Energy harvesting för sensorer i tung industriell miljö

Sammanfattning: Energy harvesting essentially involves extracting energy from processes that generate losses in theform of heat, vibrations, radiation, etc, and converting it into electrical energy that can be used topower sensors or other electrical systems. A customer of Knightec Örnsköldsvik wants to develop measurement equipment using sensors in a demanding industrial environment with rotating machines that does not allow wired energy or communication transfer. The question to be answered is which energy harvesting technology is best suited for this specific environment and how much energy it could generate. Additionally, it needs to be determined if the sensor's energy requirements for one measurement per day can be fulfilled through energy harvesting. The purpose of this work is to enable easier installation and extend the sensor's lifespan by removing batteries and cables. Due to the characteristics of the environment, only vibration-based energy harvesting is realistic. This is because the sensor is enclosed in metal, and the temperature difference required for heat based energy harvesting is not sufficient. The energy requirement for the sensor is determined, and a minimal current needed to achieve this is calculated. The tests are performed using an energy harvesting development board, AEM30300, and a supercapacitor as the storage unit. A functiongenerator is used to generate a sinusoidal waveform representing the deformation of a piezoelectric element. Different amplitudes and frequencies of the sinusoidal waveform are used as inputs to the development board. Voltage and current are measured over time to determine the average current charging the capacitor. This is compared to the theoretical current required topower the system.The result shows that a sinusoidal waveform with an amplitude of 1.5 V and a frequency between 3.5 Hz to 30 Hz can provide enough current to power the sensor, given that the system's leakagecurrent is less than 2 µA. If the desired amplitude is not available, an alternative approach is to lower the system's operating voltage to 1.8 V or implement a boost converter to boost the voltage after the supercapacitor. This is because a capacitor takes longer to charge as its voltage levelincreases, resulting in a decrease in current towards the end of the charging process when thevoltage approaches 3 V.