A Frequency-Sweep Based Load Monitoring Method for Weakly-Coupled Series-Series Compensated Wireless Power Transfer Systems

Abstract

In this paper, a frequency-sweep based load monitoring method is proposed for weakly-coupled series-series (SS) compensated wireless power transfer (WPT) systems. By only measuring the input voltage and current of the transmitter coil, the proposed monitoring method can estimate the load resistance without any feedback signals from the receiver even for mid-range applications with very small coupling coefficients. Compared to the existing monitoring methods for short-range applications, the proposed monitoring method uses a simpler estimation equation. Both simulation and experimental results are included to confirm that the proposed monitoring method can accurately estimate load resistances of weakly-coupled SS compensated WPT systems.

Fast Hardware Approach to Determining Mutual Coupling of Series–Series-Compensated Wireless Power Transfer Systems With Active Rectifiers

“…24 shows the comparative curves of the relative errors among the proposed monitoring strategy and the existing monitoring strategies when the ESR of the transmitter coil deviates about ±2%, ±4% and ±6% while the ESR of the receiver coil remains unchanged. It can be seen that the relative errors of the proposed monitoring strategy are much less than those of the monitoring strategy in [18] and [20] when the ESR of the transmitter coil deviates from the nominal value. The discrepancy of the relative errors becomes larger as the deviation increases.…”

“…The coupling coefficients of the WPT systems with the resonators-I, resonators-II and resonators-III are also monitored by the existing monitoring strategies in [18], [20] and [21], respectively. For the monitoring strategy in [20], the equivalent load resistance is primarily estimated. Then, the coupling coefficient is further monitored at the resonant frequency using…”

“…In experiment, the practical deviations of ESR are emulated by the deviations of the parameter values of ESR being adopted for the monitoring strategies in the transmitter controller. First, the proposed monitoring strategy and the monitoring strategies in [18], [20] and [21] are adopted to monitor the coupling coefficient of the WPT system with the resonators-I and the distance between the coils is 10 cm. Fig.…”

“…wireless battery charging systems with fixed parameters and high compactness, e.g., portable devices. To overcome the issues of the strategies in [18]- [20], heuristic algorithms are used to monitor the coupling coefficient of SS-compensated WPT systems without knowing the exact parameter values of the resonators and can be extended to monitor the WPT systems with inductive, inductive-resistive, or capacitive loads [21]. However, this monitoring strategy is computationally intensive and therefore cannot be used for fast and online monitoring.…”

Fundamental Investigation of Short-Range Inductive Coupling Wireless Power Transmission by Using Series-Series Capacitive Compensation Topology

“…Choosing the most convenient shape of the transforming module is defined with a number of factors such as the air gap between the separated windings; harmonic effects; Skin depth losses; eddy current losses; size limitation; displacement insensitivity; weight of the magnetic core; and sensitivity to the misalignment between the separated windings In this transforming structure, the air gap is taken into consideration because of its influence on the leakage inductance and mutual coupling, since a large air gap causes a large leakage inductance and a low mutual coupling, which in consequence implies a large magnetizing current. The SS-CCT of WPT system has been proposed in many papers to estimate the load resistance without feedback [Yang et al, 2018], to improve the efficiency with low costs [Tritschler et al, 2015] or by using a frequency-gap model, or to determine the switching frequency [Gao et al, 2017], but in this paper we proposed to improve the efficiency by changing the resonance frequency, optimizing the air gap, and fixing the Resistive load.…”