用于旋转超声加工的超声波发生器频率跟踪策略

Frequency tracking strategy of ultrasonic generator for rotary ultrasonic machining

针对旋转超声加工中采用无线传输方式传递超声电能时,在超声波发生器频率跟踪电路设计中,反馈信号无法直接从超声振动单元侧直接采集的问题,基于变压器互感耦合原理,分析无线传输变压器初级与次级间电流、电压与电流相位信息的关系。建立利用无线传输变压器初级电流、电压与电流相位信息信号反映次级信号进行超声波发生器频率跟踪的信号采集方法,结合最大电流搜索和电压与电流相位信息锁相跟踪技术,提出了用于旋转超声加工的超声波发生器复合频率跟踪策略。对超声波发生器的信号采集与频率跟踪电路进行设计,并基于STC89C51单片机编制了频率跟踪程序,研制了用于旋转超声加工的超声波发生器,并对研制的超声波发生器在空载及加工中频率跟踪性能进行测试。结果表明:研制的超声波发生器信号在空载和旋转超声加工中频率跟踪性能稳定,可以满足实际旋转超声加工要求。

In order to solve the problem that the feedback signal cannot be directly collected from the ultrasonic vibration unit side,when designing of frequency tracking circuit in ultrasonic generator,since the wireless transmission method of ultrasonic energy is employed in rotary ultrasonic machining.The relationship between primary and secondary currents,and the relationship of voltage and current phase information between the primary and secondary of wireless transformer were analyzed.A signal acquisition method that using the primary current,voltage and current phase information signals of wireless transformer to reflect the secondary signals for frequency tracking of ultrasonic generator was established,based on the principle of mutual inductance coupling of transformer.A hybrid frequency tracking strategy suitable for rotary ultrasonic machining is proposed,combining with the maximum current search and phase-locked tracking technique of voltage and current phase information.The signal acquisition and frequency tracking circuit of ultrasonic generator was designed,and the frequency tracking program was compiled,based on STC89C51 microcontroller.An ultrasonic generator for rotary ultrasonic machining was developed,and the frequency tracking performances of the developed ultrasonic generator were tested under the conditions of without load and in rotary ultrasonic machining.The results show that the developed ultrasonic generator has stable frequency tracking performance under two conditions,which can meet the practical requirements of rotary ultrasonic machining.