基于三次谐波频率跟踪方法的超声波驱动电路设计

发布时间：2018-02-01 06:04

本文关键词： 超声换能器频率自动跟踪三次谐波驱动电路　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：超声波作为声学的一个分支，近年来发展迅速。超声波具有良好的方向性、透射性等声学特性，超声波能量集中，在气体、固体和液体中均能较好传播。广泛应用于超声探测、超声检查、超声振荡、超声萃取等方面。超声波以其应用方向的不同可分为：检测超声、功率超声。在功率超声换能器使用过程中，由于换能器负载的变化、老化、磨损、温升、疲劳等因素的影响，换能器谐振频率往往会产生偏移。如何动态跟踪换能器谐振频率成为了超声应用领域的急需解决的工程技术问题。本文通过对功率超声频率跟踪技术进行分析比较的基础上，改进现有频率跟踪驱动电路，设计了一种基于超声波换能器三次谐波检测的频率跟踪技术。通过对不同信号的采样反馈，，能够较好的获取换能器串联谐振频率，提高换能器机电耦合系数。本设计对常用超声波换能器频率跟踪电路基础上进行了改良，采用了基于三次谐波检测频率跟踪技术设计的反馈处理电路，通过对三次谐波电压电流采样量化，获取相位差以及幅值信息，为输出信号频率以及阻抗匹配网络提供计算参量，从而实现了超声波换能器的自动频率跟踪。本设计电路主要包括：信号产生电路、PWM信号调制电路、逆变输出电路、阻抗匹配网络以及反馈控制电路。其中反馈控制电路包括：采样电路、三次谐波高通滤波电路、电压电流比例放大电路、相位差检测电路以及A/D转换电路。根据各电路参数要求，本文采用Proteus、Multisim对所设计的各模块进行仿真。在典型条件下（温度为300K），信号发生电路输出频率范围为15KHz~70KHz，频率精度≤1Hz；PWM信号调制电路采用定频调宽方式，输入信号幅度0~5V，PWM调制信号占空比0~100%无极可调；高通滤波电路在f=4/9fT时，要求幅度衰减大于40dB。本文通过设定超声波换能器仿真模型等效电路参数，进行系统仿真。仿真结果表明，本文设计的驱动电路实现了频率的自动跟踪，系统跟踪频率最大偏差为0.89%。
[Abstract]:As a branch of acoustics, ultrasonic has developed rapidly in recent years. Ultrasonic has good directional, transmission and other acoustic characteristics, ultrasonic energy concentration in gas. It is widely used in ultrasonic detection, ultrasonic examination, ultrasonic oscillation, ultrasonic extraction and so on. Ultrasonic can be divided into: ultrasonic detection by its different application direction. Power ultrasonic. In the use of power ultrasonic transducer, due to the load changes, aging, wear, temperature rise, fatigue and other factors. The resonant frequency of transducer is often offset. How to dynamically track the resonant frequency of transducer has become an urgent engineering technical problem in the field of ultrasonic application. Based on the analysis and comparison of power ultrasonic frequency tracking technology, the current frequency tracking driving circuit is improved in this paper. A frequency tracking technique based on the third harmonic detection of ultrasonic transducer is designed. Through sampling and feedback of different signals, the series resonant frequency of transducer can be obtained better. Improve the electromechanical coupling coefficient of transducer. This design improves the frequency tracking circuit of ultrasonic transducer and adopts the feedback processing circuit based on the frequency tracking technology of third harmonic detection. By sampling and quantifying the third harmonic voltage and current, the phase difference and amplitude information are obtained, which provides the calculation parameters for the output signal frequency and impedance matching network. Thus the automatic frequency tracking of ultrasonic transducer is realized. This design circuit mainly includes: signal generation circuit PWM signal modulation circuit inverter output circuit. The impedance matching network and the feedback control circuit include: sampling circuit, third harmonic high-pass filter circuit, voltage and current proportional amplifier circuit. Phase difference detection circuit and A / D conversion circuit. According to the requirements of the circuit parameters, this paper uses Proteus-Multisim to simulate the designed modules under typical conditions (temperature is 300K). The output frequency range of the signal generator circuit is 15kHz ~ 70kHz, and the frequency precision is less than 1Hz. The modulation circuit of PWM signal adopts the mode of constant frequency modulation and width modulation, and the input signal amplitude is 0 ~ 5V ~ (-1). The duty cycle of the modulation signal is 0 ~ 100%, which can be adjusted without a pole. The amplitude attenuation of high pass filter circuit is more than 40 dB at fi 4 / 9 fT. The simulation results show that the equivalent circuit parameters of ultrasonic transducer simulation model are set in this paper. The drive circuit designed in this paper realizes the automatic tracking of the frequency. The maximum deviation of the tracking frequency of the system is 0.89.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB55

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