Study Of FPGA-Based Ultrasonic Power For Semi-Continuous Casting Of Aluminum

With the deepening of modernization, our nation has a very high demand on the quantity and quality of aluminum products. The ultrasonic leading in aluminum semi-cuntinuous casting process when it was melted can refine the solidification microstructure and improve casting quality. The ultrasonic power is the key part of the ultrasonic casting machining technology,so it was very meaningful how to improve its automation and intelligence level for large-scale application of ultrasonic casting technology to the industrial field.The work characteristics of the transducer is analyzed in this paper, and then obtain the requirements of the control object's performance.By making a comprehensive comparison of different circuit characteristics, the main circuit is constructed with the single-phase uncontrolled bridge diode rectifier, Buck chopper voltage regulation and full-bridge inverter frequency modulation.It can not only meet the requirements of the casting process, but also to ensure the system to operate safe and reliably.For the limitations of discrete embedded systems,and considering the development of electronic devices,it proposed System on a Programmable Chip (SoPC) solution, that was integrating a soft-core processor,flash memory,A/D converters,PWM generator circuit and other modules on a single ACTEL FPGA chip. For its programmable features, without changing the hardware conditions, it also can be easily to add extension modules with the Verilog HDL language,and all of that increase the system flexibility great. In addition,this paper make a constitute a complete system by designing MOSFET driver circuit, buffer circuit, shaping circuit, and man-machine interface circuit.Because the transducer has a large impedance, so according to the impedance transformation characteristics of the transformer, A high frequency transformer is designed to improve the output efficiency of the power. The transducer is using a resonant way to deliver energy, whose resonant frequency can be easily offset with work environment affecting the system parameters. This paper design a fuzzy PLL frequency tracking method by using FPGA devices,that can easily adjust the output frequency increment with fuzzy method according to the size of the phase difference,and also regulate the inductor size through the digital port.This digital dynamic inductance frequency tracking mode can suppress overshoot and improve the speed of phase lock.The simulation and the field debugging results show that:the output frequency of ultrasonic power can quickly follow the changes of the resonant frequency, make a long-term work with resonance, so it can guarantee the smooth progress of the casting. On the other hand for the wide frequency regulation and flexible performance upgrades,the power system can adapt to a variety of applications.