Wireless power transmission to an electromechanical receiver using low-frequency magnetic fields

Abstract

A near-field, electrodynamically coupled wireless power transmission system is presented that delivers electrical power from a transmitter coil to a compact electromechanical receiver. The system integrates electromechanical energy conversion and mechanical resonance to deliver power over a range of distances using low-amplitude, low-frequency magnetic fields. Two different receiver orientations are investigated that rely on either the force or the torque induced on the receiver magnet at separation distances ranging from 2.2 to 10.2 cm. Theoretical models for each mode compare the predicted performance with the experimental results. For a 7.1 mApk sinusoidal current supplied to a transmitter coil with a 100 cm diameter, the torque mode receiver orientation has a maximum power transfer of 150 μW (efficiency of 12%) at 2.2 cm at its resonance frequency of 38.4 Hz. For the same input current to the transmitter, the force mode receiver orientation has a maximum power transfer of 37 μW (efficiency of 4.1%) at 3.1 cm at its resonance frequency of 38.9 Hz.

Microfabricated Electrodynamic Wireless Power Receiver for Bio-Implants and Wearables

“…Our research group has previously designed, built, and characterize various macroscale receivers to demonstrate the EWPT method [4][5][6][7][8]. In this paper, we present a significantly miniaturized receiver that utilizes micromachined silicon suspensions.…”

“…Therefore, there is a technology gap for mid-range (~10-100 cm) transmission to compact receivers, as is needed for Internet of Things (IoT) devices, wearables or bio-implants. Electrodynamic WPT (EWPT) has been proposed as a possible solution [4][5][6][7], wherein the magnetic fields from a transmitter (generally much lower frequencies than inductive or magnetic resonance methods) are used to excite the mechanical motion of a permanent magnet in the receiver. This mechanical motion is converted into electricity by one or more electromechanical transduction schemes.…”

Experimentally validated model and analytical investigations on power optimization for piezoelectric-based wireless power transfer systems

“…Instead of inducing voltage on a receiver as two resonant inductively coupled coils do, Challa et al (2012) proposed a near-field WPT system using an electromagnetic transducer to convert the mechanical energy from the oscillating magnet tip mass to electrical energy. The authors focused on analyzing the system efficiency (defined by the ratio of the power delivered to a load and the power input to the network), which may not be a key factor of a low-power system.…”

Wireless power transfer system with center-clamped magneto-mechano-electric (MME) receiver: model validation and efficiency investigation

“…One approach to overcome this challenge was to use an electromagnetic (electrodynamic) transducer as a receiver [9]. The authors later developed similar methods to extend the transmission range for bio-implants and wearables with torsional springs and a rotating magnet mass [15][16][17].…”