Sliding-Mode Flux
Observer With Online Rotor Parameter Estimation for Induction Motors
Amuliu Bogdan Proca and Ali Keyhani
Ohio State Univ, Columbus, OH, USA ;
This paper appears in : IEEE Transactions on
Industrial Electronics
Date: April 2007
Abstract:
Field orientation techniques
without flux measurements depend on the parameters of the motor, particularly on
the rotor resistance or rotor time constant (for rotor field orientation). Since
these parameters change continuously as a function of temperature, it is
important that the value of rotor resistance is continuously estimated online. A
fourth-order sliding-mode flux observer is developed in this paper. Two sliding
surfaces representing combinations of estimated flux and current errors are used
to enforce the flux and current estimates to their real values. Switching
functions are used to drive sliding surfaces to zero. The equivalent values of
the switching functions (low-frequency components) are proven to be the rotor
resistance and the inverse of the rotor time constant. This property is used to
simultaneously estimate the rotor resistance and the inverse of the rotor time
constant without prior knowledge of either the rotor resistance or the
magnetizing inductance. Simulations and experimental results prove the validity
of the proposed approach.