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In this paper, a triple active bridge converter is proposed. The topology is capable of achieving ZVS across the full load range with wide input voltage while minimizing heavy load conduction losses to increase overall efficiency. This topology comprises three full bridges coupled by a three-winding transformer. At light load, by adjusting the phase shift between two input bridges, all switching devices...
Electric power take-off systems in automotives requires the application of low voltage high current step up DC-DC converter with a high voltage gain. Researchers have evaluated enhancements for high efficiency and low cost designs. In this paper, a novel topology is proposed that has the capability of providing a high voltage gain over a wide range of output power. It also has fewer components and...
The 15kV SiC IGBT has second higher dv/dt turn-off slope above the punch-through level resulting in EMI. Increasing gate-resistance also slows the first dv/dt causing increased switching loss. A snubber capacitor assisted turn-off solves these issues for a high power dual active bridge (DAB) converter based on this device, but the light load turn-on ZVS becomes hard to achieve. This paper proposes...
In this paper, a single stage system which converts 400 V to 1 V within one stage and performs as the high voltage point of load (HV POL) converter for data centers is proposed. A load dependent soft switching method has been proposed for half bridge current doubler with simple auxiliary circuit. The operation principles of the soft switching converter have been analyzed in detail. A lossless RCD...
An algorithm based on new circulated current model is proposed to analyze the circulating current in the multiphase LLC converter. First of all, a virtual-open concept is introduced and LLC phases are decoupled from each other, Thus, A circulating current model can be achieved from fundamental harmonic approximation (FHA). Secondly, the ac voltages on the equivalent resistor of different phases are...
Active Power Filters (APFs) are widely applied devices in the power quality field for control flexibility and effective attenuation of the harmonic, reactive and negative components of the grid current and voltage. As the interface connecting an APF with the grid, an LCL-filter is preferred over an L-filter for its smaller size and lower price. However, the LCL-filter is a third-order system and hence...
A decomposed voltage control is proposed to integrate two favorable functions of the 3-ph electric spring (ES) to stabilize the mains voltage and to reduce power imbalance. As compared with its precedent counterpart, the proposed control can expand the usage of the 3-ph ES, simplify the control implementation, and enable the ES to conduct multiple tasks at one time. The decomposition of the 3-ph ES...
The distributed inverters are generally integrated into power grid without switching sequence coordinated control capability since they are equipped with their own micro controllers to command the output quantities. The switching ripples of all distributed inverters will then be randomly accumulated at the point of common coupling. The recently proposed global synchronous pulsewidth modulation (GSPWM)...
This paper proposes a general and an improved methodology for the design of the passive elements of Active Regenerative Rectifiers (ARR). The proposed strategy for the L-filter is based on the current area error in the time domain and on the high order current harmonics in the frequency domain. This strategy is independent of the type of control technique and it can be implemented for different modulation...
A controller is proposed for a medium voltage medium frequency (MVMF) AC collection grid for utility scale Photovoltaic (PV) farms. A new MVMF AC collection grid was presented in previous work. It enhanced the system modularity, increased the system efficiency and reduced the passive component sizes. The MVMF AC collection grid comprises modules of inverter and medium frequency transformer that are...
Current fed multilevel converters have several advantages in terms of high power capability, transformer less operation, short circuit protection and excellent quality of waveforms. For high power applications, these converters are required to be operated under low device switching frequency to necessitate thermal constraints of the semiconductor devices. However, the converter output currents under...
There has been a growing demand of using multi-function inverters for grid-connected systems applied to nonconventional energy sources, such as solar, wind and so on. In addition to power quality conditioning, the inverter can also be used for bidirectional active power exchange with a three-phase four-wire grid. Therefore, the inverter acts as a multi-function compensator. The functions of the proposed...
In this paper, operation and analysis for an improved transformer-less unified power flow controller (UPFC) is presented. As is well known, the conventional UPFC that consists of two back-to-back inverters requires bulky and often complicated zigzag transformers for isolation and reaching high power rating with desired voltage waveforms. To overcome this problem, a completely transformer-less UPFC...
Ac transmission line emulator is the bridge to interconnect ac systems to fulfill the grid emulation function, where all the emulator elements such as generators, loads and lines are implemented by universal three-phase voltage source converters. In this paper, three design issues are addressed. First, the impact of ac voltage switching noise on the performance of a transmission line emulator in terms...
The short-circuit capability of a power device is highly relevant for converter design and fault protection. In this paper a 10kV 10A 4H-SiC MOSFET is characterized and its short circuit withstand capability is studied and analyzed at 6 kV DC-link voltage. The test setup for this study is also introduced as its design, especially the inductance in the switching loop, can affect the experimental results...
We demonstrate a 900V SiC MOSFET with a record-low ON resistance of 10 mΩ in a TO-247 package. Due to their record low specific ON resistance, and a low Rds,On temperature coefficient, 900V SiC MOSFETs can far exceed the current densities of IGBTs in discrete packages. SiC MOSFETs also have a robust, low reverse recovery body diode which makes them suited to hard-switched and soft-switched topologies...
The DC power delivery system is becoming an appealing research topic and real world solution due to its higher energy efficiency compare with AC delivery system. It has already been applied in data centers, commercial buildings, electrical vehicle charge stations and micro grid systems, etc. Among many new issues that need to be addressed for the DC power delivery system, ultra-fast and accurate protection...
Paralleling devices is an effective way to achieve higher power applications while still having the convenience brought by discrete devices. However, very few papers investigate the challenges of paralleling Gallium Nitride high electron mobility transistors (GaN HEMTs) in cascode configuration, especially the potential failure modes and its related mechanisms. In this paper, a comprehensive study...
Normally-on high-voltage (HV) power transistors are usually operated in a series connection with low-voltage (LV) MOSFETs to ensure safe operation. In the widely used cascode configuration (CC) the status of the combined switch is controlled via the MOSFET gate, whereas the alternative direct drive (DD) method controls the gate of the HV switch directly and utilizes the LV transistor as a safety switch...
Cascode structure is widely used for high voltage normally-on GaN devices. However, the capacitance mismatch between the high voltage GaN device and the low voltage normally-off Si MOSFET may induce several undesired features, such as Si MOSFET reaches avalanche during turn-off, and high voltage GaN device loses ZVS turn-on condition internally during soft-switching turn-on process in every switching...
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