一种阻抗匹配可调的变频式超声波电源

发布时间：2018-11-03 11:54

【摘要】：随着工业生产自动化的发展,超声波技术在焊接、清洗、剪切、医疗等领域得到了广泛应用。作为超声波技术的核心之一,超声波电源的发展也随着电力电子技术和数字控制技术的发展发生着巨大改变。然而目前市面上的超声波电源多为专用超声波电源,一台电源只能匹配固定的换能器,实现不了宽频域内的锁相和频率跟踪。本文以频率跟踪和阻抗匹配为出发点,设计了一种变频式超声波电源,通过频率跟踪的方式,实现宽频域内的阻抗匹配调节,并在ZYNQ平台上实现了原型系统的设计。论文的主要研究内容如下:(1)在分析超声波换能器等效电路和阻抗特性的基础上,确定阻抗匹配方法和频率搜索依据:采用频率跟踪法实现阻抗匹配的动态调节,并采用变步长策略实现快速、精确的频率搜索。(2)将超声波电源主电路划分为多个子模块进行原理分析和硬件电路设计。降压斩波电路实现输出直流电压幅值可调,以达到功率自适应的目的;逆变电路采用全桥拓扑结构将直流电转换为频率可调的交流信号;匹配网络实现逆变电路输出与换能器之间的匹配;反馈电路对换能器的电压电流信号进行处理后送入控制系统,作为频率搜索、跟踪的处理依据;另外还设计了逆变电路的开关管驱动电路,保证控制系统的输出信号安全可靠的驱动逆变电路开关管。(3)根据设计指标在ZYNQ平台上进行控制系统设计,包括频率搜索、频率跟踪和功率自适应的算法的硬件电路实现,降压斩波电路和全桥逆变电路所需的驱动信号实现。(4)在理论分析的基础上完成原型样机硬件电路的制作测试和软件程序的编写调试,对实验中发现的问题进行理论分析后,针对问题修改软硬件参数,以满足设计指标要求。实验结果表明,本文设计的变频式超声波电源可以自动搜索到频域内的谐振频率点,通过频率跟踪的方式间接改变阻抗匹配网络以补偿换能器的频率漂移并锁定系统在谐振状态。
[Abstract]:With the development of industrial production automation, ultrasonic technology has been widely used in welding, cleaning, shearing, medical and other fields. As one of the core of ultrasonic technology, the development of ultrasonic power supply has changed greatly with the development of power electronics and digital control technology. However, most of the ultrasonic power sources on the market are special ultrasonic power supply, one power supply can only match the fixed transducer, which can not realize the phase-locked and frequency tracking in the broadband domain. Based on frequency tracking and impedance matching, a variable frequency ultrasonic power supply is designed in this paper. By means of frequency tracking, impedance matching in broadband domain is realized, and the prototype system is designed on ZYNQ platform. The main contents of this paper are as follows: (1) based on the analysis of the equivalent circuit and impedance characteristics of ultrasonic transducer, the impedance matching method and the frequency searching basis are determined: the frequency tracking method is used to realize the dynamic regulation of impedance matching. The variable step size strategy is used to realize fast and accurate frequency search. (2) the main circuit of ultrasonic power supply is divided into several sub-modules for principle analysis and hardware circuit design. The output DC voltage amplitude can be adjusted by the step-down chopper circuit to achieve the purpose of power adaptation, and the inverter circuit uses the full-bridge topology to convert DC to frequency-adjustable AC signal. The matching network realizes the matching between the output of the inverter circuit and the transducer, and the feedback circuit processes the voltage and current signals of the transducer and sends it into the control system as the basis for frequency search and tracking. In addition, the switching tube drive circuit of inverter circuit is designed to ensure the output signal of the control system drive inverter circuit switch tube safely and reliably. (3) according to the design index, the control system is designed on ZYNQ platform, including frequency search. Hardware circuit implementation of frequency tracking and power adaptive algorithm, The realization of the driving signal of the step-down chopper circuit and the full-bridge inverter circuit. (4) on the basis of theoretical analysis, the prototype hardware circuit is made and tested and the software program is written and debugged. After theoretical analysis of the problems found in the experiment, the software and hardware parameters are modified to meet the design requirements. The experimental results show that the variable frequency ultrasonic power supply designed in this paper can automatically search the resonance frequency points in the frequency domain. The impedance matching network is indirectly changed by frequency tracking to compensate the frequency drift of the transducer and lock the system in the resonant state.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB55

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