Design And Research Of Remote Monitoring System For Ultrasonic Power Supply

The ultrasonic power supply provides high frequency alternating current for the ultrasonic machining system,which is widely used in the fields of ultrasonic welding and ultrasonic cutting.However,ultrasonic machining has precise requirements for ultrasonic power frequency,power and other parameters.Therefore,ultrasonic power supply needs precise frequency control,automatic power regulation and other functions.When the environment and working conditions change,it is necessary to adjust the control parameters of the ultrasonic power supply.By designing a remote monitoring system for the power ultrasonic power supply to realize on-line monitoring of real-time data,it can discover production problems,avoid ultrasonic processing system in the long-term adverse conditions,prolong the appliance life;When changing the transducer’s load or appliance conditions,it can quickly realize the remote control parameters to reduce the burden of technical personnel and reduce production downtime losses.The research contents of this paper include:1.Transplanting the Ethernet technology to the ultrasonic power supply,and buiding the network communication circuit.Then,setting up a remote monitoring’s topology which combines models of C/S and B/S.And to aim at the control characteristics of ultrasonic power without operation system,choosing to transplant Lw IP protocol stack,and use built-in communication interface to realize remote monitoring function to support multi device access.2.Analyzing the equivalent circuit and the admittance relationship of the ultrasonic transducer,and choosing the anti-resonant frequency as the control target.Then selecting incremental PID control algorithm and analyzing the influence of PID control parameters on the output of ultrasonic power supply.Then puting forward a proportional coefficient’s adjustment method to improve the working state of ultrasonic transducer.3.Designing the output’s feedback system and the main control architecture of the ultrasonic power supply.The accurate measurement of the current,voltage and phase difference of the output signal is realized by using the current transformer and the digital phase detector.Using two microcontrollers as the main circuit of ultrasonic power supply,and the peripherals related to STM32 are configured on software,which realize the real-time adjustment of the analog to digital conversion of the acquisition signal and the control of the inverter module PWM.Besides,an improved SPI communication method is designed by adding external state lines,then two STM32 chips could communicate through SPI with a state table.4.Setting up the experimental platform of the remote monitoring system for ultrasonic power supply,and carring out the related experiments.The experiment on the feedback system of the signal shows that the feedback module of the output signal could accurately and quickly collect and convert output signals.Besides,the data communication and controlling experiments show that two STM32 chips could exchange data accurately with the new method of SPI communication.And users could access the remote monitoring interface of ultrasonic power supply through various devices,and adjust the control parameters quickly and accurately to avoid erroneous working state of ultrasonic power supply.The innovation of this paper is as follows.At fisrt,analyzing the basic theory of ultrasonic power supply,and proposing incremental PID algorithm as the control method to control the anti-resonant frequency,and remotely adjusting PID control parameters combined with the characteristics of ultrasonic transducer.Secondly,designing the main controlling architecture of ultrasonic power supply with two STM32F407 chips coordination,and putting forward an improved method of SPI communication to realize the stable communication between two chips.