Disturbance observer-Based control for microchannel cooling system

Disturbance observer-based systematic control is proposed for microchannel cooling systems experiencing unanticipated heat load. The objective is to apply an extended Kalman filter as the observer for a nonlinear system to estimate external disturbance and dynamic states and use active control to maintain the system parameters at desired values. Disturbance observer is designed based on one-dimensional lumped model. The robustness and performance of the observer are validated with experimental results, which show a maximum of 3% inaccuracy at steady states under various heat loads and mass flow rates. The estimated value of unanticipated evaporator heat load with the observer acts as the feedforward control signal for pump speed while the feedback control using the signal of evaporator wall temperature could further adjust the input values to achieve desired output. Results show that a system with a controller and disturbance observer can ensure the evaporator wall temperature and high heat performance under large variations of heat loads. System with disturbance observer-based control shows quick response, strong robustness, and stable operation.