Research on motor speed identification of air conditioning systems based on improved full-order sliding-mode observer

To improve the accuracy of motor speed identification for the air conditioning system, represents researches based on the improved full-order sliding-mode observer (SMO). Establishes a state equation for the full-order sliding-mode observer based on the back-electromotive force equation. Removes the low-pass filter in the traditional observer to avoid the phase error caused by the filter, and thus improves the robustness and dynamic observability of the system. Optimizes the switching function of the sliding-mode surface to reduce buffeting. Uses the third order orthogonal phase-locked loop to track the back-electromotive force output by the observer. The accuracy and robustness of the algorithm is verified by conducting the no-load start, sudden speed change and low speed experiments. By keeping the frequency error within 0.2 Hz, it can effectively improve the estimation accuracy and anti-interference ability of the observer, and consequently ensure the high efficiency, temperature constancy and excellent dehumidification performance of the air conditioning system.