Closed-loop Control of A Dual-side Series/Parallel Piezoelectric-Resonator-based DC-DC Converter

This work introduces a control strategy for hybrid piezoelectric-resonator-base (PR-based) DC-DC converters, specifically focusing on the Dual-side Series/Parallel PR-based (DSPPR) converter. By analyzing the out-of-phase operation waveforms, which occur when the switching frequency is misaligned with the steady-state PR resonant frequency, a finite-state-machine-based phase-locked loop (PLL) is established to track the optimal PR operation, thereby maximizing efficiency performance. Moreover, incorporating adaptive synchronous rectification facilitates the effective operation of a hybrid PR-based converter while enhancing overall efficiency. A voltage regulation and loss minimization loop with PI compensations is also introduced, enabling fully closed-loop operation with precise regulation capability. In addition, a frontside switched capacitor voltage balancing loop is designed to regulate the capacitor voltage. A discrete prototype of the dual-side series/parallel PR-based converter is built with a (20/0.2)mm PZT radial vibration mode PR to verify the proposed control strategy. It should be noted that the proposed control strategy is adaptable to various other hybrid PR-based converter designs.