This paper introduces a new phase-variable switchcontrol for the parallel synchronized triple bias-flip (P-S3BF) interface circuit, towards the broadband and high-capability piezoelectric energy harvesting (PEH) systems. By using the phasevariable P-S3BF (PV-P-S3BF), both the electrically induceddamping and electrically induced mass/stiffness can be tuned to acertain extent in operation, such that to simultaneously make thedual tasks of broadband and high-capability in PEH. The jointdynamics and harvested power of the PEH systems using the PVP-S3BF circuits are thoroughly discussed based on the harmonicanalysis and impedance modeling. The available range of PV-PS3BF is rationally shown in the complex impedance plane. Theexperimental results obtained with a PCB-level prototyped circuitshow agreement with the analytical results. The new PV-P-S3BFcircuit opens a promising future towards the electrically in-situtunable broadband and high-capability PEH systems.