Research On Control Of The Six-phase PMSM Drived By Matrix Converter

Variable frequency technology is extremely important in electric propulsion ships.However,the variable frequency technology which is employed now have many defects.For example,cycloconverters' output frequency is restricted,and AC-DC-AC converters are of low power density due to capacitors and inductors in DC link and cannot realize energy feedback.Matrix converters,as a kind of new converter technology,have advantages of high power density,good input-output characteristics,energy flowing bidirectional,and so on.It has great potential in electric propulsion ships for above advantages.In theory,the main drawback of three phase-three phase matrix converter is low in voltage utilization coefficient,and the multiphase motor drive system is an effective solution for the problem of low-voltage large-power.The core idea of this paper is to combine matrix converter with the multiphase motor drive system,take both advantages and fill the gap of matrix converter.Asymmetric six-phase permanent magnet synchronous motor(PMSM)has the advantages of high redundancy and reliability compared with three-phase electric machines,and of simple manufacturing and control compared with twelve-phase or fifteen-phase machine.In general,it 's an appropriate choice for electric propulsion ships.The study on matrix converter,asymmetric six-phase multiphase PMSM and the combination control of them has both the academic value and practical significance.This paper focuses on the matrix converter's double space vector modulation strategy,asymmetric six-phase multiphase PMSM's vector control and the combination control of them.This paper has mainly carried on the following work:1)Investigate the present situation of variable frequency technology in electric propulsion ships.Analyze their advantages and disadvantages and present that the matrix converter will have promising application in the future development of electric propulsion ships.Meanwhile,the present situation of the multiphase PMSM and its application in electric propulsion ships are also investigated.2)Introduce the principle of matrix converter and the theory and realization of double space vector modulation.The disadvantages of three phase-three phase matrix converter's voltage utilization coefficient's not exceeding 0.866 and the advantages of adjustable power factor are demonstrated mathematically.Prove the rationality of matrix converter's double space vector modulation.Design the input filter with damping resistance.Simulation results demonstrate the matrix converter can realize variable voltage variable frequency(VVVF)and adjustable power factor.3)Introduce the structure,principle,mathematical equations and vector control of asymmetric six-phase multiphase PMSM.Build its vector control model according to a motor's practical parameters.Simulation results demonstrate vector control's accurate controlling of speed and rapid processing of torque.4)Combine three phase matrix converter and asymmetric six-phase multiphase PMSM by phase-shifting transformer.Demonstrate this method combines both advantages of matrix converter(high power density,ability of four-quadrant operation and good input-output characteristic)and multiphase PMSM's vector control(accurate controlling and rapid processing of speed and torque).