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Vibration Energy Harvesting
Machine Monitoring – Fully autonomous condition monitoring wireless sensor nodes powered by vibration energy harvesting.
Monitoring valuable equipment eliminates unanticipated failures while enabling maintenance to be scheduled only when it is necessary. Thus, equipment utilization improves, and cascading events are prevented. Support systems such as pumps may not be high dollar value assets, but the system supported by the pump may be part of manufacturing line that can be disrupted. Low infrastructure and low cost monitoring nodes with energy harvesting solutions can have functional lifetimes of decades and can be installed on any industrial machinery to eliminate unanticipated disruptions to operations.
Vibration energy harvesting uses the inherent low level vibrations associated with rotating machinery such as electric motors to generate the hundreds of microwatts or single milliwatts necessary to power commercial wireless nodes. Texas Instruments (TI) wireless motes are being used to begin replacing previously established wired condition monitoring nodes on pumps that support the microfabrication facility at the University of California, Berkeley. We have demonstrated that current versions of our vibration energy harvesters can power the Texas instruments platform from the inherent vibrations of a 15 kW pump motor. Additionally, we have demonstrated that the vibration energy harvesters are capable of powering the TI mote with from vibration acceleration peaks with magnitudes as small as 45 mg.
The vibration harvesters are resonant devices that use a high Q spring and electromagnetic transduction to generate rectifiable voltages. A speaker motor magnetic circuit architecture that produces functional magnetic fields approaching 1 Tesla over large air gaps of several millimeters that accommodate a large number of coil turns allow several volts to be generated from vibrations of 50 mg or more.
Small scale resonant generators harvesting ambient vibrations in the 60-250 Hz frequency range by using an efficient electromagnetic circuit to convert the mechanical vibrations to electrical energy