Power and Energy Systems

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There is an increasing demand for wireless power charging of mobile electronic devices, electric vehicles, biomedical implants and IoT sensor networks. Many of the already available wireless power transmission systems are based on inductive coupling and the size ranges in the cm’s scale, linked to the large surface area requirement. A competing technology is based on an RF approach, with small size chip but impractical power levels of pW to µW, and efficiency close to unity.

Portable and wearable electronics require wireless charging to sustain mobile usage at convenient positions and locations. The goal is to develop a compact, highly power efficient wireless power transfer charging system operating at 6.78 MHz, which is compliant with the Rezence standard.The research scope includes development of a highly compact, high efficiency, ferrite-core receiver antenna; and a metamaterial lens to enhance WPT efficiency between the transmitter and the receiver.  In this work, we focus on WPT receiver modules for various portable and wearable consumable electronics with a power rating of ~10 W such as smart phones, radios, laptops, tablets, and military electronics. In future work, this technology could also be scalable to other power ranges, such as mW for biomedical implants to kW for automobiles.

There is an increasing demand for wireless power charging of mobile electronic devices, electric vehicles, biomedical implants and IoT sensor networks. Many of the already available wireless power transmission systems are based on inductive coupling and the size ranges in the cm’s scale, linked to the large surface area requirement. A competing technology is based on an RF approach, with small size chip but impractical power levels of pW to µW, and efficiency close to unity. The alternative working principle that we propose results in a more compact solution that can be reduced to mm’s chip size while producing reasonable output power (1 mW range) at low frequency ranges (50 Hz to 1 kHz).

We have developed an electrodynamic wireless power transmission (EWPT) system that relies on the magnetic-to-mechanic-to electrical conversion from a transmitter to a remote resonator, through electrodynamic transduction. The mechanical motion of a permanent magnet is converted into electrical power, when the magnet is set in motion/rotation, by a time-varying magnetic field, next to the receiver windings.

Motivation

The maintenance procedures to replace the batteries typically require physical contact or wire connections with the devices, which may be inconvenient, difficult, or costly. Even where batteries can be easily recharged, the ever-growing hunger for portable power presents an important technical challenge. For example, the modern dismounted Warfighter carries a vast array of battery-powered technologies. The logistical burden of monitoring, recharging, and replacing these batteries is overwhelming, and no soldier would willingly go on mission without fully charged batteries. For soldier power systems, there are two main issues: the large number of different electronic devices and the requirement for constant charging for maximum mission readiness.

To address these issues, the project explore the development of an electrodynamic wireless power transmission (EWPT) technology that is capable of wirelessly delivering power to a spatially distributed collection of power receivers over distances of a few centimeters to a few meters. Compared to the more widely studied inductively coupled wireless power transmission schemes, the EWPT technology enables the power receivers to be physically much smaller and with fewer restrictions on their orientation.

In the EWPT system, a transmitting coil is connected to a power source and carries an alternating current. The field generated by the transmitting coil moves a permanent magnet in the receiver through electrodynamic (magnetic) forces and/or torques. The magnet is mounted on a spring and is allowed to oscillate. This motion is then converted into electrical energy using an electrodynamic transduction within the receiver. Even using fairly weak magnetic fields, significant mechanical oscillations can be induced when the receiver magnet is excited near its mechanical resonance (assuming an underdamped mechanical system).

Despite the fact that nonlinearities are inherent in many natural and engineered systems, it is common for engineers to remove, or attempt to remove, all nonlinearity from their designs. Although this simplifies the performance analyses, it also overlooks a wide array of phenomena that could potentially enable fundamental breakthroughs.

The objective of this project is to derive fundamental insights for complex arrays of nonlinearly coupled oscillators, using structures defined as magneto-mechanical lattices. The magneto-mechanical lattices comprise periodic arrays of dynamically interacting magnets, which can be conceptualized as an array of equivalent springs and masses, or alternatively, as a solid composed of artificial macro-atoms. The nonlinear magnetic coupling is to be theoretically tailored to exploit nonlinear energy transfer behaviors, such as reconfiguring bandgaps, energy localization, internal resonances, etc. These nonlinear phenomena are to be experimentally demonstrated and measured by fabricated magneto-mechanical lattices.