In the fabrication process of the thermostats, the low temperature container system is needed to set up the operating temperatures by the setting screws in the thermostats. The quality of the products is seriously influenced by the regulating accuracy of the container system. And from the point of productivity, the rapid settling time to a reference temperature is demanded.
But until now, there has been no systematic method about the design of the controller for the easy application to the fabrication of the thermostats in the field. So this thesis aims at suggesting the method about the design of a digital controller for the low temperature container.
Comparing with the conventional P-I controller, the proposed controller has an additional sensor below the cooling pipe in order to compensate the constant disturbance heat from the cooling pipe by the feedforward loop. By using this method, the modelling is much simplified and the effect of the disturbance from the cooling pipe is reduced. For these reasons the proposed controller shows the better performance when comparing with the conventional P-I controller.
