The Research And Analysis On Control Of Pod Ship Electric Propulsion

Ship electric propulsion has been successfully applied in icebreakers, tankers,chemical tankers and others. In recent decades, with the rapid development of powerelectronics industry, the emergence of new high-performance high-power devices, and thedevelopment of new motor, especially the advent and application of pod propulsion device,the ship electric propulsion has accelerated the pace of development, and shown greatpotential for development. And it has gradually become the main steam of future shippower plant with its many advantages such as good mobility, flexible layout, goodenvironmental performance and ensuring diesel engine work in the best condition.This paper focuses on POD power propulsion system, firstly, the operationalcharacteristics are analyzed, mainly analyzes the characteristics of thrust force and torqueof propeller, as well as the resistive characteristics of ship sailing. On the basis, establishestheir own mathematical models and simulink models, and builds the ship-propellersimulation model, then in the condition of different propeller angels of pod, analyzes theship speed, thrust and resistance withstanding, and the propeller torque by the simulation,the simulation results show that modeling is correct and feasible. For the main propulsionmotor, this paper chooses the three-phase permanent magnetic synchronous motor (PMSM)as the direct study object. For motor control, this paper uses the direct torque control (DTC)to replace the vector control.Based on the traditional direct torque control, the thesis analyzes the principle andstructure of the direct torque control, and builds simulation models of each module of thesystem in the MATLAB/Simulink platform, thus establishes the overall simulation modelof the traditional direct torque control of PMSM. Following, analyzes the characteristics ofPMSM with stator flux, speed, electromagnetic torque and three-phase current of stator bysimulation. Then focused on deficiencies of the direct torque control such as flux andtorque ripple, non-fixed switching frequency of inverter, the paper induces the intelligentcontrol technology to improve it. The thesis mainly uses fuzzy control strategy and spacevector pulse width modulation technology, builds the simulation model of the improvedsystem. Show that the performance of the improved system has been enhanced overall.Finally, the pod ship-propeller model is as drag load of PMSM, gives analysis andstudy about the control of pod ship electric propulsion system, establishes DTCcomprehensive simulation system of the pod ship electric propulsion. Similarly, the fuzzy control and the space vector pulse width modulation technology are applied in it.Moreover, gives a analysis of the response characteristics of motor, as well as the responsecharacteristics of ship by comparison in different propeller angels, according to verificationof simulation, the improved DTC system of ship propulsion has a better dynamic and staticperformance.