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.     

A NEW PWM METHOD-AVERAGE VALUE PWM

In this paper, a new PWM method-average value PWM is presented. This method has been compared with other PWM methods and realized by using a micro - processor-controlled GTR inverter. Some experimental results and discussions for them have been given.     

EQUAL ARA ALGORITHM OF PWW WAVEFORM

This paper presents the equal theory of the sine wave voltage and PWM waveform in the integration of time. Using the graphic method as well as the comparison method of sequential integration the PWM control pattern is calculated. Depending on an example for PWM circuit inverter the microcomputer is investi-gated. The method is simple and effective. It is specially adeguate to the engineering control.     

Realization of Flash Stimulation with PWM in the Extraction of Visual Evoked Potential

Evoked EEG signal can be obtained by flash stimulation in the extraction of flash visual evoked potential(FVEP).Experiments show that the width,frequency and flash times of flash pulses will play key role for extracting FVEP.Aims at the feature of VEP extraction and its correlation factors,the flash stimulation method with pulse width modulation(PWM) technology has been discussed,and the realization methods based on hardware and software are studied,then the output of precise PWM with special integrated circuit is realized.So the parameters of flash stimulation can be adjusted based on the material conditions of FVEP extraction,then VEP can be extracted effectively.Experiments show that it is of better effectiveness for FVEP extraction by using the method based on the output of precise PWM to control the flashing stimulation.     

Zero Current Switching Multi-resonant Converters based on ConstantFrequency PWM and Mutual Inductance Technique

This paper introduces a novel constant frequency switching PWM converter,as well as some improvements on the conventional bridge parallel resonant converters. By introducing mutual inductance and auxiliary into the original circuit topology ,a class of novel zero current switching multi-resonant converters regulated by PWM mode at a fixed switching frequency are presented,which overcomes some drawback of the original circuits.One illustrative example is analyzed and the experimental results are given, which confirms the advantages of this approach.     

A PRACTICAL PWM CONTROL METHOD OF CURRENT SOURCE GTR INVERTER

According to the principle that the orbit of stator current vector in complerplane should be as close to a circle as possible, the PWM control pattern is derived and determined. The control method is realized by using a micro-computer.     

A NEW COMPENSATIVE SNUBBER FOR ELIMINATING THE SURGE AND NOISE IN PWM CONVERTERS

A new compensative snubber is presented for eliminating the surge current and high frequency parasitic oscillation in rectified circuit of the PWM DC-DC converters. The output surge and noise voltages are de-creased over 4/5. The working principle of the sunbber is analyesd in detail, the designing formulas are derived. The theoretic analysis is consistent with the experimental results.     

Soft-switching Analysis Phase-Shifted-FB-ZVS-PWM DC-DC Converter With Saturable Inductor

Compared with the traditional full-bridge(FB)zero-voltage-switched(ZVS) pulsewidth-modulated(PWM) converter, the FB-ZVS-PWM converter with a saturable inductor has a wider load range with ZVS and smaller circulating energy as well as smaller duty cycle loss. By analyzing the operation principle of the converter, this paper studies design considerations of the parameter bringing about ZVS and dead time of the switch, and gives out the design method, finally simulation testing has been carried out.     

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.     

Product Development Method Based on Product Development Domain

Product development is an integrated and interactive process. This paper proposes that there are three domains in the process of product development, i.e. product domain, organization domain and process domain, viewed at three angles of product, organization and process of product development. It is proposed that product domain is the core of these three domains, and then gets interrelations within them. The method of classifying parts and components in product domain is put forward, and the corresponding organization domain and process domain are put forward. The direction of parts and components domain is pointed out. In the end, this paper gives an example applied to the method in a motorcycle enterprise.     

Principal Axis Rotating Speed Control System of Friction Welding Machine

Based-on the new 8-bit microcontroller P89C51RD2 of PHILIPS company,the principal axis rotating speed of friction welding machine is controlled in closed loop by the system. That guarantee the stability of important parameter in friction welding.The design of software and hardware and the principle of the system is introduced detailedly.The output pulse of photo- coder is measured by using catching mode of P89C51RD2' PCA.And the D/A conversion is achieved by PWM pulse wide modulate mode of P89C51RD2' PCA also. With ISP function, the system program can be written or upgraded on-line and with long-distance.The whole circuit formed in module is very concision.The system runs well in practical production.     

Application of digital phase-locked loop and filtering technique in PWM rectifier

VHS-ADC high speed digital signal processing platform based on MATLAB and FPGA could be used to build three-phase voltage source rectifier with space voltage vector PWM(SVPWM).The initial phase of coordinate transformation from three phase static coordinate to two phase static coordinate which is called Park transformation and from two phase rotating reference frame to two phase static coordinate is uncertain. There existed noise in acquiring grid voltage and current. Digital phase-locked loop is added to follow the frequency and phase of grid voltage, FIR filter is added to process signal and reduce the interference. External voltage control loop, internal current control loop and the model of coordinate transformation are designed on the VHS-ADC platform. The small power experiment is conducted to verify the stability and feasibility of the control system. The experimental results show that the digital phase-locked loop and FIR digital filter can be applied to three-phase voltage source rectifier.     

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.     

Automobile anti lock braking system control based on a least squares support vector machine

Using the referenced slip rate and angle acceleration of the wheel as input vectors and the braking pressure as an output vector, an automobile anti lock braking system (ABS) controller based on a least squares support vector machine (LS SVM) was designed. Training the LS SVM controller using the supporting vector, the parameter of the controller was calculated. An anti lock braking system was designed that includes an input layer, a control layer, and an output layer. Using wheel speed as an input, the braking pressure of each wheel was calculated. The pulse width modulation (PWM) method was used to control the braking pressure, and thereby to bring ABS control. An automotive ABS test and control system was constructed. Road tests under different conditions were completed according to international standards. Test results show that an anti lock braking control method based on LS SVM has good braking stability and adaptability. It is an effective new ABS control method.     

A Methodology of Classification of Product Family for Mass Customization

Product family management is a key support technology to implement mass customized production. Various products in product family are similar in functional characters, physical characters and technological characters, which is an important character of product family. Based on the products represents and mapping relations in functional domain and physical domain, a method of classifying product family is presented by comparing similarity of both functional requirements in functional domain and design parameters in physical domain. The process of classifying product family by virtue of this method is also discussed. At last, a case is introduced to illustrate the application of this method.     

山区桥址处CFD计算域的选取方法

山区桥址处风场具有较强的随机性与不确定性,在选取其CFD计算域时,盲目参考已有的工程可能会造成较大的模型误差,或增加大量的计算开销。为解决该问题,提出了山区复杂地形CFD计算域选取的方法与步骤,验证了其准确性。具体方法为：设置一个大范围的基准计算域进行初算,通过后处理软件绘制平均风压系数极差随高度的变化曲线、壁面附近水平面上的静压偏差等值云图以及横风向各平面静压值与对应边界面的均方根差值曲线,分别筛选出基准计算域在高度方向、顺风向及横风向上对整体风场贡献可忽略的区域,余下部分则可用于该区风场的求解。     

冷诱导下毛百合甘油-3-磷酸酰基转移酶活性变化及其基因保守区的克隆

探讨了野生毛百合甘油-3-磷酸酰基转移酶活性在冷胁迫下的变化,用简并引物扩增了甘油-3-磷酸酰基转移酶基因保守区序列的结果表明,该保守区段长744 bp,推测编码247个氨基酸.在GPAT氨基酸序列中存在1个高度保守的区域(WIAPSGGRDRP),在NCBI上经过BLASTp比对分析,发现这段保守区序列为LPLAT基...     

Axial Response of Viscoelastic Pile-soil Coupling Interaction in Three-dimensional Inhomogeneous Soil

Considering the three-dimensional inhomogeneity of soil surrounding the pile, the response of non-uniform viscoelastic pile under axial dynamic loading is studied. Firstly, combining the boundary condition, the complex stiffness of axial different soil layers are obtained by the complex stiffness transfer model of radial multi-zone plane strain. Then, the analytical solution of dynamic response at pile top in frequency domain is proposed by solving the dynamic equation of non-uniform viscoelastic pile section one by one from the bottom up to the top, and the relevant semi-analytical solution response in time domain is adopted by the convolution theorem and the Inverse Fourier Transform. At last, the effect of parameters of pile and soil are investigated to get the nature of the dynamic response of pile top in frequency domain and time domain.     

Comparative study of aircraft three-phase power factor corrections

This paper summarizes the requirements of standards for aircraft power supply firstly,and then points out that the input current harmonic and output DC voltage ripple should be considered seriously when designing three-phase power factor correction (PFC)for aircraft under variable line frequency and unbalanced line supply. Based on reviewing the topologies for aircraft three-phase PFC,three typical topologies,i.e. three-phase pulse width modulation (PWM)rectifier,traditional shunt active power filter (APF)and generalized APF,are picked up. A unified single-phase equivalent model is developed for comparing the harmonic suppression performance of the three active PFC schemes. And the switching stress is also calculated for evaluating their efficiency and power density. Three 5 kW PFC are designed by employing each of the three selected schemes. Simulation is carried out to verify the correctness of the theoretical analysis. The theory and simulation results indicate that the generalized APF topology shows the most technical merit for aircraft three-phase PFC. Future research works on generalized APF are also pointed out,which are solving the uncontrollability of its DC output voltage and optimal designing the filter inductors.     

Mix Domain Decomposition Method with Boundary Element Method For Stokes Equations and Application

As the BEM was used in the knaggy domain,its approach error was big.Domain Decomposition Method change the problem in the knaggy domain to the problem in several convex domains which do not wrap.The whole solution is gained by alternating boundary conditions between Dirichlet condition and Neumann condition on the common boundary.Domain Decomposition Method for Stokes equations in the anomalistic knaggy domain is presented,the example of Domain Decomposition Method in the flow of the lake in GuiYang City is given.