Modified first harmonic approximation-based modeling of SN-compensated inductive power transfer links operating at load-independent-voltage-output frequency

Abstract

Some popular applications of wireless power transfer (such as electric vehicle charging) include a transmitter residing on a static platform (charging station) and a dynamic receiver (vehicle). In such applications, compensation may be excluded from the receiver in order to minimize, simplify and lower the cost. If transmitter compensation is also maximally simplified series to none (SN) compensation topology is created. It was recently shown that classical first harmonic approximation (FHA) based analysis fails to accurately predict RMS values of system currents, thus overestimating the achievable coil-to-coil efficiency. Consequently, this paper establishes modified FHA (MFHA) equivalent circuit of SN-compensated inductive power transfer link (IPTL), utilizing analytical expressions of primary and secondary currents based on time-domain differential equations (DE) based solution. It is shown that the outcomes of proposed MFHA and DE methods are very close, justifying the proposed methodology. Simulations and experiments demonstrate excellent matching, validating the presented analysis.