Abstract: Provided is a power generation device that restrains interference between a plurality of flows of alternating current power if the flows of alternating current power are generated in the power generation device. The power generation device includes a housing, a first power generator held in the housing so as to be allowed to vibrate, and a second power generator held in the housing so as to be allowed to vibrate. The second power generator is electrically isolated from the first power generator.

Abstract: A power generation device includes a holder with a natural frequency of fA, and two or more vibration energy harvesting elements held by the holder and having natural frequencies different from each other. Out of the vibration energy harvesting elements, one has the lowest natural frequency fBmin satisfying the following Expression 1, and another one has the highest natural frequency fBmax satisfying the following Expression 2: fBmin?(0.925?2.5 N/100)fA??(1), and fBmax?(1.075+2.5 N/100)fA??(2), where N is the number of the vibration energy harvesting elements.

Abstract: Disclosed herein is a bridge abnormality sensing device including: a pair of vibration sensors installed in an upper structure of a railroad bridge supported with a plurality of bearings, the pair of vibration sensors being provided for two of the bearings arranged in a width direction; a detector circuit configured to output a damage detection signal based on a difference between output signals of the pair of vibration sensors; and an output circuit configured to receive the damage detection signal and notify an external device of any structural damage detected from the railroad bridge. The vibration sensors are vibration power generators that generate power in a frequency range of abnormal vibration resulting from the damage. Power to drive the detector circuit is supplied from the vibration power generators.

Abstract: A power generator including: a first vibration system in which a first mass member is elastically supported by a first spring member; and a second vibration system in which a second mass member is elastically supported by a second spring member, the first and second vibration systems providing a multiple-degree-of-freedom vibration system. A power generating element disposed between the first and second mass members is configured to convert vibration energy input to the first vibration system and the second vibration system from a vibrating member to electrical energy. A resonance frequency of the first vibration system is a frequency lower than 1/?2 times a frequency of a vibration input to the first vibration system from the vibrating member. A loss factor of the first spring member of the first vibration system is at least 0.01 but not greater than 0.2.