Induction Machine Rotor Resistance Identification Based On Model Reference Adaptive System

Due to the superior performance of AC electric traction, the advanced high-power electric locomotives have been using AC drive instead of DC drive. Indirect vector control with excellent dynamic performance, has been widely used in induction motor drive control. But the control performance affected by the rotor resistance parameter. In this paper, the proposed algorithm improve the performance of induction motor indirect vector control system by identifying rotor resistance.The basic theory of model reference adaptive system (MRAS) is introduced briefly. The steady-state and dynamic impacts of vector control, which are caused by the rotor resistance variation, are analyzed in detail. The model of reactive power is deduced from the induction motor voltage equation. The reference model doesn’t have the rotor resistance information and the adjustable model has the rotor resistance information. The dynamic identification of rotor resistance is obtained by the adaptive mechanism. The traditional voltage-based flux observer is improved. The actual value of rotor resistance is identified by adaptive structure, which is driven by compare of the observed q-axis flux and the ideal q-axis flux. The principle of the two MRAS identification methods is analyzed in detail. The block diagram and the adaptive law are given.The induction motor vector control system with the proposed rotor resistance identification scheme is designed. The motor controller hardware and software are introduced. Partial block diagram and software flow charts are given. The reactive power MRAS and the q-axis flux MRAS rotor resistance identification of vector control system are studied by simulation and experiment. Simulation and experimental results verify the validity of proposed algorithm. Finally, the comparison of two methods is discussed.