Experimentally validated model and power optimization of a magnetoelectric wireless power transfer system in free-free configuration

This article presents a thorough analysis and an equivalent circuit model of a wireless power transfer system utilizing magnetoelectric (ME) effects. Based on two-port theory, explicit analytical solutions of, (i) the ME coefficient alpha(ME) defined by the derivative of the generated electric field with respect to the applied magnetic field), and (ii) the power transferred to a load resistance, are derived and rigorously validated by experiments. The compact closed-forms of the optimal load and its corresponding maximum output power are developed. In our particular experimental system, a power of similar to 10 mW is attained at an applied magnetic flux density of 318.9 mu T with a laminated composite made by two Galfenol and one PZT layers. While alpha(ME) is widely used in the literature as a standard criterion to evaluate the performance of a ME transducer, we reveal that larger alpha(ME) does not always ensure higher optimum power delivered to the load. Instead, we quantify the essential influences of each magnetostrictive and piezoelectric phases on the maximum obtainable power. We show that the transduction factor between the magnetic and mechanical domains is often more critical for power optimization than the mechanical-electrical transduction factor as it determines and limits the maximum power available for transfer to a resistive load.