Search

High degrees of coupling freedom in wireless power transfer (WPT) has emerged as a prominent research topic. The challenge lies in achieving a compact structural design for such systems. This article introduces a planar transmitter configuration composed of three decoupled and separately controlled converters to enable three-dimensional (3-D) WPT to an arbitrarily positioned receiver above the transmitter. By theoretical analysis based on the coupled mode equations, it is found that there is a direct relationship between the dc input voltages and currents of the inverters for achieving the maximum efficiency. The spatial magnetic field is shaped by controlling the input voltages based on the measured currents to achieve the best magnetic field coupling for maximum efficiency tracking, regardless of the positioning and alignment of the power pickup. A practical system is built with a 10 × 10 cm transmitter (with three decoupled coils) and 3.5 × 3.5 cm (single coil) receiver, and it is demonstrated that the system can achieve a power transfer efficiency about 80% within 3 cm above the transmitter under all 3-D coupling conditions.

In this brief, a wireless power transfer (WPT) system is proposed with the ability of parameter estimation for charging inspection robots without the need for an additional communication channel. A novel magnetic coupling and circuit tuning structure is proposed to achieve parameter estimation and closed-loop control using a sensing coil on the primary side. The design process is according to the industrial need of the application, i.e., substation inspection robots. One key procedure is the magnetic coupling design, utilizing the DD and Q coils to eliminate the undesired cross-coupling between them. Two practical series (S) and inductor-capacitor-capacitor (LCC) compensating topologies are adopted to tune with coils for improving energy transferability. Especially, the coupling parameters are identified by reconfiguring the LCC-LCC and SS topologies and detecting the two induced DC voltages of the primary detection circuit, providing the basis for the closed-loop control. Then the induced DC voltage of the primary detection circuit is used as a control feedback for realizing constant current (CC) charging, thereby obviating the need for complex pairing procedures and elimination of additional communication channels. A 480W experimental laboratory setup is constructed, and the feasibility of the proposed method has been validated through laboratory testing.

This article proposes a high-frequency bidirectional wireless power transfer (BD-WPT) system that achieves soft-switching, synchronous rectification, and a constant voltage (CV) output over a wide range of operating conditions. The system employs autonomous current-fed push–pull converters as the inverter on the transmitter (Tx) side and the rectifier on the receiver (Rx) side. Tx and Rx circuits are configured symmetrically across the magnetic couplers, enabling a reversible power flow by changing the dc source and load so that the system can facilitate a bidirectional power transfer. Theoretical analysis demonstrates that the proposed resonant system can achieve a unity voltage gain and deliver a constant output voltage, even when the load, coupling, and coil inductance vary simultaneously. The inverter gate-drive circuits are designed to enable dynamic zero-voltage soft-switching at high frequencies. Circuit simulations and experimental results show that the system can maintain soft-switching while providing a stable output voltage close to the input of 20 V, with load, coupling, and Tx-Rx coil inductance ranges between $40 \Omega $ –2 $\text{k}\Omega $ , 0.4–0.8, and 1.4– $1.8 \mu \text{H}$ , respectively.

This article proposed a dual-frequency 3-D wireless power transfer (WPT) system that can simultaneously drive two separate loads with independent voltage regulation. This dual-frequency 3-D system forms two directional magnetic fields rather than one spatial rotating field due to the dual-frequency excitations. The extended frequency channel enables the system to directly transfer power to the receiver tuned at the corresponding frequency with low magnetic field leakage. The two legs of the H-bridge inverters are driven at two different switching frequencies and duty cycles to output a transmitter current consisting of two frequency components. A dual-frequency resonant network is designed to retain the currents at the required frequency by filtering out other harmonics. By adjusting the duty cycle and phase of the corresponding bridge legs, individual current control of each frequency channel is realized without cross-interference, which provides the basis for the magnetic field orientation of either of the two loads. A proof-of-concept prototype with two receivers has been built with the rated output voltage of 12 V at 80 kHz, and 24 V at 200 kHz. It is demonstrated that this dual-frequency 3-D system can transfer about 40 and 36 W of power to the two loads at different positions, with an overall system efficiency of about 72%.