Frequency Tuning of the Resonant Wireless Energy Transfer System

Frequency Tuning in Inductive Power Transfer Systems

“…The actual values of the reactive elements of the prototypal IPTS have been measured with an Instek LCR meter model LCR-819 and the resulting values are reported in Table 2, together with the coils distance and the R L values in (14), (20) and (21). By substituting these values in the first of (4) and (7), phase θ iT,vS between i T and v S and ratio (28) have been plotted as a function of ω norm respectively in the upper half and the lower half of Figure 10.…”

“…Some papers studied how the loss of resonance affects the output power of the system [9] and other considered also its effects on the efficiency [10], but they did not propose countermeasures aimed to regain a satisfactory level of efficiency. In literature, two approaches to resonance restoration are found: some authors keep the supply frequency constant and act on the reactive parameters of the coils or of the compensation networks to achieve the resonance [11][12][13]; other authors, instead, adjust the supply frequency to reach a given performance index [14][15][16][17]. In paper [11] an additional coil, coupled with the receiving one, is suitably fed in order to induce across the latter one a voltage that changes its equivalent reactance with the aim of maximizing the voltage applied to the equivalent load.…”

“…Paper [14] follows the approach of varying the supply frequency. The authors propose to perform a sweep of the supply frequency from the minimum to the maximum to find which one gives the maximum output voltage and considers it as the resonance frequency; after this adjustment, the frequency is kept constant and no real time tuning is performed.…”

“…This paper, however, offers much more detailed insights both from the theoretical and the experimental points of view, together with the opportunity of comparing the performance of two different tuning method applied to the same IPTS, and takes into consideration the bifurcation phenomenon, not mentioned in any of the cited papers. More in detail, differently from [14], the tuning method implemented in the prototype does not require transferring any information from the receiving to the transmitting stage of the IPTS, thus greatly simplifying its implementation, and differently from [15], the resonance condition is recognized elaborating real time data instead of relaying in theoretical relations. Moreover, the frequency tuning is completely independent from voltage or current control, so that a much higher flexibility in the management of the IPTS is preserved.…”

Omnidirectional WPT and Data Communication for Electric Air Vehicles: Feasibility Study

“…Moreover, with the integration of WPT technology in the high power applications such as EV charging, UAV, drones, and AEA, the need of high transferred power increased. However, several studies focused on how to improve the system's performances [16][17][18][19]. Maximum transmission efficiency for WPT systems are reached under resonance condition, which is very sensitive to the load condition and the distances between the transceivers.…”