Vector Control Of Symmetrical Phase Loss Operation Of Nine-phase Induction Motor

Compared with three-phase induction motors,multiple sets of multi-phase induction motors have the advantages of small torque ripple,high degree of control freedom,easy to use low-voltage power devices to achieve high power,etc.,and have become the first choice for ships' first-generation large-capacity propulsion motors.The strong fault-tolerant operation capability makes multi-phase induction motors widely used in aerospace,ship propulsion and other areas involving national security,which require high reliability.Therefore,it is necessary to conduct research on multi-phase induction motors.In this thesis,a nine-phase induction motor with three sets of three-phase windings with spatial difference ?/9 electrical angle is taken as the research object,and the mathematical model under different coordinate systems is established.The SVPWM control algorithm and symmetric phase loss for the nine-phase induction motor are studied.Research on problems such as running vector control is carried out,and the research results provide theoretical support for the application and fault-tolerant operation of nine-phase induction motors.Firstly,based on the structural characteristics of the semi-symmetrical stator winding of the nine-phase induction motor,the mathematical model of the three-phase induction motor is developed by the mathematical model of the three-phase induction motor.The space vector decoupling transformation and rotation transformation are performed on the three sets of three-phase windings respectively.The mathematical model of the nine-phase induction motor in the synchronous rotating coordinate system is obtained.Secondly,based on the SVPWM control algorithm of the three-phase induction motor,the SVPWM control of the nine-phase induction motor is realized by using three reference voltage vectors with phase difference ?/9 electrical angles for three-phase SVPWM.The vector control method based on the rotor flux linkage is used to design three vector closed-loop control systems to complete the vector control of the nine-phase induction motor.In order to achieve independent regulation of voltage and current,the stator voltage of the induction motor using the voltage type inverter is voltage compensated.Finally,for the phase failure of the nine-phase induction motor or the actual work,it is necessary to cut out the symmetrical phase loss operation condition of one or two sets of windings.Under the premise that the current effective value is constant,the magnetic path and the core are extremely saturated.The upper and lower bounds of the output torque during the symmetrical phase loss operation of the nine-phase induction motor are derived,and the mathematical model and control strategy of the symmetrical phase loss operation of the motor are further reconstructed.Finally,the nine-phase induction motor is operated under the symmetrical phase loss operating condition.Smooth operation.