Test Pulse Research Articles

Experimental Verification of Pulse Shaping in Elastic Metamaterials Under Impact Excitation

Abstract We present experimental verification of pulse shaping in elastic metamaterials together with a procedure to design, fabricate, and verify metamaterial pulse shapers under impact excitation. The split Hopkinson pressure bar (SHPB) test, a fundamental dynamic test introduced more than 70 years ago, often incorporates pulse shaping as a means to alter a stress wave, providing the primary motivation for the presented study. Elastic metamaterials hold promise for enhancing conventional pulse shaping abilities and improving capabilities of the SHPB test. We first design the pulse shaper by numerically optimizing its response using finite element analysis. The pulse shaper consists of repeated unit cells based on a combination of a phononic crystal and a local resonator. Then, we fabricate and test pulse shaper candidates to validate the procedural efficacy. An iterative element corrects inaccuracies in input force and material properties and allows convergence on an appropriate pulse shaper. We carry out this procedure by designing pulse shapers fabricated from 3D-printed polylactic acid (PLA) to achieve an extended dwell acceleration pulse shape. In experimental impact tests, the procedure results in rise, dwell, and fall behaviors comparable to that predicted, effectively confirming the efficacy of the presented procedure and verifying the performance of metamaterial-based pulse shapers.

Coal permeability considering mining-induced stresses subjected to fractional derivative

Aiming at characterization of coal permeability under conditions of non-Darcian flow, in the transient pulse test, a new fractional-order decay model is developed to describe the pressure difference decay of coal considering mining-induced stresses. Coal permeability under the condition of mining-induced stress is determined experimentally by the MTS815 Flex Test GT testing machine to validate the fractional-order decay model. The results indicate that the new fractional-order decay model can estimate the permeability of coal considering mining-induced stresses more accurately than the exponential decay model. A conceptual permeability model of coal considering mining-induced stresses is obtained by characterization analysis of coal permeability evolution. Furthermore, the meaning of the fractional order is discussed, showing that it can be used to characterize the influence of mining-induced stresses on the seepage characteristics of coal.

A blended method incorporating a multi-model for pulse wind tunnel aerodynamic identification considering large-scale aircraft

Pulse wind tunnel aerodynamic tests are an important part of hypersonic aircraft design and development. With the development of hypersonic aircraft technology, the aircraft model in pulsed wind tunnels has gradually become large-scale and heavy-loaded. During the force measurement test, due to the influence of the increased size of the aircraft model, the real aerodynamic signal of the force measurement system is submerged by the interference signal. During the effective test time of several hundred milliseconds, it is impossible to obtain high-precision aerodynamic signals of the force measuring system using traditional signal-processing methods. Therefore, for the in-depth study of aerodynamic identification of short-time hypersonic pulsed wind tunnels, there is an urgent need for an identification algorithm that can adapt to the force measurement system of large-scale aircraft. In this paper, a new aerodynamic identification algorithm that combines a traditional signal-processing method and a deep neural network is proposed and applied to pulse combustion wind tunnels. The algorithm is mainly divided into signal preprocessing and deep learning. First, the original signal is decomposed into different sub-signals via variational modal decomposition (VMD), and then the real aerodynamic signal is obtained via convolutional neural network (CNN)-long short-term memory (LSTM) training. For different interference signals in the pulsed wind tunnel test, this algorithm innovatively designs VMD preprocessing and optimizes hyperparameters, to extract signal features for subsequent deep learning and to filter out interference components. To ensure the consistency between the validation and the application, the algorithm was verified using the suspension test bench during training, and satisfactory results were obtained. Finally, the algorithm is applied to the suspension force measurement system of a pulse combustion wind tunnel, and the aerodynamic identification results present satisfactory accuracy.

Investigation on holding voltage of asymmetric DDSCR with floating heavy doping in 0.18 μm CMOS process

In the ESD protection design work, the most effective way to improve the holding voltage of bidirectional silicon-controlled rectifier or SCR device is to increase the distance between the cathode and anode of it. However, for DDSCR devices with multi-finger layouts, increasing this distance will result in a decrease in failure current and require a larger layout area. In this work, five types of asymmetric dual direction silicon-controlled rectifier devices with different floating heavy doping combinations are designed based on the traditional ADDSCR structure. Meanwhile, the dimensions, number of fingers, metal layout and number of CONT holes of the five ADDSCR structures are strictly kept the same, aiming at studying the influence of different floating heavy doping combinations on the performance of SCR devices and find the optimal floating heavy doping combination. Their ESD performances are predicted and verified through the two-dimensional device simulations and transmission line pulse (TLP) test results. All the five types of ADDSCR structures are designed to improve the holding voltage. From the results, the forward and reverse holding voltage of ADDSCR_PP, which is inserted floating P+ in NW and PW, are increased to 20.4 V and 17.6 V respectively, compared with the traditional devices without floating heavy doping at 14.2 V and 8.7 V. At the same time, the physical mechanism for the effect of floating heavy doping insert into NW and PW separately were investigated. Finally, the one that best meets the ESD window of automotive application is found.

Online state of charge and state of power co-estimation of lithium-ion batteries based on fractional-order calculus and model predictive control theory

Accurate battery modelling is the cornerstone to state of charge (SOC) and state of power (SOP) co-estimation of lithium-ion batteries in electric vehicles. Due to strong battery nonlinearity over a broad frequency range, traditional integer-order models are incapable of capturing complex battery dynamics for SOC and SOP co-estimation. This paper proposes a fractional-order modified moving horizon estimation (FO-mMHE) algorithm and a fractional-order model predictive control (FO-MPC) algorithm. Firstly, a second-order FOM is constructed by performing a series of hybrid pulse tests at different SOC regions, and its model parameters are identified through a particle swarm optimization-genetic algorithm method. Secondly, online SOC estimation is converted into a constrained optimization problem in a past moving horizon and then solved by the FO-mMHE algorithm, which enables fast convergence speed and proactive smoothing of estimation outcomes. Thirdly, the FO-MPC algorithm is devised to manipulate the current sequence in a prediction horizon for maximizing discharge/charge power accumulation and determining battery SOP in real time. Moreover, different battery current–voltage behaviors are comprehensively researched in the prediction horizon over a whole battery operating range. The proposed co-estimation method is validated under different dynamic load profiles. The experimental results demonstrate a SOC estimation error reduction of up to 1.2 % compared with the commonly used fractional-order extended Kalman filter while the SOP estimation error could be limited below 0.35 W.

Determination of Polypropylene Fiber-Reinforced Concrete Compressive Strength and Elasticity Modulus via Ultrasonic Pulse Tests

Compressive strength and elasticity modulus are the main mechanical properties of concrete. The non-destructive ultrasound pulse test can be used to determine these properties without compromising the structure’s integrity. This study seeks to assess whether a correlation exists (1) between the Reinforcement Index (RI) and the mechanical properties, (2) between the RI and the dynamic properties, and (3) among the dynamic properties of polypropylene fiber-reinforced concrete. The RI was modified through fiber volume fraction (0, 0.4, 0.8 and 1.2%) and fiber length (40, 50 and 60 mm). The dynamic properties were assessed through dynamic elasticity modulus and ultrasonic pulse velocity (UPV), which were determined by direct, semi-direct, and indirect prospect methods. Finally, compressive strength, static elasticity modulus, and Poisson’s ratio were assessed through destructive tests. Their relationship with UPV and the dynamic elasticity modulus is also subsequently studied. The results reveal a correlation between RI and compressive strength and UPV; however, the static elasticity modulus only exhibits a correlation with UPV in one of its measurement methods. Finally, empirical models were developed for predicting compressive strength, elasticity modulus as a function of ultrasonic pulse velocity and RI, and dynamic elasticity modulus as a function of compressive strength and RI.

Quantitative evaluation of deep-shallow compound defects using frequency-band-selecting pulsed eddy current testing

Deep-shallow compound defects (DSCD) may occur in both single-layer and multi-layer structures and commit great loss of structural mechanical strength. Their quantification, especially in depth, is hence imperatively required for guaranteeing the integrity and safety of engineering structures. In this paper, the defect parameters of DSCD are identified by frequency-band-selecting pulsed eddy current testing (FSPECT), and a strategy of component separation is proposed. The high-frequency component is separated from the FSPECT responses for the quantification of shallow defects so that the parameters of deep defects in DSCD can be reconstructed, which is the ultimate objective of FSPECT method. Finite element analysis (FEA) was conducted on the single-layer structure to preview the feasibility of the proposed method and to highlight the signal feature of better sensitivity. Subsequently, validation experiments were implemented on the double-layer structure and identified the features suitable for the shallow and deep defects. Besides, error propagation of the proposed method was also discussed. Results from FEA simulations and experiments show that (a) the strategy of component separation enables the quantitative evaluation of DSCD, (b) peak value (PV) should be chosen for the quantification of shallow defects while for the identification of deep defects time to zero-cross (TZC) is suggested, and (c) the deep defect can still be characterized despite the little error in the estimation of shallow defects.

Research on the pitting behavior of high nitrogen austenitic stainless steel 316LN in sodium chloride solution by using modified potentiostatic pulse test

• The modified potentiostatic pulse test is used to study the pitting behavior of 316LN. • The pitting size and number of 316LN are regulated. • The Si-enriched inclusions are initial sites of metastable pit on 316LN surface. • The pitting resistance of 316LN is enhanced after the potentiostatic pulse test. The pitting behavior of high nitrogen austenitic stainless steel 316LN was studied by using the modified potentiostatic pulse test (PPT). The results show that the duration of the high potential (E h ) and the low potential (E l ) significantly affect the pitting size and number of 316LN. However, the pitting behavior of 316LN only changes during the first five pulse cycles, because the metastable pitting initiates at the limited inclusions. The optimal PPT condition is regarded as E h = 0.5 V SCE for 1 s, E 1 = 0.2 V SCE for 2 s and ten pulse cycles. Metastable pits initiate at the susceptible sites of inclusions which are identified as SiO 2 and SiC. The metastable pits will further grow or restrain with the increasing time of E h or E l , respectively. After PPT modification, the pitting resistance of 316LN is enhanced due to the removal of the Si-enriched inclusions from the 316LN surface. Meanwhile, the fewer current transitions, the lower passivation current density and the higher impedance all suggest that the protectiveness of the oxidation film formed on 316LN surface is improved after PPT.

고전계 노화 SiC-MOSFET 소자를 가지는 양방향 DC-DC 컨버터 특성 분석 연구

Recently, the use of Silicon-carbide Metal Oxide Semiconductor (SiC-MOSFET) with high frequency and low loss characteristics is increasing in power conversion systems. SiC-MOSFET is aged due to the kinetic energy of electrons and thermal stress. In this case, the aged SiC-MOSFET may not perform as expected and may cause a failure of the power conversion system. This can lead to personal injury and property damage, so it is very important to increase reliability by identifying and analysing the aging process of SiC-MOSFET. In this paper, changes in electrical characteristics due to SiC-MOSFET aging and changes in loss and efficiency of the power conversion system are verified through experiments and simulations. A high electric field aging methodology are used to accelerate the SiC-MOSFET aging. Thereafter, a change in loss occurring during device aging are measured through a double pulse test, and this is modeled. By applying the loss modeling result to a bidirectional DC-DC converter, loss changes and efficiency changes due to converter aging are analyzed to determine the effect of the SiC-MOSFET aging on the converter.

Novel and simplified implementation of digital high-power pulsed MIG welding power supply with LLC resonant converter

PurposeThis paper aims to overcome the limitations of low efficiency, low power density and strong electromagnetic interference (EMI) of the existing pulsed melt inert gas (MIG) welding power supply. So a novel and simplified implementation of digital high-power pulsed MIG welding power supply with LLC resonant converter is proposed in this work.Design/methodology/approachA simple parallel full-bridge LLC resonant converter structure is used to design the digital power supply with high welding current, low arc voltage, high open-circuit voltage and a wide range of arc loads, by effectively exploiting the variable load and high-power applications of LLC resonant converter.FindingsThe efficiency of each converter can reach up to 92.3%, under the rated operating condition. Notably, with proposed scheme, a short-circuit current mutation of 300 A can stabilize at 60 A within 8 ms. Furthermore, the pulsed MIG welding test shows that a stable welding process with 280 A peak current can be realized and a well-formed weld bead can be obtained, thereby verifying the feasibility of LLC resonant converter for pulsed MIG welding power supply.Originality/valueThe high efficiency, high power density and weak EMI of LLC resonant converter are conducive to the further optimization of pulsed MIG welding power supply. Consequently, a high performance welding power supply is implemented by taking adequate advantages of LLC resonant converter, which can provide equipment support for exploring better pulsed MIG welding processes.

166 A Comparison of key Methodologies Used to Quantify Protein Quality in Mammals: Ileal Digestibility, Indicator Amino Acid Oxidation, and in Vitro Digestibility

Abstract There are several methodologies which can be used to measure protein quality of an ingredient, however, the results of these studies are generally not compared to one another. The objectives of these studies were to 1) determine standardized ileal digestibility (SID) and in vitro digestibility coefficients for protein and amino acids (AA) from select pulses; 2) determine metabolic availability (MA) of methionine (Met) from field peas and faba beans; and, 3) compare digestibility coefficients determined via different methods. To determine SID of pulses, ileal cannulated barrows were randomly assigned to diets in a 4×4 Latin square. A nitrogen free diet was used to measure basal endogenous losses of AA and protein. Metabolic availability was determined via indicator AA oxidation by applying the principle of slope-ratio assay to F13CO2 from phenylalanine oxidation quantified through CO2 collection during breath collection using indirect calorimetry with barrows randomly assigned to diets in a 10×10 Latin square. Dietary treatments were formulated to include graded levels of Met: crystalline AA diets (Met inclusion of 50, 60, 70, and 80% of requirement), and pulse test diets (Met inclusion of 60, 70, and 80% of requirement). In vitro digestibility of diets was conducted using the TNO-gastrointestinal model. Statistical analysis of SID data was conducted using a mixed model in SAS with diet as a fixed effect and pig and period as random effects. Means were separated using Tukey HSD. Statistical comparison for digestibility coefficients compared to one another and compared to MA coefficients of Met will be conducted once all IAAO and in vitro data are finalized. The SID coefficients for protein and indispensable amino acids are summarized in Table 1. Peas had lower threonine content compared to faba beans and lentils (P < 0.05). Determination of in vitrodigestibility and MA of Met is in progress.

Modified unipolar SPWM inverter for solar PV applications using MATLAB/Simulink model interfaced with dSPACE DS1104

PurposeThe purpose of this paper is to check the Solar Photovoltaic (PV) inverter working condition with modified unipolar switching pulse. The gate pulse for the inverter switches is generated in MATLAB simulation and interfaced with hardware protype. Simulation results can be compared with hardware results.Design/methodology/approachA considerable amount of research has been done on different Pulse Width Modulation (PWM) techniques. Based on the findings, a modified Unipolar Sinusoidal PWM technique was created with one reference signal and two carrier signals+ (one for the positive half cycle and the other for the negative half cycle) and simulated in the MATLAB/Simulink platform. The prototype inverter module receives the simulated switching pulses via dSPACE DS1104 hardware software interfacing board. The hardware implementation has been done, and the hardware results compared with simulation results for various input voltage levels using resistive load.FindingsThis modified switching pulse has dead band and additional hardware setup is not required. 3-phase multi-level inverter output waveform has been achieved with six switches in this method and with low filter values, pure sine wave output can be obtained in simulation. By this method of switching pulse generation and testing, for every modification in switching pulse hardware gate driver is not required. Resulting time consumption and money investment are lower.Originality/valueModified Unipolar SPWM pulse generation technique is novel method for solar PV inverter. The switching pulse has been designed and tested in both MATLAB/Simulation and hardware prototype inverter. Hardware and software results are identical. This method of pulse generation and hardware implementation has not been done anywhere before.

Design of Radiation-Tolerant High-Speed Signal Processing Circuit for Detecting Prompt Gamma Rays by Nuclear Explosion

Electronic equipment in nuclear power plants and nuclear warfare is damaged by transient effects that cause high-energy pulsed radiation. There is a concern that this type of damage can even cause enormous economic losses and human casualties by paralyzing control systems. To solve this problem, this study proposes a complementary metal-oxide semiconductor (CMOS) logic-based, switching detection circuit that can detect pulsed radiations at a fast rate. This circuit improved response speed and power consumption by using the switching operation of digital logic compared with conventional circuits. Furthermore, radiation tolerance to total ionizing dose (TID) effects was achieved even in a cumulative radiation environment because of the use of the design using p-metal-oxide semiconductor field effect transistor (p-MOSFET). The proposed detection circuit was manufactured by a 0.18 µm CMOS bulk process for integration. Normal operation in the detection range of 2.0 × 107 rad(si)/s was verified by pulsed radiation test evaluations, and the tolerance properties to a radiation of 2 Mrad was verified based on cumulative radiation test evaluations.

A comparative study of SiC MOSFETs with and without integrated SBD

A comparative study on SiC MOSFETs is carried out with an emphasis on the design of integrated Schottky barrier diode (SBD) with numerical simulations by Sentaurus TCAD. Compared with the conventional SiC MOSFET (C-MOS) and the conventional SBD-embedded SiC MOSFET (C-MOSBD), the MOSFET (M-MOSBD) features a hybrid doping mesa above the JFET region where a Schottky contact is formed, which exhibits a superior trade-off between the on-state resistance (Rdson) and the reverse transfer capacitance (Crss). Besides, the integrated diode in M-MOSBD renders a better trade-off between OFF-state junction field (ESmax) and forward voltage (VF) when compared to C-MOSBD and the conventional junction barrier Schottky diode (JBS), i.e., the external SBD of C-MOS. In the double pulse test simulation, C-MOS exhibited the largest switch loss followed by C-MOSBD, and M-MOSBD is the smallest. Therefore, in power switching applications where reverse conduction is required, M-MOSBD greatly reduces the chip area while presenting better characteristics.

Effect of Initial Grain Temperature on Combustion Response of Composite Solid Propellants in T-burner

ABSTRACT The effect of initial grain temperature on the combustion response of composite solid propellants (AP/HTPB/RDX/Al) is experimentally investigated using a T-burner. Tests were conducted at different frequencies ranging from 200–400 Hz and at different pressures of 1–8 MPa at different initial propellant temperatures using a novel method (303 K, 243 K and 343 K) for two industrial-grade propellants, propellant-A and propellant-B. The test results revealed that the hot and cold temperatures increase the response. The combustion responses of the propellant-B are lower than propellant-A. Pulsed tests are conducted when the propellant showed low or negative response. This work highlights that the initial grain temperature is a crucial factor in determining the stability of solid rocket motors. The negative response compels us to further investigate toward a better understanding about the unsteady combustion behavior since there is no model available which could predict negative responses as of today.

Auditory clicks elicit equivalent temporal frequency perception to tactile pulses: A cross-modal psychophysical study.

Both hearing and touch are sensitive to the frequency of mechanical oscillations—sound waves and tactile vibrations, respectively. The mounting evidence of parallels in temporal frequency processing between the two sensory systems led us to directly address the question of perceptual frequency equivalence between touch and hearing using stimuli of simple and more complex temporal features. In a cross-modal psychophysical paradigm, subjects compared the perceived frequency of pulsatile mechanical vibrations to that elicited by pulsatile acoustic (click) trains, and vice versa. Non-invasive pulsatile stimulation designed to excite a fixed population of afferents was used to induce desired temporal spike trains at frequencies spanning flutter up to vibratory hum (>50 Hz). The cross-modal perceived frequency for regular test pulse trains of either modality was a close match to the presented stimulus physical frequency up to 100 Hz. We then tested whether the recently discovered “burst gap” temporal code for frequency, that is shared by the two senses, renders an equivalent cross-modal frequency perception. When subjects compared trains comprising pairs of pulses (bursts) in one modality against regular trains in the other, the cross-sensory equivalent perceptual frequency best corresponded to the silent interval between the successive bursts in both auditory and tactile test stimuli. These findings suggest that identical acoustic and vibrotactile pulse trains, regardless of pattern, elicit equivalent frequencies, and imply analogous temporal frequency computation strategies in both modalities. This perceptual correspondence raises the possibility of employing a cross-modal comparison as a robust standard to overcome the prevailing methodological limitations in psychophysical investigations and strongly encourages cross-modal approaches for transmitting sensory information such as translating pitch into a similar pattern of vibration on the skin.

Seismic Performance of a Novel Precast Beam-Column Joint Using Shape Memory Alloy Fibers-Reinforced Engineered Cementitious Composites

A novel precast beam–column joint using shape memory alloy fibers-reinforced engineered cementitious composites (SMA-ECC) was proposed in this study to achieve self-repairing of cracks and internal damage after an earthquake. Three large-scale beam–column joints were tested under displacement reversals, including one monolithically cast conventional concrete joint, one engineered cementitious composites (ECC) reinforced precast concrete joint, and one SMA-ECC reinforced precast concrete joint. Failure mode, crack pattern, hysteretic behavior, stiffness degradation, displacement ductility, and energy dissipation capacity were compared and evaluated through a cyclic loading test. The test results showed that the ECC-based (ECC, SMA-ECC) precast joints have equivalent seismic properties to the monolithically cast concrete joint. ECC-based joints enhanced the ductility and energy dissipation capacity of the joint and, remarkably, reduced crack width. The SMA-ECC reinforced joint also exhibited instant self-healing in terms of the closure of small cracks after unloading. The self-healing performance was further evaluated through ultrasonic pulse tests, with the results showing that the use of SMA-ECC material was efficient in reducing the internal damage of beam–column joints after an earthquake.

Influence of the Experimental Setup on the Damping Properties of SLM Lattice Structures

BackgroundMetal lattice structures obtained through Selective Laser Melting may increase the strength-to-weight ratio of advanced 3D printed parts, as well as their damping properties. Recent experimental results showed that AlSi10Mg and AISI 316L lattices are characterized by higher Rayleigh damping coefficients with respect to the fully dense material. However, some unclear or contradictory results were found, depending on the experimental setup adopted for modal analysis.ObjectiveIn this work the influence of the experimental setup when performing modal analysis on different SLM AISI 316L lattice structures was deeply investigated. The study provides a critical comparison of various experimental modal analysis approaches, allowing to evaluate the influence of external damping sources and material internal damping phenomena.MethodsThe dynamic behaviour of SLM AISI 316L specimens incorporating lattice structures was estimated by means of pulse testing and sinusoidal excitation through an electromagnetic shaker. The validity of the viscous damping model was assessed by means of sinusoidal excitation with different levels of vibration velocity. Moreover, the influence of experimental setup on modal analysis results was critically evaluated, by considering different actuators, contact and non-contact sensors and boundary/clamping conditions.ResultsThe classical viscous damping model describes with good approximation the damping properties of SLM lattice structures. When exciting single specimens in free-free conditions, those embedding lattice structure and unmelted metal powder filler were characterized by superior internal damping properties with respect to the specimens incorporating the lattice structure without any filler, which was however more effective than the full density equivalent material. Most of the other experimental setups introduced additional external damping sources, that could alter this important outcome.ConclusionsSLM lattice structures embedded into 3D printed components provide superior damping properties against mechanical and acoustic vibrations and the metal powder filler does significantly enhance such damping capacity. A correct estimation of material internal damping was achieved by applying non-contact sensors and free-free boundary conditions, whereas other experimental setups were partly inadequate.

Reliability Analysis of a Pulsed High Magnetic Field Facility at WHMFC

To accurately evaluate the reliability of Pulsed High Magnetic Field Facility (PHMFF) at the Wuhan National Pulsed High Magnetic Field Centre (WHMFC), a reliability analysis method based on a Markov chain is introduced in this paper. Because PHMFF is developed to generate a pulsed high magnetic field for scientific experiments by dynamically constructing diversified magnetic field systems, the reliability of PHMFF is in fact determined by the actual operating magnetic field system. Considering that all magnetic field systems are composed of pulsed power modules, magnets, control modules and experimental test systems, in this paper, the reliability of these critical modules is first discussed. In the analysis of modules, the failure mode and effect analysis (FMEA) method is used to determine the main failure modes, and then a Markov chain is established to analyze and calculate the reliability of the modules. Finally, based on the reliability of critical modules, the reliability of two typical magnetic field systems was estimated according to the reliability block diagram. The calculation results show that the reliability of all modules is above 95%, and although in complex magnetic field systems, the reliability still meets the experimental requirements.

An optimized parameter design method of SiC/Si hybrid switch considering turn-off current spike

In order to reduce the switching loss of SiC MOSFET/Si IGBT (SiC/Si) hybrid switch, the switching mode that turn off the Si IGBT prior to the SiC MOSFET is generally adopted to achieved the zero-voltage switching operation of IGBT. The minority carrier in N-base region of the IGBT are recombined in the form of exponential attenuation due to the conductivity modulation effect. When the SiC MOSFET is turned off, if the carrier recombination process of the IGBT is not finished, it needs to bear a large collector–emitter voltage change rate, resulting in apparent current spike. This current spike will increase the current stress of the device and produce additional turn-off loss. The equivalent model of double pulse test circuit of SiC/Si hybrid switch considering parasitic parameters is established, and the turn-off transient process is given analytically. The influence of turn-off delay time, circuit parameters and working conditions on current spike are analysed quantitatively. Combined with the consideration of device stress and comprehensive turn-off loss, an optimized circuit design method of SiC/Si hybrid switch considering turn-off current peak is proposed, which provides theoretical and design guidance for high reliability and high efficiency SiC/Si-based converters.