Maximum Power Transfer Capacity Research Articles

Modeling Single-Wire Capacitive Power Transfer System With Strong Coupling to Ground

This article presents the modeling of a single-wire capacitive power transfer (CPT) system to reveal its power transfer mechanism with strong coupling to ground. An equivalent circuit is proposed by treating the ground as a quasi-conductive medium. The parameters of the equivalent circuit model are determined, including the capacitance between the coupling plates of the CPT system, the single-wire inductance and capacitance between the wire and the ground, and the ground equivalent impedance. The maximum power transfer capacity corresponding to the system's resonant frequency is analyzed by using the proposed model to guide the system tuning design. A prototype single-wire CPT system is built, and a computer simulation technology (CST) model is undertaken to show the electric and magnetic field distributions, and the Poynting vector indicating the direction and magnitude of the power flow in the system. It is shown that the output voltage and the power predicted by the theoretical model are in good agreement with the simulation and practical results under the frequency and load variations. Different lengths of the dangling single wire at the secondary side of the CPT system are also investigated to validate the model with different levels of ground effects.

Comparison of Power Transfer Characteristics between CPT and IPT System and Mutual Inductance Optimization for IPT System

The capacitive power transfer (CPT) system and inductively power transfer (IPT) system are the two typical wireless power transfer systems. Based on the power transfer characteristics, the power transfer capacity of the two wireless power transfer systems were analyzed. Firstly, the maximum power transfer capacity and its existing condition of the two wireless power transfer systems were analyzed, and the choose gist of wireless power transfer system was presented according to the analysis result; then, the mutual inductance of 4 typical IPT systems was optimized for achieving maximum power transfer; finally, the theoretical research was justified via a simulation and experiment. Index Terms—capacitive power transfer (CPT), inductively power transfer (IPT); mutual inductance; optimization.

A Wireless Power Pickup Based on Directional Tuning Control of Magnetic Amplifier

This paper proposes a novel inductor-capacitor-inductor wireless power pickup with directional tuning control (DTC) for a magnetic amplifier. The proposed technique allows the power pickup to achieve full-range tuning/detuning operation to regulate power flow and maintain the output voltage to be constant. The method eliminates the tedious fine-tuning process associated with traditional fixed power pickup tuning methods and eases the component selection. Moreover, it can overcome the online circuit parameter variations and automatically achieve the maximum power transfer capacity when required. In order to meet dynamic load demands, a magnetic amplifier is used as a variable inductor and is controlled by a novel DTC algorithm to change the tuning condition of the power pickup. The effectiveness of the proposed power pickup and its applicability to general wireless power transfer applications have been demonstrated by both simulation and experimental results.

Determining optimal tuning capacitor values of TET system for achieving maximum power transfer

Optimal tuning capacitor values corresponding to the maximum power transfer of a voltage-fed series-tuned transcutaneous energy transfer (TET) system are derived. The theoretical analysis is verified by experimental results. The maximum power transfer capacity can be three times greater compared to the traditional method, which tunes the capacitor at the nominal resonant frequency without considering the mutual inductance effect. These results are useful to enable an existing series-tuned TET system to meet short-term high-power demands where efficiency is not a key factor.

Improved Power Flow Control for Contactless Moving Sensor Applications

An improved power flow control method for contactless moving sensor applications is proposed. The method allows the design of a system where sensors with different power ratings or a wide range of load variations can be implemented. A phase-controlled variable inductor is used to tune the resonant circuit of the power pickups of an inductively coupled power transfer (ICPT) system according to the actual power requirements of the sensors, thereby, helping to reduce the power losses without affecting the maximum power transfer capacity. Soft switching is achieved in the variable inductor control, and the effect of the equivalent tuning parameters on the power flow is analyzed theoretically. Simulation results show that a significant improvement of the existing controllers is achieved at no load or very lightly loaded conditions.