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For the field orientation control of an induction motor, the rotor time constant is a very important parameter. Theoretical analysis and experimental verification of three rotor time constant measuring methods are presented in this thesis. An experimental system which a line voltage feedback loop is included; the first method derives the rotor time constant by human judgment or assistance of mathematical package software (such as MATLAB) On teh basis of a general ac drive, the second method doesn't require additional sensors. According to the torque command and the speed performance during the initial state of an ac drive or using a mode selection, the rotor time constant is tuned and identified. With a phase voltage feedback, the last method estimates the torque of an induction motor. This method compensates the variation of rotor time constant which is caused by the environment factor such as temperature.
Furthermore, this thesis develops a DSP based controller. An intelligent IGBT based PWM inverter accompanies with the controller consist of an integrated and flexible fully digital servo drive. Apply the measured parameter to the drive, the DSP controller achieves: software-based current control, indirect rotor flux orientation current decoupling control, speed and position servo control. The dynamic braking, soft star and protect circuits are all included in the PWM inverter. TMS320C14 and TMS320C50 DSPs which are generated by the TI company are used in the system. Because the use of dual DSPs, the complicated computattion can be achieved and there will be more opportunities for advaanced control theories to be applied to ac servo control in the future.
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