Applied Mechanics and Materials Vols. 556-562

Abstract: First of all, this article creates the mathematical model of blushless DC Motor. Secondly, analysis the reduction theory of commutation torque ripple. Finally, put forward a strategy to reduce the commutation torque ripple from the low-speed level and high-speed level. This method guarantee equal between current decline rate of shutdown phase and current rising rate of opening phase during commutation, thus keep the current of un-commutation stable. Build a real brushless DC motor control platform for experimental verification, the proposed strategy of brushless DC motor commutation torque ripple is suppressed effectively.

Abstract: Specific to the parameters in the process of three-phase smart meter calibration, such as DC offset, AC offset, AC gain, etc. impact on measurement results, a design of a three-phase smart meter based on CS5463 chips is introduced in this paper. Through theoretical analysis, optimized calibration, and experimental verification, parameters such as voltage, current, active power, reactive power, apparent power, power factor can be measured by the meter. After calibrated, the voltage and current measurement accuracy of the three-phase smart meter can reach above 0.2%. It can meet the needs of the practical application.

Abstract: Adaptive antenna array combines array antenna and adaptive signal processing technology together, and has the capacity of effectively restraining strong interference in airspace. The paper starts from the analysis on formation and array parameters, adopts the electromagnetic calculation software FEKO to make Circular array modeling and simulation, and optimizes the phase values of various array elements via genetic algorithm in the circumstances of taking SIR (signal to interference plus power ratio) and of not taking SIR into consideration separately to achieve the purpose of anti-interference, and the result shows that the optimization taking SIR into consideration results in more powerful anti-interference capacity of Circular array, and conforms to the needs of practical engineering more.

Abstract: The high-capacity lithium batteries are optimization in coal mine backup power supply. Their electricity properties directly affect their related equipment performance. So it is crucial importance for controlling lithium battery charge and discharge and understanding their characteristics. It puts forward design scheme of lithium-ion battery charging and discharging controller with STM32F103 chip. It includes DC/DC adopting full bridge phase shift high power switch, the sampling and processing circuit of voltage, current and temperature, charge and discharge control circuit, and software design flow of the real-time monitoring of lithium-ion batteries. The test shows that the charging and discharging control meet the design requirements.

Abstract: In the absence of a three-phase power source, single-phase operation of three-phase induction motor used single-phase power source had a certain practical significance. In this paper, utilized symmetrical component method analysed the asymmetric circuit system of motor, will be voltage and current of the three-phase stator windings decomposed into positive, negative and zero sequence three groups symmetrical components. The theory is analyzed and the formula is deduced of capacitor phase shift method, solved the problem of starting torque, proposed to add starting capacitors and deduced the optimal value of starting capacitor. Finally, the single-phase operation of three-phase induction motor is simulated and verified by simulation software.

Abstract: Principles of traditional Boost PFC circuit are introduced. Based on average current control, a large signal model is obtained and turned into small signal model carrying constant load. And current regulator and voltage regulator are designed accordingly. Directing at strong non-linear characteristics of the circuit, this paper adopts double average method to analyze its low frequency stability. This converter can achieve high power factor in wide range of input and load power and simulation result shows that power factor is above 0.99.

Abstract: In this paper, the deficiency of the general transient stability constrained OPF model was analyzed,on the basis of which, a multi-objective transient stability constrained OPF model was proposed. The transient stability constraints was to be as a objective function instead of the general constraints,which and power generation cost function were taken weighted sum to be converted into a single-objective optimization model. Multiple optimal solutions under different weights were given based on the original dual interior point method,which can offer a variety of options for operating personnel according to actual needs. In terms of improving the efficiency of the algorithm,The two groups of differentiated rotor equations were eliminated to be one set of equations.And the transient differential equations were dispersed to inequality constraints instead of equality constraints.the dimensions of the correction equation and the scale of the problem solved were significantly reduced. Numerical simulations on the New England 10-generator 39-bus power system, demonstrated the effectiveness and feasibility of the proposed method.

Abstract: Aimed at fatigue damage in the antenna structure caused by large amplitude vibration with long time fluctuating wind loads, this paper use the harmonic synthesis method to transform power spectrum of Davenport fluctuating wind to fluctuating wind speed time series based on time domain. Then comprehensively considering the surface roughness coefficient, wind pressure coefficient of variation with height, wind vibration coefficient in Beijing area ,it transforms the fluctuating wind speed into the fluctuating wind pressure curve, takes the structural dynamics simulation and is obtained the dynamic response of the antenna structure in turbulent wind Loads; By the method of rain-flow counting , the fatigue life is analyzed with the statistics for the dangerous location of the antenna structure coursed of fatigue stress with time.

Abstract: With the rapid development of emerging applications and data transmission rate in LTE (Long Term Evolution) system, terminal power consumption is becoming seriously. In LTE, the discontinuous reception (DRX) mechanism was taken as an important method of saving energy of terminal. Through operations of all sorts of timers, a detailed analysis of the principle of DRX is introduced in this paper. And based on this, adjustable DRX long cycle is proposed. On the basis of the DRX semi-Markov process and ETSI data model, formulas of power saving factor and wake-up delay for adjustable LTE DRX are derived. Then from the comparisons of fixed frame DRX cycle and adjustable DRX cycle in terms of power saving and wake-up delay, we know that this optimizing mechanism has obvious improvement in the reduction of terminal power consumption.

Abstract: With the rapid increase of vehicles, road congestion problem is becoming increasingly serious, the ETC system requirements getting higher and higher, the railings ETC system is difficult to meet the requirements. This article uses the 5.8G RFID technology to gives free-flow ETC system's overall design, front-end design of key equipment of the RSU and OBU. The system operation results show that greatly improved the traffic speed, realize fully free flow, and achieve the design goal of free flow ETC system.