Research On Design And Vibration Control Technology Of Marine Hybrid Magnetic Bearing-rotor System

Ship propulsion shafting is the core component of ship power plant.Propeller blades work in the non-uniform wake field to produce unsteady exciting force,resulting in longitudinal vibration of shafting,and thentransmitted to the hull,resulting in low-frequency vibration and radiation noise,which seriously affects the ship’s navigation concealment.The vibration of propulsion shafting has become the research focus and difficulty in the field of vibration and noise reduction of ship machinery.Traditional passive vibration isolation technology can not be used for vibration control based on specific line spectrum.With the development of ship detection means to extremely low frequency,it is necessary to developnew active control vibration reduction technology for propulsion shafting to meet the high concealability requirements.Hybrid magnetic bearing(HMB),as a non-contact high-performance bearing,has the advantages of active control of supporting characteristics,large bearing capacity with the same volume and low power consumption,which has shown broad application prospects in the vibration control of propulsion shafting.Therefore,the paper proposes a marine propulsion shafting structure supported by HMBs,and the PID controller design method,multi-physical domian coupling system modeling,longitudinal vibration control method of shafting and ship environmental adaptability of the system are deeply studied.The main research work and achievements of this paper are as follows:(1)Firstly,the structural design of HMB suitable for marine propulsion shafting was carried out.The radial hybrid magnetic bearing(RHMB)and radial-axial hybrid magnetic bearing(RAHMB)are taken as the research objects.Combined with the equivalent magnetic circuit analytical model,the parameter design method of HMB is proposed with taking the maximum electromagnetic force as the design index,and the three dimensional finite element simulation is carried out.In addition,aiming at the problem that the traditional PID control parameters mainly rely on experience and lack the guidance of system theory,the influence law of each control parameter on the dynamic characteristics of the system is analyzed,and a feasible decentralized PID controller design method is proposed.The above research work provides theoretical support for the construction of virtual prototype and test prototype of HMB system.(2)In view of the complex coupling between multiple physical domains involved in HMB-rotor system,a virtual prototype modeling and analysis method based on Simscape is proposed in this paper,which realized the modeling and simulation of HMB-rotor system on a single computing platform,effectively overcoming the inconvenience and complexity caused by the traditional method calling different commercial software indirect interfaces.Further,an experimental prototype with the same structure and mechanical parameters as the virtual prototype is built to realize the rapid and stable suspension and operation of the rotor,which greatly shortened the development cycle of the test system.Virtual prototype simulation and experimental results verify the correctness of the HMB structure and PID controller design in this paper.(3)Aiming at the longitudinal vibration control requirements of ship propulsion shafting,a longitudinal vibration control method based on HMB variable stiffness control is proposed in this paper.Based on the difference of longitudinal excitation frequency under different rotational speeds,this method realizes dynamic adjustment of shafting vibration transmission characteristics and avoids longitudinal resonance by adjusting controller parameters in real time and changing the longitudinal support stiffness of shafting.The variable stiffness control method is applied to the virtual prototype and the experimental prototype.The results show that compared with the resonant condition,the base acceleration vibration is effectively reduced by approximately 5-20 d B.At the same time,the displacement of the shaft system vibration is decreased correspondingly,leading to improved system stability,which provides a new solution for controlling propulsion shaft system vibrations.(4)In order to improve the adaptability of HMB system to complex ship environment,combined with the engineering application background in the field of vibration and noise reduction,a state-space model of HMBelastic support system suitable for dynamic characteristics analysis is constructed,and a matching design method of elastic support and magnetic bearing mechanical parameters is proposed.The simulation and experimental results show that,compared with the traditional rigid support,the elastic support structure can effectively attenuate the vibration displacement of the rotor in the large motion of the ship foundation and the resonance of the rotor speed,thus effectively improving the stability of the system,which provides an important theoretical basis for the optimization design and engineering application of the marine HMB system.In summary,the paper focuses on the design and vibration control technology of marine HMB-rotor system,which has a clear engineering application background and practical needs.Relevant research results provide strong support for the development and application of vibration and noise reduction technology for marine propulsion shafting.