| With the development of power electronics, micro-processor and new technology of motor control, the performance of AC speed regulation system is highly promoted. It seems that DC speed regulation system will be replaced by AC speed regulation system, when variable frequency technology comes out. But the high development of national economy needs higher precision, wider peed-regulating range and faster response of AC variable frequency speed regulation system, while Field orientated control (FOC) is suitable for its direct control of induction torque. In this paper, the research and analysis of Field orientated control is done, FOC system is designed based on high-performance digital signal processor (DSP). Also, the dead time effect of inverter is analyzed, dead time compensation is done.In this paper, the development and method of variable frequency, the national and international research of FOC are introduced. The mathematic model of three-phase AC asynchronous motor in two-phase rotating coordinates is educed from the mathematic model in three-phase coordinates by Clarke transform and Parke transform. Based on the rotor flux orientation theory and this mathematic model, the rotor flux observer is designed to make sure the magnetizing and torque current components of asynchronous motor is decoupled suitably. According to control theory of DC motor, current and speed dual closed loop control system of FOC is worked out. Arithmetic of FOC is built on the hardware platform with TMS320LF2407A as main controller. The theory and common methods of space vector pulse width modulation (SVPWM) is dissertated, a new improved method of SVPWM is advanced, and the dead time compensation of inverter is carried out.Experiment indicates field orientated control system using rotor flux orientation theory is excellent to meet torque and speed need of modem asynchronous speed-regulation system, for its simple structure, convenient decoupling of current, high dynamic performance and precision. |
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