An AC-DC converter with maximum power tracking for multi-input electromagentic energy harvester

Electromagnetic energy harvesters (EMEHs) have the potential to harvest various energy forms from different frequencies. But there is no AC-DC power converter that can achieve impedance matching for multi-input of a single energy harvester to extract maximum power from all frequency points. The article proposes a new AC-DC converter based on feedforward control to realize variable input impedance under different input frequencies. The article proposes an auxiliary coil to obtain the reference signal for feedforward control. The model of the auxiliary coil is built to guide the design. The AC-DC converter realizes variable impedance matching at different frequencies using an auxiliary coil. The article also analyzes the impedance mismatching loss caused by current ripple and builds a numerical calculation model. It can provide guidance for the design of key parameters, such as threshold voltage. The article designs a prototype of the AC-DC converter and EMEH with auxiliary coils. According to the measurement, the MPPT efficiency of the AC-DC converter is 98.7% at input frequency of 50 Hz and 97.7% at 1000 Hz. The converter transmission efficiency is 86.3%. The output voltage of AC-DC converter is 5 V with load resistor of 837 Ω. The overall of the multi-input energy harvesting system is 84.8%.