An optimised algorithm for velocity estimation method for motor drives

Traditionally two different algorithms are used for the estimation of angular velocity with an incremental encoder. At steady state, both of them ensure good performances only in a restricted range of velocity. In the paper an innovative hybrid algorithm specifically conceived for digital control system is proposed. The algorithm is quite easy to implement and guarantees a reduced relative error in a wide range of velocity variation. The algorithm is analyzed with an analytical approach and the results are confirmed by numerical simulations. Since in dynamic conditions the error in the measurement of the angular velocity with an encoder is strictly connected with the observation time, a correct method for the dimensioning of the observation time is discussed. The method can be combined with the preceding algorithm to obtain adaptive capabilities.