摘要
分析了夹心式压电换能器的阻抗特性,讨论了基于相位方式的现有跟踪方案的不足,提出了一种新的频率跟踪方案,介绍了实现该方案的电路系统。该方案的特点是:采用先扫频后跟踪的策略,解决了频率范围设定难的问题;增加解锁控制,使得系统在死锁或误跟踪时自动回到频率搜索状态;采用直接数字合成器(DDS)作为频率调整和信号产生的器件,实现了全数字系统,调整方便,精度高;采用复杂可编程逻辑器件(CPLD)做相位比较和DDS控制,使频率跟踪速度快,并且跟踪精度和速度均可控制。
This paper analyzes the impedance characteristics of the sandwich piezoelectric transducer, discuses the inadequacy of present frequency tracing schemes using phase locking method.It then proposes a novel scheme, and presents the circuitry that realizes the scheme. The distinguishing features of this scheme are as follows： utilizes a strategy of sweeping frequency before tracing and thus keeps away from the difficulty of settling the frequency tracing band; adds an unlock function which renders the system back to frequency sweeping state in the case of dead-locking or false tracing; uses a direct digital synthesizer（DDS） to adjust the frequency and generate driving signal, thus forms an all-digital system which is convenient to manipulate and can achieve high degree of accuracy; uses complex programmable logic device （CPLD） to detect phase difference and to control DDS, thus achieves high tracing speed and makes the tracing speed and the tracing accuracy controllable.
出处
《应用声学》
CSCD
北大核心
2009年第4期314-320,共7页
Journal of Applied Acoustics
基金
国家自然科学基金(基金批准号60673152)资助
