Papers by Keyword: Loss

Abstract: The influence of the recovery characteristics on the switching behavior of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) with different switching speeds was investigated. A comparative analysis of the devices with different recovery characteristics revealed an increase in the turn-on loss (E_on) owing to the higher output capacitance charge (Q_oss) and reverse recovery charge (Q_rr) in the recovery arm. On the other hand, a higher Q_oss in the recovery arm resulted in a lower turn-off loss (E_off). In addition, an increase in Q_oss and Q_rr further influenced E_on and E_off at a higher switching speed. Furthermore, a higher Q_rr observed at a higher switching speed indicated a more significant impact of Q_rr on E_on at a high switching speed than that of Q_oss. The findings clarified in this study highlight the necessity of focusing the recovery characteristics to ensure a desirable switching loss of SiC MOSFETs.

Abstract: Minimizing energy consumption in the processing of parts on metal-cutting equipment is most effective at the stage of designing the content of operations. Important in this process is the precise determination of the initial parameters - cutting forces. This parameter allows you to plan both energy consumption and perform additional calculations for the deformation of the tooling and workpiece in order to predict the geometric accuracy of the machined part. The article presents the results of experiments on measuring the circumferential cutting force during milling operations of an aluminum alloy workpiece with an end mill. The measurements were carried out by an indirect method - by recording the electrical power on the spindle and then calculating the circumferential cutting force. Theoretical analysis of the methods of calculation of cutting forces showed significant differences between the results obtained by domestic methods and recommendations of world manufacturers of cutting tools. Statistical analysis of the results of calculations based on reference data and measurements made it possible to assess the adequacy of the known methods for calculating cutting forces in order to minimize energy consumption in operations of processing parts on metal-cutting equipment

Abstract: Taking the area within 10 km along Beijing section of Jingcheng expressway as study area, this paper calculates the area changes and conversions of landuse types based on the land use map derived from TM images of 1995, 2004 and 2009, and analyze the variation of ecosystem services value of landuse types. The following results are gotten:(1) the construction of the expressway hadadramatic influence to the land use types along and the agricultural structure change obviously; (2) The total value is 20.77×10⁸Yuan in 1995, and increased to 20.96×10⁸ Yuan in 2004, then decreased to20.78×10⁸ Yuan in 2009; (3)The reduction of cultivated land and the increase of construction land were the most important reason for the loss of the ecosystem services value, but because of the increase of garden plot, the total ecosystem services value was stable and increased a littlefrom 1995 to 2009.

Abstract: In order to increase the cost and material conditions as little as possible for improving the efficiency of the motor, and reduce the losses of the motor. This paper have YE3-132S-6X3 super-efficient motor loss analysis first. According to the characteristics of its loss analysis, this paper change the motor slot coordination, and through the finite element analysis, further has carried on the design of slot type and winding. Finally, in order to further reduce iron loss, this paper uses the new type of silicon steel, and then by comparing with the finite element analysis and experimental tests found YE3-132S-6X3 motor efficiency have achieved the purpose of the ultra-super efficient, and other performance parameters can also meet the requirements.

Abstract: Considering the requirement of Shenzhen power grid development, this paper investigates the parameters selection for 220/20kV gas insulation transformer, including capacity, short circuit impedance, cooling mode, insulation level, over-load capability, temperature rise tolerance, loss , noise level and bushing selection. For different capacity value, the investment and loss concerning substation, 220kV grid and 20kV grid are analyzed and compared, by which the final capacity value is determined. The short circuit current level, transformer loss, manufacturing capability and investment is investigated to determine the short circuit impedance for the gas insulation transformer. The characteristic and application condition of gas cooling as well as liquid cooling mode is studied and the cooling mode for the gas insulation transformer is determined. The insulation level, overload capability and temperature rise tolerance are determined by considering related standards and the requirement of Shenzhen. The loss and noise level for the gas insulation transformer is determined by considering related standard and parameters of the domestic gas insulation transformers in operation. The gas-gas bushing is used to connect cable box and the transformer.

Abstract: The paper describes the results of analytical investigation on the application of vane-turbine in the propeller slipstream. The vane-turbine is attached on single-and twin-screw ships with total number of investigated ships are 20. Performance of the turbine was analyzed by actuator disc method. The effect of vane-turbine on ship performance is investigated. Discussions are focused on two main topics, namely speed loss and power efficiency gain. Final result finds out that the ratio of the thrust-power producing by vane turbine and thrust-power producing by propeller will influence the efficiency gain.

Abstract: Problems of power quality have been increasingly concerned by the researchers, as the domestic appliances we are usually used are single-phase load, which mainly causes the unbalance of three-phase voltage of power supply. If the induction motor is supplied by three-phase unbalanced voltage, the currents, active and reactive power, efficiency, and losses are affected as the negative-sequence current appears, this paper is emphasized on the induction motor’s characteristics when its’ power supply is three-phase unbalanced voltage by experimental research.

Abstract: Based on the object-oriented programming of MATLAB, we developed a software for visualization and manipulation to indicate whether the transformer works in the economic range. This software can show the curve of relationship between efficiency and load rate, automatically calculate the load range of the transformer to achieve the best efficiency according to the load. Based on the user supplied data, it can also calculate the operation efficiency of the transformer, and show in the graphic. This software has the advantages of efficiency, accuracy and visualization.

Abstract: The losses of the off-axis rotary optical fiber communication system were derived from optical fiber coupling, three kinds of misalignments between optical fiber collimators (Axial separation Z₀, lateral offset X₀, angular tilting θ), incomplete alignment of optical fiber collimator during rotation and system tremble caused by high speed rotating. Some measures were taken to reduce the loss. The thermally expanded core fiber collimator cut down the influence of axial separation and angular tilting. The position of the optical fiber collimator on the flange was adjusted and infrared right angle prisms were installed to reduce the losses during rotation of the system. In addition, improving the precision and optimizing device of mechanical structure can increase the stability of the whole experiment platform and decrease the losses.

Abstract: In order to research the working status of the field-modulated asynchronous magnetic coupling under loading condition, the electromagnetism characteristics such as the distributions of induced current, torque and loss were obtained by using the ANSOFT software to carry on the transient analysis. The results show that the induced current in the whole of magnetic coupling is not evenly distributed. The induced current of copper is maximum, followed by the ferromagnetic pole-pieces. The highest induced current density is in the outside boundary of the copper layer so that the skin effect of current is verified. The current density and loss increases with increasing of the workload, while the torque increases firstly and then decreases with increasing of the workload. When the slip ratio exceeds 12%, the coupling appear skid phenomenon because the loads is greater than the maximum load which the coupling can bear.