the underwater propeller are designed.The torque characteristics of the magnetic coupler and the hydrodynamic characteristics of the propeller are simulated by the finite element software.It provides the experimental basis for the performance verification of the sensorless control algorithm for underwater thrusters.Research on sensorless control of permanent magnet synchronous motor with parameter identification is carried out.The mathematical model of permanent magnet synchronous motor with underwater propeller is established,and the sensorless control algorithm model is built on this basis.Aiming at the problem that motor parameters lead to the degradation of sensorless control performance,an improved student psychological optimization algorithm based on permanent magnet synchronous motor parameter identification strategy was proposed.Based on the standard student psychological optimization algorithm model,the shortcomings of the algorithm are analyzed.Tent mapping strategy and t distribution variation strategy are introduced to improve the algorithm,and the improved algorithm is applied to the identification of motor parameters.The effectiveness of the proposed improved parameter identification strategy is verified by simulation and experiment.Research on rotor position and speed identification of permanent magnet synchronous motor is carried out.An adaptive phase-locked loop(PLL)was proposed to solve the problem of identifying rotor position and velocity in traditional PLL.The PI parameter adaptive link based on stochastic gradient descent algorithm was introduced to improve the dynamic performance of PLL by dynamically adjusting the PI parameters of loop filter according to the actual working conditions.A phase compensation step is introduced to compensate the phase estimation error caused by loop delay by reconstructing error signal.The effectiveness of the proposed adaptive PLL is verified by simulation and experiment.Based on the improved sensorless control scheme,the experimental work on the electric propulsion system of underwater robot is carried out.The system modules are tested and assembled for joint commissioning experiments,and the functionality of the system is verified through land-based and underwater experiments respectively.The experimental results show that the electric propulsion system designed in this thesis can meet the technical requirements and the underwater thruster has excellent control performance.