A Comparison between Class-E DC-DC Design Methodologies for Wireless Power Transfer

Abstract

We consider the design of Wireless Power Transfer (WPT) systems based on inductive links and focus on recent works where the whole WPT system (i.e. both energy transmitter and energy receiver) is designed as an isolated resonant class-E DC-DC converter characterized by a loosely-coupled transformer. The aim of this work is to compare the classic WPT design approach with a novel one, which allows achieving the same performance with a significant reduction in the number of reactive components of the circuit, with beneficial effects in terms of system complexity, size, and cost. We will also show that such a reduction in the number of reactive components leads to improved performance robustness to variations in the inductive link coupling factor.

A Primary-side Maximum Efficiency Transfer Solution in Wireless Power Transfer Systems: Theory and Validation

“…However, when changing either k or the value of the input or output voltage, ZVS is not achieved anymore. Indeed, thanks to the low k, only a limited variation in the operating point is expected, as observed in [37], with also a limited variation in the efficiency.…”

Mutual Inductance Measurement in Wireless Power Transfer Systems Operating in the MHz Range

“…1(a). Modeling the system as a (loosely coupled) transformer may prove helpful in the analysis of the circuit [7], [8], [15]- [17].…”

“…Indeed, many reasons suggest that the mutual inductance M must be carefully evaluated, not only because it affects both the link gain and the load received power, but also because it features a strong sensitivity with respect both to the medium attenuation and to the coils distance and misalignment. If we also consider that many WPT systems are designed with resonant circuits [1], [7]- [10] whose behaviour strongly depends on all circuit parameters, the appropriate knowledge of M is even more fundamental. Of course, it is possible to base the circuit design on the expected system parameters (including M ) estimated by means of accurate electromagnetic simulation results.…”