基于FPGA的串联谐振逆变器斩波调功的研究与实现

发布时间：2018-06-13 23:40

本文选题：感应加热 + 逆变斩波调功　；参考：《河北大学》2017年硕士论文

【摘要】：由于感应加热技术具有加热温度高、效率高、速度快、加热温度容易控制、易于实现机械化、自动化、无空气污染等优点,现在感应加热己广泛应用于金属熔炼、透热、热处理和焊接等工业过程。但是目前工业领域广泛应用的感应加热电源多采用模拟电路控制,控制精度不高,灵活性较差,系统可靠性低。而数字式电路控制精确,软件设计灵活,整个控制系统简单、可靠,因此研究感应加热电源的数字化电路控制具有十分重要的意义。本文以串联感应加热电源为研究对象,简要介绍了感应加热的基本知识和感应加热技术的发展过程,同时对感应加热的控制问题也作了简要的介绍。接下来分析并制定了电源的构成方案,并分析了感应加热电源的各种调功方式,在对比几种功率调节方式的基础上,为了克服由串联谐振逆变器构成的感应加热电源调压式调功和移相式调功存在的不足,提出了一种逆变斩波式调功的控制方法,在满足频率跟踪的条件下,产生了四路脉宽相间依次可调的逆变触发脉冲信号,通过控制H桥四个开关元件的导通时间达到了对输出功率调节的目的。由于感应加热过程中负载参数的变化会引起负载谐振频率的变化,为了保证感应加热电源工作在弱感性准谐振状态,逆变控制电路必须具有频率跟踪功能,系统中需要设计一种锁相环电路。传统的锁相环易受电网电压、温度漂移等因素的影响,使得系统的同步调节很难实现,本文设计了一种基于FPGA的数字锁相环,该电路控制精度高、软件设计灵活。并分别对触发脉冲信号、引前触发角度以及死区时间等功能进行了分析与设计;对其工作原理和电路模块作了详细描述,通过实验结果表明,该电路产生的脉冲信号达到了预期的结果。
[Abstract]:As induction heating technology has the advantages of high heating temperature, high efficiency, high speed, easy control of heating temperature, easy to realize mechanization, automation and no air pollution, induction heating has been widely used in metal smelting, heat permeation, etc. Industrial processes such as heat treatment and welding. However, the induction heating power supply widely used in the industrial field is controlled by analog circuit. The control precision is not high, the flexibility is poor, and the system reliability is low. But the digital circuit control is accurate, the software design is flexible, the whole control system is simple and reliable, so it is very important to study the digital circuit control of the induction heating power supply. In this paper, the basic knowledge of induction heating and the development process of induction heating technology are briefly introduced, and the control problems of induction heating are also briefly introduced. Then, it analyzes and formulates the constitution of the power supply, and analyzes the various power regulation methods of the induction heating power supply. On the basis of comparing several power regulation modes, In order to overcome the shortcomings of voltage regulation and phase shift modulation of induction heating power supply composed of series resonant inverter, a control method of inverter chopping power regulation is proposed, which satisfies the condition of frequency tracking. The output power can be adjusted by controlling the switching time of the four H-bridge switching elements. In order to ensure that the induction heating power supply works in the weak inductive quasi-resonant state, the inverter control circuit must have the function of frequency tracking because the change of load parameters in induction heating process will cause the change of load resonant frequency. It is necessary to design a phase-locked loop circuit in the system. The traditional PLL is easy to be affected by the voltage and temperature drift of the power network, which makes it difficult to realize the synchronous regulation of the system. In this paper, a digital PLL based on FPGA is designed, which has high control precision and flexible software design. The functions of trigger pulse signal, trigger angle and dead time are analyzed and designed respectively, the working principle and circuit module are described in detail, and the experimental results show that, The pulse signal produced by this circuit achieves the expected result.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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