| At present, with the develop of the computer-controlled technology, modern power electronics technology and modern control theory, the traditional three-phase servo motor drive system has been widely used in the electric drive occasions, by the voltage source inverter-powered motor relative to the number of drive system relative to the number of power supply is no longer subject to restrictions. Especially in the high-power, high reliability and low DC voltage power supply of the occasion, multi-phase motor drive system is more advantage, so multi-phase motor drive systems are particularly suitable for applications in large-scale milling machining center which is demanded low-speed and large torque and a high-profile speed ratio, Researchers has been more and more focus on multi-phase motor drive system.In this thesis,starting from any number of multi-phase motor, focusing on the six-phase induction motor drive system, Main of the full text is following:Generalized Park's Transformation is proved based on Symmetrical Component Transformation, and modeling of n-m winding induction machines is developed.Pointed out that the multi-phase motor control is a multi-dimensional control problem. Through analyzing mathematical models of multi-phase motor and the traditional SVPWM method, pointed out that the deficiencies of traditional SVPWM method in multi-phase motor control. If use a traditional SVPWM methods to control six-phase induction motor, although in each sector only choose two space voltage vectors,the computing time of vector role is shorter, but the amplitude of stator harmonic currents is large, low-frequency pulse frequency of electromagnetic is about 250Hz, while the mechanical vibration frequencies of all parts of the large-scale milling machining center are below 500Hz, so the torque ripple which in this frequency range can cause mechanical resonance.In order to solve the mechanical resonance which caused by the electromagnetic torque ripple. Proposed a new SVPWM methods, new methods in each sector choose four space voltage vectors synthesis for a given voltage vector, reducing the stator current harmonics which in the traditional SVPWM method, so that the frequency of the electromagnetic torque ripple to 3KHz above, avoid the processing center mechanical resonance which is generated by the electromagnetic torque ripple. And to study the zero-voltage vector in the control cycle, the role of different positions on the system performance. Carried out using Simulink simulation proved the feasibility of a new SVPWM method greatly reduces the sub-current harmonics and torque ripple. Six-phase induction motors for all-digital controller software and hardware design. |
