In Dynamic Wireless Power Transfer (DWPT) systems, the power oscillation phenomena caused by coupling fluctuation are always hard to avoid. Moreover, if the adjacent track coils are excited by different inverters without synchronized drive signals, there will be severe power oscillations due to the frequency difference between the track coil currents. To address these issues, this work proposes a novel DWPT system based on dualreceiver coils and the Voltage Doubler (VD) rectifier. Depending on whether the induced voltages of the two receiver coils are balanced, the rectifier will switch between full-bridge mode and VD mode with no extra controller to maintain the system output under different positions. By designing the dimensions of the coupler, the DWPT system can achieve excellent output stability while avoiding the oscillation caused by the frequency difference between the track coil currents. In addition, the operation characteristic, power divisions, and boundary conditions of each operation mode are clarified. Finally, a 2.2 m 220 V-800 W prototype is built. The experimental results show that even with the track current frequency difference, the output voltage fluctuation is limited to 3.4% during motion, and the system efficiency remains above 90.76% in the case of an 8 cm air gap. Index Terms-Dynamic wireless power transfer (DWPT), Power fluctuation suppression, Dual-receiver coils, Voltage doubler rectifier.
I. INTRODUCTIONN recent years, the applications of electric vehicles and automatic guided vehicles have developed rapidly. However, the onboard battery capacity limitation, distance anxiety, and inconvenient charging operations are still roadblocks to the mass acceptance of these vehicles. To solve these issues, Manuscript
Narrow linewidth lasers have important applications in optical communication and sensing. To accurately measure the linewidth, we built a laser linewidth measurement system based on 3×3 coupler. It uses the demodulation algorithm of Differential Cross Multiplication to get the phase noise, and then obtains the linewidth value according to the β-separation line method. At the same time, we introduced wavelet denoising in the signal processing in order to reduce the influence of low frequency noise. Two wavelet bases, db4 and sym11, which were more effective for this system were identified through simulation, and experiments were conducted using a 2 μm band laser. The results prove that the frequency noise power spectral density and linewidth values are reduced after using wavelet denoising.
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