Wireless Charger Design of Robot Vacuum Cleaners with Power Repeaters for High Compatibility

Curved coils constructed by flexible printed circuit board (PCB) or hand-wound Litz-wire have been steadily becoming popular due to its applicable potential on devices that have a curved body. Inductive Power Transfer (IPT) systems based on curved coils and flexible ferrite sheets may provide more flexible charging solutions for various electronic devices such as rice cookers and robot vacuum cleaners. Power repeaters are also used in IPT systems to extend wireless charging range by guiding magnetic fields to the receiving coil. The interaction of these three topics could be inspiring. In this paper, two adjustable power repeaters are applied to an IPT charging system with various curved receiving coils designed for vacuum cleaners. Two power repeaters share the identical structure as the Tx coil and could be rotated to mirror symmetrically. The input and output power are calculated by analyzing the equivalent circuit model. The self-inductance, mutual inductance, and coupling coefficient of the proposed system are obtained via finite element method simulation with variable rotating angles. Three typical IPT designs have also been simulated in ANSYS Maxwell and compared with the proposed magnetic design. The comparison indicates the enhancing feature of the passive power repeaters on coupling performance and the ability to guide the magnetic flux for better magnetic field coupling. Furthermore, two types of co-simulations defined by the power source via Simplorer are conducted to explore how much power could be transferred. The tuned system is shown to be able to provide about 32 W under 100 kHz operating frequency for charging the battery of a robot vacuum cleaner. The results from theoretical calculation and simulation align well with each other.

Investigation of ellipticity and pump power in a passively mode-locked fiber laser using the nonlinear polarization rotation technique

An elliptical initial polarization state is essential for generating mode-locked pulses using the nonlinear polarization rotation technique. In this work, the relationship between the ellipticity ranges capable of maintaining mode-locked operation against different pump power levels is investigated. An increasing pump power, in conjunction with minor adjustments to the polarization controller＇s quarter waveplate, results in a wider ellipticity range that can accommodate mode-locked operation. Other parameters such as noise, pulsewidth, and average output power are also observed to vary as the ellipticity changes.

High peak power laser-diode-pumped passively Q=switched Nd:YVO_4/Cr^(4+):YAG laser

In this paper, we report a high peak power passively Q-switched laser-diode-end-pumped Nd:YVO_4/Cr^(4+):YAG laser polarized along the C axis, generating 4.23-W average power and 18-kW peak power (144-μJ pulse power) with 8.0-ns time duration (29.4-kHz repetition rate) at 1064 nm while the pump power is 21.2 W.

An ultra-broadband distributed passive gate-pumped mixer in 0.18μm CMOS

A broadband distributed passive gate-pumped mixer（DPGM） using standard 0.18μm CMOS technology is presented.By employing distributed topology,the mixer can operate at a wide frequency range.In addition,a fourth-order low pass filter is applied to improve the port-to-port isolation.This paper also analyzes the impedance match and conversion loss of the mixer,which consumes zero dc power and exhibits a measured conversion loss of 9.4—17 dB from 3 to 40 GHz with a compact size of 0.78 mm^2.The input referred 1 dB compression point is higher than 4 dBm at a fixed IF frequency of 500 MHz and RF frequency of 23 GHz,and the measured RF-to-LO, RF-to-IF and LO-to-IF isolations are better than 21,38 and 45 dB,respectively.The mixer is suitable for WLAN, UWB,Wi-Max,automotive radar systems and other millimeter-wave radio applications.