中频感应加热电源谐振频率自适应追踪方法的研究

Research on frequency adaptive tracking method of medium frequency induction heating power supply

为解决中频感应加热电源在受到温度、工件材质等因素变化影响时固有频率发生波动的问题,提出了一种基于模数转换(Analog to Digital,A/D)采样优化的感应加热电源谐振频率自适应追踪方法。在一个感应加热电源的输出周期内,细化电流A/D采样过程,找到输出电流与电压的相位差并判断系统状态。在优选A/D采样次数的基础上,设计自适应调节机制来追踪谐振频率,使系统达到准谐振状态。以TMS320F28335控制芯片为基础搭建感应加热电源样机,对所采用频率自适应追踪方法进行了验证。实验结果表明,频率自适应追踪方法在环境温度变化剧烈时可避免系统受到干扰,并且能在无硬件过零检测电路的情况下快速追踪负载的谐振频率。

In order to solve the problem that the natural resonance frequency of the medium frequency induction heating power source fluctuates due to factors such as changes in temperature and component material,an adaptive tracking method of induction heating frequency based on A/D sampling optimization is proposed.First,in a cycle of the output of the induction heating power supply,the sampling times of the current A/D are subdivided,the phase difference between the output current and the voltage is found,and the system state is judged.Then,based on the optimal number of A/D samples,an adaptive adjustment mechanism was designed to adjust the frequency so that the system can reach a quasi-resonant state.Finally,an induction heating power supply prototype is built by using the TMS320F28335 control chip,and the adopted frequency tracking method is verified.The experimental results verified the effectiveness of this method.The method can avoid system interference when the ambient temperature changes drastically,and can quickly track the load resonant frequency without a hardware zero-crossing detection circuit.