A novel frequency tracking method based on improved ESC control method for megasonic cleaning system

To address the issue of poor frequency tracking accuracy in conventional frequency tracking algorithms for megasonic cleaning systems under continuous operating conditions, this paper proposes a maximum current tracking method based on an improved ESC (Extremum Seeking Control) algorithm. First, the expression for the dynamic branch current of the megasonic transducer is derived. The relationship between the input current corresponding to the voltage driving pole and the dynamic branch current near the resonant frequency is established. To compensate for the limited sampling rate of ADC (Analog-to-Digital Converter) chips, a smoothing algorithm based on CIC (Cascaded Integrator-Comb) interpolation is proposed, and the effectiveness in peak-seeking is verified through simulation. The control experiments confirm that, in the megahertz frequency domain, the CIC current sampling method demonstrates higher sampling accuracy when compared to the existing sampling methods. Dual - channel sampling experiments verify the effectiveness of the proposed method for extracting dynamic branch currents. Subsequently, an improved ESC frequency tracking method is introduced, which combines peak-seeking techniques with maximum dynamic current tracking. Experimental results demonstrate that the extremum-seeking method proposed in this paper can effectively track the resonance frequency of the megasonic generation system and significantly enhance the driving current of the megasonic transducer. Comparative experiments show that, compared with existing control methods, the frequency tracking method presented in this paper can provide a higher driving current and a greater acoustic pressure output for megasonic transducers, thus significantly improving the cleaning efficiency of megasonic cleaning systems.