A surface plasmon resonance (SPR) sensor based on a D-shaped photonic crystal fiber (PCF) with an uncomplicated structure is proposed to detect the change of refractive index of liquid analytes, and numerical simulation is carried out by the finite element method (FEM). Using silver as the plasmonic metal, the performances of the SPR-PCF sensor coated with a graphene layer and zinc oxide (ZnO) layer were assessed. The sensor designed is only coated with material on the polished surface, which makes the sensor production uncomplicated and solves the problems of filling material in the hole and coating on the hole wall. The effects of structural parameters such as graphene layer thickness, silver layer thickness, ZnO thickness, lattice spacing and manufacturing tolerance of blowhole diameter on the sensor performance were numerically simulated. The numerical results show that the sensitivity of the SPR-PCF sensor coated with 25 nm ZnO is highest in the ZnO thickness range from 10 to 25 nm. In the refractive index range of 1.37–1.41 for liquid analyte, the maximum sensitivity and corresponding resolution reach 6000 nm/RIU and 1.667 × 10⁻⁵, respectively. In addition, the sensor has good stability and high structural tolerance under the tolerance of ±5% of blowhole diameter. This work has wide application value in the detection of biochemical analytes, water pollution monitoring, food quality, and medical diagnosis.

A novel high-conversion-ratio bidirectional dc-dc converter with coupled inductor is proposed in this paper. Compared with the bidirectional converters based on coupled inductor, this new topology can realize a higher step-up voltage gain and lower step-down voltage gain with a lower turn ratio in an appropriate duty cycle. In proposed converter, the windings of the coupled inductor are reversely connected to transfer energy from high voltage source or low voltage source. Then, a clamp capacitor is applied to reduce voltage stress on main switch; therefore, the conduction loss of the main switches can be reduced by using a low resistance switch, and the clamp capacitor can also recycle the energy of the leakage inductor in coupled inductor. Besides, the soft-switching technique is used to achieve zero voltage switching, so the efficiency can be further improved. The main circuit and its steady-state operating principle are analyzed in detail. Finally, a 25-200 V 200 W bidirectional dc-dc converter is implemented to verify its performance.

This paper introduces a cascaded high step-up converter realized with a tightly coupled three-winding coupled inductor. Compared with existing high step-up converters, the proposed converter features that the smaller the turns ratio, the larger the conversion gain. So, the name coupled inductor-reverse is given to represent reverse-coupled inductor principle of operation. In addition, diode-capacitor circuit is introduced to not only recycle leakage energy to output, but also further lift voltage conversion gain. This paper illustrates operation principle of the proposed converter, discusses effect of leakage inductance on voltage gain, and deduces voltage and current stresses of components. Finally, a prototype rated at 400 W has been established, and experimental results verify correctness of the above theoretical analysis.

A family of dc-dc converters based on impedance source dc-dc converters is presented. The scheme of the proposed family is that the switch of impedance source dc-dc converters is moved forward. The derived topologies are suitable for high-voltage step-up ratio. Compared to the typical impedance source dc-dc converters, the presented topology dramatically reduces the voltage stresses on the power semiconductor devices. In addition, the passive lossless clamped circuit is introduced into the proposed family to restrict the peak voltage of the main switch. This paper presents an analysis of the converter and results from a prototype converter to validate the topology's performance.

Aiming at the problems of large switching loss and large output power fluctuation in the existing omnidirectional wireless power transfer (OWPT) system, a novel OWPT system with zero-switching-loss inverter and cylindrical transmitter coil is proposed. By introducing an auxiliary resonant network with simple structure and low-loss on each phase arm of the three-phase inverter, zero-voltage switching turn- on and zero-current switching turn- off within the full power range can be acquired. The switching loss in the main circuit of inverter is reliably eliminated. The transmitter coil is a cylindrical coil composed of the three curved rectangular coils, whose excitation current amplitude is equal and the phase difference is 120°. It can arise a spatial rotating magnetic field around the transmitter coil and provide an omnidirectional energy transmission channel. The operating principle of soft-switching is analyzed in detail, and the design rules of soft-switching in full power range and the parameter design method of coupler to reduce the fluctuation of output power are given. Ultimately, an experimental prototype is used to verify the feasibility of the proposed OWPT system. The experimental results indicate that the system output power is retained at 93.4–104.7 W and transfer efficiency is retained at 71.2%–78.1% under arbitrary angular misalignment of receiver.