基于运放退饱和的电阻炉温度控制系统设计

Design of resistor furnace temperature control system based on desaturation process of op-amp

为了实现电阻炉的快速升温及温度控制,采用运放退饱和的方法,当电阻炉温度未达到设定值时,运放饱和输出,所控制的驱动电路输出脉冲的占空比最大,IGBT近似全导通,电炉加热功率最大,温度快速上升;当温度达到设定值时,运放开始退饱和,输出电压逐渐减小,从而减小驱动电路输出脉冲的占空比,IGBT导通时间变短,电炉加热功率减小,实现温度控制。通过Multisim软件仿真及硬件电路测试,验证了本设计的可行性。该温度控制系统具有升温速度快、易于操作、滞后性较低的优点。

In order to quickly rise the resistor furnace temperature and realize the temperature control, the system is de- signed based on the advantages of the process that op-amp breaks away from saturation region. Before the temperature of re- sistor furnace reaches the set value, the op-amp outputs the saturated voltage. Thus, the driving circuit outputs pulses with the largest duty ratio and IGBT is close to normally on. So the heating power of the resistor furnace is the highest and the temperature rises rapidly. When the temperature approaches the set value, op-amp begins to break away from the saturation region, so that the output voltage reduces. As a result, the conduction time of IGBT decreases. Therefore, the resistor furnace heating power reduces. In this way, the temperature control is realized. The results of Multisim simulations and the hardware circuit tests show that this method is feasible. This temperature control system has the advantages of quick heating, easy operating and low hysteresis.