Purpose <p>This study aims to investigate the bandgap regulation mechanisms of cantilever-structured piezoelectric phononic crystals (PPCs) with shunting circuits and propose a parameter matching approach for targeted low-frequency bandgap design, to enhance vibration suppression in clean energy vehicle powertrains.</p> Methods <p>The bandgap influence mechanisms of combined shunting circuits, including resistance-inductance (RL) and negative capacitance (NC) circuits, were investigated through theoretical analysis and experimental validation. Based on the NC circuit analysis, a parameter matching methodology was developed to derive circuit parameters from the target bandgap characteristic frequency.</p> Results and Conclusions <p>Experimental results demonstrate that the proposed approach enables precise tuning of the locally resonant bandgap within the 200 Hz to 500 Hz range by adjusting the negative capacitance value, achieving over 15 dB of attenuation and significantly enhanced vibration suppression compared to conventional phononic crystals without circuits. This research provides a novel and effective methodology for targeted bandgap design in phononic crystals, offering a practical solution for active low-frequency vibration reduction in engineering applications.</p>