Research On Current Loop Control Strategy Of Ship Six-phase Permanent Magnet Synchronous Motor

With the development of ship towards high reliability,electrification,intelligence and greenness,ship electric propulsion technology is widely concerned.The six-phase permanent magnet synchronous motor(PMSM)has many advantages such as high efficiency,high reliability and low voltage and high power drive,so it has wide application space in the Marine electric propulsion system.In order to ensure the maneuverability and maneuverability of the ship,reduce the energy loss of the propulsion motor,and ensure the smooth and stable power output,the current loop of the propulsion motor drive control system should have good dynamic and steady-state performance.To achieve these goals,this paper takes six-phase PMSM as the research object.After analyzing the basic theory of its vector control,aiming at cross-coupling of d and q axes,delay of current loop system,and current harmonics and other problems in its vector control,the current loop dynamic performance improvement strategy and current harmonic suppression technology of six-phase PMSM are studied.Firstly,the vector space decoupling(VSD)mathematical model and double d-q mathematical model of six-phase PMSM are established respectively.The advantages,disadvantages and internal relations of the two mathematical models are compared,and the characteristics of different six phase vector pulse width modulation(PWM)algorithms are discussed.A set of vector control scheme suitable for six-phase PMSM is selected.Secondly,in view of the problems of dynamic coupling between d-axis and q-axis of six-phase PMSM and time delay of current loop,which affect its dynamic regulation abili ty,the method of complex vector decoupling is used to decouple d-axis and q-axis,and the method of double sampling and double updating PWM is used to shorten the time delay of current loop system.The simulation results show that the strategy effectively improves the dynamic performance of current loop.Thirdly,in view of the problem that the dead time effect of the inverter and the asymmetry of the motor winding will cause a lot of harmonic currents in the six-phase PMSM,which will cause the steady-state speed and torque ripple of the motor,the conclusion that the four new harmonics in the d-q subplane and the dz-qz subplane are caused by the dead time effect of the inverter and the asymmetry of the winding is deduced.Based on this,a current loop controller based on quasi proportional resonance control is designed,which effectively suppresses harmonic current and improves the steady-state control performance of the motor.Finally,according to the actual needs,a set of six phase permanent magnet synchronous motor frequency conversion drive control device for small ships is designed and manufactured,and the detailed design scheme of frequency conversion drive device software and hardware is given.The hardware part mainly includes the power module,the main circuit module and the control circuit module,which provides the hardware conditions for the motor to realize the frequency conversion control.The software part adopts the modular programming concept,mainly including initialization program,main program and interrupt service subroutine,to realize double closed-loop,PWM algorithm,detection and alarm functions.