感应加热的放空火炬LLC负载匹配研究

Research on High Frequency Induction Heating Load Matching Based on LLC Resonant Circuit

利用高频感应加热技术,将感应线圈中的工件加热至高温,天然气遇高温迅速点燃,实现天然气放空火炬点火,从而取代传统高压电子点火。放空火炬点火装置的感应线圈、工件和匹配电容构成了LLC谐振负载电路,由于负载参数的影响,负载等效阻抗与电源阻抗通常不匹配,因而电源效率不高,负载得到的功率不足,工件达不到理想温度。为使负载获得最大加热功率,电源保持高的效率,需要进行负载匹配。此外,分析了LLC谐振槽路的负载匹配特性,并给出了匹配原件的参数选择方法。最后,结合脉冲频率调制(PFM)法,基于LLC负载谐振电路搭建了实验平台。实验结果表明,LLC谐振电路在放空火炬点火系统中阻抗匹配表现良好。

In the use of high frequency induction heating technology, induction coil workpiece is heated to high temperatures, to light gas in high temperature quickly, it realizes gas emptying torch ignition, to replace the traditional high voltage electronic ignition. The induction coil, workpiece and matching capacitance of emptying torch ignition device constitute the LLC resonant load circuit. Due to the influence of load parameters, load equivalent impedance and source impedance usually are not match, so power efficiency is not high, the power obtained from the load is insufficient, the workpiece is heated up to less than ideal temperature. In order to obtain the maximum heating power of the load, the power supply maintains a high efficiency and needs to be matched with the load. Besides, the LLC circuit load matching characteristics is analyzed, and components＇ parameter selection method is presented. At last, combining with PFM control method, the experiment platform based on LLC circuit is established. The experiment results prove that the performance of LLC circuit impedance matching in high-frequency induction heating is good. The experimental results prove that the performance of LLC resonant circuit in the emptying torch ignition system is good.