Research On Vector Control For A Twelve-phase Induction Motor

On the basis of increasing the number of stator windings,the twelve phase induction motor reduces the voltage and current level of the power device under the same motor power requirement.When the number of motor phase is increased,the electromagnetic torque ripple will decrease.The twelve phase induction motor is better than three phase motor in many part of characteristics.Because of the less study of twelve phase induction motor,there is no detailed description about the control method of twelve phase induction motor.The twelve phase induction motor is a multi-variable,strongly coupled complex system in the natural coordinate system,so it is hard to control it in the coordinate system.In this paper,the twelve phase induction motor,in the natural coordinate system,is transformed into an orthogonal decoupled space with the aid of a space decoupled transform matrix.Thus,the motor model and complexity of twelve phase induction motor are simplified.In this paper,the current hysteresis control and vector control which is based on UVM are applied into the control of twelve phase induction motor.The current hysteresis control is simple control and easy realization,and the control effect will be changed when the hysteresis width vary,however,the switching frequency of the power switching device under the control the current hysteresis is not fixed.In this paper,drawing on the experience of three phase UVM modulation algorithm and vector control method,the modulation and control method is applied into the control of twelve phase induction motor,this control method is not only simple but also can fix the switching frequency of the power switching device.In this paper,these two method are simulated,and the result shows that the proposed method can get better control effect.In this paper,the mathematical model and control method of twelve phase induction motor after phase missing are analyzed,because the twelve phase induction motor is charged by the switch of the power switch device,when one or more power switch device fail,the motor will be in the running state of phase missing;firstly,the mathematical model will be changed after the phase missing,and the mathematical model of the motor will be different when the number and position of the phase missing are different.In this paper,the mathematical model of twelve phase induction motor is analysed in the case of one phase,two phase and three phase missing.Secondly,the method of vector control will vary after the motor is out of phase,the virtual coordinate is used to carry out the vector control after motor phase missing.The simulation result shows that the control method can get better control effect,the control effect will be different when the number of missing phase is different.At last,the experiment platform of twelve phase induction motor is established,the proposed twelve phase induction motor control method and running state after phase missing are analyzed,the experiment result shows the consistency of theoretical analysis and experiment result,which shows the correctness of the proposed control method.