基于集成芯片的压电换能器频率跟踪技术研究

Research on Frequency Tracking Technology of Piezoelectric Transducer Based on Integrated Chip

针对超声驱动电源在不同共振频率跟踪(RFT)方案下存在的频率搜索范围小、跟踪进程长、软硬件设计复杂等问题,研究了基于集成芯片的频率跟踪方案。该方案以集成芯片为核心,结合逻辑控制及其外围接口电路,实现了压电换能器在毫秒量级的频率智能跟踪。此外,还设计了一种输出频率范围可调的VCO电路,来搭配使用频率跟踪模块;以匹配电路的电压放大倍数和换能器电流为目标函数计算出匹配参数。最后基于频率跟踪模块实现了小型化、低成本的超声驱动电源,验证了基于集成芯片的频率跟踪方案。所设计的电源拥有27 kHz~29 kHz频率搜索范围,0.5 Hz的频率跟踪精度。实验结果表明,其能在3.5 ms左右完成频率搜索和跟踪的进程。

To address the disadvantages of narrow frequency tracking range,long tracking time,and complex software and hardware of the traditional resonance frequency tracking(RFT)schemes of ultrasonic generator,a frequency tracking scheme based on integrated chips is proposed.Based on the integrated chip and combined with peripheral interface circuits,the proposed scheme can capture the resonant frequency of the transducer within several milliseconds.In addition,an off-chip VCO is used to control the driving frequency of the generator;the matching parameters are calculated according to the voltage magnification of the matching network and the transducer current.Finally,a miniaturized and low-cost ultrasonic power supply is realized using the frequency tracking module,and the frequency tracking scheme based on the integrated chip is verified.The frequency tracking rang of the ultrasonic power supply is designed from 27 kHz to 29 kHz with a frequency resolution of up to 0.5 Hz.The proposed scheme is finally verified through experiment and the results show that it can capture the resonant frequency of the transducer within 3.5 ms.