Analysis and modification of a common energy harvesting system using magnetic shape memory alloys

In this paper, a common energy harvester is investigated which uses a specimen of magnetic shape memory alloy (MSMA). The aim of this study is to improve system performance and to evaluate the magneto-mechanical loading on the MSMA material. Since demagnetization effect is not included in the employed original MSMA model, a method to incorporate this effect is proposed which has a good performance for the specific magneto-mechanical loading of this problem. In order to decrease the need for bias magnetic field and increase system efficiency, a new return mechanism for the MSMA specimen is proposed. The results indicate that the maximum harvested power from the improved system is obtained at 0.55 T bias field, with 30% increase in power. Then, input mechanical loading in the system is studied. Firstly, applied strain rate caused by mechanical loading is studied, and a nonlinear relation between the induced RMS voltage and strain rate is observed. Next, 2D applied mechanical loading is investigated, and it is shown that by increasing the phase difference between mechanical loads in two directions, the induced voltage decreases. Moreover, applying dynamic effect to the model shows that for thin MSMA specimens, this effect is minor, but by increasing the thickness and loading frequency, the effect becomes tangible.