A Self-Powered Bipolar Rectifierless Series-SSHI Circuit With Dual-Polarity Energy Extraction for Piezoelectric Energy Harvesting

This article presents a self-powered, bipolar, rectifier-less series synchronized switch harvesting on inductor (BiReL-SSHI) interface circuit for piezoelectric energy harvesting. At both the positive and negative peaks of the piezoelectric transducer (PZT) voltage, a synchronous switch is automatically activated, enabling energy transfer from the PZT to a storage capacitor, while the inductor simultaneously inverts the PZT voltage for the next half cycle. Compared to conventional full-bridge rectifiers (FBR) and series synchronized switch harvesting on inductor (S-SSHI) circuits, the BiReL-SSHI topology employs fewer components by optimizing the positive and negative synchronous switches, thereby reducing power loss and improving energy extraction efficiency. Experimental results show that the BiReL-SSHI achieves a 5.4× improvement in power extraction compared to an FBR, when the open-circuit voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V_{oc}$</tex-math></inline-formula>) of the PZT is 8 V. Furthermore, in scenarios where a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V_{oc}$</tex-math></inline-formula> is converted to a low output voltage, the BiReL-SSHI achieves superior energy transfer efficiency compared to other interface circuits. Experimental results further demonstrate that at a 3.3 V output under identical vibration conditions, the BiReL-SSHI delivers 5.86× higher output power than the FBR.