Research On Control Technique Of Variable Frequence System To Five-Phase Induction Machine

Multiphase induction machine adjustable speed drive system has many advantages. In addition to has high power handling capability, the multiphase winding structure provides a multiphase induction machine with capabilities of starting and running even with one or more of its stator excitation sets failed. It has been applied to some special situation successfully. However, as a new technology, there are many problems and issues to be investigated and solved related to the use of multiphase induction machines as a potential alternative to the conventional three-phase induction machines.This thesis chooses the five phase induction machine as the subject to be investigated. A detailed theoretical analysis and research have been carried out on the model of five phase induction machine drives, the five phase inverter PWM algorithms, the control strategies of five phase induction machine adjustable speed drives and the behaviors of the machine under unbalanced operation conditions.The dynamic state models and their equivalent circuits for the five phase induction machine are developed by means of the generalized symmetric component transformation. Based on the generalized two phase real transformation, the generalizedα?βmodel and their equivalent circuits of the machine is developed in stationary reference frame.Based on space vector theory and unified modulation theory, a unified voltage modulation (UVM) algorithm applied to the five phase induction machine is proposed under studying the unified mathematical model of three phase PWM algorithms. Because this algorithm makes use of lots of space voltage vectors of the five phase inverter, which result in machine currents with lower harmonics and flux linkage with lower distortion, it contributes to the decrease of toque ripple and the fast torque response performance.With the specialty of five phase induction machine considered, a new control strategies of five phase induction machine adjustable speed drives has been proposed by synthesizing the virtue of FOC(Field Oriented Control) and DTC(Directed Torque Control).Steady-state performances of five phase induction machines under balanced and unbalanced operation conditions are analyzed and simulated. Although the operation performance of five phase induction machines at unbalanced operation conditions are degraded, the machine is superior to that one of three phase induction machines.A computer simulation of the five phase induction machine adjustable speed drives has been carried out by using MATLAB/SIMULINK. A digital experimental system for the five phase induction machine drive controlled by digital signal processor (DSP) has been constructed, Experiments on five phase motor adjustable speed drives have been performed. Finally, the experiment results have been presented.