Operation Of Phase Six-phase Asynchronous Motors

With high-power electronic technologies become more sophisticated, multi-phase induction motor has been widely used widely. Advantage of the squirrel-cage rotor motors lies in the using of the entire distance and concentrated winding, it has a simple structure, strong redundancy and can operation reliably, and other advantages, the motor of phase loss can still steady-state operation in the short-term. There still remain many problems to study in parameters and operation performance when the six-phase induction machine has a phase-failure. This paper focuses on analyzing of the performance of open phase motor and presents the modulation strategy of open phase motor to ensure steady-state operation of the motor.Two types of winding in six-phase induction machines are briefly introduced. And the mathmatical model and conversion method for six-phase induction machines in both natural and synchronous systems of coordinates are also listed. Based on symmetric steady-state operation, introduce briefly method of solving the stator leakage reactance using numerical analysis, and use this method to calculate the stator leakage reactance of the prototype, including:slot leakage reactance, leakage reactance and end leakage reactance. In the case of the known of fundamental excitation current, calculate the corresponding fundamental magnetizing reactance using distributed magnetic method. Under the assumption of a linear magnetic, the steady-state operation motor of phase loss using the network graph theory is analyzed to obtain the size of the stator leakage reactance and the size of input power, output power and operating efficiency after the absence of a phase or two-phase. Compare changes of parameters of motor in both cases of symmetry steady-state operation and phase loss steady-state operation, verify the advantages of strong fault-tolerant of multi-phase motor.In order to maintain the stable operation of the motor and keep the air gap magnetic potential constant in operation of phase loss, develop two modulation strategy of motor phase loss. The motor modulation is fundamentally modulating excitation current, and solve them using the methods of nonlinear programming. Get the size and the phase under different modulation strategies in two different cases of one open-phase and two open-phase. Compare the advantages and disadvantages of two modulation strategies, and find out the best modulation method in line with the actual project.The basic conception and solving process of finite-element method are briefly introduced. And the distribution maps of magnetic lines of flux, oscillograms of torque and speed, as well as the graphs of air-gap magnetic flux density are both obtained in normal steady state and phase-failure steady state of six-phase induction machine with the help of magnetic field simulation in Ansoft. The validity and accuracy of the analytical method proposed are verified by comparison of the parameters in these two changed conditions.