The rapid heating and temperature control of a box-type resistance furnace use an operational amplifier (op-amp) desaturation method. When the furnace temperature has not reached the set value, the op-amp is saturated, and the control drive circuit outputs pulses with a high duty cycle—almost fully on—so the furnace heating power increases and temperature rises rapidly. As the temperature approaches the set value, the op-amp begins to desaturate, the output voltage gradually decreases, reducing the pulse duty cycle of the drive circuit. This shortens conduction time, lowers heating power, and achieves precise temperature control.
Software simulations and hardware tests have confirmed the feasibility of this design. The temperature control system offers fast heating, ease of operation, and low lag.
In heat treatment processes, resistance furnaces are widely used, and studying control methods is of great significance. Currently, furnace temperature control mainly uses PID control or PID-based derivative methods. While PID is widely applied due to easy tuning and good adaptability, it has a relatively long stabilization time for processes with large lags, such as temperature control. The proposed op-amp desaturation method adjusts the pulse duty cycle to control the on/off timing, offering a simple, practical approach with fast heating, providing an alternative method for precise temperature regulation.