Ice-clamping devices are of great advantage in deformation-free and sustainable workpiece clamping by using frozen water to fix pieces during machining operations. The adhesive bonding of ice generates high forces, encapsulating the piece form-fitted around and underneath its surface. The freezing is generated by thermoelectric coolers (TECs), placed under a clamping plate. The colder the plate is chilled, the higher the total forces of ice bonding are, guaranteeing a secure grip during machining. However, process heat generated by machining tools pose the risk of thawing the ice, illustrating an external disturbance which is needed to be controlled. Traditional control strategies for TECs use PID algorithm due to its simplicity. To attenuate disadvantages of a PID controller, such as oscillations, overshoots and settling time as well as to attain a better performance and robustness in the presence of parameter uncertainties and disturbances, a model based feedforward regulator including Anti-windup method is proposed additionally to a PI controller for the nonlinear thermal system. Furthermore, a technical requirement is formulated mathematically proving the existence of a structural stability of the thermal system. Simulation results, performed in MATLAB Simulink, are shown and are validated with experimental data.

A model based feedforward regulator improving PI control of an ice-clamping device activated by thermoelectric cooler

This study presents a control scheme for thermoelectric coolers (TECs), based on the implementation of a double PI control loop for supply current and ventilation regulation. A test bench was developed, including a thermal closet and all the necessary automation for data acquisition. Industrial thermocouples were employed in order to record the heat flow and, by extension, the coefficient of performance (COP). Thus, the cooperation of heat sink's control via fans and TECs' supply current control via a DC/DC converter is investigated. Also, a multistage TEC structure was considered in order to improve COP factor and reduce power consumption.

Implementation of current and ventilation control for enhanced TEC performance

Aiming at the problems containing complex working conditions, modeling difficulties and long-time delay of thermoelectric cooler temperature control system, an improved ADRC control method combining ADRC and Smith predictor is proposed in this paper. ADRC deals with the disturbances and uncertain dynamics in the system, SP compensates the time delay to improve the control performance. Compared with the traditional PID controller, the proposed control method has faster response speed and stronger anti-disturbance ability, meanwhile, overcomes the dependence of Smith predictor on object parameters to a certain extent. Through simulation and experimental verification, a good control effect is obtained, which provides a positive guidance of the related application of thermoelectric cooler. 

Temperature Control System of Thermoelectric Cooler Based on Improved ADRC

Thermoelectric (TE) technology is promising for reducing thermal discomfort of workers during their routine professional activities. In this manuscript, a preliminary evaluation of a newly developed personal cooling system (PCS) with flexible TE modules is presented based on an analysis of cooling efficiency and power consumption. For this purpose, tests with human participation were performed involving the monitoring of local skin temperature changes and electrical parameters of the controller. Thanks to TE cooling, a significant reduction of local skin temperature was observed at the beginning of the experiment, reaching as much as 6 °C. However, the observed effect systematically became weaker with time, with the temperature difference decreasing to about 3 °C. Cooling efficiency stayed at the same level over the ambient temperature range from 25 °C to 35 °C. The obtained results showed that a proper fitting of the PCS to the human body is a crucial factor influencing the PCS cooling efficiency.

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Evaluation of Performance and Power Consumption of a Thermoelectric Module-Based Personal Cooling System—A Case Study

https://robots.iopscience.iop.org/article/10.1088/1757-899X/932/1/012063/pdf

Adaptive PD Controller Performance for Direct Cooling of Thermoelectric Refrigerator

The Thermoelectric cooler (TEC) is widely known device which have low coefficient of performance (COP) as compare to the conventional compressed refrigerator. However, it is suitable for portable refrigeration that requires light weight, small and fast control. Therefore, the proportional integral derivatives (PID) control was implemented to control input and output while reducing its power consumption. Mathematical model for TEC was develop base on black box model to get its transfer function. The transfer function consist of ratio output and input that been used for analysis during development of controller. This study is focus on performance of PID controller in simulation and real hardware in order to reduce time constrain. The method proposed is integral of time multiplied absolute value of error (ITAE) criteria to determine the coefficient of PID controller. The finding shows that the lowest temperature is 7 °C and the time taken is around 940 second.

M.Z. Zolkifly

Papers

Design and development of controller for Thermoelectric cooler system