Efficient Power-Transfer Capability Analysis of the TET System Using the Equivalent Small Parameter Method

Abstract

Transcutaneous energy transfer (TET) enables the transfer of power across the skin without direct electrical connection. It is a mechanism for powering implantable devices for the lifetime of a patient. For maximum power transfer, it is essential that TET systems be resonant on both the primary and secondary sides, which requires considerable design effort. Consequently, a strong need exists for an efficient method to aid the design process. This paper presents an analytical technique appropriate to analyze complex TET systems. The system's steady-state solution in closed form with sufficient accuracy is obtained by employing the proposed equivalent small parameter method. It is shown that power-transfer capability can be correctly predicted without tedious iterative simulations or practical measurements. Furthermore, for TET systems utilizing a current-fed push-pull soft switching resonant converter, it is found that the maximum energy transfer does not occur when the primary and secondary resonant tanks are "tuned" to the nominal resonant frequency. An optimal turning point exists, corresponding to the system's maximum power-transfer capability when optimal tuning capacitors are applied.

Optimal Tuning of Inductive Wireless Power Links: Limits of Performance

“…The complete result for with optimizer constrained to be nonnegative is then from (21) and (22), if , if . Fig.…”

“…Two notable performance criteria for designing wireless power systems are maximizing delivered power for a given input drive voltage [2], [11]- [14], [21], [24] and maximizing power transfer efficiency [3]- [6], [8], [15], [22], [23]. Although maximizing efficiency minimizes the required input power for a given delivered power, it can result in a higher driving voltage being required.…”

Predicting the unstable period-1 orbit (UPO-1) of DC–DC converters by extracting harmonic content

“…According to the previous hypothesis, the UPO-1 has similar harmonic contents with the SPO-1, and so, the ESP method (Qiu and Filanovsky, 2000) is adopted here. This method takes advantages of the harmonic balance method and perturbation method, and it has been used to acquire the steady-state periodic solutions of switching converters (Wu et al ., 2011; Chen et al , 2017). Here, it is going to be extended to extract the UPO-1 of converters in chaotic state.…”

“…The parameter ε i is introduced temporarily to indicate that the corrections are much smaller than the main wave, that is, ε i+1 x i +1 < ε i x i ≪ x 0 . Whenever the specific value of ε should be given, we put ε = 1 (Wu et al ., 2011).…”

“…From the analysis results, we extrapolate that the state variables of the UPO-1 have similar harmonic contents with those of the stable period-1 orbit (SPO-1). Thus, a predicting scheme based on the Equivalent Small Parameter (ESP) method (Qiu and Filanovsky, 2000; Wu et al ., 2011; Chen et al ., 2017) is proposed; the harmonic contents of the UPO-1 are assumed first, and are corrected step by step then. At last, an approximate analytical description about the UPO-1 can be acquired.…”