Research On Minimum Loss Control Of Magnetic Field Modulation Motor Based On Harmonic Analysi

In the context of increasing global energy demand,climate change,and other related issues,the development of new energy sources is receiving more attention and recognition from the international community.Compared to the combination of mechanical gearboxes and highspeed motors,the field-modulated motor is considered more suitable for wind power generation due to its high torque density and low-speed direct drive advantages.Unlike traditional permanent magnet synchronous motors,the field-modulated motor is based on the principle of air gap field modulation to achieve electromechanical energy conversion,resulting in rich air gap magnetic field harmonics under the action of the modulation unit.While providing high torque characteristics,the complex magnetic field harmonics can cause motor losses and increase torque pulsations.This study focuses on a flux-concentrating field-modulated permanent-magnet(FCFMPM)motor with an external rotor magnetization structure and the following research topics:1.Based on electromagnetic laws and analysis of the structure and operating principles of field-modulated motors,a simulation model of the FCFMPM motor and its control equations in different coordinate systems were developed using Matlab/Simulink.2.The air gap magnetic field composition of the FCFMPM motor was analyzed and summarized based on magnetic circuit methods,and the characteristics of the motor’s harmonic magnetic field were studied.The principles of motor losses and electromagnetic torque pulsations were elucidated based on the research on harmonic magnetic fields,and loss and torque calculation models were established.3.To address the high complexity and low accuracy of equivalent loss resistance calculation in traditional minimum loss control,a minimum loss model based on harmonic analysis was proposed to predict torque control strategies for FCFMPM motors.This control strategy achieves online low complexity equivalent loss resistance calculation and fully considers the eddy current losses of the permanent magnet caused by the air gap harmonic magnetic field of the FCFMPM motor.Combined with the model-predictive torque control,the motor’s efficiency is improved while ensuring stable and dynamic responses.4.By analyzing the harmonic magnetic field,the harmonic magnetic field causing torque pulsations in the FCFMPM motor was identified.As the modulated magnetic field resulting from the injected harmonic current affects the effectiveness of torque pulsation suppression,a harmonic magnetic field optimization control strategy based on harmonic current injection was proposed in this study.The air gap harmonic magnetic field causing torque pulsations was taken as the optimization target,and the number of harmonic current injections,amplitude,and phase were used as optimization parameters.The optimal harmonic current was incorporated into the control loop,achieving high-performance torque pulsation suppression.5.An experimental platform for motor control based on dSPACE1103 was established.Corresponding hardware circuits for the dSPACE1103 control system were designed,and a motor drive platform was constructed.The proposed control strategies were experimentally verified and analyzed.