中文摘要：

针对超声清洗过程中超卢换能器谐振频率发牛漂移的问题，设计了一种由D触发器、单片机、数字电位器和压控振荡器组成的频率跟踪系统。该系统利用单片机检测超声清洗电源负载的电压、电流的相位差，并通过数字电位器来改变压控振荡器的输山频率。与其它频率跟踪方法梢比，该系统降低了程序编写的复杂性，电路简单且易于实现。

英文摘要：

During the process of ultrasonic cleaning, the resonant frequency of ultrasonic transducer may drift. Aimed at this problem, a frequency tracking system is designed in this paper, which mainly consists of D Flip-flops, single-chip microcomputer, digital potentiometer and voltage-controlled oscillator （VCO）. In this system, the output frequency of VCO is changed by a digital potentiometer which is controlled by a single-chip microcomputer measuring the phase difference between voltage and current. Compared with other frequency tracking methods, the system reduces the complexity of programming, and the hardware circuit of this system is simple and easy to realize.