Model-free Adaptive Sliding Mode Vector Control Method For Ship Propulsion Motor

The propulsion motor system of the pod is a complex nonlinear system,which not only involves the parameter uncertainty caused by load mutations,real-time changes in propeller thrust and torque coefficients,as well as frictional and wave-induced flow changes,but also is susceptible to load disturbances caused by unknown circumstances such as sea wind and waves due to the absence of intermediate shaft equipment in the propulsion motor transmission structure.Therefore,there are certain limitations in establishing a high-precision control of the propulsion motor based on the model through mechanism modeling and other methods in practical applications.This paper considers the uncertainty factors such as model uncertainty and unknown disturbances of the propulsion motor under the conditions of ship navigation and docking,and utilizes the I/O data generated during the operation of the propulsion motor to improve the adaptability and control accuracy of the control system based on the model-free adaptive control algorithm and sliding mode control algorithm.The specific content is as follows:1.In response to the difficulties in establishing models for the pod propulsion motor system and the low control accuracy,a model-free adaptive predictive vector control method for the propulsion motor is proposed.This method utilizes input-output data of the non-linear discrete system of the propulsion motor at the current and future time steps to establish a system data model and multi-step prediction equations.Then,the minimum speed error of the motor is used as the optimal index for controller design,and an error feedback correction term is added to the controller to avoid control maladjustment caused by sustained deviation.Simulation results have verified the effectiveness of the proposed control method for the propulsion motor control system.2.To address the issue of load disturbances and unknown interferences that the pod propulsion motor encounters in complex sea conditions,a sliding mode vector control method based on compact form dynamic linearization is proposed.This method utilizes compact form dynamic linearization to establish a data model for the propulsion motor that includes time-varying parameters and load disturbance terms.It then designs a sliding mode controller based on the minimum speed tracking error index and employs a neural network observer to estimate and compensate for unknown load disturbance terms in the controller.The simulation validation indicates that the method effectively enhances the robustness of the system.3.To address the issue of complex coupling between propulsion motors in ship propulsion systems,which in turn leads to difficulties in coordinating motor drives and poor disturbance resistance,a model-free adaptive terminal sliding mode synchronous vector control method is proposed.By introducing a virtual propulsion motor link to improve deviation coupling control structure,a speed synchronization compensator is designed based on the speed difference between the virtual propulsion motor and the propulsion motor.The Compact form dynamic linearization is used to transform the propulsion motor system model into a data model.Furthermore,the equivalent control principle is used in combination with the model-free adaptive control and terminal sliding mode control methods to design a model-free adaptive terminal sliding mode synchronous vector control method with strong robustness.Finally,simulation results confirm the effectiveness of the proposed control method in improving system speed synchronization performance and disturbance resistance.