Multimodal Energy Regulation Strategy Of Six-phase Motor Applied In Combined Propulsion System

With the development of power electronic devices and the innovation of inverter technology,AC motor no longer has to be a three-phase motor to match the power grid,it has become a new degree of freedom.Compared with the three-phase motor AC speed control system,the multi-phase motor AC speed control system has the advantages of high output power,high fault tolerance,low torque fluctuation and high reliability.Therefore,it has a broad application prospect in the fields of energy power,transportation and defense military industry,among which the field of ship electric propulsion is the main application direction of multi-phase motor drive system.This paper takes the different working conditions of the six-phase induction motor in the combined propulsion system as the research object,taking the motor speed control as the basis of the control method of the combined propulsion system,and studies the control strategy of the six-phase induction motor under different working conditions,as well as the power flow regulation strategy when switching between different working conditions.The feasibility of the mathematical model and control strategy is verified by building a simulation model under the Matlab/Simulink simulation software.The key research contents of this paper are summarized as follows:(1)Based on the topology of the double Y shifted 30°six-phase induction motor,a mathematical model of the six-phase induction motor based on the natural coordinate system is derived.The voltage equation,magnetic chain equation,electromagnetic torque equation and motion equation of the six-phase induction motor are obtained.(2)The mathematical model of the bidirectional three-phase converter is studied from the rectifier side and the inverter side respectively.According to the voltage and current equation,coordinate transformation is introduced to analyze the mutual coupling of the dq axis voltage and current components on the rectifier side and propose a decoupling scheme.Design the double closed-loop control system on the rectifier side.(3)Vector control technology of double Y shifted 30°six-phase induction motor is studied.According to the structure of propulsion system,which is powered by two three-phase inverters,and two three-phase windings with a difference of 30°are equivalent to the base wave components of the six-phase windings,the control block diagram of the two-phase vector control system is derived from the mathematical model of the six-phase induction motor.This paper introduces the basic principle and realization method of traditional SVPWM technology,analyzes the common mode voltage produced by three-phase system and its characteristics,and introduces SVPWM technology which can inhibit common mode voltage.(4)Based on the derived mathematical model and control block diagram,double Y shifted 30°six-phase induction motor,bidirectional three-phase inverter and two-dq vector control system were constructed and analyzed by using Matlab/Simulink simulation platform.Four operating conditions of the six-phase induction motor in the combined propulsion system are expounded:motor independent propulsion,motor decoupling and parallel propulsion,and motor follow-up power generation.Taking the motor speed control as the basis of the control method of the combined propulsion system,the control strategies of the system under four conditions are analyzed,and the simulation model is built to verify these four conditions.