The Modeling And Research Of Multiphase Induction Machine With Structural Unbalance

Since the eighties of the last century, with the development of power electronics and motor drives, the limitation of the number of phases of the drive being equal to that of the power supply was removed and opened the scope of exploring the multiphase motor. Multiphase machine has many advantages over the traditional three-phase motor drives such as reducing the amplitude and increasing the frequency of torque pulsation, reducing the stator current per phase without increasing the voltage per phase, lowering the dc link current harmonics and higher reliability. For that multiphase machine with capabilities to start and run even with one or more of its stator phases open-circuited when the winding structure is multiphase, recently, several papers studying the performance of multi- phase machine concerning when one or more stator phase open- circuited have been published.In this paper, the author presents the modeling of dual-three-phase induction machine with two stator phase windings opened using vector space decomposition method. The model can be used analysis and control of the machine. The dynamic performance of the machine with structure unbalance is simulated with the help of MATLAB/SIMULINK.Simulation model of dual-three-phase induction machine when two stator phase windings opened with voltage source inverter (VSI) is set up. This model is based on the theory of switch function and the conventional model of multiphase induction machine.To study the dynamical performance of dual-three-phase induction machine under two stator windings open-circuited, simulations by means of MATLAB/SIMULINK are implemented using the model presented in this paper. For the sake of making comparison, two cases of the machine with lost a phase and lost two phase stator windings are simulated. The trace of stator voltage vector inα-βsubspace is a circle, which means the shape of the air-gap flux is also a circle. So, there not exists torque or speed ripple in steady state when 1st and 6th phase windings opened. Compared with dual-three-phase induction machine under two stator windings open-circuited and one stator windings open-circuited, diverse space place of lost stator phase has different influence on machine.A rule based optimums election scheme of space voltage vector is proposed for direct torque control of dual-three-phase induction machine under two stator windings open-circuited. Fast torque response with low ripples of torque and flux is achieved.