共查询到16条相似文献,搜索用时 125 毫秒
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与超声塑料焊接相比,超声金属焊接负载重且变化剧烈,容易导致换能器出现无阻性点状态或者频率误跟踪。现有的频率跟踪方法往往只能在换能器有阻性点的状态下正常工作,在出现误跟踪时也无法自动复位。针对上述问题,本文基于梅森等效电路,推导出一种能够同时适配于谐振频率与反谐振频率,能够自行判断是否误跟踪频率跟踪算法。当换能器处于无阻性点状态时,算法将自动把跟踪目标变为相位差最小点,实现全状态频率跟踪。算法利用三个不同频率及其发波时换能器的电压电流相位进行计算,以此算出理想的频率跟踪步长和方向。最后通过MATLAB对算法进行仿真,验证算法在目标频率发生非线性变化时频率跟踪的效果。结果表明,新算法能够实现误跟踪的自复位和全状态频率跟踪,同时能在启动后10ms以内完成频率跟踪,跟踪精度达0.1hz。 相似文献
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超声波雾化技术由于其良好的雾化效果获得了广泛关注,具有极大的研究价值和应用前景。但是在超声雾化的过程中,由于换能器的温度变化、刚度变化以及在水中的负载变化等因素,会产生谐振频率漂移的现象。当工作频率偏移谐振频率时,将造成换能器的工作效率降低和元器件损坏等问题。针对此问题,设计了基于改进粒子群算法优化PID参数的超声雾化电源频率跟踪算法,并对该算法进行频率跟踪的仿真验证和实验对比,在频率跟踪上实现了更好的效果,使换能器能够稳定工作在谐振状态,提高了电源的利用率。 相似文献
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本在介绍用PLL(Phase-Locked Loop锁相环)电路进行频率跟踪的原理和实质的基础上,给出一种够跟踪压电换能器并联频率fP区间的具体电路,并通过实验研究了匹配电感和负载等对电路跟踪性能的影响,结果表明,这个电路具有很好的频跟踪和功率自动调节性能。 相似文献
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本文提出了一种利用补偿原理直接测量压电换能器串联谐振频率fs和并联谐振频率fP的新方法一补偿法。在这种方法测量原理的基础上,进行了实际测量,并设计了一种实用的测量电路。采用此方法测量的测量结果与电桥法的结果相符得很好。 相似文献
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压电换能器往往因受到温度与负载的影响,导致其谐振频率、反谐振频率和机械品质因数等特征参数发生变化。通过在压电换能器中设计用于调节的压电陶瓷片,并在调节压电陶瓷片两端外接电负载,可以实现压电换能器的频率调节,修正由于温度和负载导致的频率漂移。基于压电换能器的Mason等效电路,建立外接LC调节电路的压电换能器的谐振频率、反谐振频率模型,分析LC调节电路中调节电感对频率调节特性的影响;通过实验研究外接LC调节电路对可调压电换能器机械品质因数的影响,并验证调节电感对频率调节特性的影响。理论分析和实验研究的结果表明:随着调节电感的增大,调节电容对频率的调节灵敏度提高,可调压电换能器的频率调节宽度拓宽,但也会使压电换能器的机械品质因数降低。合理选择调节电感和调节电容能兼顾频率调节宽度和机械品质因数的要求。此研究可为后续自适应压电换能器的频率调节系统设计提供指导。 相似文献
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针对超声波电源工作时负载状态改变,换能系统产生谐振漂移的问题,提出了一种基于STM32的频率自动跟踪超声波电源的设计。电源逆变电路采用带辅助网络的全桥结构,阻抗匹配电路选择了一种改进型的T型匹配网络,应用PWM移相调功技术控制电源的输出功率,通过数字鉴相技术得到电压电流的相位差作为电路谐振状态的反馈信号,结合STM32主控制器进行PI控制,调节PWM波的输出频率使电路始终工作于谐振状态,实现了谐振频率的自动跟踪。最后基于该设计方案,实际制作了一款应用于超声波清洗仪的电源,并通过实验验证了该电源具有输出功率稳定,负载适应性强,输出频率自动跟踪等特点。 相似文献
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Shuyu L 《Ultrasonics》2005,43(5):365-373
Based on the equivalent circuit theory, the load characteristics of high power piezoelectric ultrasonic sandwich transducers are studied. Two types of loads are studied. One is liquid load as in ultrasonic cleaning, and the other is solid load as in ultrasonic drilling and machining. The effect of load and structure of the transducer on the resonance frequency of the transducer is analyzed. It is shown that the effect of load on the resonance frequency of sandwich transducers with different structures is different. For liquid load as in ultrasonic cleaning, the effect of the load on the resonance frequency of the sandwich transducer with symmetrical structure is the largest. It is the smallest for the transducer with its displacement node in the back metal cylinder. For solid load as in ultrasonic drilling and machining, the effect of the load on the resonance frequency of the sandwich transducer with its displacement node in the front metal cylinder is the largest. It is also the smallest for the transducer with its displacement node in the back metal cylinder. On the other hand, for some applications, such as ultrasonic drilling, when the lateral dimension of the tool is much less than that of the transducer, its effect on the resonance frequency of the transducer is small. The conclusions are useful in designing vibrating systems for different ultrasonic applications. 相似文献
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针对超声金属焊接过程中出现的负载变化导致谐振频率漂移和焊接振幅失恒问题,设计了一种基于步进追频及恒振幅控制的超声电源。在负载变化对谐振频率影响的研究基础上,根据FPGA-DDS步进追频原理设计了负载变化追频逻辑;结合全桥逆变电路的移相控制方式,研究了不同占空比下的最大输入电流与最大焊接振幅的关系,提出了基于输入电流反馈下的步进移相恒振幅控制方案;实验结果表明,负载变化追频逻辑实现了谐振频率快速变化下的动态实时追踪,解决了因频率失谐导致的焊接振幅非线性下降问题。同时,在加入了振幅闭环控制后,实现了焊接振幅相对极差稳定在10%以内。 相似文献
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During ultrasonic welding, unnecessary ultrasound together with audible sound is radiated into the air. Audible sound is noisy and uncomfortable, and ultrasound may have bed effects on adjacent equipment. However, it is considered that these sounds potentially contain useful information such as welding state. This article reports the relationship between radiated ultrasound and the change of the welding state during ultrasonic welding. It is known that the welding state can be presumed from the change of the mechanical load impedance, which can be calculated from resonant frequency, motional voltage and the driving current of the vibrating system for the welder when a constant-velocity motional-feedback power oscillator is used. In this study, radiated ultrasound picked up with a microphone and an amplifier is recorded and analyzed with a personal computer. Analyzed results are compared with the change of the mechanical load impedance that is also calculated from the recorded data of the resonant frequency, motional voltage and the driving current of the vibrating system for the welding. Experiments were made on the ultrasonic welding of plastic rods. The relationship between the parameters of radiated ultrasound and the electrical parameters of the vibrating system were compared. The peak amplitude of the radiated ultrasound and the mechanical impedance versus time were very similar. It is shown in this study that radiated ultrasound contains lots of useful information. 相似文献
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High power resonant tracking amplifier using admittance locking. 总被引:2,自引:0,他引:2
A high power resonance tracking ultrasonic amplifier is described. The amplifier is a class D type inverter, configured as a half-bridge in which the output MOSFETs are driven into saturation when on. The resonance tracking system makes use of a new method of frequency locking; admittance locking is used to track the optimum power conversion frequency for the transducer. This new arrangement offers some advantages over phase locking and motional feedback methods. The system is capable of delivering up to 3 kW at up to 25 kHz in resonance tracking operation. 相似文献