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Control-to-output Transfer Function of the Open-loop Step-up Converter in CCM Operation
Faqiang Wang,Xikui Ma 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5
Based on the average method and the geometrical technique to calculate the average value, the average model of the open-loop step-up converter in CCM operation is established. The DC equilibrium point and corresponding small signal model is derived. The control-to-output transfer function is presented and analyzed. The theoretical analysis and PSIM simulations shows that the control-to-output transfer function includes not only the DC input voltage and the DC duty cycle, but also the two inductors, the two energy-transferring capacitors, the switching frequency and the load. Finally, the hardware circuit is designed, and the circuit experimental results are given to confirm the effectiveness of theoretical derivations and analysis.
Faqiang Wang,Xikui Ma 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6
By using fractional calculus and the circuit-averaging technique, the modeling and analysis of a Buck converter with fractional order inductor and fractional order capacitor in discontinuous conduction mode (DCM) operations is investigated in this study. The equivalent averaged circuit model of the fractional order Buck converter in DCM operations is established. DC analysis is conducted by using the derived DC equivalent circuit model. The transfer functions from the input voltage to the output voltage, the duty cycle to the output voltage, the input impedance, and the output impedance of the fractional order Buck converter in DCM operations are derived from the corresponding AC-equivalent circuit model. Results show that the DC equilibrium point, voltage ratio, and all derived transfer functions of the fractional order Buck converter in DCM operations are affected by the inductor order and/or capacitor order. The fractional order inductor and fractional order capacitor are designed, and PSIM simulations are performed to confirm the correctness of the derivations and theoretical analysis.
Wang, Faqiang,Ma, Xikui The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.6
By using fractional calculus and the circuit-averaging technique, the modeling and analysis of a Buck converter with fractional order inductor and fractional order capacitor in discontinuous conduction mode (DCM) operations is investigated in this study. The equivalent averaged circuit model of the fractional order Buck converter in DCM operations is established. DC analysis is conducted by using the derived DC equivalent circuit model. The transfer functions from the input voltage to the output voltage, the duty cycle to the output voltage, the input impedance, and the output impedance of the fractional order Buck converter in DCM operations are derived from the corresponding AC-equivalent circuit model. Results show that the DC equilibrium point, voltage ratio, and all derived transfer functions of the fractional order Buck converter in DCM operations are affected by the inductor order and/or capacitor order. The fractional order inductor and fractional order capacitor are designed, and PSIM simulations are performed to confirm the correctness of the derivations and theoretical analysis.
Control-to-output Transfer Function of the Open-loop Step-up Converter in CCM Operation
Wang, Faqiang,Ma, Xikui The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5
Based on the average method and the geometrical technique to calculate the average value, the average model of the open-loop step-up converter in CCM operation is established. The DC equilibrium point and corresponding small signal model is derived. The control-to-output transfer function is presented and analyzed. The theoretical analysis and PSIM simulations shows that the control-to-output transfer function includes not only the DC input voltage and the DC duty cycle, but also the two inductors, the two energy-transferring capacitors, the switching frequency and the load. Finally, the hardware circuit is designed, and the circuit experimental results are given to confirm the effectiveness of theoretical derivations and analysis.
Sarah L. Gaffen,Xikui K. Liu,James L. Clements 한국분자세포생물학회 2005 Molecules and cells Vol.20 No.3
IL-17 (IL-17A or CTLA-8) is the founding member of a novel family of inflammatory cytokines, and emerging evidence indicates that it plays a central role in inflammation and autoimmunity. IL-17 is made primarily, if not exclusively by T cells, but relatively little is known about how its expression is regulated. in the present study, we examined the requirements and mechanisms for IL-17 expression in primary mouse lymphocytes. Like many cytokines, IL-17 is induced rapidly in primary T cells after stimulation of the T cell receptor (TCR) through CD3 crossinking. Surprisingly, however, the pattern of regulation of IL-17 is different in mice than in humans, because “costimulation”of T cells through CD28 only mildly enhancedIL-17 expression, whereas levels of IL-2 were dramatically enhanced. Similarly, several other costimulatory molecules such as ICOS, 4-1BB and CD40L exerted only very weak enhancing effects on IL-17 production. In agreement with other reports, IL-23 enhanced CD3-induced IL-17 expression. However, IL-17 production can occur autonomously in T cells, as neither dendritic cells nor IL-23 were necessary for promoting shortterm production of IL-17. Finally, to begin to characterize the TCR-mediated signaling pathway(s) required for IL-17 production, we showed that IL-17 expression is sensitive to cyclosporin-A and MAPK inhibitors, suggesting the involvement of the calcineurin/
HGO and neural network based integral sliding mode control for PMSMs with uncertainty
Ge, Yang,Yang, Lihui,Ma, Xikui The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5
This paper proposes an integral sliding mode control that integrates a high-gain observer (HGO) and a radial basis function neural network (RBFNN) for a permanent magnet synchronous motor (PMSM) with uncertainty. Since the second-order motion equation of the PMSM is used to improve the control performance, the speed derivative, which cannot be measured directly, is required. Thus, the HGO is designed to estimate the unknown state (speed derivative). In addition, the RBFNN is designed to approximate the compounded disturbance including the lumped disturbance of system and the HGO error effect. Unlike previous studies, the output of the RBFNN is compensated by both the controller and the HGO to improve the system robustness and observer accuracy. The sliding function and the HGO error are both taken into account in the RBFNN to explicitly guarantee the stability of the whole system. To demonstrate the superiority of the proposed method, comparative simulations and experiments were carried out in different cases.
Lili Pan,Zihua Chen,Wenxiu De,Guangjie Yang,Xikui Liu 한국고분자학회 2016 Macromolecular Research Vol.24 No.4
The past decades have witnessed significant advance in the synthesis of covalent organic frameworks (COFs), however, their formation and morphology revolution mechanism have been rarely reported. Here, through an acid modulated dynamic covalent chemistry approach, pure and uniform micro-octahedral covalent imine frameworks were obtained for the first time. Formation mechanism based on the stacking of initially formed two-dimensional nanoplates followed by surface smoothing enabled by the dynamic nature of imine bonding was proposed. Furthermore, we revealed for the first time that nonstoichiometric method can be applied to the synthesis of covalent organic frameworks. Thus we provide novel strategy for the morphology control COFs which will surely facilitate their application in energy-related area.