DCM,FSM,dead time and width controllers for a high frequency high efficiency buck DC-DC converter over a wide load range

This paper presents a width controller,a dead time controller,a discontinuous current mode（DCM） controller and a frequency skipping modulation（FSM） controller for a high frequency high efficiency buck DC-DC converter. To improve the efficiency over a wide load range,especially at high switching frequency,the dead time controller and width controller are applied to enhance the high load efficiency,while the DCM controller and FSM controller are proposed to increase the light load efficiency.The proposed DC-DC converter controllers have been designed and fabricated in the Chartered 0.35μm CMOS process,and the measured results show that the efficiency of the buck DC-DC converter is above 80%over a wide load current range from 8 to 570 mA,and the peak efficiency is 86%at 10 MHz switching frequency.

Active disturbance rejection control for hydraulic width control system for rough mill

The highly nonlinear behavior of the system limits the performance of classical linear proportional and integral （PI） controllers used for hot rolling. An active disturbance rejection controller is proposed in this paper to deal with the nonlinear problem of hydraulic servo system in order to preserve last response and small overshoot of control system. The active disturbance rejection （ADR） controller is composed of nonlinear tracking differentiator （TD）, extended state observer （ESO） and nonlinear feedback （NF） law. An example of the hydraulic edger system case study is investigated to show the effectiveness and robustness of the proposed nonlinear controller, especially, in the circumstance of foreign disturbance and working condition variation, compared with classic PI controller.

Technological investigation on the Short Stroke Width Control Rolling in the Rougher Mills of Hot Strip Continuous Rolling Mill Train

According to technological requirement of hot charge rolling and hot direct rolling,in this paper,we investigated the technology of the width control rolling in the rougher mills of hot strip continuous rolling mill train.On the basis of improving width range of continuous casting of slab,we obtained a good result of greatly increasing the yield of slab→coil is achieved.

Synthesis of two-dimensional/one-dimensional heterostructures with tunable width

Two-dimensional/one-dimensional(2D/1D)heterostructures as a new type of heterostructure have been studied for their unusual properties and promising applications in electronic and optoelectronic devices.However,the studies of 2D/1D heterostructures are mainly focused on vertical heterostructures,such as MoS_(2) nanosheet-carbon nanotubes.The research on lateral 2D/1D heterostructures with a tunable width of 1D material is still scarce.In this study,bidirectional flow chemical vapor deposition(CVD)was used to accurately control the width of the WS_(2)/WSe2(WS_(2)/MoS_(2))heterostructures by controlling reacting time.WSe2 and MoS_(2) with different widths were epitaxially grown at the edge of WS_(2),respectively.Optical microscope,atomic force microscope(AFM),and scanning electron microscope(SEM)images show the morphology and width of the heterostructures.These results show that the width of the heterostructures can be as low as 10 nm by using this method.The interface of the heterostructure is clear and smooth,which is suitable for application.This report offers a new method for the growth of 1D nanowires,and lays the foundation for the future study of the physical and chemical properties of 2D/1D lateral heterostructures.

Neuron self-learning PSD control for backside width of weld pool in pulsed GTAW with wire filler

In this paper, the weld pool shape control by intelligent strategy was studied. A neuron self-learning PSD controller for backside width of weld pool in pulsed GTAW with wire filler was designed. The PSD control arithmetic was analyzed, simulating experiment by MATLAB software was done, and the validating experiments on varied heat sink workpiece and varied gap workpiece were successfully implemented. The study results show that the neuron self-learning PSD control method can attain a perfect control effect under different set values and conditions, and is suitable for the welding process with the varied structure and coefficients of control model.

A new dimmer for alternating-current directly driven light-emitting-diode lamp

A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.

Optimization and perfection of the roughing model for ferritic SUS430

Based on the characteristics of ferritic SUS430 heating and deformation,and combined with the features of the 1780 mm hot-rolling mill,a roughing model was introduced in two aspects:optimizing the rough rolling passes and improving the width control precision.Through reducing the rough rolling passes,the rough rolling time can be shortened,the precision rolling startup temperature can be raised and the yield of the hot-rolled products can be increased.Moreover,on the premise that the slab width fluctuation was great,the precision of the width control can be improved through optimizing the parameters of the hot-rolling width control model.The result shows that the optimization and perfection of the original rolling process of the stainless steel 430 series further improved its capacity and product quality.

Optimization of Short Stroke Control Preset for Automatic Width Control of Hot Rolling Mill

Automatic width control is a key issue in hot strip rolling process. The edge rolling has been widely used in the roughing stand of hot strip mill to control the width of the slab. However, the edge rolling and consequent hori- zontal rolling will cause a significant width change in the head part and tail part of the slab, which have to be trimmed before the finishing stands. Based on the width reduction deformation curve of the head and tail along the longitudinal direction of slab, the short stroke control （SSC） technology has been developed to overcome this problem. The finite element method has been used to simulate the unsteady edge rolling process. Three short stroke control curves have been compared in order to obtain the best width control result. The optimized short stroke control curve has been ap- plied to the automatic width control system of industrial hot rolling mill, and good performance is obtained.

A low noise high efficiency buck DC-DC converter with sigma-delta modulation

Some research efforts to improve the efficiency and noise performance of buck DC-DC converters are explored.A carefully designed power MOSFET driver,including a dead time controller,discontinuous current mode（DCM） controller and gate width controller,is proposed to improve efficiency.Instead of PWM modulation, sigma-delta modulation is introduced into the feedback loop of the converter to move out the clock-referred harmonic spike.The proposed converter has been designed and fabricated by a 0.35μm CMOS process.Measured results show that the peak efficiency of the converter can reach 93%and sigma-delta modulation suppresses the harmonic spike by 30 dB over PWM modulation.