A practical analytical model to calculate the switching loss of cascode gallium nitride high electron mobility transistors(GaN HEMTs)is *** facilitate analysis and application,the transmission delays introduced by Si ...
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A practical analytical model to calculate the switching loss of cascode gallium nitride high electron mobility transistors(GaN HEMTs)is *** facilitate analysis and application,the transmission delays introduced by Si MOSFET and interconnection inductances are ignored in ***,the nonlinear junction capacitances of the device and circuit stray inductances are also incorporated to increase the accuracy of the *** turn-on and turn-off switching processes are described in detail and the simplified equations can be easily solved by using mathematical *** on the analytical model,loss evaluation of totem-pole PFC converter is introduced ***,the accuracy of the model is validated by comparing the calculated loss and converter’s efficiency with experiment *** efficiency of 99.26%is achieved for a 3.6 kW single phase CCM Totem-Pole PFC AC/DC converter switching at 50 kHz based on 650 V cascode GaN HEMTs.
The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power ...
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The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power plant(CCPP).A linear re-dispatch strategy is introduced to compensate the wind power deviation from the spot *** robust optimization technique is employed to obtain a reliable commitment plan against all realizations of wind power within the uncertainty set given by probabilistic *** proposed model is validated with IEEE 39-bus *** advantages of flexible CCPPs are compared to the normal coal-fueled plants and the impacts of robustness controlling are discussed.
A set of four in-vessel saddle coils was designed to generate a helical field on the J- TEXT tokamak to study the influences of the external perturbation field on plasma. The coils are fed with alternating current up ...
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A set of four in-vessel saddle coils was designed to generate a helical field on the J- TEXT tokamak to study the influences of the external perturbation field on plasma. The coils are fed with alternating current up to 10 kA at frequency up to 10 kHz. Due to the special structure, complex thermal environment and limited space in the vacuum chamber, Jt is very important to make sure that the coils will not be damaged when undergoing the huge electromagnetic forces in the strong toroidal field, and that their temperatures don＇t rise too much and destroy the in- sulation. A 3D finite element model is developed in this paper using the ANSYS code, stresses are analyzed to find the worst condition, and a mounting method is then established. The results of the stress and modal analyses show that the mounting method meets the strength requirements. Finally, a thermal analysis is performed to study the cooling process and the temperature distribution of the coils.
Nonlinear magnetohydrodynamic（MHD） simulations of an equilibrium on the J-TEXT tokamak with applied resonant magnetic perturbations（RMPs） are performed with NIMROD（non-ideal MHD with rotation,open discussion）.Nu...
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Nonlinear magnetohydrodynamic（MHD） simulations of an equilibrium on the J-TEXT tokamak with applied resonant magnetic perturbations（RMPs） are performed with NIMROD（non-ideal MHD with rotation,open discussion）.Numerical simulation of plasma response to RMPs has been developed to investigate magnetic topology,plasma density and rotation *** results indicate that the pure applied RMPs can stimulate 2/1 mode as well as 3/1 mode by the toroidal mode coupling,and finally change density profile by particle *** the same time,plasma rotation plays an important role during the entire evolution process.
Plasma equilibrium has been calculated using an analytical method. The plasma profiles of the current density, safety factor, pressure and magnetic surface function are obtained. The analytical solution of the Grad–S...
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Plasma equilibrium has been calculated using an analytical method. The plasma profiles of the current density, safety factor, pressure and magnetic surface function are obtained. The analytical solution of the Grad–Shafranov（GS） equation is obtained by the variable separation method and compared with the computed results of the equilibrium fitting code EFIT.
Commutation failure is one of the most common failures that may lead to serious consequences in high-voltage direct current (HVdc) systems. Superconducting fault current limiters (SFCLs) have been proved effective to ...
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An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is ...
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An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 10^17m^-3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 10^17m^-3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain （FDTD） method also. All results are compatible both of theoretical analysis and experimental measurement.
Minimum energy storage(ES)and spinning reserve(SR)for day-ahead power system scheduling with high wind power penetration is significant for system operations.A chance-constrained energy storage optimization model base...
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Minimum energy storage(ES)and spinning reserve(SR)for day-ahead power system scheduling with high wind power penetration is significant for system operations.A chance-constrained energy storage optimization model based on unit commitment and considering the stochastic nature of both the wind power and load demand is *** solve this proposed chance-constrained model,it is first converted into a deterministic-constrained model using p-efficient point theory.A single stochastic net load variable is developed to represent the stochastic characteristics of both the wind power and load demand for convenient use with the p-efficient point theory.A probability distribution function for netload forecast error is obtained via the Kernel estimation *** proposed model is applied to a wind-thermal-storage combined power system.A set of extreme scenarios is chosen to validate the effectiveness of the proposed model and *** results indicate that the scheduled energy storage can effectively compensate for the net load forecast error,and the increasing wind power penetration does not necessarily require a linear increase in energy storage.
Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic *** pape...
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Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic *** paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range(CTR)and output ***,the structure with two sets of windings and the operation principle of the proposed slotted LATM is ***,a brief design procedure is presented,the structure selections of open slot and double-stator single-rotor(DSSR)interior rotor with surface mounted quasi-Halbach permanent magnet(PM)array are illustrated,and the geometric parameters are optimized to obtain the optimal design of the proposed slotted ***,3-D finite-element method(FEM)is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque,no-load back EMF,and output torque,and the results show that the proposed LATM with quasi-Halbach array has a 10%improvement in output torque and a 25%improvement in ***,the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic ***,prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.
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