Energy harvesting microgenerators

Paul Boughton

Following the launch of a vibration energy harvesting microgenerator by Perpetuum, the company’s new version of the device is designed for use on helicopters.

The PMG27 harvests the vibration induced by the rotor to generate electrical power. This enables installation of complete wireless transmission systems incorporating sensors such as those used in health and usage monitoring systems (HUMS), without the need for batteries, expensive cabling or maintenance. It enables new sensors to be installed at very low cost without wiring and without the associated paperwork.

Vibration is present throughout the body of the aircraft at frequencies that depend on the speed of the rotor and the number of blades but usually including at least one peak source of vibration in the range 10-25Hz.

The PMG27 is designed to harvest the energy from anywhere in the aircraft structure. It converts the kinetic energy of the vibration into electrical power up to 4mW - enough to drive a wireless transmitter sending up to 6Kbytes of critical data every few minutes or smaller amounts of data - such as a temperature reading - several times a second.

Widely used in civil and military aircraft, HUMS technology has been credited with providing significant safety, maintenance and cost saving benefits by improving maintenance scheduling and providing accurate usage recording.

However, conventional HUM systems require sensors to be hardwired, making them relatively expensive to install. Now, with the possibility of wireless sensing enabled by Perpetuum's new technology, the HUMS market is likely to be extended significantly, to embrace large numbers of smaller aircraft and privately owned helicopters. The wireless option also offers a cost-effective method for adding extra sensors to an existing system.

PMG27 is a practical device, designed to operate in the harsh environment of a helicopter in flight. It is very easy to install and requires no further maintenance. Its robust construction means it has an anticipated life well in excess of the electronics it powers; a truly perpetual source of power

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