一种超声治疗仪的自动跟踪锁频电路设计

针对超声治疗仪中压电超声换能器因制造工艺导致固有频率出厂误差的问题，以及因温度变化等因素导致频率漂移，使其工作在非谐振状态下影响压电超声换能器电-声转化效率降低、治疗波形变化以及输出功率不稳定，从而影响超声治疗仪的治疗效果的问题，设计了一种超声治疗仪的自动跟踪锁频电路。该系统采用STM32F103ZET6作为微控制器。利用压电超声换能器逆向压电效应特性原理和最大电压式反馈法，通过扫频采样将最大电压值和谐振频率进行实时反馈，使得压电超声换能器始终工作在谐振点上，以实现自动跟踪锁频。实验测试证明，基于该自动跟踪锁频电路的超声治疗仪能够保持较稳定的输出功率以及良好的治疗波形、频率跟踪精准且成本低，能够达到良好的治疗效果。因此本课题具有较好的创新性和应用前景及广泛的适用价值。

A circuit design of automatic tracking and frequency locking for ultrasonic therapeutic apparatus

Aiming at the problem of the natural frequency of the piezoelectric ultrasonic transducer in the ultrasonic therapy apparatus that causes the factory error of the natural frequency due to the manufacturing process,and the frequency drift caused by temperature changes and other factors, it will work in a non-resonant state, which will greatly reduce the electro-acoustic conversion efficiency of the piezoelectric ultrasonic transducer, and the treatment waveform will change and the output power will be unstable, which will affect treatment effect of the ultrasonic therapeutic apparatus. An automatic tracking frequency locking circuit of ultrasonic therapeutic apparatus is designed.The system uses STM32F103ZET6 as a microcontroller. Using the principle of inverse piezoelectric effect of piezoelectric ultrasonic transducer and the maximum voltage feedback method, the maximum voltage value and the resonant frequency are fed back in real time through frequency sweep sampling, so that the piezoelectric ultrasonic transducer always works at the resonance point, so that the To achieve automatic tracking frequency locking. The experimental test proves that the ultrasonic therapeutic apparatus based on the automatic tracking frequency locking circuit can maintain a relatively stable output power, a good treatment waveform, accurate frequency tracking and low cost, and can achieve a good treatment effect. Therefore, this subject has better innovation, application prospect and broad applicable value.