This study proposes an optimally tuned Model Reference Adaptive System (MRAS) based speed estimator using back electromotive force (EMF) vector, which does not require pure integration. The PI (Proportional and Integral) gain coefficients in the speed estimator are optimally determined by utilizing Differential Evolution (DE) algorithm. The performance of the speed estimator is tested with both simulation and real-time experiments for a wide speed range. The obtained results verify the desired performance of speed estimation. © IFAC.