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The working state of the online detection system can improve the visualization performance of the inductive power transfer (IPT) system. The main variation parameters are load and mutual inductance. The compensation topology with strong misalignment tolerance and constant voltage/current has a one-to-one relationship between mutual inductance, load, and system input impedance. Based on this relation, a parameter identification method of the IPT system is proposed in this article. The errors of parameter identification are reduced by the design method of load equivalent impedance. In addition, the load and coupling independent characteristics of compensation topology with strong misalignment tolerance can further reduce the identification error of output current. A prototype is built to measure the parameter identification accuracy of the system. The parameter identification errors of mutual inductance, load resistance, and output current are 1.6%, 4.3%, and 1.1%, respectively. The identification error of output current is far less than the errors of load and mutual inductance.

In this article, an underwater simultaneous wireless power and data transfer (SWPDT) system with 1-Mbps full-duplex communication link is proposed. The communication channel shares the coupler with the power channel without using additional communication coils. The transducers inject and extract high-frequency data carriers through the taps of the coupling coils to send and receive data. The proposed method for constructing a full-duplex communication channel no longer pursues the resonant relationship between inductance and capacitance. It takes advantage of the inherent characteristics of the higher-order circuit to simplify the circuit structure and maintain a high degree of design freedom. In addition, the center frequencies of the two communication channels do not shift with the change in the transmission distance, realizing the capability of misalignment tolerance. To improve the utilization efficiency of the communication frequency bands and achieve a high data rate, the system uses the minimum shift keying (MSK) modulation and coherent demodulation implemented by Xilinx Zynq-7000 FPGA. A 1-kW underwater SWPDT prototype with 1-Mbps full-duplex communication is presented to demonstrate the proposed system.

The capability of misalignment tolerance between the primary and secondary coils in an inductive power transfer system is vital. This paper proposes a novel coupling structure composed of a solenoid and a planar square coil with a third coil (SPS-TC) that can significantly improve the misalignment tolerance of couplers. The novelty of SPS-TC is the combination of concentrated magnetic fields and reverse magnetic fields. The proposed SPS-TC has an excellent characteristic that when coils are misaligned in the horizontal direction, the coupling coefficient varies within a very small range. A 1-kW prototype is fabricated. The experimental results show that when the horizontal misaligned distance does not exceed 37.5% of the coil size, the output voltage variation range is extremely small, and the minimum system efficiency is 90.12%. The benefits of SPS-TC are a smaller outer side length and excellent horizontal and rotational misalignment tolerance. It can be used for wireless charging applications in robots, rockets, satellites, unmanned aerial vehicles, etc.

The compensation topology with a misalignment tolerance capability is highly important for an inductive power transfer system. This paper proposes a novel compensation method for the parallel-series/series-parallel (PS/SP) compensation topology. The proposed PS/SP compensation topology has four forms in light of different combinations of the compensation components and has the characteristics of load-independent constant voltage output, good capability of misalignment tolerance, flexibly adjustable output voltage gain and nearly zero phase angle (ZPA). Prototypes with the PS/SP compensation topology and the LCC/S compensation topology are fabricated to make a comparison and verify the theoretical analysis of this paper. The experimental results show that under the same experimental conditions, the output voltage volatility coefficient using the PS/SP compensation topology is only 2.80%, while the output voltage volatility coefficient using the LCC/S compensation topology is 6.62%, which proves that the PS/SP compensation topology has a good capability of misalignment tolerance.

This letter proposes an undersea simultaneous wireless power and data transfer (SWPDT) system with extended communication distance and 1-Mb/s full-duplex communication. The proposed system operates in inductive power transfer-electric field communication mode, thus reducing the crosstalk between the power channel and communication channel. This letter proposes a novel communication channel construction method based on the single capacitor coupling principle, which can effectively extend the communication distance without additional mechanisms. The extended communication distance enables precommunication before charging and maintaining communication after completing charging, which is critical for undersea dynamic equipment. The resonant condition and transmission characteristics of the communication channel are analyzed. Two MHz communication bands are constructed to achieve full-duplex communication based on frequency division duplexing. Finally, the proposed undersea SWPDT prototype has a maximum output power of 1.2 kW and can maintain 1-Mb/s full-duplex communication within a range of 50 cm.

An LC filter rectifier with a diode bridge is widely used in an inductive power transfer (IPT) system. However, when the load resistance reduces, the rectifier input impedance becomes capacitive. In addition, the filtered inductor is not infinite, and its harmonic currents cause the input impedance to be biased inductively. In order to solve the above two problems, a novel LC filter rectifier is proposed in this article, which achieves zero input impedance angle of the rectifier. First, the mechanism of the traditional LC rectifier filter is analyzed in detail, and an accurate circuit model is proposed. Then, an improved LC filter rectifier is analyzed and designed, and the input impedance angle of the rectifier is zero. Finally, a prototype with the load of 8–120 Ω is built, which verified the correctness and feasibility of the improved rectifier. Compared with the traditional rectifier, the efficiency of the IPT system with an improved rectifier is increased by 1.10%, and the output voltage fluctuation is smaller.