Application Of Magnetic Gear And Field-Modulated Permanent Magnet Generator In Ocean Energy Generation

Among the various forms of ocean energy,the utilization of marine current energy and wave energy are relatively mature and in the critical stage of technology progress.In consideration of the low velocity at the location where the marine current generating device is placed,it is not recommended to adopt direct drive,so a speed-increasing device is needed between the generator and turbine.At present,the marine current generation device generally contains the gearbox,but the mechanical fault of the gearbox is one of the drawbacks that affects the long running of the device.In addition,because the wave is moving at a low speed,the conventional direct-drive wave generation system has the disadvantages of small power density and large volume.The application of magnetic gear and field modulated permanent magnet generator in ocean energy generation can provide a good solution to the problems existing in marine current energy and wave energy generation system.In this paper,two kinds of magnetic gear driving devices and two kinds of magnetic field modulated permanent magnet generators are introduced.They have the common research foundation of magnetic field modulation principle.The main research results of this paper include the following aspects:(1)The 3-D analytical method which based on the theory of equivalent current model is presented for calculating the torque of coaxial magnetic gear(CMG).Compared with the 3-D finite element method(FEM),3-D analytical method is characterized by its fast calculation,precision,easy implementation and perfect practice.(2)The problem in the marine current generation system is the increasing operation cost caused by the maintenance of the gearbox.This problem can be effectively solved by using CMG instead of mechanical gear.Considering the characteristics of the marine current,the asynchronous motor is used to simulate the mechanical characteristics of the water turbine.The platform is used to make quantitative analysis on the performance of gear ratio,out-of-step torque,transmission efficiency.Based on the successful experience of platform experiment,the underwater experiments are conducted.The experiment verifies the feasibility and effectiveness of applying CMG to the marine current generation.The research of this paper can provide some useful experience for the exploitation of the marine energy resources in China.(3)In order to accelerate the design period of tubular linear magnetic gear(TLMG)and reduce the cost of computing resources,the hybrid optimization algorithm based on response surface method and particle swarm optimization(RSM-PSO)with fewer sampling points,faster computing speed and higher efficiency is proposed.The RSM-PSO is aimed to improve the thrust capacity and reduce the thrust fluctuation of TLMG.(4)The conventional linear permanent magnet generator(CLPMG)for direct-drive wave energy conversion(WEC)has experienced many drawbacks that are unable to overcome,such as low power density and bulky system volume,etc.Aiming to improve power density,the linear magnetic-geared interior permanent magnet generator(LMGIPMG)is proposed.The disadvantage of LMGIPMG is that the structure of double-gap and double-mover makes the processing difficult,which limits its development and application.Therefore,the magnetic field modulated linear permanent magnet generator(FMLPMG)with simple structure and easy manufacturing was designed and produced.The test results show that when the volume and operating conditions of the two motors are the same,the power density of FMLPMG is higher than that of the CLPMG.