Research On Harmonic Surppression Strategy Of Dual Three-phase Permanent Magnet Synchronous Motor Drive System

With the development of power electronic and control theory,the power transmission system has got rid of the limitation of three-phase power supply.Compared with traditional three-phase motors,multi-phase motors have the advantages of small torque ripple,easy to implement fault-tolerant control and low-voltage high-power output,which is especially suitable for high-reliability high-power transmission occasions such as aerospace,ship propulsion,and electric vehicles.Because the current in the harmonic subspace cannot form a rotating magnetic potential,multiphase motors are more likely to generate current harmonics,thereby increasing the loss of the motor and reducing the efficiency of the speed regulation system.Therefore,this paper takes dual three-phase permanent magnet synchronous motor(dual-PMSM)as the research object,deduces the mathematical modeling,modulation strategy,control strategy,and conducts an in-depth study on the current harmonic suppression strategy.The mathematical model of the dual-PMSM in the natural coordinate system is established,and model the dual-PMSM based on the vector space decoupling(VSD)transformation and the double d-q coordinate transformation to achieve degradation decoupling.The difference and connection between the above two modeling methods are analyzed.Through simulation,the correctness of the mathematical model is verified.Based on the idea of vector space decoupling(VSD),the voltage vector distribution of dual three-phase motors is derived,thereby introducing two-vector and four-vector SVPWM algorithm.Aiming at the problem that SVPWM for dual-PMSM cannot achieve four-dimensional current control,double zero sequence injection PWM is introduced.The zero-sequence component is injected into two sets of mutually independent three-phase PWM modulation signals to improve the utilization rate of DC bus voltage.Through simulation,the effectiveness of the modulation strategy is verified.Based on double d-q coordinate transformation and vector space decoupling respectively,a dual three-phase permanent magnet synchronous motor vector control system is established,and the differences and connections between the two control strategies are analyzed.This paper analyzes the current harmonic generation mechanism of dual-PMSM.Based on PI controller and quasi-PR controller,the 5th and 7th harmonic current harmonics in the stator winding are suppressed.A novel current suppression strategy for dual-PMSM based on least mean square(LMS)adaptive notch filter is proposed.This strategy suppresses the 5th and 7th current harmonics in the motor stator by introducing four LMS adaptive notch filters in the harmonic subspace.In the process of motor acceleration and deceleration,the algorithm can quickly converge and has a certain robustness to the deviation of the motor parameters.The simulation proves the effectiveness of the algorithm.Finally,an experimental platform of dual-PMSM drive system is built,and the harmonic suppression strategy proposed in this paper is experimentally verified,which proves the validity and feasibility of the theory studied in this paper.