Browsing by Author "Chowkwale, Bhakti"

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Pulsed Self-Oscillating Nonlinear Systems for Robust Wireless Power Transfer
(2019-11-18) Liu, Fu; Chowkwale, Bhakti; Jayathurathnage, Prasad; Tretyakov, Sergei
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
While wired-power-transfer devices ensure robust power delivery even if the receiver position or load impedance changes, achieving the robustness of wireless power transfer (WPT) is challenging. Conventional solutions are based on additional control circuits for dynamic tuning. Here we propose a robust WPT system in which no additional tuning circuitry is required for robust operation. This is achieved by our systematically designing the load and the coupling link to be parts of the feedback circuit. Therefore, the WPT operation is automatically adjusted to the optimal working condition under a wide range of load and receiver positions. In addition, pulsed oscillations instead of single-harmonic oscillation are adopted to increase the overall efficiency. An example system is designed with use of a capacitive coupling link. It realizes a virtual, nearly-ideal oscillating voltage source at the load site, giving efficient power transfer comparable to that of the ideal wired-connection scenario. We numerically and experimentally verify the robustness of the WPT system under the variations of load and coupling, where coupling is changing by our varying the alignment of aluminum plates. The working frequency and the transferred power agree well with analytical models. The proposed paradigm can have a significant impact on future high-performance WPT devices. The designed system can also work as a smart table supporting multiple receivers with robust and efficient operation.
A Self-Oscillating Approach for Wireless Power Transfer
(2018-10-08) Chowkwale, Bhakti
Sähkötekniikan korkeakoulu | Master's thesis
We introduce a robust wireless power transfer scheme that theoretically works for any load and receiver position. We show that capacitive wireless power transfer systems with these new properties can be implemented by modifying simple operational Amplifier oscillator circuits. The load and the wireless power link are incorporated into the feedback of the oscillator. The operating frequency adopts to the best possible working condition when the load or receiver position change. We prove the concept by deriving a theoretical model and implementing the same experimentally. The experimentally measured frequency of operation and transferred power agrees well with our analytical solutions.