Electromagnetic Footstep Energy Harvester Using Hybrid Stepper Motor with Maximum Power Point Tracking Algorithm

Abstract

Kinetic energy from footsteps can be harvested and transformed into usable energy. To effectively utilize the slow-moving prime mover caused by stepping in the rack and pinion design, the researcher used a high pole count motor - a hybrid stepper motor as a generator. In addition, a flywheel was used to lessen the effect of torque in the hybrid stepper. The maximum power produced depends on the instantaneous force acted by the mechanical energy to rotate the generator. Hence, this study incorporates the implementation of a maximum power point tracker (MPPT). The main goal of this study is to design and implement a mechanical energy harvester using a hybrid stepper motor as a generator with an MPPT using an incremental conductance algorithm. A working dynamic model using Simulink was produced that can almost match the output electrical frequency of the motor used with the mechanical energy harvester. The mechanical energy harvester was constructed and was able to generate 5.9 Wmax with the MPPT controller, which is higher than the power produce with only resistive load, thus, confirming the merit of the MPPT. It was determined that there is a significant relationship between the charge produced by the mechanical energy harvester and the number of steps per second. Neglecting the idle current, transmitting current, and considering the data gathered for 98kg individual, it was found that it will take 18.7 hours or 122,377 steps for the mechanical energy harvester to fully charge the 12V 1.3 Ah battery.