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Lateral GaN-on-Si HEMT technology enables integrated high-voltage half-bridges with gate drivers. However, the capacitive coupling through a common conductive substrate influences switching characteristics. The measured hard-switching turn-on time with floating substrate increased to over 16 ns as compared to conventional source-connected substrate (1 ns), switching 300 V/4A with GaN ICs comprising...
Following the recent advances in the production of 3.3 kV and 10 kV SiC power MOSFETs, Wolfspeed launched an effort to develop a new generation 6.5 kV SiC power MOSFET to fill the medium-to high-voltage fast switching device void in applications such as rail traction and mediumvoltage motor drives. The characteristics of the new generation 6.5 kV SiC power MOSFET rated at a drain current of 30 A,...
This paper presents an evaluation of a newly released power stage direct drive GaN HEMT. The double pulse test is performed and the dynamic performance is characterized. PCB layout optimization is also investigated for improved switching transients. It is shown that the direct drive system provides simplified circuit design, reduced number of external components, and small gate loop parasitics. Also,...
This work presents the operation of a PCB-embedded diode-clamped multilevel-converter integrated circuit (IC) fabricated in a lateral, high-voltage AlGaN/GaN-on-Si heterojunction technology. It is demonstrated, that PCB-embedding is an appropriate assembly technique for lateral power ICs with high-integration levels. By placing DC-link capacitors onto the IC-package, parasitc inductances in the power...
The goal of this work is to develop a real time degradation monitoring tool for Silicon Carbide (SiC) power MOSFETs. The conventional methods for prognosis and reliability monitoring are mostly based on parametric measurements as on state resistance, threshold voltage, leakage currents etc. The change in switching characteristics of aged devices and the root cause analysis behind this change are also...
With fast growth of data centers and automotive electronics, DC-DC converters are the crucial modules, which deliver power to these systems. High conversion ratio (HCR) step down DC-DC converters are gaining growing attention for usage in these high tech emerging applications. The main design challenge of these converters is maximizing conversion ratio, efficiency, and power density simultaneously...
This paper presents a clock-feedthrough compensation technique for bootstrapped switches. The proposed technique utilizes a dummy transistor to generate a reverse voltage, which compensates the input-dependent error caused by clock feedthrough effect of sampling switch. Simulation result shows the differential sampling error of bootstrapped switch reduces from 7.2mV to 1.4mV for the worst case, operating...
Three GaN-based buck switching power stage architectures are implemented using discrete GaN High Electron Mobility (HEMTs) devices and compared with respect to efficiency, switching speed (2 to 10MHz), and power conversion ratio for medium-power applications. The three presented power stage architectures are: a single-stage buck, a multi-phase buck with 2 phases, and a stacked interleaved configuration...
This paper presents the project procedure to develop a Half-Bridge (HB) Non-Isolated DC-DC converter applying a Normally-On GaN-based switch. Normally-on devices (D-mode) present the benefit of lower costs in terms of production if compared with E-mode devices, which gives an economic motivation to study and develop power electronics converters applying this technology. The devices under test (DUTs)...
This paper introduces a dead-time optimization technique for a 2-level voltage source converter (VSC) using turn-off transition monitoring. Dead-time in a VSC impacts power quality, reliability, and efficiency. Silicon carbide (SiC) based VSCs are more sensitive to dead-time from increased reverse conduction losses and turn-off time variability with operating conditions and load characteristics. An...
SiC power devices exhibit low on-resistance and are capable of processing high switching frequencies at elevated temperatures. When SiC MOSFETs are employed as switch, minimizing switching power losses is crucial. A proper design of gate driving circuit for SiC MOSFET can ensure minimum losses, safe operation of the device and reliable performance. A comparative study of gate drivers for SiC MOSFETs...
This paper reports on the design and experimental verification of a 200 kVA traction inverter using three 900 V, 2.5 mΩ, SiC MOSFET-based half-bridge power modules comprising the power stage. Each dual power module contains four 900 V, 10 mΩ SiC MOSFETs per switch position and uses synchronous conduction to achieve high average and peak efficiencies over its entire operating region to meet the demands...
An improved SiC MOSFET-gate driver integrated half-bridge module with folded layout using direct bonded copper (DBC) substrate is designed, fabricated, and tested. The bottom layer of the DBC is used as part of the power loop to achieve major reduction in the loop stray inductance. Due to the low parasitic inductance and capacitance, the gate resistor is chosen as zero to reduce the switching loss...
Outsourcing middleboxes brings threats to the enterprise's private information including the trafflc and rules of middleboxes. We present a secure and dynamic middlebox outsourcing framework SICS, short for Secure In-Cloud Service. SICS encrypts each packet header and uses a label for in-cloud rule matching, which enables the cloud to perform its functionalities correctly with minimum header information...
The superior electrical and thermal properties of silicon carbide (SiC), when compared to silicon (Si), has lead to it being used in power converter designs that require high efficiency and low volume. However while choosing the semi-conductor material for these high performance designs is relatively simple, the specific type of SiC device (e.g. JFET, MOSFET or BJT) is not so straight-forward. This...
Parasitic capacitances of silicon carbide (SiC) MOSFET exert an significant influence on the switching performance with direct determination of the switching speed, switching loss and EMI noises, among which the nonlinear gate drain capacitance (Miller capacitance) dominates due to the well-known Miller effect. A precise and comprehensive model of the miller capacitance is proposed according to the...
The future electricity grid for the electric power distribution network is slowly moving in the direction of dc transmission. In order to prevent the fault propagation, provide protection against overload and fault, and isolate the faulty load in a dc power network, an overcurrent protection device must be applied to the switch gear for electric power management and control of the systems in dc power...
In this paper, key aspects of silicon-carbide (SiC)-based automotive traction drives are reviewed. Firstly, the required supporting factors to achieve optimal operating conditions and best performance are described. Major component sizing methodologies and constraints are included. Expectations on gate threshold voltage, trans-conductance, and transient oscillation are discussed. Tolerance against...
This paper presents a novel procedure to determine the internal gate-source voltage inside a multi-chip power module using the example of a SiC half bridge module. Based on the lumped elements of the gate circuit calculated by a quasi-static electromagnetic simulation, each field-effect transistor is represented by a single, voltage dependent capacitor. The procedure is validated by clamped inductive...
The U.S. Army Research Laboratory (ARL) and Wolfspeed developed silicon carbide (SiC) vertical MOSFETs for linear-mode operation. The motivation is to determine whether SiC's material properties enable SiC MOSFETs to withstand higher pulse-current density and energy dissipation than is achievable with commercial silicon linear-mode MOSFETs. The SiC device is a 3.3 mm × 3.3 mm chip with a thick gate...
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