Research On Current Harmonic Suppression Strategy Of Double-three-phase Permanent Magnet Synchronous Motor Based On Winding Asymmetry And Inverter Nonlinear Analysis

At present,the global energy crisis and environmental pollution problems are becoming more and more serious,the electric drive system has been the trend of The Times.Because of the advantages of small torque ripple,high efficiency and high reliability,the polyphase motor is especially suitable for high-power industrial applications,such as pure electric vehicles,electric propulsion of ships and electric aircraft.However,the non-linearity of the inverter and the process deviation during the manufacture of the motor body will lead to the emergence of current harmonics,which will produce additional motor loss and vibration caused by torque ripple.These will seriously affect the control performance of multiphase motor,which greatly limits its application in high performance occasions.Therefore,this paper takes the asymmetric double-three-phase permanent magnet synchronous motor as the research object,and mainly studies the current harmonics of the double-three-phase permanent magnet synchronous motor to improve the performance of the control system.Firstly,this paper introduces the type,structure and operation mechanism of doublethree-phase permanent magnet synchronous motor,and compares the advantages of asymmetric double-three-phase permanent magnet synchronous motor and traditional three-phase permanent magnet synchronous motor.The mathematical model of doublethree-phase permanent magnet synchronous motor based on double DQ transformation and VSD transformation is established,and the internal relations and differences between the two transformations are compared and analyzed.According to the two kinds of different transformation,the corresponding control strategies are formulated to realize the vector control of the motor.From the point of view of system control,the differences and relations between the two control strategies in the control system are studied.Secondly,in order to realize the vector control of two-three-phase motor,this paper analyzes the influence of voltage modulation method on motor control,and analyzes the difference and connection of different voltage modulation algorithms.In order to realize the four-voltage vector modulation PWM algorithm with less computation,this paper adopts the three-phase voltage vector decoupling PWM algorithm,and uses the SVPWM of two traditional three-phase motors to realize the four-vector voltage modulation.Through the analysis of voltage modulation method,the vector control of two-three-phase motor is realized,which lays the foundation for the algorithm in the following.This paper also simulates the vector control of the two-three-phase motor by building a simulation model,which provides theoretical guidance for the analysis and experiment below.Thirdly,this paper analyzes the inverter nonlinear,establishes the mathematical model of the voltage harmonics caused by the dead zone effect,and analyzes the generation mechanism of the motor torque ripple caused by the inverter nonlinear.The mathematical model of inverter dead zone in the harmonic subplane of two-three-phase motor is deduced.Based on the dead zone compensation strategy of inverter,the suppression method of harmonic subplane harmonic current is obtained from the output of current loop integrator under synchronous coordinate axis,and the compensation algorithm of torque ripple is obtained.In addition to the nonlinearity of the inverter,this paper studies the relationship between the structural asymmetry of the motor and the current harmonics,and finds out the action law of the current harmonics in the harmonic subplane.According to the analysis method of positive and negative sequence,a new transformation matrix is constructed,and the current harmonics generated by the asymmetric structure of the motor are mapped into two rotating reference frames,namely synchronous and anti-synchronous,and the harmonic is suppressed by PI controller.Then,by designing the hardware and software of the motor controller,this paper builds the experiment platform of the double-three-phase permanent magnet synchronous motor.In this paper,three experiments are carried out to verify the equivalence of VSD transform and double DQ transform.Verify the practicability of inverter nonlinear compensation algorithm;Effectiveness of current optimization algorithm for motor imbalance.Experiments show that the proposed algorithm can effectively suppress the current harmonics of the two-three-phase motor.Finally,the thesis is summarized and prospected,and the further research directions are pointed out to provide research ideas and theoretical reference for improving the control performance of double-three-phase permanent magnet synchronous motor and promoting the further application of double-three-phase permanent magnet synchronous motor in the industrial field.