Transmitter Current Tracking Method of Improving Power-Transfer Efficiency for Two-Coil Wireless Power Transfer System

Xu, Dong; Wang, Dongqing; Li, Jiadong

doi:10.1109/cac.2018.8623806

Cited by 1 publication

(1 citation statement)

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“…Content may change prior to final publication. [14] >100 ms [12], [13] [14] Peak detection of the primary resonant current [15], [16] >100 ms [15], [16] PLL used for sensing the phase difference between:…”

Section: Introductionmentioning

confidence: 99%

Auto-Resonant Detection Method for Optimized ZVS Operation in IPT Systems With Wide Variation of Magnetic Coupling and Load

Grazian

Soeiro

Duijsen³

et al. 2021

IEEE Open J. Ind. Electron. Soc.

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In wireless charging systems, the H-bridge converter's switching frequency is set close to the system's natural resonance for achieving optimized zero voltage switching (ZVS). Variations to the system's natural resonance are commonly tracked by following the changes in the resonant current's polarity, i.e., current zero-crossings. The main implementation challenge is accounting for the time delay between the real monitored current and the final resulting switches' commutations. This becomes critical at high switching frequencies, particularly when the magnetic coupling and loading vary widely. This paper proposes an autoresonant detection method that continuously ensures optimized ZVS turn-on with the minimal circulating current over the operable range of magnetic coupling and load. The suggested implementation provides two split variable references for the resonant frequency detection, which adaptatively compensate for the propagation delay based on the resonant current slope. The auto-resonant scheme is benchmarked against the commonly employed method with fixed current detection references. The results highlight the auto-resonant strategy's advantages, namely extended operable range, wider ZVS turn-on region, ease start-up, and improved DC-to-DC efficiency. The auto-resonant features and functionality are verified experimentally with a 200W low-voltage e-bike wireless charger. Finally, the benefits of the presented method are analytically explored for high-power applications by considering the H-bridge semiconductor losses of a state-of-art 50kW wireless charging system.INDEX TERMS Control, H-bridge converter, inductive power transfer, inverter, resonant converters, softswitching, wireless charging, zero voltage switching.

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