Harmonic And Performance Analysis Of Asynchronous Motor Under Variable Frequence Power Supply

With the large-scale use of power electronic devices,the harmonic problems contained in the power supply have become increasingly prominent.Moreover,in the engineering practice,in order to make the starting performance of the motor better,the inverter is usually used to supply power to the motor.But the variable frequency power supply contains a large amount of harmonic components,which increases the loss.And the loss is also an important factor of affecting the motor’s efficiency.Through theoretical analysis and simulation experiments,this paper analyzes the harmonic in the variable frequency power supply,the iron loss generated by the motor and the starting performance of the motor in detail.The main work is as follows:In this paper,an 11 kW asynchronous motor is used as the research object.Firstly,The Double Fourier series expression of the single-phase inverter voltage is carried out and carried on the programming emulation.And the motor iron consumption model based on time-step finite element method is established.Motor stator core is divided into five typical regions for magnetic density track analysis.The imitation results are used to verify the correctness of the simulation results The three methods of sinusoidal power supply are compared and calculated.Secondly,the Double Fourier series expression of the three-phase inverter voltage is derived and programmed by Matlab.It obtains the harmonic spectrum map under the different modulation ratios and the different carrier ratios.Comparing the analytical method with the harmonic spectrum diagram under the different carrier ratios and the different modulation ratios by modeling and simulation,the accuracy of the result is vertified.Lastly,the variation of the magnetic density of the stator core at different modulation ratios and carrier ratios is studied.And the distribution law of iron consumption at each typical position of the motor under different modulation ratios and carrier ratios,and the distribution law of iron consumption under different loads are studied.And the iron loss under the two power supply modes is opposed and analyzed.The starting performance of the motor under different power supply modes is analyzed.In this paper,the correlation regular of harmonics and performance of the motor under variable frequency power supply is obtained by analytical method and simulation method,which provides a reasonable basis for the calculation of other fields.