中文摘要：

针对超声理疗仪中压电超声换能器谐振频率漂移问题,提出了一种频率自动跟踪技术。该技术以模糊控制器为核心,通过比较计算超声换能器两端电压、电流信号的相位差,实时调整超声理疗仪DDS信号发生器的输出频率,保证超声换能器始终工作在谐振点上。测试表明,基于模糊控制的频率自动跟踪技术跟踪准确,超声理疗仪的工作效率得到了提高,输出超声强度可达3 W。

英文摘要：

A frequency auto-tracking method is presented which can be used in ultrasound physiotherapy apparatus against the frequency shift problem during the physiotherapy processof ultrasound transducer.Based on the fuzzy control theory,the voltage and current signal of the transducer are compared,and the frequency generated by the DDS signal generator will be adjusted in real-time,which ensures that the ultrasound transducer is always working on the resonance point.The experimental result shows that,with the advantage of rapid and accurate tracking,the efficiency of ultrasound physiotherapy apparatus can be improved using the frequency auto-tracking method based on fuzzy control and the output ultrasound intensity can be up to 3 W.