A new family of zero current and zero voltage switching pulse width modulation converters

A new family of zero current and zero voltage switching (ZC ZVS) pulse width modulation (PWM) converters was proposed, based on a new ZC ZVS PWM switch cell. The main switches operate at ZCS on and off, the auxiliary switches operate at ZVS on and off, and the passive semi conductor devices in the ZC ZVS converters operate at ZCS on and off. In addition to operating at constant frequency and reducing commutation losses, the new converters have no additional current stress or conduct loss in the main switch in comparison to hard switching converters. The principle of the new ZC ZVS PWM Boost converter was analyzed. The simulation results of the ZC ZVS PWM converter are provided to verify the performance of the new ZC ZVS PWM converters.     

Topology Analysis of Phase-shifted Full-bridge Soft-switching Converter

Phase-shifted full-bridge(FB) soft-switching converters are developing form the basic phase-shifted FB-ZVS-PWM converter to phase-shifted FB-ZVZCS-PWM converter and phase-shifted FB-ZCS-PWM converter,to a series of the other new phase-shifted full-bridge circuits,which make up of the converters with developmental and useful foreground.The topology structures,operation characteristics,as well as their merits and demerits are compared and analyzed.The improved phase-shifted FB-ZVS-PWM converter enlarge the load range of ZVS in lag-arm.Phase-shifted FB-ZVZCS-PWM converter solves the problem mentioned above,and insulated gate bipolar transistor(IGBT) is fit for the lag-arm.Phase-shifted FB-ZCS-PWM converter could achieve ZCS in every power tube,and is used in high-power occasion.What's more,the developmental trend of soft-switching converting technic without resonance network is pointed out.     

Analysis,Modeling and Simulation of the Phase shift Full Bridge Zero-Voltage-Switched PWM Converter

Based on the analysis of the phase shift Full Bridge Zero Voltage Switched PWM Converter(FB ZVS PWM converter),a smal signal model is derived,and simulation results of frequency domain and time domain are given.[WT5HZ]     

Three-Effect Catalytic Converter of Vehicle Exhaust and the Latest Development

How to control exhaust of vehicle has become a hot topic in China. In the system of out engine's purification, a three-effect catalytic converter should be the preferential technique undoubtedly because of its maturation and reliability. All new Chinese cars have been now installed a three effect catalytic converter which is imported. However it is not able to hold up a national automobile industry. China should seek its own three effect catalytic converter to fit the specific situation. This paper expounds harm of the exhaust, configuration, catalytic theory, manufacturing processes, deactivation mechanism and others like that on the converter. Particularly, it discuses its demands and some approaches to satisfy ones. Out of that, how China should develop a catalytic converter is indicated which is suitable for the present situation.     

The modeling and simulation of a new USBCAN bus converter in Stateflow

The USBCAN bus converter is a connector of USB bus and CAN bus.It is difficult to judge whether the device works well or not and meets design requirement or not by ordinary ways.Regarded the Matlab/Simulink/Stateflow toolbox as the platform,the model of a USBCAN bus converter is established.The model of the bus converter is tested and verified in the Matlab/Simulink simulation environment.The results of the simulation analysis show the model is suitable for simulating the working state of the device.A new simulation and judging method for bus converters is proposed.     

Simplified Big-Signal Model of Three-Phase Boost Six-Switch Rectifiers

A reduced-order big-signal model of three-phase pulse-width-modulation (PWM) rectifiers is proposed. The analysis and design of the three-phase boost Power Factor Correction (PFC) circuit is far more complex than the dc-to-dc converter, in that the coefficient of the state equation are time-variant. Although they become constants when in steady state in d-q frame, it is difficult to design due to the couple of the d- and q-channel. By combination of the topology transformation and Tellegen's theorem, the mains can be simplified to a boost dc-to-dc converter, thus reduce the mains' order to two, and the parameter of the simplified circuit is deduced. The proposed model can also be linearized to obtain the small-signal model. The small-signal model greatly simplifies the system design, therefore the traditional trial-and-error procedure is deserted. The contrast simulation results indicate that the simplified model can represent the low-frequency big-signal dynamic behavior of the six-switch three-phase PFC circuit.     

Fuzzy Control and Simulation of Regulating System for Permanent Magnet Synchronous Motor

This paper researches the fuzzy control and simulation of regulating system for PMSM in electrical vehicle. The mathematics model is set up.The PMSM,the PMSM measures demux, dq to abc converter and the three phrase PWM converter models are set up in MATLAB/ Simulink. The fuzzy controller is designed with two dimension fuzzy design method, and take E and EC as input variable, U is the output variable. According to the controller and models, the fuzzy control model of regulating system for PMSM is created in matlab/simulink. At last, to test the accuracy of the control method with the simulation result.     

谷物冷却机复冷降温储粮生产性试验报告

对上年用谷物冷却机处理后密闭储藏的粮食，在不揭膜的情况下进行了谷物冷却降低粮温的试验。同时，对变频与非变频谷冷机的能耗、白天开机与夜间开机的能耗等经济指标进行了探讨，对合理利用谷冷机、节 约能耗，提高冷通效果提供科学依据。     

改进二次型Boost变换器的研究与分析

传统二次型Boost变换器具有较高的升压能力,但其开关器件的电压、电流应力较大,增加了电路的体积与成本。笔者在传统二次型Boost变换器的基础上,结合高增益Boost三端网络,提出改进二次型Boost变换器,并对其连续工作模式下的工作原理及各开关器件的电压、电流应力进行了分析。分析结果表明,改进二次型Boost变换器不仅升压能力有所提升,而且在输出电压相同的情况下,开关器件的电压、电流应力有所降低。最后,通过仿真分析验证了该变换器的正确性和可行性。     

BOF-caster matching model in steelmaking plant of all plate and strip using precision design principle

Using precise design principle, a multi-objective programming mathematical model of the BOF-Caster matched is established for single production line in the steelmaking plant of all plate and strip, according to the segmentation of steel grade and product specification of product mix. Objectives of the model have less investment, less difference between production capacity of the converter and continuous caster, higher operating rate of converter and higher level of weighted average casting speed. The model is solved by the improved delaminating sequence method. Then, the overall configuration method of BOF-continuous casting in the steelmaking plant is proposed through integrating single production lines. According to the production outline of a new large steel plant, the result of the model shows that the configuration scheme of the steelmaking workshop of the steel plant is a better design scheme.     

Research on a Novel Inverter of VSC

In order to improve waveform performance of light HVDC system, a lot of switches which operate in high frequency are used, which causes large switching losses and results high cost. A new Buck type voltage source converter(BVSC) is proposed. The new BVSC comprises a dual-buck converter and a three-phase inverter operating in grid frequency. Only two high frequency switches are used, which results good output waveform performance. In order to reduce the high frequency switching losses, a novel improved double-frequency Buck type voltage source converter(DBVSC) is also proposed. An additional dual-Buck converter is added to the BVSC, the added dual-Buck converter deals with the fundamental power that operates in low frequency, and BVSC only deals with harmonic power that operates in high frequency. The output waveform is enhanced and the switching losses are reduced in DBVSC, and the power rating is also increased. The DBVSC is very suitable for large power rating application. The one cycle control theory is adopted to control the proposed DBVSC with analog circuit, which is very simple. The proposed DBVSC and control method are verified by simulation.     

Application of Hydraulic Torque Converter Incorporated in Mechanical Continuously Variable Transmission

Continuously Variable Transmission which is the ideal transmission for automobile can improve dynamical and economical performance and reduce pollution emission effectively. Vehicle equipped with CVT where hydraulic torque converter is acted as start clutch have better acceleration performance and its starting control is very simple. Based on performance test of hydraulic torque converter and simulation on lock-up dynamic process of torque converter clutch, matching characteristic between engine and torque converter is evaluated , and the lock-up control rule of torque converter clutch and the control strategy of standing start of vehicle equipped with Continuously Variable Transmission with torque converter is proposed. By computer simulation on start process, vehicle equipped with CVT have better acceleration performance than equipped with five-speed MT.     

An asymmetric fault ride-through control method forPMSG wind turbine based onsuper-capacitors

With the rapid increasing interaction between wind turbines and power systems, wind turbines have to have the fault ride-through (FRT) capability to ensure the safe operation of power grid. In order to improve the asymmetric FRT capability of permanent magnet synchronous generator (PMSG) wind turbine, a novel control FRT method based on super-capacitors is proposed. In this method, super-capacitors are connected to the DC bus of AC-DC-AC converter via a bi-directional DC-DC converter, and the power processed by the super-capacitors is controlled to limit the increasing of the DC bus voltage of the AC-DC-AC converter in grid failure condition, and to reduce the 2nd order voltage ripple in the DC bus. Meanwhile, the proposed control method employs the grid voltage feed-forward approach to reduce the negative sequence current component in the grid side converter. According to the low voltage ride through (LVRT) standard, the selection of the super-capacitor capacity is also discussed, and then a mathematical model of the super-capacitor with the bi-directional DC-DC converter is established for designing the controller. Simulation results for a 1MW PMSG wind turbine by MATLAB show that the proposed control method reduces both the negative sequence current component in grid side converter and the 2nd order voltage ripple in DC link at the same time. The results also demonstrate that the asymmetric FRT capability of PMSG wind turbine is improved, which verifies the effectiveness of the proposed control method in this paper.     

Dual mode AC DC AC converter for contactless power transfer system

A new type AC DC AC converter which can work in Buck or Boost mode is proposed in order to overcome the deficiencies of the primary circuit of the traditional contactless power transfer system. Through switching this two modes and turning the duty cycles of the switches, not only the resonant current amplitude of the primary resonant current can be controlled to be constant against a wide range variation of input voltage, but also the problems, such as surge current, high cost, complex control etc., caused by the DC filter and DC/DC converter in a traditional CPT system are effectively eliminated. The topology and operation principle of the proposed converter have been analyzed. The corresponding control strategy has been presented and verified by simulation results.     

插电式混合动力汽车能量管理策略研究现状和发展趋势

目前国内外学者对插电式混合动力汽车能量管理策略进行了较为广泛和深入的研究，取得了良好的节能减排效果，为进一步提升其性能，有必要对插电式混合动力汽车能量管理策略的研究现状进行总结并对其发展趋势进行分析。首先对插电式混合动力汽车动力源能量流分配方法进行了归纳和分析，指出了当前插电式混合动力汽车能量管理策略两个亟待解决的问题：未考虑发动机冷却液温度和三元催化器温度等温度因素对油耗和排放影响；当前插电式混合动力汽车能量管理策略是以行驶功率需求作为输入，忽略了驾驶室制冷/供暖功率需求。最后提出了计及发动机冷却液温度和三元催化器温度等温度因素的能量管理策略和计及驾驶室制冷/供暖功率需求的能量管理策略两个未来研究方向。     

Integrated Control Strategy for Dual State Continuously Variable Transmission System

Continuously variable transmission (CVT) is the ideal transmission for automobile, it is also one of the most important research items of researchers and automobile companies all over the world. In order to research vehicle with torque converter as starter and metal pushing belt as high speed transmission equipment(dual state CVT system), based on the test data of engine and torque converter, the integrated control strategy for vehicle with dual state CVT system is proposed and integrated control simulation for car with dual state CVT system is finished at the condition of multi mode. The research results provide the theory method of analysing and designing for CVT vehicle.     

THE ERRECT OF HIGH HARMONICS ON THE SELECTION OF THE SIZE OF TRANSFORMER CONDUCTOR

This paper analyses the additional stray losses of transformer winding caused by harmonics,and suggests that the influence of harmonics should be taken into consideration in the selection of the conductor' s size in rectifier transformer and converter transformer design.     

Passive Lossless Forward Converter with Current Double Rectifier

To reset transformer excitation flux reliably,reduce the switching losses and improve influence of EMI noises in high frequency forward converters,several kinds of methods have been proposed,including RCD snubbers,active snubbersand resonant converters,and so on.These methods have many shortages.In consideration of these shortages,this paper puts forward a passive lossless forward converter with current double rectifier(CDR).The circuit does not require an extra switch or additional control circuit,and can resets the transformer excitation flux reliably,and does not include lossy components.So the circuit has higher reliability and higher performance/price ratios than above several kinds of methods. The paper analyzes the frame and operating principle of main circuit in detail.The key parameters design principles of the circuit are given.The simulation results confirm validity of the theoretical analysis results.     

Testing Study on Hydraulic Torque Converter for Car

A test bed with computer control for hydraulic torque converter test is built up. The structure and principle of the test bed are introduced. The performance characteristic of torque converter for a CVT car is studied, and the mathematic model of the torque converter is established based on test results, which lays a foundation for the exploitation of automatic transmission car with hydraulic torque converter.     

Changes in nutritive value of alfalfa (Medicago × varia T. Martyn) and Festulolium (Festulolium braunii (K. Richt) A. Camus) under drought stress

Legume–grass mixtures showed a weaker response to adverse environmental conditions than to monocultures. A yield decrease due to the scarcity of water is well documented, while the impact on the food value is inconsistent. Therefore, we undertook studies to assess the impact of water deficit in the soil on the content of the nutrients in alfalfa and Festulolium grown in monoculture and in mixture. A pot experiment was carried out in 2012–2014 in a completely randomized design, with four replications. The research was carried out at two levels of soil moisture: 70% field water capacity FWC (optimal conditions) and 40% FWC (drought stress). We found that the effect of drought stress on the food value of alfalfa and Festulolium was smaller than on the yield. Water deficit caused a significant yield decrease, the biggest in alfalfa in monoculture. Drought stress significantly reduced the content of crude fibre, the contents of crude protein and crude fat tended to increase. The influence of stress on water‐soluble carbohydrates content was not determined. Nutrient content was varied depending on a species. Introducing alfalfa as a component to a mixture with Festulolium caused a significant yield increase and improved the nutritional value of dry matter.