Non-inverting Buck-Boost (NIBB) Converter Analysis of GaN Half Bridges Operation for 24V Unity Conversion Ratio

DC-DC converters are essential for providing a fixed voltage to power LEDs and automotive systems. This paper introduces the non-inverting buck-boost (NIBB) DC-DC converter, which uses GaN half bridges to achieve a 24V unity conversion ratio operation. NIBB converter has been developed and tested for high-frequency feedback control under simulated LED load conditions. The feedback control was employed using FPGA and a high-speed ADC. The converter performance is examined for the high-frequency feedback control at switching frequencies of 500kHz and 800kHz corresponding to changes in the load condition. In addition, the efficiency performance for two different PCB designs of NIBB power converter circuit boards are compared under different operating conditions.journal articl

Simulation Platform for GaN-Based Three-Phase Voltage Source Inverter Analysis: Switching Frequency and Deadtime

Wide bandgap (WBG) devices have emerged as an alternative solution to silicon-based devices in many applications, considering the possible design and construction of converters with lower power losses, higher power density, and the ability to operate on high switching frequency. However, straightforward drop-in-replacement of the devices cannot provide the optimum desired performance. A simulation platform is essential for optimal design and system development. This paper presents the study of the development platform for a GaN-based three-phase 2-level voltage source inverter (VSI) system and analysis considering switching frequency and dead time. A modelling platform utilizing GaN enhancement mode power transistor EPC2016 was developed for the 3-phase VSI system. GaN-based 3-phase VSI system was analyzed for 60 V DC input using the modeling platform at different switching frequencies (50 kHz, 75 kHz, 100 kHz, 125 kHz) under deadtime conditions of 70 ns, 50 ns and 30 ns. Additionally, the system is investigated for the sinusoidal PWM (SPWM) and space vector PWM (SVPWM) techniques for all the cases.journal articl

Fractional order pole fixed second order generalized integrator based control for grid connected solar photovoltaic system

In this article, the development of multi-functional grid connected solar photovoltaic (PV) system using improved Fractional order Control theory-based Pole fixed Second Order Generalized Integrator (FO-PFSOGI) is proposed. The fractional order (FO) control technique offers an advantage to adjust the fixed structure of the integer order and provide additional degree of freedom to achieve accurate response during the system operation. The FO-PFSOGI control technique is used to extricate fundamental constituent of the non-sinusoidal load current. The PV system is competent of feeding the local load requisite and may also inject surplus power into the grid. The voltage source converter (VSC) utilized in the grid-connected system can also be operated as power quality compensator, taking care of harmonics, unbalancing and excess reactive power demand of the local load. The feasibility of multifunctional operations of the converter is established in this article, thus achieving maximum utilization of the power electronics used in the system and reducing the overall cost. A performance comparison of the developed control technique is presented with the conventional techniques in terms of harmonic compensation, weight convergence and computational complexity. The implementation of the controller is modest and extracts fundamental quantities without any phase delay under different loading conditions. The developed system is validated using both simulation and experimental study. A scaled down experimental setup of grid-connected PV system is implemented in the laboratory and real time performance of the FO-PFSOGI is demonstrated using variations in system load and PV irradiance.journal articl

Peak detection for current balancing of parallel-connected SiC power devices using PCB sensors

The parallelling of power semiconductor devices is essential for desired current ratings and the system is prone to the current unbalancing due to parameter variations. SiC devices with significant variable threshold voltage due to manufacturing yield and temperature distribution have a consequential possibility of dynamic current unbalancing. This paper presents the peak detection-based current balancing of parallel-connected SiC devices to minimize the turn-on and turn-off current unbalancing. PCB current sensors are used for the measurement and feedback of the signal for this peak detection-based current balancing mechanism.conference pape

Paralleling of IGBT Power Semiconductor Devices and Reliability Issues

Paralleling of power semiconductor devices is inevitable considering their widespread application and exploitation in the extended horizon of these applications. However, paralleling of power semiconductor devices is prone to severe unbalancing corresponding to the non-idealities of device parameters, which leads to non-identical dynamic and static characteristics of the power devices, as well as the operating conditions and aging. Therefore, the currents are generally non-uniform and cause the derating of the system. This paper discusses and analyzes issues associated with the paralleling of IGBT power devices, which can evoke serious reliability issues. Furthermore, the paper examines the techniques and methodologies that have been proposed to reduce the issue of current unbalancing of parallel-connected power devices.journal articl

Imputation based wind speed forecasting technique during abrupt changes in short term scenario

It is tough and complex to forecast wind speed due to its intermittent and stochastic nature as well as sudden and abrupt variations in the wind speed. Further, it is required to handle the variety of scenarios e.g. cyber-attacks, unexpected power device malfunction, communication/sensor outages etc. that can cause the missing data. This paper proposes and employs a de-noising autoencoder algorithm for wind speed forecasting to ensure the handling of missing data information. At the next step, the data is processed via variational mode decomposition technique to mitigate the noise and improves the model's prediction accuracy. Furthermore, the bi-directional long-short term memory deep learning approach is tied with convolution neural network to increase prediction accuracy and anticipating the sudden/abrupt changes in wind speed accurately. Finally, actual wind speed related data is examined to scrutinize meticulousness of projected forecast methodology particularly during sudden/abrupt changes in the wind speed. The parameter indicators of the wind speed forecasting technique exhibit the capability of improved predictions under the diversified conditions.journal articl

Unbalanced Half-bridge Split Capacitor Power Decoupling with Multi-Order Frequency Control for 800V On-board Battery Charger

This paper proposes a new method for the design and control of a Half-bridge Split Capacitor based Power Decoupling (HSC-PD) circuit to eliminate the bulky Electrolytic Capacitors (E-cap) at dc-link, targeting 800V OBC applications with higher reliability and power density. In the proposed method, both capacitance and dc-offset voltage of the decoupling capacitors are designed unbalanced with the bottom capacitor having a dominant effect over the top one, which reduces the decoupling capacitance requirements compared to the previous works. In addition, the effect of lower dc-link capacitance in reducing power rating of the pre-charge resistor, typically used in OBC applications, is presented. This effect, overlooked in previous literature, leads to reducing volume and cost of the OBC. A small signal model of the HSC-PD is introduced, and a modified feedback control strategy is proposed, offering lower memory usage and calculation effort for the DSP microcontroller when compared with conventional Proportional Resonant (PR) controllers. Comparisons of the proposed method with other HSC-PD counterparts as well as with the conventional E-cap method are given. Finally, a 7.4kW prototype of an 820V interleaved totem-pole PFC with HSC-PD is built and tested to verify the superior performance of the proposed method.journal articl

Observation of B+ → χc0K+

journal articl

The effect of glutamine-mediated synchronization on complement susceptibility in breast cancer cell lines

<p><b>Copyright information:</b></p><p>Taken from "Complement susceptibility in glutamine deprived breast cancer cells"</p><p>http://www.celldiv.com/content/2/1/20</p><p>Cell Division 2007;2():20-20.</p><p>Published online 11 Jul 2007</p><p>PMCID:PMC2031881.</p><p></p> All populations of cells were grown to confluency in separate culture flasks. Unsynchronized cells were maintained in 10% FBS DMEM supplemented with 2 mM L-glutamine, while some cells were subsequently maintained in glutamine deficient-media for 48 hours (Gln Deprived), and of this group, some were subsequently supplemented with 2 mM L-glutamine for 8 hours (Gln Restored). All populations of cells were sensitized with 20 μg of rabbit polyclonal antibody to β-microglobulin and subjected to 25% fresh normal human serum (NHS). After 4.5 hours of incubation with NHS at 37°C, supernatants were collected and tested for LDH activity to determine percent lysis

Optimal NHS Dilution for Complement-mediated lysis of human breast cancer cell lines

<p><b>Copyright information:</b></p><p>Taken from "Complement susceptibility in glutamine deprived breast cancer cells"</p><p>http://www.celldiv.com/content/2/1/20</p><p>Cell Division 2007;2():20-20.</p><p>Published online 11 Jul 2007</p><p>PMCID:PMC2031881.</p><p></p> The Bcap37 and MCF7 cells (1 × 10) were sensitized 20 μg rabbit antibody to β-microglobulin and incubated with specified dilutions of normal human serum (NHS). After a total 4.5 hours of incubation at 37°C, supernatants were collected and tested for LDH activity to determine percent lysis