私立中原大学 电机工程学系 硕士学位论文
应用於感应加热的负载串联共振电压型反 流器设计与研制
Design and Implementation of Voltage-Fed Load Series Resonant Inverter for Induction Heating System
指导教授:何金满 研 究 生:许国展
中华民国九十一年六月
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摘
要
感应加热技术是二十世纪初才开始应用於工业界,由於它具有 加热速度快,安全性高,产品质量好,几乎无环境污染等许 多优 点,而得到迅速的发展.另一方面,随著半导体元件制作技术的进 步,反流器上的功率开关能够操作在更高频率的范围,使得高频感 应加热装置具备了轻,薄,短,小,效率高的特色. 本论文的主要目标在建立一个以单晶片TMS320C240微处理器 为基础的数位化高频感应加热器.此数位化高频感应加热器已将切 换频率提高至70kHz,减短加热过程所需的时间,并使用零电压切换 相移式脉波宽度调变技术,降低功率开关元件之切换损失,切换应 力及电磁干扰.有鉴於加工物件在加热过程中,其本身的电气特性 会随之而改变,致使共振频率亦随著加热时温度之变化而变动.所 以利用变频控制技术来使驱动频率追随共振频率,促使系统在运转 时的效率随时保持於最佳状态.同时,为了能够调整输出功率,乃 藉由相移脉波宽度调变控制技术来改变输出电压的工作周期,来达 成此一目标. 最后,将对加热时产生的负载参数变化现象以及在负载变动下 反流器的运转性能等进行实际的量测及探讨,并验证此零电压切换 技术的确提高了系统的整体效率.
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Abstract
Since the early twentieth century, induction heating have been widely used and rapidly developed in the industrial applications because of their distinctive advantages such as high-speed heating, safety, high products quality, cleanliness, and etc.. In addition to this, with tremendous advance in the latest power semiconductor devices permiting switches of inverters to operate under high frequencies, the induction heating systems have become lighter, compacter, and more efficience. The main purpose of this study is to investigate the application of a single chip, TMS320C240, microprocessor to a fully digital high frequency induction heating system. By using the phase-shifted fullbridge zero-voltage-switched PWM technique, this system can reduce switching loss, component stress, and electromagnetic interference of power semiconductor devices. In induction heating applications, because the electrical characteristics of the workpieces will change in the processing, the circuit resonant frequency must be changed in accordance. Hence, the variable frequency control technique is used for tracking the resonant frequency to keep the system operating at the optimal condition. The phase-shift Pulse-Width-Modulated (PWM) is used for regulating the duty-cycle to control the output power. Finally, the efficiency of this heater are measured and analyzed under load variations. Experimental results show that the ZVS PWM technique can improve the efficiency of this system.

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