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This paper presents a Modified model reference adaptive system (MMRAS) speed controller for speed estimation of induction motor using model-reference adaptive scheme (MRAS) approach in a direct torque control system. A good speed controller of induction motor can enhance the speed estimation of sensorless drives. The MMRAS controller can reduce effect of parameter variations and nonlinearities in the induction motor, and approaches to desired performance of referenced model. So, the presented controller can enhance the performance of speed estimation. The availability of the proposed structure scheme is verified by through under computation simulations with MATLAB software. Simulation results are presented in order to prove the availability of the proposed structure scheme.

The paper presents a weighted tuning PI controller for speed estimating of induction motor using model reference adaptive system (MRAS) approach in a direct torque control system. The performance of speed controller affects the performance of sensorless each other. The objective of presented weighted tuning PI controller is to improve the performance of induction motor drive and enhance the performance of speed estimation. The presented controller is based on Ziegler-Nichols (Z-N) tuning formula with weighted tuning. The method improves the problem of parameter choice, reduces the over shoot and is simple as Z-N without system model. The availability of the proposed structure scheme is verified by through simulation results.