Design and evaluation of a controller for the process of microwave joining of ceramics

A temperature control system is designed and simulated for the process of microwave joining of ceramics. The overall goal is to develop a control system that allows reliable, high-quality joints to be produced on a variety of ceramics. The described procedure permits the derivation of a closed-loop configuration for controlling temperature. The ceramics (alumina) heating model equation is linearized around an operating point and represented as a transfer function. A compensator is designed based on the 'worst case' for the value of the gain. Conditions for closed-loop stability with any linearized plant model are presented and mathematically proven. Expressions for the time response parameters of the compensated system are derived. A simulation is implemented in MATLAB for the closed-loop control, and a numerical integration method is used for solving the nonlinear heating equations. The results obtained for the simulation are excellent and show that the temperature can be regulated to a set point value and the thermal runaway problem in the ceramics can be prevented.< >