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Simultaneous wireless power and data transfer (SWPDT) is widely investigated because of increasing requirement on real-time communication between the primary and secondary sides in wireless power transfer (WPT) systems. This paper classifies SWPDT systems into four categories according to the type and number of data channel and data carrier generation method. They are power carrier based SWPDT system, high-frequency data carrier based SWPDT system, multiple inductive channels SWPDT system, and inductive-capacitive hybrid channels SWPDT system, respectively. Four key issues including crosstalk minimization, improvement of signal-to-noise ratio (SNR), modulation method for high data rate and low bit error rate (BER), and special design to achieve full-duplex communication and improve misalignment tolerance are discussed. The advantages, disadvantages, and applications of the four types of SWPDT systems are summarized. Finally, conclusions and outlook of SWPDT system are given.

With the increase of load resistance, the impedance angle of the rectifier with passive C filter also increases, which may have some negative effects on the characteristics of the inductive power transfer (IPT) system. This article presents an impedance analysis method for C -filter rectifiers in continuous conduction mode. The calculation formula of critical load resistance is given and the relevant values are calculated. An improved C -filter rectifier circuit is proposed to reduce the phase angle of the IPT system. A very tiny capacitance is connected in parallel at the input end of the rectifier to reduce the impedance angle as load resistance changes, with hardly increased costs. This improved method not only improves the system efficiency, but also reduces the fluctuation of output voltage or current. Simulation and experiment results verify the feasibility of the proposed topology. A 1 kW prototype with primary series, secondary series compensation topology was built. The maximum system efficiency from dc power supply to the load is 94.5%. The efficiency under rated load is as high as 93%. Compared with traditional method, it has increased by 0.6%.

In this article, a 10 MHz dc/dc converter based on three-dimensional air core transformer with zero-phase difference synchronous driving signals is designed. By using the characteristics of no leakage inductance in the inner winding of the nested toroidal air core transformer, the phase difference between the output voltage of the inverter and the input voltage of the rectifier can be regarded as zero, so that the rectifier and the inverter can use the same driving signal, which simplifies the control of the synchronous rectifier switches, and realizes the reliable and efficient synchronous rectification control at 10 MHz. The prototypes with primary and secondary compensation are proposed and the experimental results verify the feasibility of the proposed control method and numerical design method.

In this article, a 10-MHz low-profile converter for bendable equipment based on aircore inductor is proposed. The mathematical model and inductance calculation method of the bendable planar circular spiral coil under different bending situations is analyzed. An optimal design method of the T type matching network is depicted in detail which helps to guarantee soft-switching characteristics and high efficiency within the whole bending range by realizing weak inductive equivalent input impedance. A 32 V input, 9V/6.3 W output prototype is proposed in the laboratory and the experimental results verify the feasibility of the proposed optimal design methodology, the system efficiency can be improved by 4% than the traditional method.

A novel multiresonant dc–dc converter is presented in this article, which owns a wide input voltage range and better voltage gain characteristics. Due to the addition of an antiresonant tank with a notch filter function, the converter introduces third harmonics in the power transmission, which can reduce the circulating energy in the resonant tank and reduce the loss of rectifier diode, thus improving the efficiency. The CL–LLC converter can realize soft switching in the full-load range. This article introduces the operating principle of the converter and the method of the parameters design. Finally, a 350–500 V input and 24 V/400-W prototype is designed to verify the correctness of the theory.

In this article, a soft-switching transformer-less step-down converter based on a resonant current balance module is proposed. An LED driver is taken as an example of the analysis and design of the converter. The converter is made up of a stacked half-bridge, resonant current balance modules, and pairs of light-emitting diode (LED) strings. The resonant current balance modules allow the proposed converter to realize automatic current sharing, soft switching, and extending to a 1/ N converter. The proposed converter can operate in discontinuous conduction mode (DCM) or continuous conduction mode (CCM) mode by choosing different operation frequencies, and achieve zero current switching or zero voltage switching (ZVS), respectively. Also, by using frequency doubling technique in the half-bridge, the switching losses are reduced by half under the same conditions. A 15.8-W experimental prototype with 100 V input voltage and 25 V output voltage has been implemented in the laboratory, verifying the feasibility of the soft-switching transformer-less step-down converter.

Simple but effective output voltage/current control schemes are essential for electric vehicle wireless charging systems (EVWCSs). This article proposes an EVWCS using interleaved boost converter (IBC) and flat solenoid coupler (FSC). The closed-loop control between the primary and secondary is realized by adjusting the duty cycle of the IBC. The currents and losses in the primary are reduced in the proposed system because the dc bus voltage in the primary is increased by using the IBC. The input current ripple is diminished owing to the interleaved structure. This article also proposes a parameter optimization method to obtain the optimal FSC. Without loss of generality, the total area of the transmitter (Tx) and receiver (Rx) is assumed to be constant, and the Tx is assumed to be larger than the Rx. A scale-down prototype whose output power is 500 W was built in the laboratory to verify the theoretical analysis. The output voltage of the prototype kept constant when the misalignment was 200 mm in the winding direction or 100 mm in the magnetic direction. A highest system efficiency, from dc input to dc output, of 90.1% was achieved when the power transfer distance was 170 mm.

The capability of misalignment tolerance is vital for an inductive power transfer system. The conditions satisfied by the high-misalignment-tolerant compensation topology are proposed in the article. It is proven that all compensation topologies with secondary parallel compensation component have a strong capability of misalignment tolerance if the parameters of the compensation circuit are properly designed. And, their misalignment-tolerant capability was analyzed. The impedance characteristics of the simple S/T compensation topology are analyzed. Two prototypes of approximately 300 W used S/SP (primary series, secondary series–parallel) compensation topology with strong misalignment tolerance were designed to verify the system performance. They have the characteristics of constant-voltage and constant-current output, respectively.

A novel high step-up dc–dc converter with coupled inductor and switched capacitor is proposed in this article. The proposed converter adopts capacitors charged in parallel and discharged in series with a coupled inductor to achieve high step-up voltage gain. By utilizing the energy stored in the leakage of the coupled inductor, both of the switches can realize zero-voltage switching, which can reduce switching loss and improve efficiency. In addition, the voltage stress of the switches and diodes are also reduced. Therefore, low voltage components can be utilized and the input current is continuous. The operating principle, steady-state, and parameter design are shown in details, and a 100-W experimental prototype with 25-V input voltage and 380-V output voltage is established in the laboratory to verify the feasibility of the proposed converter, and the highest efficiency is 96.21%.

Inductive power transfer (IPT) systems designed with conventional methods offer optimum performance only at specific operational points. These methods are not applicable for dynamic IPT systems where both the coupling and load change throughout the operation. This study proposes a novel particle swarm optimization (PSO)-based parameter design method and aims to obtain a steady output voltage regardless of the coupling and load. The proposed method addresses the constraints of the conventional methods where the compensation capacitors/inductors are designed to resonate with certain other inductors/capacitors at the system's operational frequency. The S/ CLC (primary series, secondary capacitor–inductor–capacitor) compensation topology is chosen in this research as it offers many appealing characteristics. The procedure to design an IPT system using the proposed method is presented. Two IPT systems, one designed with the proposed scheme and the other using conventional methods, are theoretically and experimentally compared in terms of fitness, voltage variation ripple (VVR), and power transfer efficiency (PTE). It is demonstrated that the fitness and the VVR of the conventional system are 1400.8% and 372.3% higher than those of the proposed system.

A high-performance impedance-source converter utilizing switched inductor is proposed in this paper, which can be adopted in the applications demanding high-voltage conversion. The proposed converter not only retains the advantage of quasi-Z-source of sharing common ground between the input and output but also possesses the superiorities of enhanced boost ability and lower stresses as well as higher efficiency. Mathematical analysis of the converter and its performance comparison with other converters are presented in detail. Finally, a 100 W prototype is built and the experimental results are provided to verify the feasibility of the proposed converter.

The capability of misalignment tolerance is vital for an inductive power transfer system. This paper proposes a novel unsymmetrical coupling structure that can remarkably enhance the output voltage stability with respect to the horizontal, vertical, and angular displacements. The core of this structure is concentrated magnetic field. The optimization method to derive the optimal loosely coupled transformer providing the strongest tolerance to misalignment and fulfilling the requirement of the minimum coupling coefficient is presented. The proposed structure is compared with planar circular and square coils and double-D (DD) coupler from the perspectives of magnetic coupling and anti-misalignment capability. A 200-W prototype is finally fabricated, where the primary series, secondary series-parallel compensation topology is employed to further improve the system's tolerance to misalignment. A maximum output voltage ripple factor of 2.83% and a minimum system efficiency of 91.9% are achieved when the horizontal displacement is as high as one-third of the coupling coil.

Wireless power transfer (WPT) has attracted a large amount of attention owing to its inherent advantages such as convenience, safety, low maintenance, being weather proof, etc. A parameter tuning method is crucial for a WPT system due to its function of reducing reactive power and improving system efficiency. Three deficiencies of the conventional double-sided inductor–capacitor–inductor (DS- LCL ) compensated system, i.e., low design freedom, weak high-order harmonic suppression capability, and discontinuous input current of a full-wave diode rectifier (FDR), are first analyzed by means of theoretical derivation, numerical calculation, and Pspice simulation. In order to overcome these disadvantages, a novel parameter tuning method is proposed. The characteristic of constant current output of the proposed DS- LCL system is analyzed, followed by a detailed derivation about secondary compensation inductance. Theoretical analysis indicates that the proposed system has four attractive characteristics: higher design freedom, reduced coil current, enhanced high-order harmonic suppression capability, and continuous input current of the FDR. The overall efficiencies of two comparative WPT prototypes, tuned by conventional and proposed methods, are 87.3% and 90.2%, respectively. Experimental results show great coincidence with theoretical analysis, demonstrating the superiority of the newly proposed parameter tuning method.

With the development of high frequency converters, driving circuits have gained more and more attention. Self-driven methods can effectively simplify system design and reduce components’ number. A basic self-driven circuit can be achieved by adding a series resonant inductor at the switch gate; however the losses of driving circuit are high. To reduce the corresponding losses, a high efficiency self-driven network with an additional parallel branch is proposed, which can significantly improve the system efficiency. A 13 MHz prototype is built to verify the feasibility of the proposed self-driven circuit. The system efficiency can be improved from 80% to 83.9%.

A 1 MHz half-bridge resonant dc/dc converter based on GaN FETs and planar magnetics is proposed in this paper, which improves the system efficiency and power density. The resonant network can achieve satisfactory soft-switching characteristics based on a small impedance angle, which greatly reduces the losses of switches and diodes. The losses characteristics during the turn-on and turn-off transitions are analyzed in detail. The calculation results show that the GaN FETs with low output capacitance and on resistance can achieve fast switching speed and low losses in high-frequency conditions. To reduce the profile and increase the power density of the system, planar magnetics are used in this paper. The response surface methodology (RSM) and modular layer model (MLM) are adopted to help design the planar inductor and transformer, respectively. Both of the methods offer clearer and more effective ways to design the planar magnetics. A 25-W prototype is built to verify the feasibility of the proposed high-frequency converter.

A novel high-power-factor single-stage single-switch light-emitting diodes (LEDs) driver for street lighting system is proposed in this paper. By integrating the single-ended primary-inductor converter (SEPIC) power factor correction circuit and Class-E resonant dc/dc converter, the proposed converter exhibits extreme simplicity and high reliability, as there is only one active power switch. The LED driver could achieve nearly a unit power factor by operating the SEPIC circuit at discontinuous conduction mode. With careful parameters design of a single Class-E resonant converter, the proposed converter can achieve soft-switching characteristics, which could significantly reduce the switching losses and greatly improve the system efficiency. Operational principle, analytical results, and design considerations at 100 kHz are presented, and a 100-W laboratory prototype is proposed to verify the theoretical analysis, whose efficiency is as high as 91.2% in full-load state under 110 VAC input.

A three-stage-five-coil inductive power transfer (IPT) system which is based on cylindrical solenoid coupler (CSC) is proposed in this article. The shape and parameters of the CSC are optimized. The five litz coils compensated by series capacitors are considered to form an IPT system based on equivalent CLC/S/CLC compensation topology with constant voltage characteristics. The mutual inductance between compensation auxiliary coil (CAC) and power transfer coil could be changed by moving the position of CAC, and the freedom of parameter design is enhanced. Mathematical model and loss model of the system are established, and power transfer characteristics of the system are analyzed. The system is considered to be used as a power source for state detection equipment of high-voltage (HV) device to achieve long-distance IPT, the effect of the coupler on the HV electric field is verified. Finally, a prototype with a length of 1.54 m was built. Based on the platform, output voltage and dc–dc power transfer efficiency curves with changed input voltage and load are obtained. The maximum efficiency of the dc–dc system can reach about 60%.

In the paper, a novel pulse ignition circuit is proposed for electronic ballast with the zero-voltage-switching quasi-square wave (ZVS-QSW) converter; the voltage pulse of the proposed igniting circuit contains both a high frequency part and a low frequency part; the high frequency part made it easy to exit the gas in the ionization conduction state in the high-intensity discharge lamp, and the low frequency part makes it easy to lower the igniting potential and provides the continuous pulse energy. The circuit is with few components, low costs, high reliability, and easy to control. The circuit model is analyzed in detail and the influence of the circuit parameters on the pulse amplitude and width is given in this paper. The peak current is limited and the amplitude variation caused by the deviation of the parasitic capacitor for the transformer is restricted by the auxiliary inductor. The auxiliary inductor and the transformer parasitic capacitor form another resonant circuit. As a result, an igniting pulse sequence with two different frequencies is applied to the lamp and both pulse amplitude and width are guaranteed. In the laboratory, the circuit is used in a 70-W metal halide lamp electronic ballast with the ZVS-QSW converter, and the lamp can be ignited reliably.