Non-resonant piezoelectric transformer based power converter for ultra-low-power electronic devices

Piezoelectric transformer is used in its resonance frequency range to step-up or -down the input voltage. When the transformer is operated with alternating voltage in the non-resonance frequency range, which can be a few hertz, the transformer input works as an actuator, and the isolated output as a sensor to step-down the voltage. The output voltage has a linear relationship to its input the voltage. In this paper, the piezoelectric transformer in the non-resonant and low frequency range is represented by an equivalent circuit. A power converter that steps-down the mains voltage of 220 V and 60 Hz to supply power to a micro-watt consuming wireless sensor node is presented. This small size, fewer component, isolated, low EMI, and no inductive component converter has total input power consumption of 31 mW with 3 V and 11.2 μW of output voltage and power respectively.