| Permanent magnet synchronous motors are increasingly used in industrial manufacturing due to their high efficiency and good stability.With the development of power electronics technology,inverters are widely used in permanent magnet synchronous motor control systems.However,the inverter drive will introduce current time harmonics,which introducing additional harmonic loss in permanent magnet motors.In order to meet the requirements of "Made in China 2025" on the energy efficiency of the motor,in this article,the additional harmonic loss of permanent magnet synchronous motor under inverter drive supply is investigated.The research is carried out from three aspects: the output current waveform of inverter drive,the time harmonic distribution of permanent magnet motor,and the harmonic loss suppression method.The main research contents of this paper are as follows:In the first part,Simulink is used to build the main circuit and pulse trigger circuit of the inverter,the influence of sine pulse width modulation and space vector pulse width modulation on the harmonics of the inverter output current is analyzed.The influence of the carrier ratio and modulation ratio on the current waveform distortion rate,the distribution of harmonics and the amplitude of the current fundamental wave under the two modulation methods is also analyzed.By testing two permanent magnet motors with different speeds,the current harmonic distribution characteristics,the current waveform distortion rate of the inverter and the influence of the two inverter parameters on the additional harmonic loss of the permanent magnet motor is verified.The analysis results provide a basis for suppressing current time harmonics through inverter parameters.In the second part,Simulink,Simplorer,and Maxwell field-circuit coupling calculation simulation model is established.Based on the vector control method with id = 0,the additional harmonic loss of the four surface mount permanent magnet synchronous motors for robots are calculated.The distribution law of time harmonics is analyzed.Refer to the GB/T 32877-2016,the additional harmonic loss of four permanent magnet motors is tested,the calculated and tested values are analyzed and compared.The calculation correction coefficients are calculated and summarized on the additional harmonic loss of this type of permanent magnet synchronous motor,facilitating the calculation of additional harmonic loss in the preliminary design phase of permanent magnet motor.In the last part,based on a 5k W surface mount permanent magnet motor,the field-circuit coupling analysis method is used to study the influence of the different slot-pole combination,stator slot size,air-gap length,and permanent magnet axial and circumferential segment number on current time harmonics of permanent magnet motor.The influence law of these factors on the amplitude and distribution of the additional harmonic loss on the stator core and permanent magnets of the motor is analyzed.From the perspective of motor body design,the methods to suppress the additional harmonic loss caused by the inverter drive are summarized.It provides a basis for selecting appropriate motor parameters in the motor design stage to suppress current time harmonics. |
