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This paper proposes a transient modeling and analysis method for the fractional-order DC-DC converters in continuous conduction mode (CCM), in which a fractional-order Buck converter is taken as an example. By extending the usage of equivalent small parameter method (ESP), the converter is modeled by a general state vector differential equation. Then by adopting the principle of harmonic balance,...
Based on the dynamic behavior of IGBT and diode, this paper proposed an experimental method for extracting stray inductance of bus bars without high bandwidth current measurement. The experiment is implemented by a double pulse test of the 4.5kV/3000A HVIGBTs. The stray inductance extraction results of several methods were analyzed and compared, verifying the accuracy of the proposed method.
Active gate driving has been shown to provide reduced circuit losses and improved switching waveform quality in power electronic circuits. An integrated active gate driver with 150 ps resolution has previously been shown to offer the expected benefits in GaN-based converters. However, the use of low-voltage, high-speed transistors limits its output voltage range to 5 V, too low for many emerging SiC...
A novel modification of the Z-source circuit breaker topology is presented for low voltage applications. An ultra-fast mechanical switch has been used in place of the solid-state switch (thyristor) in the Z-source circuit breaker to reduce the energy loss utilizing the very low resistance of mechanical contactors. The proposed modification also facilitates bi-directional current flow for distributed...
In this paper, a fully ZVT auxiliary cell for boost type resonant converters is proposed to achieve soft switching in ON-OFF control mode. In conventional ON-OFF methods, transient and switching losses at the beginning and end of each power pulse decrease the overall efficiency of the system at high modulation frequencies. This ZVT cell offers zero voltage switching without imposing extra resonant...
With switching transients as fast as 100 V/ns and a low threshold voltage of 1–2 V, GaN FETs in bridge-leg topologies are potentially vulnerable to crosstalk and the resultant unwanted partial turn-on, noise interference, and increased losses. Constant-strength gate drivers for GaN FETs limit switching speed to suppress crosstalk. In this work, active gate driving is shown to permit faster switching,...
Silicon carbide (SiC) MOSFETs benefiting from the wide bandgap materials offer a significant performance improvement compared with Silicon devices. However, the high switching speed makes the power switching to be a source of EMI. The suppression of the EMI generation can be achieved by shaping the switching transient to an “S-shape”. The active voltage control (AVC) strategy is a feasible method...
Half wavelength AC transmission (HWACT) is a promising technology with unique advantages in the field of large power transmission over long distance. However, there is little study on the grid connection of HWACT, which shall be an important technical point for its engineering application. This paper deals with the point-to-grid connection of an HWACT line. Firstly, the requirements of grid connection...
Non-inverting Buck Boost converters (NIBB) have been utilized as interfacing converters for energy storage, due to the high steady-state efficiency offered by the asynchronous control. However, classical asynchronous control has inherent poor dynamic performance when the input and output voltages are near. To solve the problem, concept of “dynamic mode switching” is first proposed in this paper. Instead...
The paper has presented a new augmented buck converter to improve its transient performance. At first, an augmentation circuit based on diode-capacitor topology is introduced. The voltage across the inductor can be increased during load transients, and the rate of inductor current can be higher compared with conventional buck converters. Then, a hysteresis control algorithm based on output voltage...
This paper proposed switched fractional order controller (SFOC) for grid connected Wind Energy Conversion System. The SFOC consists of conventional PI controller, fractional order IP controller and decision maker. The SFOC controller is applied to control PMSG connected to the grid. The proposed control aims to extract maximum power under fluctuating wind speed. SFOC controller designed to solve the...
The amount of switching operations of unloaded transformers increases with the developments of smart grids and integration of renewable energy sources. A random energization of an unload transformer can cause high amplitude and high frequency inrush currents. Controlled switching can eliminate the inrush currents effectively, the key to realize which is measuring residual flux in transformer core...
This paper is focused on studying a 1200V SiC JFETs cascode device released recently. The gate drive circuit design and switching performance are compared with its counterpart, 1200 V SiC MOSFETs. The research finds out the gate drive circuit design of SiC JFETs cascode is similar to that of SiC MOSFETs. In addition, an optimized gate driver is designed to minimize the device switching loss without...
Vacuum as switching medium has been established widely in the distribution systems for more than 30 years. Well known for its outstanding and reliable interrupting capability of fault and load currents of all possible nature, the vacuum switching technology is now dominating the medium voltage level up to 52 kV. Technical advancements in the field of vacuum physics in last decades made it possible...
High-voltage direct current (HVDC) circuit breaker with rapid fault clearing is an important equipment for protecting DC transmission system. The mechanical vacuum circuit breaker based on artificial current zero (ACZ) is excellent to interrupt the large current. A prototype of mechanical HVDC circuit breaker based on ACZ is simulated by Matlab in this paper. The main circuit breaker and the commutation...
This paper presents the evaluation of a 650 V GaN transistor which is used for a motor drive application. The influence of parasitic effects, e.g. cross conduction and stray inductances, in a GaN phase-leg configuration are analyzed by means of simulation. Additionally, experimental results of the switching transients are shown. Furthermore, measurement issues and other practical challenges are discussed.
This paper discusses the challenges of paralleling dual modules with special focus on the currently introduced dual modules like LinPak, nHPD2, XHP, LV/HV100, etc. Compared with IHM/IHV Modules 3 to 4 times as many modules have to be paralleled to achieve the same output power. Therefore the parallel connection will play a major role in designing high power converters, used e.g. in traction applications...
We propose a MHz-switching-speed current-source gate driver for Silicon-Carbide (SiC) power MOSFETs. The proposed gate driver uses an inductor as a current source during switching transient. Compared with a conventional gate driver, the proposed gate driver reduces switching time ioff and ion by 20% and 32% respectively.
In the paper the approaches how to develop models of electrotechnical objects using the test example of two-winding transformer are discussed. A comparing of the continuous model created using the description of physical processes and discrete macromodel obtained using the “black box” approach based on field experiment are carried out. It is shown that the model obtained using the “black box” approach...
Different from conventional multiphase switched-capacitor (SC) DC-DC converters, the proposed unsymmetrical parallel switched-capacitor (UP-SC) regulator provides more controllable input variables to increase available conversion ratios for improved load regulation. Even under higher conversion ratio numbers, the UP-SC regulator uses the fast searching optimum ratio (FSOR) technique to search the...
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