Papers by Keyword: Rotor Time Constant

Abstract: The indirect vector control scheme is machine parameter dependent. And parameter identification schemes are themselves dependent on some motor parameters. This paper analyzes parameter sensitivities of two identification methods, reactive power model and q-axis flux model based on MRAS are analyzed through extensive simulations and experiments on an induction motor. Then a novel scheme is proposed based on hybrid model by combining the two adaptive models. The results demonstrate that the hybrid scheme is almost parameter independent in different operation conditions. And it is considered useful in practical application.

Abstract: Decoupling the stator current into magnetizing current and torque current, the vector control technique improves the performance of AC drive system effectively. However, the rotor time constant varies widely with rotor temperature and the flux level of the machine, which decreases the quality of the drive system. By the contrastive analysis of the variable current on-line estimation methods, this paper uses the Model Reference Adaptive System (MRAS) and designs a set of self-adaption estimation arithmetic which has its basis on the Lyapunov theorem of stability. The simulation shows that the estimation arithmetic has the characteristics of fast convergence speed, few stability errors, good track performance and etc. On the basis of simulation of the rotor time constant on-line estimation, this paper designs the system of vector control with the rotor time constant on-line estimation and has the simulation. According to the simulation results, applying the estimation to the vector control system can improve the performance of the system effectively and establish the theoretical basis of the research on the high-performance AC drive system.

Abstract: In the vector control the time constant of rotor changes will affect the system, generally required online identification. This paper puts forward a identification method based on model reference adaptive, using popov exceed stable to design a adaptive rate. Analyses identification system by torque effects, and proposes a kind of compensation algorithm, to improve the system robustness. Under the MATLAB/Simulink environment build simulation model to verify the correctness of the algorithm, and points out the advantages of compensation algorithm.

Abstract: Vector control system is dependent of parameters of motor, and rotor time constant usually changes with temperature. Through analyzing the influence of rotor time constant variations on the control system performance, a novel identification method based on adaptive flux observer is presented. Different with traditional pole assignment method, it implies robust control theory and Lyapunov stability theory, by solving a linear matrix inequality (LMI) to obtain the feedback gain matrix. The simulation results show that this method can identify the rotor time constant of induction motor accurately, and it has rapid converge, good indiscrimination degree and strong robustness.

Abstract: This paper presents an adaptive controller based on the passivity theorem to control the position of an induction machine. Firstly, an open-loop flux observer estimates the rotor flux linkages, and then adaptive laws are designed to estimate the inverse rotor time constant, mechanical parameters, and load torque. The passive properties of the feedback connection of the rotor flux observer to the inverse rotor time constant estimator, and the adaptive controller are analyzed by the passivity theorem. The overall control system is formally verified to be globally stable by the theorem instead of Lyapunov-like functions. Experimental results show that the parameter estimation errors converge to zero when the position command is a sinusoidal signal with two distinct frequencies. Furthermore, good position tracking responses can be obtained, and the approach is robust with regard to the variation of the parameters and load torque disturbances.