Applied Mechanics and Materials Vols. 644-650

Abstract: In dual three-level converter system, the rectifier and inverter have unified problems of the neutral point potential imbalance.This paper analyzed the reasons of imbalance of neutral point potential in detail and summarized the relationship between vector status and four-quadrant status of three-level converters.Then a method based on fuzzy logic control (FLC) is proposed,which could be automatically adjust the balance factor.Combined the balance factor with the status of the converter the duration of positive and negative small vectors action could be obtained.Finally the balance of the neutral point potential is achieved.This method could be generally used on rectifier and inverter.At last, the simulation was done on both inverter and rectifier side.The results verified the feasibility of the proposed method.

Abstract: Under the effects of remanent magnetization, total magnetization direction is different from geomagnetic field direction, which makes magnetic data processing and interpretation complexity. In this paper, we present a new approach for estimating the total magnetization direction of sources via cross-correlation between the reduced-to-pole anomaly and the normalized source strength (who is less sensitive to remanent magnetization). The geomagnetic field direction is used to calculated the normalized source strength, while various assumed total magnetization directions are used to calculated the RTP anomalies. The maximum correlation between the RTP anomalies and the normalized corresponds to the estimated total magnetization direction. Test on synthetic data showed that the new approach is simple and effective.

Abstract: A second-order single bit Sigma - Delta modulator which can be applied to pressure sensor is designed in this paper.The modulator uses switched-capacitor circuit,and the operational amplifier adopts a differential folded-cascode structure with PMOS tube as input. Optimizes the coefficients at the system level design using Simulink tool. The schematic simulation and analysis is by the tools of Spectre and MATLAB with Global Foundry 0.35um CMOS technology. The modulator with oversampling rate of 256 is designed at the 3.3V power supply. Finally, this paper shows the circuit simulation results of the sigma-delta modulator whose signal-noise rate is 103.9dB and resolution is 16.97bits.

Abstract: As a digital input device, the current LCD writing board is widely used. Taking the MSP4 microcomputer with 16 bits bus and FLASH memory as the core, a high-resolution PCB coordinate positioning system is designed and fabricated. The simple handwriting input device is fabricated with the PCB common copper clad laminate of 10*15cm. Due to its material, such input device can form a small resistance array, so it will involve a problem about how to select the measurement methods of the small resistance. Through many repeat tests of various experimental schemes and the high-precision A/D sampling, the voltage signal transmit from the resistance through the instrument transporting and filtering is indicated on the LCD12864. And through certain approximate algorithm and data processing, the contact coordinates of the digitizer pen can be indicated in real time, and you can also draw simple graphics through the system. In addition, the system is characterized by high resolution and low power consumption.

Abstract: It studies the impacts of the wind speed disturbance such as the gradient wind and gust on the active power, reactive power and voltage of the system. In the process of wind speed disturbance, double fed wind turbine increases or reduces the reactive output of wind turbine timely according to the changes of system voltage, ensure the machine terminal voltage to operate in the normal range .

Abstract: First, a certain type of ship azimuth servo system as an example, mathematical model with friction is established, then using LADRC to estimate and compensate the friction disturbance, greatly inhibit the effects of these disturbances on the servo system. The simulation results show that the method of ADRC can greatly improves system capacity and anti-friction disturbance.

Abstract: Aimed at rejecting the bad effect of friction for Ship-borne Servo Control System, the position loop ADRC(LADRC) is designed. The simulation results show that the method of ADRC active immunity, which greatly improves system capacity and anti-friction disturbance which has tracking accuracy and fast response, simple parameter adjustment, can get good control performance for a certain type of ship control servo system.

Abstract: This paper mainly analyses, improvement and experiment using the device of Wuhan Hua gong Electric Automation Co., Ltd. existing. As a comparison, this paper firstly analyzes the measuring principle of electromagnetic current transformer and the saturation problem, coil measurement principle and error, a brief summary of the distinction between the two. One time, two times of converter and the merging unit as part of electronic current transformer, this paper also made some analysis. Then analyzed some improvement of transformer differential protection of electronic current transformer based on improved. Firstly, the hardware protection data interface part of, through the analysis of the reasonable selection, then it is based on transformer differential protection of electronic current transformer, the two line ratio braking curve formulation through the analysis of unbalanced current sources, make do with electromagnetic current transformer current unbalance and the ratio braking curve based on the comparative analysis. Finally, the relay protection software the program is changed the basic function of the device is tested, the test results showed that the improved protection device.

Abstract: Because the shortcoming of the traditional Boost-ZVT has large shutdown losses for the auxiliary switch on hard-working, the circuit has disadvantage of low efficiency. The paper discusses a new Boost-ZVT circuit, and the new circuit designs the absorption circuit in the auxiliary switch circuit to achieve soft turn-off. Compared to ordinary Boost-ZVT circuit, all the switches work in a state of soft-switching for an improved Boost-ZVT circuit. So the new Boost-ZVT circuit can improve the efficiency of the system, at the same time it can eliminate the interference because of switch temperature rising, and can ensure the reliability of the whole system. Finally, the paper builds circuit model and make simulation based on PSPICE, and the simulation results show that the theoretical analysis is correct.

Abstract: The conventional detection technology can not accurately determine the casing damage point and the corresponding physical condition. So it is difficult to determine the working solution. This paper introduces a logging tool which uses the C8051F040 as the main control chip controlling the CMOS cameras for image acquisition and the 2G high-capacity FLASH as the storage for the image information. The scheme has been proved feasible and the obtained image is direct and clear. It has great significance for the maintenance of casing well and the salvage of the objects.