Research On The Speed Sensorless Vector Control System For Dual Three-phase Permanent Magnet Synchronous Motor

With the continuous development of power electronics and control theory,the field of AC speed regulation is no longer limited to the traditional three-phase speed control system,and is moving toward greater power and higher reliability.The dual three-phase motor drive system has the advantages of large power output with low voltage,low torque ripple and fault tolerant operation.It is especially suitable for some application areas where high power and reliability are required,such as electric vehicles,aerospace,marine propulsion etc.Considering the defects of reliability reduction,the increase of hardware cost and environmental impact caused by the installation of position sensors in the system.This paper focuses on the speed sensorless vector control system of dual three-phase permanent magnet synchronous motor(PMSM).By double d-q coordinate transformation and vector space decoupling(VSD)transformation,the mathematical model of dual three-phase PMSM in natural coordinate system is transformed into rotating synchronous coordinate system,to realize the decoupling of the motor physical model.And the correctness of the model is verified by simulation.Based on the idea of VSD,the voltage verctor distribution in the six-phase is obtained.Two-vector and four-vector SVPWM modulations are introduced,and their characteristics and applicable occasions are analyzed.An extended four-vector overmodulation technique based on virtual voltage vector synthesis is introduced to minimize harmonic injection while increasing voltage utilization.At the same time,a dual zero-sequence injection PWM modulation strategy suitable for four-dimensional current vector is analyzed based on the double d-q coordinate transformation decoupling,to increase the voltage modulation range by superimposing zero-sequence components on two independent three-phase modulated signals.A four-dimensional current vector control system is established based on the proportional resonant(PR)regulator.The harmonic current suppression effect of the proportional resonant regulator and the traditional proportional integral regulator is compared.The vector control is built based on double d-q coordinate transformation,to analyze the influence of mutual coupling between two sets of three-phase windings on the stability of equivalent harmonic current subplane control.A speed sensorless control system based on model reference adaptive system(MRAS)is established.Considering that traditional MRAS speed identification method are more sensitive to system parameter changes,the traditional MRAS method is improved and multi-parameter identification is introduced.Due to the proplem of under-rank in multiparameter identification,it is impossible to identify more than two parameters online at the same time.Hence the motor operation is segmented,the stator resistance is estimated when the motor is starting or running at low speed and the rotor magnet flux linkage is valued when the motor is running at medium or high speed stably.The effectiveness of the improved scheme is verified by simulation.The experimental platform of dual three-phase PMSM control system is built.The experimental verification of speed sensorless control scheme shows the validity and feasibility of the theory studied in this paper.