THERMAL MODEL BASED ESTIMATOR

Embodiments described herein provide a method in a thermal model based estimator and a thermal model based estimator for estimating a temperature of a transducer. The method comprises receiving a first signal wherein the first signal is representative of an impedance across the transducer; receiving an indication of a current across the transducer; determining an estimated thermal power based on the indication of the current and an estimated temperature signal, determining, based on the estimated thermal power, the estimated temperature signal using a thermal model of the transducer comprising states defined by a thermal state vector; comparing the first signal with a second signal derived from the estimated temperature signal; updating the thermal state vector of the thermal model based on the comparison; and; outputting the estimated temperature signal.