Abstract
This dissertation is mainly concerned with the transient and static performance improvements for a field-weakened (FW) indirect field-oriented (IFO) induction motor driver. First, the operating characteristics of an IFO induction motor drive under conventional field-weakening control are studied to comprehend its limitations. Then the improved field-weakening scheme is proposed. In which, a normal d-axis flux current command is first set. It consists of a major component generated based on improved approach, a loading compensating and a transient compensating components. The last two components are added to yield closer current tracking control during transient period. In addition, a simple robust current controller and a detuning compensator are developed to enhance the current tracking performance of a detuned induction motor. As the transient being elapsed and entering static period, the slip angular speed command or the flux current command is tuned to let the motor quickly reach a stable condition having improved energy conversion efficiency. Having established the induction motor drive with adequate field-weakening scheme, its speed control improvement is made. To yield good tracking and regulation speed control performances, the proposed control scheme consists of a feedback controller and a command feedforward controller (FC) to possess two-degree-of-freedom (2DOF). At nominal case, the feedback controller is designed according to the given regulation control requirements, and the command feedforward controller is set as the inverse of plant nominal model to let the tracking response follow the one defined by a reference model. Then, to reduce the effects of system dead-time and parameter variations on the speed control performance, a variable-structure system (VSS) adapted dead-time and disturbance compensator (DTDC) is developed. An estimated signal containing plant uncertainties and disturbances is generated and used for canceling their effects on dead-time compensation control. Moreover, the tracking response is further enhanced by on-line adjusting the parameters set in the FC and the DTDC according to the estimated mechanical inertia change. Finally, the closed-loop regulation control is provided by adding a model following control scheme. In performing the analysis and design of the constituted components in a motor drive, a suitable simulation tool is preferable. Hence finally in this dissertation, a Simulink-based simulation environment for the established FW IFO induction motor drive is built up. Some simulation results are provided to verify the correctness of the established simulation scheme.