The Design And Implementation On Power Supply Of Ultrasonic Embedded Device

With the people’s Bank of Chinese on chip card to replace the magnetic stripe card deployment,the domestic smart card production field set off a new wave of development boom.Smart card production process is complex,the embedding(antenna implant)is a crucial step.It is directly related to the performance and quality of smart cards and demand embedding system a lot.The core part of the embedding device is some parts associated with ultrasonic.Ultrasonic system is divided into ultrasonic power supply and oscillator.The ultrasonic power supply is the core part of the ultrasonic system.It is related to the efficiency and stability of the energy output.Ultrasonic power supply has digital power supply and analog power supply.Analog power supply development earlier,technology is more mature,so the market is the largest in china.But it is not convenient to adjust the output power and oscillator can not automatically match or large-scale integrated control.All of this lead to that analog power supply can not meet the requirements of modern industrial production.The digital ultrasonic power supply control speed can not keep up with analog power supply,so the stability is temporarily less than the analog power supply.In this paper,digital power ultrasonic power supply is studied in the application of smart card embedding domain,in order to achieve the stability of digital power supply with analog power.In the hardware circuit design,this paper mainly expounds the matching,feedback,master three circuit module.The matching circuit part firstly describes the static matching can not meet the real-time characteristics of the transducer resonance point drift.On this basis,a dynamic matching is proposed.The circuit and transducer,as a whole based on coupled oscillation theory is analyzed so as to realize the real-time tracking device on the resonant point.The feedback circuit describes the meaning of the current and the phase of the control and the design of the acquisition circuit.In the main control circuit,the main purpose is to control the frequency and duty ratio of the output PWM wave.And then by comparing the accuracy of the output frequency of the PWM module with the MCU,the design scheme of the frequency and duty ratio of the waveform can be introduced.In the software design,the paper mainly introduces several control algorithms: search algorithm,frequency tracking algorithm,constant current algorithm.Search algorithm is the search for the completion of the positive and anti resonance point at the start of the power.Positive resonant point is regard as the initial output frequency of the power source.Positive and anti resonance points will be brought into the algorithm to calculate the constant current reference value.The frequency tracking algorithm is to adjust the output frequency of the power source keeping its value is equal to the transducer resonance frequency.The most import thing about frequency tracking algorithm is the simple frequency tracking algorithm and the method to judge whether the transducer is in anti resonance.The core of the constant current algorithm is the traditional PID algorithm.In this paper,we make it improved,and the P regulation is used only in the beginning of the power supply,the PI regulation is used only in the course of work.The power ultrasonic equipment designed in this paper is put into production in YUANMINGJIE Technology Co.,Ltd.to achieve at least 720 hours of stable operation.And longer time stability also need time to test.Generally speaking,continuous collection of industrial use feedback and improvement in detail can achieve more stable than analog power.