| With the development of power electronic technology and control theory,the power level and reliability requirements of AC drive system have increased.Multiphase permanent magnet synchronous motor has the characteristics of high power density,high reliability and small torque ripple,and is especially suitable for applications such as offshore wind power generation,aerospace,electric vehicles,etc,which require high power level and reliability.The distributed control of multi-phase(taking the multiple phase of three as an example)permanent magnet synchronous motor is to regard the whole motor as a combination of N three-phase permanent magnet synchronous motor units,and then control each sub-unit.In the permanent magnet synchronous motor control system,the use of position sensors will increase the hardware cost,be easily disturbed by the surrounding environment,and reduce the reliability of the system.And the coupling between the three-phase windings of the multi-phase the permanent magnet synchronous motor is strong,the control is complex,and the portability of the algorithm is poor.In view of the above problems,this paper focuses on the position sensorless control of multi-phase permanent magnets in a distributed architecture.The main contents are as follows.(1)By analyzing the spatial structure and winding distribution of the multi-phase permanent magnet synchronous motor,the mathematical model of the multi-phase permanent magnet synchronous motor in the natural coordinate system is constructed.The mathematical model in the natural coordinate system is transformed into the rotation coordinate,and the mathematical model of the motor based on the d-q coordinate system is constructed.And the PWM modulation strategy and vector control method of the multi-phase permanent magnet synchronous motor are analyzed.(2)The existing problems of the traditional sliding mode observer based on the super-twisting algorithm are analyzed,and an improved sliding mode observer based on the super-twisting algorithm is proposed.First,using a proportional resonance controller instead of the sign function can reduce chattering.Secondly,considering the influence of back-EMF harmonics on the position observation accuracy,a back-EMF observer is used to filter out the harmonic components in the back-EMF and reduce the position observation error.(3)The problems of strong coupling between the three-phase windings,complex control,and poor algorithm portability in the multi-phase permanent magnet synchronous motor are analyzed,and a model transformation method is proposed.The N*3 phase permanent magnet synchronous motor is decoupled into N equivalent independent three-phase permanent magnet synchronous motor units.After the model transformation,each three-phase sub-unit can continue to use the ordinary three-phase permanent magnet synchronous motor control algorithm,which has strong expansibility.At the same time,combined with the sensorless control technology,the sensorless control of the multi-phase permanent magnet synchronous motor under the distributed architecture is proposed.The sensorless control algorithm is applied to each three-phase permanent magnet synchronous motor unit.Each three-phase sub-unit can obtain position information without the help of position sensors,which is suitable for all kinds of harsh environments,so as to improve the reliability of the distributed control system of polyphase permanent magnet synchronous motor.Finally,the correctness and effectiveness of the proposed method are verified on two experimental platforms of three-phase permanent magnet synchronous motor and dual three-phase permanent magnet synchronous motor. |
