High Power Supply Of Digital Ultrasonic Generator Based On DSP Chip

With the in-depth application of ultrasonic technology in the field of cleaning, welding, grinding and other industries, there are urgent needs for the new generation ultrasonic power supply in the power market. Combining with direct digital frequency synthesis (DDS) technology, phase shift pulse width modulation (PS-PWM) technology and series-resonant full-bridge inverter with soft-switching circuit, a new kind of ultrasonic generator power supply which uses TMS320F2812 chip as its microcontroller is proposed.The main research work of this paper includes: a full-bridge inverter using IGBT as switching component is presented, and the drive circuits which correspond to the IGBT are also designed. For the matching circuit module, an improved matching circuit based on the traditional matching circuits is introduced, which successfully meets the requirements of the impedance transformation for the ultrasonic power. In the aspect of power regulation, PS-PWM combined with the soft-switching technology is selected as the power regulator through the comparison of several typical power regulators. Since it can adjust the power via full-bridge inverter with the soft-switching technology, it doesn't need to add any more components to adjust power continuously with low switching loss. Meanwhile, in order to overcome the shortcomings of traditional frequency-tracking technology, the paper proposed an PI-DDS frequency-tracking method to replace the traditional methods,which successfully takes advantages of the swift response of PI controller and the high accuracy of DDS circuit to ensure the power supply run in the resonant frequency always. Besides, the protection circuits including over-current, over-voltage and temperature protection are also designed, which guarantee the power more reliable.Finally, on the basis of theoretical analysis, the simulations and experiments are carried out. The results prove that the ultrasonic power supply which is introduced by the paper can achieve automatic frequency-tracking, continuous adjustment of output power and the various protection functions. Moreover, with the application of soft-switching technology, the power reduces the switching loss and enhances the efficiency of the power obviously. So it has a brightness way in future.