Test Pulse Research Articles

Central Aortic Blood Pressure Waveform Estimation with a Temporal Convolutional Network.

A novel temporal convolutional network (TCN) model is utilized to reconstruct the central aortic blood pressure (aBP) waveform from the radial blood pressure waveform. The method does not need manual feature extraction as traditional transfer function approaches. The data acquired by the SphygmoCor CVMS device in 1,032 participants as a measured database and a public database of 4,374 virtual healthy subjects were used to compare the accuracy and computational cost of the TCN model with the published convolutional neural network and bi-directional long short-term memory (CNN-BiLSTM) model. The TCN model was compared with CNN-BiLSTM in the root mean square error (RMSE). The TCN model generally outperformed the existing CNN-BiLSTM model in terms of accuracy and computational cost. For the measured and public databases, the RMSE of the waveform using the TCN model was 0.55 ± 0.40 mmHg and 0.84 ± 0.29 mmHg, respectively. The training time of the TCN model was 9.63 min and 25.51 min for the entire training set; the average test time was around 1.79 ms and 8.58 ms per test pulse signal from the measured and public databases, respectively. The TCN model is accurate and fast for processing long input signals, and provides a novel method for measuring the aBP waveform. This method may contribute to the early monitoring and prevention of cardiovascular disease.

Dynamic on‐state resistance instability characterization of a multi‐chip‐GaN MIS‐HEMTs cascode power module

AbstractThe dynamic on‐state resistance instability of a high‐current cascode multi‐GaN‐chip power module under high frequency and voltage switching conditions is demonstrated in this paper. The presented double pulse test topology is utilized to evaluate switching dependencies on voltage, current, and frequency, showing its versatility in investigating the switching instability of the device. The extended defects in the buffer layer resulted in a decrease in dynamic on‐state resistance (RDS‐ON) under hard switching conditions. Despite this, no noticeable RDS‐ON degradation occurs under harsh switching conditions due to electron de‐trapping. This study comprehensively analyzes the dynamic stability of a multi‐GaN‐chip cascode module with devices.

Thermal Impedance Calibration for Rapid and Noninvasive Calorimetric Soft-Switching Loss Characterization

Virtual prototyping, multi-objective optimization and design automation are increasingly being used to meet the growing demands of modern power electronic applications in terms of efficiency and power density. These concepts are based on accurate loss models of the power semiconductors used. While for hard-switching the double pulse test is an established electrical characterization method, soft-switching losses can only be determined by calorimetric measurements. Despite significant improvements in using transient approaches, calorimetric characterization of soft-switching loss energy is very time-intensive and requires complex measurement setups. This paper presents a new automated calorimetric method with thermal impedance calibration that enables rapid and non-invasive switching loss measurements. Using ultra-fast transient measurements and accelerated cooling phases in between, soft-switching loss maps can be determined based on hundreds of individual readings. The proposed measuring method is validated against hard-switching electrical double pulse test measurements. The method achieves a maximum error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1.9 \,\%$</tex-math></inline-formula> for the total loss measurement from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1-9 \,\mathrm{W}$</tex-math></inline-formula> and an average measurement error of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$16.5 \,\%$</tex-math></inline-formula> for the soft-switching energy from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1-4 \,\mu \mathrm{J}$</tex-math></inline-formula> of wide bandgap power semiconductors. In addition to comparing the results of different semiconductor technologies for use in a charger application, the manufacturers' simulation models are also analyzed with respect to soft-switching energy.

A hybrid nondestructive testing method of pulsed eddy current testing and electromagnetic acoustic transducer techniques based on wavelet analysis

It is found that the electromagnetic acoustic testing (EMAT) signal itself contains part of the pulsed eddy current testing (PECT) signal. Therefore, if the pulsed eddy current signal embedded in the electromagnetic ultrasound signal can be effectively extracted and used, the hybrid nondestructive testing method of electromagnetic ultrasound and pulsed eddy current can be truly realized. Based on the above concept, the authors have obtained some preliminary results through simple signal processing try, and which gave us a promising hope of this hybrid method. To further verify the validity and strengthen the usability of the hybrid method, more effective signal separation and extraction way to the hybrid detection signals is expected, which is the core step. In this study, a new signal separation and extraction method is proposed for the hybrid detection signals in the PECT/EMAT nondestructive testing method based on wavelet analysis strategy. The effectiveness and merits of the proposed signal separation method compared to the previous way is verified through the numerical simulation as well as experiment.

Development and Performance Evaluation of Integrated Hybrid Power Module for Three-Phase Servo Motor Applications.

This study aims to develop a 30 kHz/12 kW silicon carbide (SiC)/Si integrated hybrid power module (iHPM) for variable frequency drive applications, particularly industrial servo motor control, and, additionally, to theoretically and experimentally assess its dynamic characteristics and efficiency during operation. This iHPM integrates a brake circuit, a three-phase Si rectifier, and a three-phase SiC inverter within a single package to achieve a minimal current path. A space-vector pulse width modulation (SVPWM) scheme is used to control the inverter power switches. In order to reduce parasitic inductance and power loss, an inductance cancellation design is implemented in the Si rectifier and SiC inverter. The switching transients and their parasitic effects during a three-phase operation are assessed through an electromagnetic-circuit co-simulation model, by which the power loss and efficiency of the iHPM are estimated. The modeled parasitic inductance of the inverter is validated through inductance measurement, and the effectiveness of the simulated results in terms of switching transients and efficiency is verified using the experimental results of the double pulse test and open-loop inverter operation, respectively. In addition, the power loss and efficiency of the SiC MOSFET inverter are experimentally compared against those of a commercial Si IGBT inverter.

Tissue Resistance Decrease during Irreversible Electroporation of Pancreatic Cancer as a Biomarker for the Adaptive Immune Response and Survival

PurposeTo correlate irreversible electroporation (IRE) procedural resistance changes with survival outcomes and the IRE-induced systemic immune response in patients with locally advanced pancreatic cancer (LAPC). Materials and MethodsData on IRE procedural tissue resistance (R) features and survival outcomes were collected from patients with LAPC treated within the context of 2 prospective clinical trials in a single tertiary center. Preprocedural and postprocedural peripheral blood samples were prospectively collected for immune monitoring. The change (ie, decrease) in R during the first 10 test pulses (ΔR10p) and during the total procedure (ΔRtotal) were calculated. Patients were divided in 2 groups on the basis of the median change in R (large ΔR vs small ΔR) and compared for differences in overall survival (OS) and progression-free survival and immune cell subsets. ResultsA total of 54 patients were included; of these, 20 underwent immune monitoring. Linear regression modeling showed that the first 10 test pulses reflected the change in tissue resistance during the total procedure appropriately (P < .001; R2 = 0.91). A large change in tissue resistance significantly correlated with a better OS (P = .026) and longer time to disease progression (P = .045). Furthermore, a large change in tissue resistance was associated with CD8+ T cell activation through significant upregulation of Ki-67+ (P = .02) and PD-1+ (P = .047). Additionally, this subgroup demonstrated significantly increased expression of CD80 on conventional dendritic cells (cDC1; P = .027) and PD-L1 on immunosuppressive myeloid-derived suppressor cells (P = .039). ConclusionsIRE procedural resistance changes may serve as a biomarker for survival and IRE-induced systemic CD8+ T cell and cDC1 activation.

A Compact High-Stability Nanosecond Pulse Test System Using Corona-Stabilized Switch and Coaxial Resistance Divider

Due to the lack of a standard nanosecond high-voltage pulse generator for sensor calibration, a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test. By establishing the equivalent circuit model of the nanosecond pulse generator, the circuit component parameters of the five-stage Marx loop and the one-stage compression steepening unit were simulated. The influence of the action performance of the steepening gap on the characteristics of output nanosecond pulse was analyzed. The nanosecond pulse test system was established through the structural design of the nanosecond pulse-generating circuit, the development of a high-performance corona-stabilized switch, and the measurement of a fast-response resistance divider made of metal oxide thin-film resistors. The nanosecond pulse test system has the capability to output a double exponential nanosecond pulse voltages in the amplitude range of 10–60 kV with a rise time of 2.3 ± 0.5 ns and a half-peak time of 23 ± 5 ns. In addition, the output pulse voltage has a high consistency and stability in the full amplitude range. The maximum relative standard deviation of the peak value is 1.517%, and the relative standard uncertainty is less than 5‰.

Comparative analysis of signal accuracy of three SpO2 monitors during motion and low perfusion conditions

To compare pulse oximetry performance during simulated conditions of motion and low perfusion in three commercially available devices: GE HealthCare CARESCAPE ONE TruSignal SpO2 Parameter, Masimo RADICAL-7 and Medtronic Nellcor PM1000N. After IRB approval, 28 healthy adult volunteers were randomly assigned to the motion group (N = 14) or low perfusion (N = 14) group. Pulse oximeters were placed on the test and control hands using random assignment of digits 2–5. Each subject served as their own control through the series of repeated pair-wise measurements. Reference co-oximetry oxyhemoglobin (SaO2) measurements from the radial artery were also obtained in the motion group. SpO2 readings were compared between the test and control hands in both groups and to SaO2 measurements in the motion group. Accuracy was assessed through testing of accuracy root-mean squared (ARMS) and mean bias. In the simulated motion test group the overall Accuracy Root Mean Square (ARMS) versus SaO2 was 1.88 (GE), 1.79 (Masimo) and 2.40 (Nellcor), with overall mean bias of − 0.21 (Masimo), 0.45 (GE), and 0.78 (Nellcor). In the motion hand, ARMS versus SaO2 was 2.45 (GE), 3.19 (Masimo) and 4.15 (Nellcor), with overall mean bias of − 0.75 (Masimo), − 0.01 (GE), and 0.04 (Nellcor). In the low perfusion test group, ARMS versus the control hand SpO2 for low PI was 3.24 (GE), 3.48 (Nellcor) and 4.76 (Masimo), with overall bias measurements of − 0.53 (Nellcor), 0.96 (GE) and 1.76 (Masimo). Experimental results for all tested devices met pulse oximetry regulatory and testing standards requirements. Overall, SpO2 device performance across the three devices in this study was similar under both motion and low perfusion conditions. SpO2 measurement accuracy degraded for all three devices during motion as compared to non-motion. Accuracy also degraded during normal to low, very low, or ultra low perfusion and was more pronounced compared to the changes observed during simulated motion. While some statistically significant differences in individual measurements were found, the clinical relevance of these differences requires further study.

Dynamic Behavior and Residence Characteristics of Space Charge in Oil-Paper Insulation Under Polarity–Reversal Electric Field

As one of the core components of the direct current (dc) transmission system, the converter transformer bears not only the alternate current (ac) electric field but also complex electric fields, such as polarity reversal. In the process of polarity reversal, the phenomenon of space charge residence occurs in the oil-paper insulation inside the converter transformer, which distorts the internal electric field, leading to insulation deterioration or even failure. However, studies on the dynamic characteristics of space charge during the reversal process and the mechanism of insulation degradation are not comprehensive. Therefore, in this study, a test pulse matching circuit was developed to accurately match the test pulse with the polarization voltage of polarity reversal and perform the multi-point rapid test of the space charge transient characteristics during polarity reversal. The space charge tests (of the unaged specimen) were performed at the polarity–reversal time of 60, 30, and 10 s, and the influence of polarity–reversal time on the charge residence characteristics of oil-paper insulation was compared and analyzed. Additionally, space charge tests were performed on oil-paper insulation samples with accelerated electro–thermal–mechanical aging treatment for 0, 2.5, 5, 10, and 15 days to compare and analyze the influence of oil-paper insulation aging degree on charge residence characteristics under the action of multi-physical field coupling. Research results indicate that the shorter the reversal time, the shorter the time required for the charge to dissipate, and the more the charge resides, the stronger its enhancement effect on the electric field. As the aging degree of the sample increases, the dissipation rate of the resident charge becomes slower during the reversal process, and the resident charge increases, so that the maximum electric field intensity inside the sample increases under the same polarization electric field. The study of the charge residence characteristics and the dynamic charge behavior during the polarity inversion process has important guiding significance for clarifying the deterioration mechanism of the converter transformer oil-paper insulation under polarity–reversal electric field.

Tonotopic Ca2+ dynamics and sound processing in auditory interneurons of the bush-cricket Mecopoda elongata

Two auditory neurons, TN-1 and ON-1, in the bush-cricket, Mecopoda elongata, have large dendritic arborisations which receive excitatory synaptic inputs from tonotopically organised axonal terminals of auditory afferents in the prothoracic ganglion. By combining intracellular microelectrode recording with calcium imaging we demonstrate that the dendrites of both neurons show a clear Ca2+ signal in response to broad-frequency species-specific chirps. Due to the organisation of the afferents frequency specific auditory activation should lead to local Ca2+ increases in their dendrites. In response to 20 ms sound pulses the dendrites of both neurons showed tonotopically organised Ca2+ increases. In ON-1 we found no evidence for a tonotopic organisation of the Ca2+ signal related to axonal spike activity or for a Ca2+ response related to contralateral inhibition. The tonotopic organisation of the afferents may facilitate frequency-specific adaptation in these auditory neurons through localised Ca2+ increases in their dendrites. By combining 10 and 40 kHz test pulses and adaptation series, we provide evidence for frequency-specific adaptation in TN-1 and ON-1. By reversible deactivating of the auditory afferents and removing contralateral inhibition, we show that in ON-1 spike activity and Ca2+ responses increased but frequency-specific adaptation was not evident.

Diatomites from the Iberian Peninsula as Pozzolans.

The object of this work is to study and characterize diatomites from the southeast of the Iberian Peninsula to establish their character and quality as natural pozzolans. This research carried out a morphological and chemical characterization study of the samples using SEM and XRF. Subsequently, the physical properties of the samples were determined, including thermic treatment, Blaine particle finesse, real density and apparent density, porosity, volume stability, and the initial and final setting times. Finally, a detailed study was conducted to establish the technical properties of the samples through chemical analysis of technological quality, chemical analysis of pozzolanicity, mechanical compressive strength tests at 7, 28, and 90 days, and a non-destructive ultrasonic pulse test. The results using SEM and XRF show that the samples are composed entirely of colonies of diatoms whose bodies are formed by silica between 83.8 and 89.99% and CaO between 5.2 and 5.8%. Likewise, this indicates a remarkable reactivity of the SiO2 present in both natural diatomite (~99.4%) and calcined diatomite (~99.2%), respectively. Sulfates and chlorides are absent, while the insoluble residue portion for natural diatomite is 1.54% and 1.92% for calcined diatomite, values comparatively lower than the standardized 3%. On the other hand, the results of the chemical analysis of pozzolanicity show that the samples studied behave efficiently as natural pozzolans, both in a natural and calcined state. The mechanical tests establish that the mechanical strength of the mixed Portland cement and natural diatomite specimens (52.5 MPa) with 10% PC substitution exceeds the reference specimen (51.9 MPa) after 28 days of curing. In the case of the specimens made with Portland cement and calcined diatomite (10%), the compressive strength values increase even more and exceed the reference specimen at both 28 days (54 MPa) and 90 days (64.5 MPa) of curing. The results obtained in this research confirm that the diatomites studied are pozzolanic, which is of vital importance because they could be used to improve cements, mortars, and concrete, which translates to a positive advantage in the care of the environment.

Dynamic optical clamp: A novel electrophysiology tool and a technique for closed-loop stimulation

Optical methods of neuromodulation show great promise. Recent research has shown that optogenetic and electrical stimulation interact both in vitro and in vivo to facilitate action potentials. With standard electrophysiology approaches, it is not possible to directly compare the cell’s response to a test pulse after an optical or electrical stimulation that lead to the same depolarisation. This paper describes the development of a new “dynamic optical clamp” technique, which aims to build on existing voltage clamp methods, but using light as the clamping input in place of electrical currents. We propose a technique based on combinations of optical and electrical stimulation to clamp membrane potential optically. After illustrating the problem in the context of optogenetically-active spiral ganglion neurons from transgenic mice, the proposed optical clamp was first tested within a NEURON simulation and then demonstrated in vitro with NG108-15 cells transfected with a Channelrhodopsin-2 plasmid. Testing of different control schemes within the NEURON simulation showed that a proportional–integral–derivative controller was appropriate for this application. The dynamic optical clamp technique allowed the membrane voltage of optogenetically-modified NG108-15 cells to be controlled using only light during electrophysiology studies. In order to translate optical approaches into implantable devices, a greater understanding of both the mechanisms of optical modulation and the engineering limitations is desirable. The dynamic optical clamp can be adapted for use in closed-loop neuronal control in future generations of neuroprosthetic devices. The enhanced control afforded by this technique could facilitate future investigations of ion channel dynamics during optical stimulation.

Estimation of Flexural Strength of Plain Concrete from Ultrasonic Pulse Velocity

The aim of this study is to propose mathematical expressions for estimation of the flexural strength of plain concrete members from ultrasonic pulse velocity (UPV) measurements. More than two hundredpieces of precast concrete kerb units were subjected to a scheduled test program. The tests were divided into two categories; non-destructive ultrasonic and bending or rupture tests. For each precast unit, direct and indirect (surface) ultrasonic pulses were subjected to the concrete media to measure their travel velocities. The results of the tests were mointered in two graphs so that two mathematical relationships can be drawn. Direct pulse velocity versus the flexural strength was given in the first relationship while the second equation describes the flexural strength as a function of indirect (surface) pulse velocity. The application of these equations may be extended to cover the assessment of flexural strength of constructed concrete kerb units or in-situ concreting kerbstone and any other precast concrete units. Finally, a relation between direct and indirect pulse velocities of the a given concrete was predicted and suggested to be employed in case when one of the velocities is notavailable can be measured for other ultrasonic pulse test applications

High Slope Efficiency Double and Triple Junction 808 nm Vertical Cavity Surface Emitting Lasers

High-performance 808 nm double and triple-junction vertical cavity surface emitting lasers (VCSELs) are designed and investigated. The light-current-voltage (L-I-V) characteristics of 808-nm single, double, and triple-junction VCSELs are compared. In the paper, the double-junction VCSELs with two oxide apertures exhibit a very high slope efficiency (SE) of 2.32 W/A at 25 °C, and the peak SE of 2.51 W/A is achieved at 10 °C. The power conversion efficiency (PCE) of 53.14% is achieved for double-junction individual VCSEL emitter. The peak SE of the triple-junction VCSELs reach 3.40 W/A with the PCE of 53.02% for individual VCSEL emitter. Under narrow pulse test conditions (400 Hz, 60 ns pulse width), the peak output powers of the designed double-junction and triple-junction VCSEL arrays reach 216.11 W and 325.77 W under the injection current of 80 A, respectively. Such high-performance multi-junction 808-nm VCSELs are very important for pumping solid state lasers and medical aesthetics.

Predicting battery impedance spectra from 10-second pulse tests under 10 Hz sampling rate

Onboard measuring the electrochemical impedance spectroscopy (EIS) for lithium-ion batteries is a long-standing issue that limits the technologies such as portable electronics and electric vehicles. Challenges arise from not only the high sampling rate required by the Shannon Sampling Theorem but also the sophisticated real-life battery-using profiles. We here propose a fast and accurate EIS predicting system by combining the fractional-order electric circuit model-a highly nonlinear model with clear physical meanings-with a median-filtered neural network machine learning. Over 1000 load profiles collected under different state-of-charge and state-of-health are utilized for verification, and the root-mean-squared-error of our predictions could be bounded by 1.1mΩ and 2.1mΩ when using dynamic profiles last for 3min and 10s, respectively. Our method allows using size-varying input data sampled at a rate down to 10Hz and unlocks opportunities to detect the battery's internal electrochemical characteristics onboard via low-cost embedded sensors.

A Miniaturized Sealed-Off Double-Gap Pseudospark Switch for High Power and High Repetition Rate Pulsed Discharge Applications

Pulsed power systems can deliver high peak power in a micro/nano-second timescale to various loads in scientific and industrial applications, whose performances are significantly influenced by the pulsed discharge switch. This paper presents the development and comprehensive tests of a miniaturized sealed-off pseudospark switch. The structure of double-gap and multi-channel is adopted to achieve the high hold-off voltage and high current capacity. In single pulse tests, the influence of pressure in the switch is analyzed. As the pressure increases, values of multiple parameters decrease, like self-breakdown voltage, trigger delay, and voltage dropping time. In a wide pressure range, trigger jitter is below 3 ns, and the minimum is < 1 ns. At low pressure, the transient voltage across two gaps becomes inconsistent, and two types of current quenching are observed, which are related to processes occurring on cathode surface. In repetitive pulse tests, the direct repetitive operation is up to 3.5 kHz while higher repetition rate is limited by the trigger system. In double-pulse tests, the maximum repetition rate can be higher than 8 kHz for 40 kV pulsed voltage. Meanwhile, the insulation recovery speed is higher at lower pressure, and as the time delay between two pulses increases, the second pulse breakdown voltage increases nonlinearly. In high current tests, the switch is also used in metal wire explosion experiments and operates at the condition of 30 kV/40 kA for more than 104 shots without performance degradation. Further lifetime tests point out that the switch can work for >106 shots stably at moderate current. Experiments prove that the designed switch has superior performances including high hold-off voltage (>50 kV), low jitter (<1 ns), high repetition rate (>3.5 kHz), high peak current (>40 kA), long lifetime (>106 shots) and miniaturized size.

Mechanical Strength and Microstructure of GGBS-SCBA based Geopolymer Concrete

This paper deals with the attempt to develop and study the performance of ground granulated blast furnace slag (GGBS) and sugarcane bagasse ash (SCBA) based sustainable geopolymer concrete. NaOH (8M, 10M, and 12M) and Na2SiO3 were used as alkaline activators with a ratio of 2.5. SCBA mainly acted as amorphous silica and has been utilized as a substitute material for GGBS. The effect of SCBA contents (0%, 5%, 10%, 15% & 20% by the mass of binder) in terms of fresh, hardened, microstructural, and correlation properties of geopolymer concrete developed have been evaluated. Different tests such as the slump cone test, compression test, split tensile test, flexure test, and ultrasonic pulse velocity test were conducted. Scanning electron microscopy, Energy dispersive analysis, and X-ray diffraction analysis were investigated for understanding the microstructural properties. The research findings have shown that with an increase in molarity from 8M to 12M there is an increase in the strength properties of geopolymer concrete. The results in this current study show that 28 days compressive strength was found to increase by 4–15% when the NaOH molarity was increased from 8M to 10M and 8–21% when the NaOH molarity was increased from 8M to 12M. The geopolymer concrete developed with 20% SCBA and 80% GGBS with 8M NaOH solution and SS/SH ratio of 2.5 can be used for a target strength of 30–35 MPa. Scanning electron microscope images show a packed and dense matrix, which clearly outlines the reason behind the attainment of higher strength in higher molarity of GGBS-SCBA based geopolymer concrete samples and the presence of CASH gel confirmed this in the geopolymer matrix. Furthermore, there is a strong correlation between the experimental findings and the model equations proposed. These presented models will be useful in improving the strength of geopolymer concrete incorporating agricultural and industrial wastes.

Active Gate Driver for Dynamic Current Balancing of Parallel-Connected SiC MOSFETs

In high-power applications, parallel connection of discrete silicon carbide (SiC) MOSFETs is necessary to increase the current rating. However, the unbalanced dynamic current during switching transient may cause unequal power loss and thermal distribution, which is a great challenge in parallel applications. In this paper, a dynamic current balancing method based on a new active gate driver (AGD) is proposed to improve the current sharing. The principle of the AGD is based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">di/dt</i> feedback control and voltage controlled current source to adjust gate drive current of SiC MOSFETs. Therefore, the switching trajectory of the paralleled devices can be changed to achieve current balance. In addition, by using master-slave control strategy, the proposed AGD can be easily used for multiple paralleled devices. The double pulse tests are conducted to verify the effectiveness of the proposed AGD. For two paralleled devices, the turn-on and turn-off switching energy imbalances are reduced from 13.4% and 56.0% (12.1% and 52.9%) to 8.8% and 15.3% (8.0% and 8.8%) by the current source (current sink) circuit. For six paralleled devices, the degrees of turn-on and turn-off switching energy imbalances can be reduced from 21.8% and 16.1% to 11.8% and 7.8% by the proposed AGD. <fn fn-type="other" id="fn3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This work was supported by Key-Area Research and Development Program of Guangdong Province under Grant 2021B0101310004, and the research program sponsored by Eaton. (<i>Corresponding author</i>: <i>Junming Zhang</i>) Y. He, X. Wang, S. Shao, and J. Zhang are with the College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China (e-mail: ; ; ; ). </fn>

Double Sided Integrated GaN Power Module with Double Pulse Test (DPT) Verification

Wide Bandgap devices (WBG) have led to an era of high speed and high voltage operations that were not previously achievable with silicon devices. However, packaging of these devices in the power module has been a challenge due to higher switching rates which can cause several amperes of displacement current to flow through the parasitic capacitance of the package thus impacting the gate driver operation and the switching ability of the device. The severity of this current increases in thin packaging substrates unlike the traditional inorganic substrates e.g. DBC and thus a thorough investigation is needed before it can be used with WBG semiconductors. The objective of this paper is to discuss ways to reduce as well as manipulate the parasitic capacitance at different locations in the power modules to reduce the magnitude of the peak and RMS value of the displacement current and have a better gate drive signal and power waveform. To study this, a Double Pulse Test (DPT) simulation study has been conducted to show how an intelligent distribution of parasitic capacitance benefits the device functioning. This has been validated through experimental fabrication and DPT of dense power module following proposed guidelines. A detailed description of the design of a high-speed capable DPT circuit and measurement setup has been specified to show the steps needed for reliable testing and measurement.

High Bandwidth Active Gate Driver for Simultaneous Reduction of Switching Surge and Switching Loss of SiC-MOSFET

This study investigates an active gate driver (AGD) for an SiC-MOSFET. The source current feedback type AGD utilizes the induced voltage of the source wire inductance as a negative feedback signal to regulate the source current di/dt. Recent improvements in the switching performance of the AGD is limited due to the feedback system bandwidth. In this paper, a high bandwidth current feedback type power operational amplifier is applied as the gate drive circuit. Switching characteristics of the conventional resistive gate driver and AGD are experimentally investigated via a double pulse test setup. The switching setup condition is 700 V / 80 A. This paper describes the development of the AGD circuit and experimental results. The over-shoot and ringing of the Vds and Is are reduced using the AGD. Moreover, the switching loss is simultaneously reduced.