Revisit of series-SSHI with comparisons to other interfacing circuits in piezoelectric energy harvesting

Abstract

SSHI (synchronized switch harvesting on inductor) techniques have been demonstrated to be capable of boosting power in vibration-based piezoelectric energy harvesters. However, the effect of frequency deviation from resonance on the electrical response of an SSHI system has not been taken into account from the original analysis. Here an improved analysis accounting for such an effect is proposed to investigate the electrical behavior of a series-SSHI system. The analytic expression of harvested power is proposed and validated numerically. Its performance evaluation is carried out and compared with the piezoelectric systems using either the standard or parallel-SSHI electronic interfaces. The result shows that the electrical response of an ideal series-SSHI system is in sharp contrast to that of an ideal parallel-SSHI system. The former is similar to a strongly coupled electromechanical standard system operated at the open circuit resonance, while the latter is analogous to that operated at the short circuit resonance with different magnitudes of matching impedance. In addition, the performance degradation due to non-ideal voltage inversion is also discussed. It shows that a series-SSHI system avails against the standard technique in the case of medium coupling, since its peak power is close to the ideal optimal power and the reduction in power is less sensitive to frequency deviation. However, the consideration of inevitable diode loss in practical devices favors the parallel-SSHI technique, since the frequency-insensitive feature is much more pronounced in parallel-SSHI systems than in series-SSHI systems.

Coupling analysis of linear vibration energy harvesting systems

“…(9), (18) and (25) in Table 1 or comparing Eqs. (11), (20) and (27) in Table 3, it is seen that the resonant mean harvested power is identical for the cases of the zero and strong coupling, so is the resonant energy harvesting efficiency. The resonant mean harvested power in the cases of the zero and strong coupling is different from that in the case of the weak coupling, so is the resonant energy harvesting efficiency.…”

“…Electro-mechanical coupling factor k 2 e of the electromagnetic and piezoelectric vibration energy harvesters was defined in [1,2,[5][6][7][8][9][10][11]15,19,[22][23][24], which is a numerical measure of the conversion efficiency between electrical and vibration energy. Electro-mechanical coupling factor k 2 e of piezoelectric materials is equal to squared piezoelectric coefficient of the piezoelectric disk divided by the product of the free stress permittivity and short-circuited elastic rigidity of the piezoelectric disk or equal to the squared force factor divided by the product of the short-circuited stiffness and the capacitance of the piezoelectric disk.…”

A high-efficiency, self-powered nonlinear interface circuit for bi-stable rotating piezoelectric vibration energy harvesting with nonlinear magnetic force

“…In order to overcome these drawbacks, synchronized switch harvesting on inductor (SSHI) circuits have been studied and proved to increase the harvested power by several times than that of a SEH circuit under the same inputs, including parallel SSHI (P-SSHI) and series SSHI (S-SSHI) circuits [9,10]. Subsequently, SSHI circuits have been improved in many ways [11][12][13][14]. Up to now, several classes of switching strategies have been proposed, such as switching driven by external logic circuits [15], mechanical switching [16] and switching through velocity control [17].…”

A study of electromagnetic vibration energy harvesters with different interface circuits

“…In addition to the energy generation apparatuses, interface circuits are indispensable elements in these energy harvesting systems to control and regulate the flows of energy. Previously, piezoelectric vibration energy harvesters with different electric energy extraction and storage interface circuits were studied to enhance the power outputs of energy harvesters as listed in Table 1, including dimensionless and normalised harvested power studies [2][3][4][5]13,18,20,24,30,31,[38][39][40][41][43][44][45][46]47], energy efficiency investigations [4,39,43,47], single load resistor interface circuit [4,5,8,11,13,21,22,26,[31][32][33][37][38][39][41][42][43][44]47], standard interface circuit [6,7,16,…”