The Design Of Downhole Turbine Permanent Magnet Generator And Control System

The deviation control and fast drilling through high-dip formations are difficult problems of the exploration and exploitation of deep oil and gas fields in China.The development trend of modern drilling is intelligent drilling.In order to overcome the problem of drilling in China and adapt to the development trend of modern drilling,MWD,LWD,automatic vertical drilling system and rotary steering system must be used.With more and more functions of intelligent tools,the demand for electric power is increasing.Downhole turbine generator can be used to supply power to the underground intelligent instrument,which is the premise and foundation of work.Because of the shortcoming of the permanent magnet generator and the magnetic coupling permanent magnet generator,so it is very necessary to design a kind of downhole turbine generator which has good sealing performance and works long hours.On the basis of previous studies,this paper designs a kind of downhole turbine permanent magnet generator and control system,from two aspects of theory and simulation.The work of the paper is as follow:(1)Magnetic circuit calculation and structure design of downhole turbine permanent magnet generator are completed.It is confirmed that the generator is a 3phase 4 pole 24 slot,which is connected with the structure of the magnetic seal and the magnetic seal.It outputs phase voltage of 48 V and power of 1000 W at 2500 rpm.(2)The electromagnetic field simulation and thermodynamic simulation of this machine are completed.Based on electromagnetic field simulation by Ansoft Maxwell,the radial length of the magnetic steel is determined to be 150 mm.At the same time,the correlation curve of the generator is also studied,such as no-load voltage curve,load voltage curve,load output power curve,load efficiency curve,load driving torque curve,the output voltage curve of different load and the output voltage curve of a certain speed.Through Ansoft and workbench joint temperature field simulation,that maximum temperature of this machine is 21.99? is known.(3)The design and simulation of drive turbine are completed.The relevant parameters of the turbine is calculated and designed on the basis of the driving torque curve.By CFD based on fluent,the correlation curve of turbine is determined such as torque curve,pressure drop curve,output power curve,input power curve and efficiency curve.The maximum speed that generator meets the requirements of driving torque and current density is 4050 rpm.(4)Rectification voltage-stabilized circuit and control system are design.Rectification voltage-stabilized circuit is composed of Three-Phase Full-Bridge Controlled Rectifier and voltage stabilizing circuit.Based on circuit simulation by Simulink,the output voltage of rectifier with different input voltage is obtained.The control circuit is based on Arduino UNO,that achieve the following functions such controling duty cycle based on rectified output voltage,power-supply by battery based on the condition of generator,battery charging based on storage battery SOC.Control system control program is written in Arduino C.The main results of the paper(1)complete he structure design of the downhole turbine permanent magnet generator,obtain the characteristic curve of the generator.The output voltage is 48.68 V at 2500 rpm and 91.8V at 4800 rpm.(2)complete the design of the driving turbine,which provides the basis for the generator drive.(3)complete rectification voltage-stabilized circuit and control system,which provides the basis for stable power supply.By studying the change of duty ratio,capacitance and inductance,we know the change regulation of impulse voltage,stable time and scope range of the fluctuation of voltage.Through relevant research,I have a deeper understanding of the downhole turbine permanent magnet generator and control system.The innovation of the paper lies on the structure and the analysis method of the generator.There are some reference value for future research in rectification voltage-stabilized circuit and control system.