An inductive wireless power system is particularly appealing for secured short-range operation, considering its non-contacting and non-radiative nature....
An inductive wireless power system is particularly appealing for secured short-range operation, considering its non-contacting and non-radiative nature. However, one of the major challenges of inductively and wirelessly powering chip-scale apparatuses stems from the miniature size of chip-scale apparatus. The effective range of power transfer or communication is limited by the size of the coil that resides on the implanted chip or the hardware root of trust. For a distance exceeding five diameters of the coils, the power transfer efficacy diminishes to practically nothing even with high Q coils and magnetic resonance enhanced designs.
The lab employs a novel approach of treating multi-coil WPT systems as RF filters formed by spatially and weakly coupled resonators, for which the final power transfer efficacy (PTEF) can be determined similarly to the insertion loss of a filter. The effectiveness and accuracy in predicting the performance of the designed WPT systems are tested by micro fabricating the coils on a Si wafer and measuring the power transfer efficacy. The measurement and modeling results reach excellent agreement. As a result, inductive wireless power transfer over a long distance (~5 times the coil diameter) has been achieved with an unprecedented high efficacy (-27 dB).
The electric vehicle market continues to expand rapidly, with advances in battery technologies and charging infrastructure making EVs an attractive choice for a growing...
The electric vehicle market continues to expand rapidly, with advances in battery technologies and charging infrastructure making EVs an attractive choice for a growing number of consumers in the US and across the world. While EVs allow vehicles to be powered from domestic energy sources and reduce reliance on foreign oil imports, manufacturers remain heavily dependent on a small number of non-domestic raw materials to create the permanent magnets needed for conventional EV motor drives. Price volatility, supply chain constraints, and geopolitical pressures make the ongoing reliance on permanent magnet EV motors unsustainable.
Variable pole induction motors are of great interest for use in electric vehicles due to their increased efficiency compared to fixed pole induction motors and their lack of reliance on the scarce and geopolitically strained resources needed for permanent magnet motors. Consumers have been less than enamored with the performance of early variable-pole induction machines, however, as these models suffered from rough torque bumps that were felt by drivers during vehicle operation. Professor Arijit Banerjee and collaborators at the University of Illinois have developed two approaches to address this issue. The first employs a "bumpless" electronic pole changing method to minimize torque bump to less than 5% while achieving transition times under 200 ms. The second uses "virtual poles" to obviate bumps and achieve continuous transition. Both approaches improve transient performance during speed changes, providing a smooth driver experience. An accomopanying optimization, control, and modulation suite further optimizes performance and thermal management, allowing motors to be designed with a smaller footprint.
Benefits
Reduced reliance on scarce raw materials sourced from geopolitically unstable regions
