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Control of a two-thermoelectric-cooler system for ice-clamping application using Lyapunov based approach

Homogeneous cooling of a metallic plate with the help of thermoelectric elements is crucial in terms of using it as a clamping device. By applying water on a plate and chilling it under sub-zero temperatures the resulting ice structure is able to fix workpieces form-fitted, ensuring proper holding and clamping forces for upcoming machining operations. For this purpose a number of thermoelectric coolers (TECs) need to be controlled such that a homogeneous temperature profile on the clamping plate is guaranteed as well as the prevention of thawing, especially if external thermal disturbances occur due to machining processes like drilling, turning or milling. To face these challenges a robust controller is designed based on the Lyapunov Theory, proving its asymptomatic stability by means of two sliding surfaces. A clamping system consisting of two TECs, an aluminium clamping plate and a heat sink with forced convection is chosen for simulation purposes. This paper shows the model of such a system with corresponding controller design as well as the simulation results of the control strategy.