Numerical Analysis of Magnetic-Shielding Effectiveness for Magnetic Resonant Wireless Power Transfer System

Magnetic radiation phenomena appear inevitably in the magnetic-resonance wireless power transfer （MR-WPT） system, and regarding this problem the magnetic-shielding scheme is applied to improve the electromagnetic performance in engineering. In this study, the shielding effectiveness of a two-coil MR-WPT system for different material shields is analyzed in theory using Moser＇s formula and Schelkunoff＇s formula. On this basis a candidate magnetic-shielding scheme with a double-layer structure is determined, which has better shielding effectiveness and coils coupling coefficient. Finally, some finite element simulation results validate the correctness of the theoretical analysis, and the shielding effectiveness with the double-layer shield in maximum is 30？dB larger than the one with the single-layer case.

Soft switching circuit to improve efficiency of all solid-state Marx modulator for DBDs

For an all solid-state Marx modulator applied in dielectric barrier discharges（DBDs）,hard switching results in a very low efficiency.In this paper,a series resonant soft switching circuit,which series an inductance with DBD capacitor,is proposed to reduce the power loss.The power loss of the all circuit status with hard switching was analyzed,and the maximum power loss occurred during discharging at the rising and falling edges.The power loss of the series resonant soft switching circuit was also presented.A comparative analysis of the two circuits determined that the soft switching circuit greatly reduced power loss.The experimental results also demonstrated that the soft switching circuit improved the power transmission efficiency of an all solid-state Marx modulator for DBDs by up to 3 times.

Comprehensive Review and Analysis of Two-element Resonant Compensation Topologies for Wireless Inductive Power Transfer Systems

Wireless power transfer(WPT)is gaining much attention for battery charging of electric vehicles(EVs).Resonant WPT systems play a crucial role in achieving efficient power transfer from source to load.An overview of two-element resonant compensation techniques and their characteristics under various operating conditions are presented.Also the converter and control strategies used for different topologies are reviewed.The behavior of the performance factors are evaluated against the operating conditions and compared for the different topologies.

A review of high frequency resonant DC-DC power converters:Topologies and planar magnetic technologies

With the development of high frequency resonant DC-DC power converters,the system efficiency,power density and dynamic characteristics have been significantly improved.High frequency resonant DC-DC converters have been applied in DC grid,renewable energy,transportation,aerospace,point-of-load(POL)power supply and many other fields.Under high switching frequencies,switching loss and magnetic loss are the main concerns;thus,the resonant topology and planar magnetic are two key technologies to reduce loss.This review compares different resonant topologies and analyzes the advantages and disadvantages respectively,such as LLC circuit,dual active bridge(DAB)circuit,and other high order resonant circuits.For planar magnetic components,optimal winding structures,modeling methods and integration methods are thoroughly surveyed.With corresponding topics,the opportunities and challenges in the future development are summarized,which mainly focus on the characteristics of wide bandgap devices,such as the dynamic resistance,output capacitance loss and also the integrated module.This review can be a helpful guidance when designing high frequency resonant DC-DC converters.

An efficient continuous-wave YVO_4/Nd:YVO_4/YVO_4 self-Raman laser pumped by a wavelength-locked 878.9 nm laser diode

We report an efficient continuous-wave self-Raman laser at 1176 nm based on a 20-mm-long composite YVO4/Nd：YVO4/YVO4 crystal and pumped by a wavelength-locked 878.9 nm diode laser.A maximum output power of 5.3 W is achieved at a pump power of 26 W,corresponding to an optical conversion efficiency of 20%and a slope efficiency of 21%.The Raman threshold for the diode pump power was only 0.92 W.The results reveal that in-band pumping by a wavelength-locked diode laser significantly enhances output power and efficiency of self-Raman lasers by virtue of improved pump absorption and relieved thermal loading.

A 20 μW 95 dB dynamic range 4th-order Delta-Sigma modulator with novel power efficient operational transconductance amplifier and resonator

A low power high performance Delta-Sigma modulator for portable measurement applications is presented. To reduce power consumption while maintaining high performance, a fully feedforward architecture with a comprehensive system-level design is implemented. As a key building block, a novel power efficient current mirror operational transconductance amplifier (OTA) with a fast-settling less-error switched-capacitor common-mode feedback (SC CMFB) circuit is introduced, and the effects of both gain nonlinearity and 1/f noise of OTA are discussed. A new method to determine the voltage gain of an OTA is also proposed. The bottom terminal parasitic effect of poly-insulator-poly (PIP) capacitors is considered. About an extra 20% of capacitance is added to the total capacitance load. A power and area efficient resonator is adopted to realize a coefficient of 1/90 for 50% power and 75% area reduction compared with conventional designs. The chip is implemented in a low cost 0.35 μm complementary metal oxide semiconductor (CMOS) process. The total power consumption is 20 μW with a 1.5 V supply, and the measured dynamic range (DR) is 95 dB over a 1 kHz bandwidth. Experimental results show that a high figure-of-merit (FOM) is achieved for the designed modulator in comparison with those from the literature.