Single- and multi-source battery-less power management circuits for piezoelectric energy harvesting systems

This paper presents a battery-less power management unit for piezoelectric energy harvesting which exploits a diode-based rectifier, a storage capacitor, and a custom trigger circuit to extract energy from a piezoelectric converter and to intermittently power an electronic load. The low power consumption and the high versatility of the power management unit allow its implementation within single- and multi-source power management circuits for piezoelectric converters. Experimental results show that the proposed single-source power management circuit is able to extract energy from a piezoelectric converter excited by sinusoidal vibrations with an acceleration amplitude of 0.5 gRMS in the frequency range between 38 and 49 Hz, yielding an operating bandwidth of 12 Hz. Such operating bandwidth is up to 71.4% greater than tailored commercial energy harvesting solutions under the same experimental conditions. Innovative multi-source power management circuits which exploit the series-like and parallel-like combinations of multiple power management units are presented. The limitations of traditional topolo- gies are overcome by connecting each piezoelectric converter to a power management unit. In particular, the proposed inverting, buck-boost, parallel-like, power management circuit combines the energy from the storage capacitors of each power management unit in a single storage capacitor exploiting a switch on inductor through trigger circuits. Experimental results show that the proposed inverting buck-boost power stage has an overall efficiency of about 8.5%.