Search

As the main force of new energy generation, photovoltaic power generation is widely used in microgrid. Considering the coordinated operation of photovoltaic and energy storage system (ESS) in the island operation mode, the control strategy of voltage stability and power balance was studied for the low-voltage DC microgrid composed of the distributed generations. When the loads of DC microgrid system change abruptly, the DC bus power will be excessive or deficient, which will affect the stability of bus voltage. In this paper, a parallel structure of ESS and photovoltaic cell was used, and a bidirectional DC/DC converter was used to connect the energy storage battery with the DC bus. Based on RBF neural network tuning PID control, an improved bidirectional DC/DC converter operation mode control algorithm was proposed. When the system load changed suddenly, the voltage stability and power balance of DC bus were realized simultaneously. The effectiveness of the proposed algorithm was verified by simulation.

The traditional communication technology between electric vehicles (EVs) and DC charging piles often causes problems such as low reliability, high cost of communication line and high maintenance cost. The power line communication (PLC) technology is a mature technology and has the advantages of simplifying charging cable, reducing cable cost, which has certain practicability and feasibility. This paper deeply analyzes the channel characteristics, noise characteristics and uses OFDM as transmission method for the PLC signal between EVs and DC charging piles. The bit error rate (BER) is a measure index in this paper, this paper calculates the BER under various working conditions in order to determine the performance of OFDM technology in the power line channel. The simulation results indicate that PLC technology based on OFDM could meet the communication demand between EVs and DC charging piles, which have some certain utilities.

AlGaN/GaN high electron mobility transistors (HEMT) are exposed to 3 MeV protons irradiation. The drain saturation current decreases 20% and the maximum transconductance decreases 5% at a fluence of 1× 1015 protons/cm2. As fluence increases, the thread voltage is shifted toward more positive values. After proton irradiation, the gate leakage current increases. The degradation caused by 1.8 MeV proton is significantly higher than by 3 MeV proton irradiation at the same fluence. The radiation damage area and the density of vacancies at a given depth are obtained from software SRIM. As the energy of the incident proton increases, the non-ionizing energy transferred to the crystal lattice decreases. It is concluded that vacancies introduced by proton irradiation may be the primary reason for the degradations of electrical characteristics of AlGaN/GaN HEMT.

A field emission cathode composed of multiple tungsten pins providing uniform discharge and a Wehnelt cylinder performing focusing and triggering are the new features of this pulsed electron beam source. We have successfully annealed ion-implanted CdTe, Culn S 2 and silicon from their damage states. The activation of p-type CdTe dopants can reach as high as 3 × 10 18 cm −3 .