  Magnetic resonance wireless power transfer (WPT) technology is increasingly
being adopted across diverse applications. However, its effectiveness can be
significantly compromised by parameter shifts within the resonance network,
owing to its high system quality factor. Such shifts are inherent and
challenging to mitigate during the manufacturing process. In response, this
article introduces a rapid frequency tuning approach. Leveraging
switch-controlled capacitors (SCC) to adjust the resonance network and the
primary side's operating frequency, alongside a current zero-crossing detection
(ZCD) circuit for voltage-current phase determination, this method circumvents
the need for intricate knowledge of WPT system parameters. Moreover, it
obviates the necessity for inter-side communication for real-time
identification of the secondary side resonance frequency. The swift response of
SCC and two-step perturb-and-observe algorithm mitigate output disturbances,
thereby expediting the frequency tuning process. Experimental validation on a
200W Series-Series compensated WPT (SS-WPT) system demonstrates that the
proposed method achieves frequency recognition accuracy within 0.7kHz in less
than 1ms, increasing system efficiency up to 9%.
