Applied Mechanics and Materials Vol. 577

Abstract: In this paper, the design and simulation of a photovoltaic (PV) emulator are presented. The output characteristic and I-V curve are produced based on mathematical engineering PV module, so that they are similar to the practical curves. The proposed system consists of a single-phase full-bridge PWM rectifier and a DC/DC buck converter, which can reduce the voltage ripple and improve the power factor near the grid. The rectifier uses double-loop control strategy and the buck circuit uses the formula of the PV module to control output voltage and load current. Using Matlab simulation, the result proves feasibility and good performance of this scheme, and simulation waves can reflect the change of temperature and light intensity.

Abstract: This paper introduces the topology and working principle of modular multilevel converter, simplifying its equivalent circuit before obtaining virtual equipotential. On the ground of the theoretical model of equivalent circuit, MMC-HVDC could adapt the same control strategy as the traditional method. So, on the platform of PSCAD/EMTDC, an eleven level MMC Dual-infeed HVDC system is established and nearest level modulation is adopted as its control strategy to sort voltage sharing of the modules. Experimental results prove the validity of the proposed model.

Abstract: Sideslip angle and yaw rate can reflect the essential characteristics of the vehicle steering motion in steer by wire system, and determine the stability of the vehicle, sideslip angle is generally obtained through observation. In order to enhance the stability of the vehicle, hybrid observation method for side slip angle is used, in which dynamic integration is mainly used when the raw rate is relatively small, and extended kalman filtering is mainly used when the raw rate is large. In the observer design, the value and change rate of raw rate is used to calculate a weight coefficient to determine the proportion of two observation method in the observer. The simulation results show that the method can efficiently decrease the observation error of the side slip and improve the observation accuracy.

Abstract: Optimal controlled islanding strategy searching is a complex combinational optimization problem. Artificial fish swarm algorithm (AFSA) based on the simulation of fish swarm is an intelligent meta-heuristics. In this paper, AFSA is applied to the searching of optimal controlled islanding strategy. In order to minimize the unbalanced power in each island, a mathematic model is established with some constraints. Simulation result on IEEE-39 node system shows that the proposed method can obtain the optimal strategy promptly and has strong global search ability.

Abstract: The accurately mathematical models, simulation models and protection algorithms of high impedance fault (HIF) on transmission lines are difficult problems. Based on the measured data and physical phenomena, a new mathematical model of HIF was presented by numerical analysis methods and MAYR’s equation. Using EMTP, the model of HIF includes a group of nonlinear time-varying resistances and a dynamic arc resistance. Based on the features of HIF under different frequency bands, this paper presents HIF comprehensive detection algorithms containing four algorithms, and analyzes the logic between each algorithm. Finally, the models and algorithms are simulated.

Abstract: An up-conversion mixer has been designed for 0.7-2.6GHz multi-mode and multi-standard RF subsystem working under 1.8V voltage based on TSMC 0.18μm process in this paper. The circuit is based on the use of pseudo-differential structure of the Gilbert cell, and in order to increase the gain and linearity, is using a complementary trans-conductance current bleeding structure. In addition, a T-type LC networks can reduce the effect of the parasitic capacitance of the LO switching pairs, and make the linearity of the high-frequency greatly improved. Simulation results show that the circuit is working at 0.7-2.6GHz, the gain of the up-conversion is 9.5-9.7dB , the IIP3 of the circuit is 11.4-12.2dBm, and NF is 13.1-13.5dBm.

Abstract: This design used a low noise enhanced high electron mobility transistor ATF54143 and Agilent's ADS simulation software to achieve the good performance of operating frequency at 2.45GHz, noise figure (NF) is less than 0.8dB, band gain (S₂₁) is greater than 15dB, input voltage standing-wave ratio (VSWR1) is less than 1.4dB, output voltage standing-wave ratio (VSWR2) is less than 1.6dB.

Abstract: A fully integrated LC VCO with 1V low voltage supply, applied in the frequency synthesizer for wireless sensor network applications, is designed and implemented in TSMC 0.18μm RF/MS CMOS process with low power consumption and good phase noise performance. To conquer the problems brought by low voltage, the structure of VCO is carefully selected. A 4 bit switched capacitor array is used to widen tuning range without worsen the phase noise performance. Besides, a 2 bit switched tail current source array is used to achieve power consumption adapted to the desired operating scenario. Second harmonic filter technology is taken to improve phase noise performance. The VCO designed in this paper has good phase noise performance and low power consumption by optimization. The chip size is 860μm×730μm. Post-simulation results show that the frequency range is between 4.57~6.18GHz with tuning range 30%, the center frequency is 5.375GHz, and the power consumption of VCO core is between 2.6~4mW. At the meanwhile, phase noise is between-116.0~ -117.8dBc@1.0MHz.

Abstract: With the increase of nuclear radiation, soil pollution, water pollution and other man-made pollution, people are increasingly concerned about healthy eating. It gradually becomes a hot spot for scientists to develop a new green planting method. In this context, a design of smart plant growth cabinet based on LED lighting is put forward in this paper. From the analysis of social needs and the user′s analysis, transformation has been made from user requirement to the thinning mapping of product function and performance requirements. The main function and implementation principle of it and the design of the hardware are introduced in detail. This design has simple hardware structure, convenient maintenance, good stability, anti-interference ability and other characteristics. It has broad application prospect and great using value.

Abstract: This paper describes methods to utilize the multi-core PC as well as computers connected by internet to perform MOSFET circuit simulations. The Combining Simulation Method (CSM) is the used parallel algorithm. This paper also presents an automatic method to partition the simulation jobs in CSM. All proposed methods have been implemented and tested. Experimental results justify pleasing effects of proposed methods.