Influence of a Medium on Capacitive Power Transfer Capability

Abstract

Despite the advantages of capacitive power transfer (CPT), inductive power transfer (IPT) is still preferred. The reason: IPT systems have a gap power density in air that is 400 times greater. Conclusively, IPT can transmit more power than CPT over greater distances in air, but what about other media? This paper gives an answer on how media, different from air, influence the power transfer over different distances. First, we analyze theoretically the capacitive coupling with different media in the gap. Next, we simulate the CPT system using finite-element software and compared it with the theoretical analysis. Finally, we employ the results of the finiteelement simulation in a power electronic simulation to examine the influence of the medium on the electrical power transfer.

Wireless Power Transfer: Systems, Circuits, Standards, and Use Cases

“…Thus, in theory, a different medium can enable capacitive power transfer over longer distances without using complicated compensation circuits. More research on the influence of a medium is needed to open opportunities for actual applications [ 107 ].…”

“…Therefore, further research is needed into the losses in the coupler. This will give a better estimation of coupling and system efficiency [ 107 , 156 , 157 ]. Technologies and developments for charging EVs and robots are another important area of research, such as dynamic wireless power transfer (DWPT) and multiple phase WPT [ 158 ].…”

Automated Test Setup for Capacitive Power Transfer Coupler Impedance Measurements

“…Equation ( 1) can be used for CPT systems with two parallel plates in series. This approximates the capacitance for a CPT system quite well for symmetrical systems bridging distances of less than 20 mm [4]. However, this approximation does not take into account the influence of the frequency of the electrical field between the plates.…”

“…If the CPT setup is symmetrical (C main = C 13 = C 24 ), and the distance between transmitter and receiver is smaller than e.g. 20 mm, the following assumptions can be made [4]. The cross-coupling and parasitic capacitances are negligible making the mutual C M , primary C P and secondary C S capacitances equal to half of C 13 and C 24 [1].…”

Modeling, simulation and experimental validation of solid media in capacitive wireless power transfer

“…The cross coupling and leakage impedance, Z cross and Z leak can be neglected when the distance between the transmitter and receiver is smaller than 25 mm [27]. At this distance the parasitic impedances are significantly larger than the main impedance Z main , and so are Z tr and Z rcv significantly larger than Z m .…”