Optimal Design And Vector Control Of Interior Ferrite Permanent Magnet Synchronous Motor

Thanks to the merits like compact structure,high power density and high efficiency,permanent magnet synchronous motors(PMSMs)are widely used in many applications,such as aerospace,transportation traction,industry and domestic applications.The PMSMs using cheap ferrite material have received more and more attentions in recent years.In some low cost,high performance applications,such as fans and pumps,the ferrite PMSMs can dramatically reduce the system volume and weight and increase the efficiency if compared with the induction motors.Considering that the magnetic performance of the ferrite permanent magnet material is not good as the rare earth permanent magnet materials,an interior ferrite permanent magnet synchronous motor with flux-focusing structure is studied in this thesis.The motor exhibits high efficiency,high power factor and low torque ripple,and can be used for low cost applications.Furthermore,for the motors like interior PMSMs and synchronous reluctance motors,of which the parameters may vary with the core saturation,two optimal control strategies based on the maximum torque per ampere(MTPA)control are proposed in this thesis.The MTPA control can effectively reduce the copper loss and increase the efficiency.However,the motor parameter uncertainty,which is due to the difference between the actual and designed parameters as well as parameter variation with the load condition,makes the MTPA trajectory shift,and causes the motor operation status differing from the ideal one.To solve this problem,an optimal MTPA control strategy is proposed,which fits the parameter variation.In order to improve the power factor of the motor over the full load range,an optimal three-segmented control strategy is proposed,which helps to extend the operation speed range under heavy load.Finally,the actual MTPA trajectory of the prototype is measured in the test.