Development of low voltage management circuit for low frequency vibration energy harvesting
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Date
2016-03-01
Authors
Mohamad Izudin Alisah
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Abstract
This research presents a development of a low frequency vibration energy harvesting based on electromagnetic harvester with voltage management circuit to power up wireless sensor nodes. This is important for cases where the sensors have no consistent energy supply especially at installations where access is difficult. Since the generated voltage and power are strongly dependent on the input frequency, it is necessary to have specific low voltage management circuit to condition and store the electrical energy. The electromagnetic harvester consists of four voice coil actuators made of neodymium magnet and copper coils. Maximum power output of 0.94, 3.3, 6.4 and 15.5 mW were generated by the harvester for frequency of 4 Hz, 6 Hz, 8 Hz and 10 Hz at acceleration level of 3.5 m/s2. The sensor node based on NI-WSN thermocouple input consumed 9.5 mW during standby mode, 42.1 mW when temperature sensing and 105.3 mW during data transmission mode. The main contribution of this research is the circuit which can rectify low voltage as low as 0.24 V and requires no external power supply to operate. It comprises of low threshold diode voltage multiplier, LTC3105 boost converter and supercapacitor as storage energy. The stored energy was enough to power up the sensor node transmission for 3300 and 2100 cycles when connected to sensor node for every 5 s and 1 s reading samples. The integration of the electromagnetic harvester and voltage management circuit constructed has successfully powered the NI-WSN 3212.