Improvement in Output Power of Vibration Generators based on Piezoelectric Elements using Passive Devices

Improvement in output power of vibration generators based on piezoelectric elements by using internal capacitor cancel control rectifier

“…The proposed C3 circuit is connected in parallel to piezoelectric elements to generate electric current that is necessary to achieve same effect as with LC resonant circuit. 13,14 This solution proved effective for vibrations including harmonics 16,17 and for vibrations with variable frequency. 18 The present paper proposes an internal capacitor cancel control (ICCC) rectifier 19 that combines the C3 circuit with output control 1 , and shows that output power is further increased as compared to the C3 circuit.…”

“…Prior to presenting C3 circuit and the proposed ICCC rectifier, this subsection explains about the principle and drawbacks of LC resonant circuit in previous research. 13 Figure 4 shows LC resonant circuit connected to piezoelectric element (Figure 2B). Output of vibration-driven generator is small, and therefore, must be increased.…”

“…In addition, Subsection 3.2 of this paper gives a detailed theoretical explanation that output power depends on the internal capacitor C p even in case of variable vibration frequency containing harmonics. Thus, in the previous research, 13 a parallel indicator L A is introduced to reduce C p and boost output power. In addition, an auxiliary capacitor C A is used to adjust resonant frequency.…”

“…With reference to previous studies, 13,14 the rectifier's smoothing capacitor C o is set to 32 μF to ensure sufficient smoothing. Besides, inductor L used in C3 circuit and ICCC rectifier is set to 11.4 mH, and its internal resistance is set to R L = 0.39 Ω.…”

“…As mentioned above, output power of vibration-based generator using piezoelectric elements is small; in our previous research, output was improved by connecting inductors in parallel to piezoelectric elements to produce LC resonance. 13,14 However, LC resonance using parallel inductors involved a number of problems; namely, vibration frequency must be unchanged to obtain any effect, while parallel inductors are large in size. In realworld vibrations, frequency changes and includes harmonics so that the effect of LC resonance can be hardly be maintained.…”