Study on large time-delay constant temperature control system based on TEC

This paper designes a diminutive constant temperature control system based on thermoelectric cooler (TEC). Considering that the system is a large time-delay control system, the paper proposes a new method to determine the transfer function of the controlled system which gets the transfer function by doing nonlinear fitting of the step response of the controlled system. The characteristics of system model which is established by the method are basically same as the actual constant temperature control system. This method provides a new way of thinking to the design of large time-delay control system.