The Experts below are selected from a list of 1143 Experts worldwide ranked by ideXlab platform
Muhammad Nawaz - One of the best experts on this subject based on the ideXlab platform.
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analytical Pspice Model for sic mosfet based high power modules
Microelectronics Journal, 2016Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:Abstract A simple analytical Pspice Model has been developed and verified for a 4H–SiC based MOSFET power module with voltage and current ratings of 1200 V and 120 A. The analytical simulation Model is a temperature dependent silicon carbide (SiC) MOSFET Model that covers static and dynamic behavior, leakage current and breakdown voltage characteristics. The technology dependent MOSFET Modeling parameters are extracted from characterization measurements, datasheets and Pspice simulations at various temperatures. The SiC MOSFET Model is implemented in the Pspice circuit simulation platform using Pspice standard components and analog behavior Modeling (ABM) blocks. The MOSFET switching performance is investigated under influence of different circuit elements, such as stray inductance, gate resistance and temperature, in order to study and estimate on-state and switching losses pre-requisite for design of various converter and inverter topologies. The performance of the SiC MOSFET Model is fairly accurate and correlates well with the measured results over a wide temperature range.
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development of a simple analytical Pspice Model for sic based bjt power modules
IEEE Transactions on Power Electronics, 2016Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:A simple analytical Spice-type Model has been developed and verified for the first time for 4H-SiC-based bipolar junction transistor (BJT) power module with voltage and current rating of 1200 V and 800 A. The simulation Model is based on a temperature-dependent silicon carbide (SiC) Gummel–Poon Model for high-power applications. Pspice simulations are performed to extract technology-dependent Modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. Influence of various circuit elements, for instance, stray inductance and base resistance and internal device Modeling parameters, carrier life time, and emitter doping, on switching losses has been studied. The performance of the SiC BJT Model is fairly accurate and correlates well with the measured results over a wide temperature range.
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development of a Pspice Model for sic mosfet power modules
Materials Science Forum, 2016Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:In this paper, the static and dynamic characteristics of a 1200 V and 120 A silicon carbide (SiC) MOSFET power module has been measured, simulated and verified in the Pspice circuit simulation platform. Experimental measurements and Pspice simulations are performed to extract the technology dependent Modeling parameters. The Model is implemented in the Pspice circuit simulation platform using both standard components and analog behavior Modeling (ABM) blocks. The simulation results of the Model is fairly accurate and correlates well with the measured results over a wide temperature range. The developed Model is used to facilitate converter design at cell level and hence predict and optimize the cell performance (i.e., energy losses) with varying circuit parameters (e.g., stray inductances, temperatures, gate resistances etc.,).
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assessment of Pspice Model for commercial sic mosfet power modules
IEEE Workshop on Wide Bandgap Power Devices and Applications, 2015Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:In this paper, a circuit level simulation Model for SiC MOSFET power modules has been assessed. The static and dynamic characteristics of a 1.2 kV 800 A SiC MOSFET power module has been measured, simulated and verified in the Pspice circuit simulation platform. The SiC MOSFET power module is evaluated in two case studies, first where the power module is treated as a single device (simulated with one sub-module) and secondly where the performance of the power module is simulated as multiple MOSFET chips in parallel (multiple sub-modules). Here, the bond-wires between the chips are also included as inductive elements. The simulated static characteristics of the SiC MOSFET power module are well aligned with the measured data. In the first case, the simulation Model in Pspice shows accurate dynamic performance overall, with exceptions from high-frequency oscillations that arises during turn-on and turn-off. The second case study shows that the oscillations can be captured by introducing multiple MOSFET chips in parallel and where the bond-wires in between are represented by inductors. A slight increase of high-frequency oscillations is noticed but on the cost of reduced simulation robustness (e.g. convergence issues) due to a more complex simulation circuit. Finally, it is concluded that the simulation Model performance is overall accurate, both for static and dynamic performance. Further, the Model is capable to estimate on-state loss and switching loss in a satisfactory manner and is utilized to evaluate and optimize power electronic converter cell parameters, for instance stray inductance, gate resistance and temperature, and their impact on converter energy loss.
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development of a Pspice Model for 1200 v 800 a sic bipolar junction transistor power module
Materials Science Forum, 2015Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:The characteristics of a 1200 V and 800 A bipolar junction transistor (BJT) power module has been measured, simulated and verified for the first time in the Pspice platform. The simulation Model is based on a silicon carbide (SiC) Gummel-Poon Model for high power applications. The implemented Model has been extended with temperature dependent equations in order to extend the BJT operating temperature range. Pspice simulations are performed to extract technology dependent Modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. The performance of the SiC BJT Model is fairly accurate and correlates well with the measured results over a wide temperature range.
Daniel Johannesson - One of the best experts on this subject based on the ideXlab platform.
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analytical Pspice Model for sic mosfet based high power modules
Microelectronics Journal, 2016Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:Abstract A simple analytical Pspice Model has been developed and verified for a 4H–SiC based MOSFET power module with voltage and current ratings of 1200 V and 120 A. The analytical simulation Model is a temperature dependent silicon carbide (SiC) MOSFET Model that covers static and dynamic behavior, leakage current and breakdown voltage characteristics. The technology dependent MOSFET Modeling parameters are extracted from characterization measurements, datasheets and Pspice simulations at various temperatures. The SiC MOSFET Model is implemented in the Pspice circuit simulation platform using Pspice standard components and analog behavior Modeling (ABM) blocks. The MOSFET switching performance is investigated under influence of different circuit elements, such as stray inductance, gate resistance and temperature, in order to study and estimate on-state and switching losses pre-requisite for design of various converter and inverter topologies. The performance of the SiC MOSFET Model is fairly accurate and correlates well with the measured results over a wide temperature range.
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development of a simple analytical Pspice Model for sic based bjt power modules
IEEE Transactions on Power Electronics, 2016Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:A simple analytical Spice-type Model has been developed and verified for the first time for 4H-SiC-based bipolar junction transistor (BJT) power module with voltage and current rating of 1200 V and 800 A. The simulation Model is based on a temperature-dependent silicon carbide (SiC) Gummel–Poon Model for high-power applications. Pspice simulations are performed to extract technology-dependent Modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. Influence of various circuit elements, for instance, stray inductance and base resistance and internal device Modeling parameters, carrier life time, and emitter doping, on switching losses has been studied. The performance of the SiC BJT Model is fairly accurate and correlates well with the measured results over a wide temperature range.
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development of a Pspice Model for sic mosfet power modules
Materials Science Forum, 2016Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:In this paper, the static and dynamic characteristics of a 1200 V and 120 A silicon carbide (SiC) MOSFET power module has been measured, simulated and verified in the Pspice circuit simulation platform. Experimental measurements and Pspice simulations are performed to extract the technology dependent Modeling parameters. The Model is implemented in the Pspice circuit simulation platform using both standard components and analog behavior Modeling (ABM) blocks. The simulation results of the Model is fairly accurate and correlates well with the measured results over a wide temperature range. The developed Model is used to facilitate converter design at cell level and hence predict and optimize the cell performance (i.e., energy losses) with varying circuit parameters (e.g., stray inductances, temperatures, gate resistances etc.,).
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assessment of Pspice Model for commercial sic mosfet power modules
IEEE Workshop on Wide Bandgap Power Devices and Applications, 2015Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:In this paper, a circuit level simulation Model for SiC MOSFET power modules has been assessed. The static and dynamic characteristics of a 1.2 kV 800 A SiC MOSFET power module has been measured, simulated and verified in the Pspice circuit simulation platform. The SiC MOSFET power module is evaluated in two case studies, first where the power module is treated as a single device (simulated with one sub-module) and secondly where the performance of the power module is simulated as multiple MOSFET chips in parallel (multiple sub-modules). Here, the bond-wires between the chips are also included as inductive elements. The simulated static characteristics of the SiC MOSFET power module are well aligned with the measured data. In the first case, the simulation Model in Pspice shows accurate dynamic performance overall, with exceptions from high-frequency oscillations that arises during turn-on and turn-off. The second case study shows that the oscillations can be captured by introducing multiple MOSFET chips in parallel and where the bond-wires in between are represented by inductors. A slight increase of high-frequency oscillations is noticed but on the cost of reduced simulation robustness (e.g. convergence issues) due to a more complex simulation circuit. Finally, it is concluded that the simulation Model performance is overall accurate, both for static and dynamic performance. Further, the Model is capable to estimate on-state loss and switching loss in a satisfactory manner and is utilized to evaluate and optimize power electronic converter cell parameters, for instance stray inductance, gate resistance and temperature, and their impact on converter energy loss.
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development of a Pspice Model for 1200 v 800 a sic bipolar junction transistor power module
Materials Science Forum, 2015Co-Authors: Daniel Johannesson, Muhammad NawazAbstract:The characteristics of a 1200 V and 800 A bipolar junction transistor (BJT) power module has been measured, simulated and verified for the first time in the Pspice platform. The simulation Model is based on a silicon carbide (SiC) Gummel-Poon Model for high power applications. The implemented Model has been extended with temperature dependent equations in order to extend the BJT operating temperature range. Pspice simulations are performed to extract technology dependent Modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. The performance of the SiC BJT Model is fairly accurate and correlates well with the measured results over a wide temperature range.
Nicholas Sperelakis - One of the best experts on this subject based on the ideXlab platform.
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Propagation velocity profile in a cross-section of a cardiac muscle bundle from Pspice simulation
Theoretical Biology and Medical Modelling, 2006Co-Authors: Nicholas Sperelakis, Lakshminarayanan RamasamyAbstract:Background The effect of depth on propagation velocity within a bundle of cardiac muscle fibers is likely to be an important factor in the genesis of some heart arrhythmias. Model and methods The velocity profile of simulated action potentials propagated down a bundle of parallel cardiac muscle fibers was examined in a cross-section of the bundle using a Pspice Model. The Model (20 × 10) consisted of 20 chains in parallel, each chain being 10 cells in length. All 20 chains were stimulated simultaneously at the left end of the bundle using rectangular current pulses (0.25 nA, 0.25 ms duration) applied intracellularly. The simulated bundle was symmetrical at the top and bottom (including two grounds), and voltage markers were placed intracellularly only in cells 1, 5 and 10 of each chain to limit the total number of traces to 60. All electrical parameters were standard values; the variables were (1) the number of longitudinal gap-junction (G-j) channels (0, 1, 10, 100), (2) the longitudinal resistance between the parallel chains (R_ol2) (reflecting the closeness of the packing of the chains), and (3) the bundle termination resistance at the two ends of the bundle (R_BT). The standard values for R_ol2 and R_BT were 200 KΩ. Results The velocity profile was bell-shaped when there was 0 or only 1 gj-channel. With standard R_ol2 and R_BT values, the velocity at the surface of the bundle (θ_1 and θ_20) was more than double (2.15 ×) that at the core of the bundle (θ_10, θ_11). This surface:core ratio of velocities was dependent on the values of R_ol2 and R_BT. When R_ol2 was lowered 10-fold, θ_1 increased slightly and θ_2decreased slightly. When there were 100 gj-channels, the velocity profile was flat, i.e. the velocity at the core was about the same as that at the surface. Both velocities were more than 10-fold higher than in the absence of gj-channels. Varying R_ol2 and R_BT had almost no effect. When there were 10 gj-channels, the cross-sectional velocity profile was bullet-shaped, but with a low surface/core ratio, with standard R_ol2 and R_BT values. Conclusion When there were no or few gj-channels (0 or 1), the profile was bell-shaped with the core velocity less than half that at the surface. In contrast, when there were many gj-channels (100), the profile was flat. Therefore, when some gj-channels close under pathophysiological conditions, this marked velocity profile could contribute to the genesis of arrhythmias.
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Transverse propagation in an expanded Pspice Model for cardiac muscle with gap-junction ion channels
BioMedical Engineering OnLine, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Transverse propagation was previously found to occur in a two-dimensional Model of cardiac muscle using the Pspice software program for electronic circuit design and analysis. Longitudinal propagation within each chain, and transverse propagation between parallel chains, occurred even when there were no gap-junction (g-j) channels inserted between the simulated myocardial cells either longitudinally or transversely. In those studies, there were pronounced edge (boundary) effects and end-effects even within single chains. Transverse velocity increased with increase in Model size. The present study was performed to examine boundary effects on transverse propagation velocity when the length of the chains was held constant at 10 cells and the number of parallel chains was varied from 3 to 5, to 7, to 10, and to 20. The number of g-j channels was either zero, both longitudinally and transversely (0/0), or 100/100. Some experiments were also made at 100/0, 1/1, and 10/10. Transverse velocity and overall velocity (both longitudinal and transverse components) was calculated from the measured total propagation time (TPT), i.e., the elapsed time between when the first action potential (AP) and the last AP crossed the zero potential level. The transverse g-j channels were placed only at the ends of each chain, such that propagation would occur in a zigzag pattern. Electrical stimulation was applied intracellularly between cells A1 and A2. It was found that, with no g-j channels (0/0), overall velocity increased almost linearly when more and more chains were placed in parallel. In contrast, with many g-j channels (100/100), there was a much flatter relationship between overall velocity and number of parallel chains. The difference in velocities with 0/0 channels and 100/100 channels was reduced as the number of chains was increased. In conclusion, edges have important effects on propagation velocity (overall and transverse) in cardiac muscle simulations.
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Effect of transverse gap-junction channels on transverse propagation in an enlarged Pspice Model of cardiac muscle
Theoretical Biology and Medical Modelling, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Background In previous Pspice Modeling studies of simulated action potentials (APs) in parallel chains of cardiac muscle, it was found that transverse propagation could occur between adjacent chains in the absence of gap-junction (gj) channels, presumably by the electric field (EF) generated in the narrow interstitial space between the chains. Transverse propagation was sometimes erratic, the more distal chains firing out of order. Methods In the present study, the propagation of complete APs was studied in a 2-dimensional network of 100 cardiac muscle cells (10 × 10 Model). Various numbers of gj-channels (assumed to be 100 pS each) were inserted across the junctions between the longitudinal cells of each chain and between adjacent chains (only at the end cells of each chain). The shunt resistance produced by the gj-channels (R_gj) was varied from 100,000 MΩ (0 gj-channels) to 1,000 MΩ (10 channels), 100 MΩ (100 channels) and 10 MΩ (1,000 channels). Total propagation time (TPT) was measured as the difference between the times when the AP rising phase of the first cell (cell # A1) and the last cell (in the J chain) crossed 0 mV. When there were no gj-channels, the excitation was transmitted between cells by the EF, i.e., the negative potential generated in the narrow junctional clefts (e.g., 100 Å) when the prejunctional membrane fired an AP. For the EF mechanism to work, the prejunctional membrane must fire a fraction of a millisecond before the adjacent surface membrane. When there were many gj-channels (e.g., 100 or 1,000), the excitation was transmitted by local-circuit current flow from one cell to the next through these channels. Results TPT was measured as a function of four different numbers of transverse gj-channels, namely 0, 10, 100 and 1,000, and four different numbers of longitudinal gj-channels, namely 0, 10, 100 and 1,000. Thus, 16 different measurements were made. It was found that increasing the number of transverse channels had no effect on TPT when the number of longitudinal channels was low (i.e., 0 or 10). In contrast, when the number of longitudinal gj-channels was high (e.g., 100 or 1,000), then increasing the number of transverse channels decreased TPT markedly. Conclusion Thus, complete APs could propagate along a network of 100 cardiac muscle cells even when no gj-channels were present between the cells. Insertion of transverse gj-channels greatly speeded propagation through the 10 × 10 network when there were also many longitudinal gj-channels.
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effect of transverse gap junction channels on transverse propagation in an enlarged Pspice Model of cardiac muscle
Theoretical Biology and Medical Modelling, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Background In previous Pspice Modeling studies of simulated action potentials (APs) in parallel chains of cardiac muscle, it was found that transverse propagation could occur between adjacent chains in the absence of gap-junction (gj) channels, presumably by the electric field (EF) generated in the narrow interstitial space between the chains. Transverse propagation was sometimes erratic, the more distal chains firing out of order.
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Effect of transverse gap-junction channels on transverse propagation in an enlarged Pspice Model of cardiac muscle
Theoretical Biology and Medical Modelling, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Background: In previous Pspice Modeling studies of simulated action potentials (APs) in parallel chains of cardiac muscle, it was found that transverse propagation could occur between adjacent chains in the absence of gap-junction (gj) channels, presumably by the electric field (EF) generated in the narrow interstitial space between the chains. Transverse propagation was sometimes erratic, the more distal chains firing out of order. Methods: In the present study, the propagation of complete APs was studied in a 2-dimensional network of 100 cardiac muscle cells (10 × 10 Model). Various numbers of gj-channels (assumed to be 100 pS each) were inserted across the junctions between the longitudinal cells of each chain and between adjacent chains (only at the end cells of each chain). The shunt resistance produced by the gj-channels (Rgj) was varied from 100,000 MΩ (0 gj-channels) to 1,000 MΩ (10 channels), 100 MΩ (100 channels) and 10 MΩ (1,000 channels). Total propagation time (TPT) was measured as the difference between the times when the AP rising phase of the first cell (cell # A1) and the last cell (in the J chain) crossed 0 mV. When there were no gj-channels, the excitation was transmitted between cells by the EF, i.e., the negative potential generated in the narrow junctional clefts (e.g., 100 A) when the prejunctional membrane fired an AP. For the EF mechanism to work, the prejunctional membrane must fire a fraction of a millisecond before the adjacent surface membrane. When there were many gj-channels (e.g., 100 or 1,000), the excitation was transmitted by local-circuit current flow from one cell to the next through these channels. Results: TPT was measured as a function of four different numbers of transverse gj-channels, namely 0, 10, 100 and 1,000, and four different numbers of longitudinal gj-channels, namely 0, 10, 100 and 1,000. Thus, 16 different measurements were made. It was found that increasing the number of transverse channels had no effect on TPT when the number of longitudinal channels was low (i.e., 0 or 10). In contrast, when the number of longitudinal gj-channels was high (e.g., 100 or 1,000), then increasing the number of transverse channels decreased TPT markedly.
Lakshminarayanan Ramasamy - One of the best experts on this subject based on the ideXlab platform.
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Propagation velocity profile in a cross-section of a cardiac muscle bundle from Pspice simulation
Theoretical Biology and Medical Modelling, 2006Co-Authors: Nicholas Sperelakis, Lakshminarayanan RamasamyAbstract:Background The effect of depth on propagation velocity within a bundle of cardiac muscle fibers is likely to be an important factor in the genesis of some heart arrhythmias. Model and methods The velocity profile of simulated action potentials propagated down a bundle of parallel cardiac muscle fibers was examined in a cross-section of the bundle using a Pspice Model. The Model (20 × 10) consisted of 20 chains in parallel, each chain being 10 cells in length. All 20 chains were stimulated simultaneously at the left end of the bundle using rectangular current pulses (0.25 nA, 0.25 ms duration) applied intracellularly. The simulated bundle was symmetrical at the top and bottom (including two grounds), and voltage markers were placed intracellularly only in cells 1, 5 and 10 of each chain to limit the total number of traces to 60. All electrical parameters were standard values; the variables were (1) the number of longitudinal gap-junction (G-j) channels (0, 1, 10, 100), (2) the longitudinal resistance between the parallel chains (R_ol2) (reflecting the closeness of the packing of the chains), and (3) the bundle termination resistance at the two ends of the bundle (R_BT). The standard values for R_ol2 and R_BT were 200 KΩ. Results The velocity profile was bell-shaped when there was 0 or only 1 gj-channel. With standard R_ol2 and R_BT values, the velocity at the surface of the bundle (θ_1 and θ_20) was more than double (2.15 ×) that at the core of the bundle (θ_10, θ_11). This surface:core ratio of velocities was dependent on the values of R_ol2 and R_BT. When R_ol2 was lowered 10-fold, θ_1 increased slightly and θ_2decreased slightly. When there were 100 gj-channels, the velocity profile was flat, i.e. the velocity at the core was about the same as that at the surface. Both velocities were more than 10-fold higher than in the absence of gj-channels. Varying R_ol2 and R_BT had almost no effect. When there were 10 gj-channels, the cross-sectional velocity profile was bullet-shaped, but with a low surface/core ratio, with standard R_ol2 and R_BT values. Conclusion When there were no or few gj-channels (0 or 1), the profile was bell-shaped with the core velocity less than half that at the surface. In contrast, when there were many gj-channels (100), the profile was flat. Therefore, when some gj-channels close under pathophysiological conditions, this marked velocity profile could contribute to the genesis of arrhythmias.
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Transverse propagation in an expanded Pspice Model for cardiac muscle with gap-junction ion channels
BioMedical Engineering OnLine, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Transverse propagation was previously found to occur in a two-dimensional Model of cardiac muscle using the Pspice software program for electronic circuit design and analysis. Longitudinal propagation within each chain, and transverse propagation between parallel chains, occurred even when there were no gap-junction (g-j) channels inserted between the simulated myocardial cells either longitudinally or transversely. In those studies, there were pronounced edge (boundary) effects and end-effects even within single chains. Transverse velocity increased with increase in Model size. The present study was performed to examine boundary effects on transverse propagation velocity when the length of the chains was held constant at 10 cells and the number of parallel chains was varied from 3 to 5, to 7, to 10, and to 20. The number of g-j channels was either zero, both longitudinally and transversely (0/0), or 100/100. Some experiments were also made at 100/0, 1/1, and 10/10. Transverse velocity and overall velocity (both longitudinal and transverse components) was calculated from the measured total propagation time (TPT), i.e., the elapsed time between when the first action potential (AP) and the last AP crossed the zero potential level. The transverse g-j channels were placed only at the ends of each chain, such that propagation would occur in a zigzag pattern. Electrical stimulation was applied intracellularly between cells A1 and A2. It was found that, with no g-j channels (0/0), overall velocity increased almost linearly when more and more chains were placed in parallel. In contrast, with many g-j channels (100/100), there was a much flatter relationship between overall velocity and number of parallel chains. The difference in velocities with 0/0 channels and 100/100 channels was reduced as the number of chains was increased. In conclusion, edges have important effects on propagation velocity (overall and transverse) in cardiac muscle simulations.
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Effect of transverse gap-junction channels on transverse propagation in an enlarged Pspice Model of cardiac muscle
Theoretical Biology and Medical Modelling, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Background In previous Pspice Modeling studies of simulated action potentials (APs) in parallel chains of cardiac muscle, it was found that transverse propagation could occur between adjacent chains in the absence of gap-junction (gj) channels, presumably by the electric field (EF) generated in the narrow interstitial space between the chains. Transverse propagation was sometimes erratic, the more distal chains firing out of order. Methods In the present study, the propagation of complete APs was studied in a 2-dimensional network of 100 cardiac muscle cells (10 × 10 Model). Various numbers of gj-channels (assumed to be 100 pS each) were inserted across the junctions between the longitudinal cells of each chain and between adjacent chains (only at the end cells of each chain). The shunt resistance produced by the gj-channels (R_gj) was varied from 100,000 MΩ (0 gj-channels) to 1,000 MΩ (10 channels), 100 MΩ (100 channels) and 10 MΩ (1,000 channels). Total propagation time (TPT) was measured as the difference between the times when the AP rising phase of the first cell (cell # A1) and the last cell (in the J chain) crossed 0 mV. When there were no gj-channels, the excitation was transmitted between cells by the EF, i.e., the negative potential generated in the narrow junctional clefts (e.g., 100 Å) when the prejunctional membrane fired an AP. For the EF mechanism to work, the prejunctional membrane must fire a fraction of a millisecond before the adjacent surface membrane. When there were many gj-channels (e.g., 100 or 1,000), the excitation was transmitted by local-circuit current flow from one cell to the next through these channels. Results TPT was measured as a function of four different numbers of transverse gj-channels, namely 0, 10, 100 and 1,000, and four different numbers of longitudinal gj-channels, namely 0, 10, 100 and 1,000. Thus, 16 different measurements were made. It was found that increasing the number of transverse channels had no effect on TPT when the number of longitudinal channels was low (i.e., 0 or 10). In contrast, when the number of longitudinal gj-channels was high (e.g., 100 or 1,000), then increasing the number of transverse channels decreased TPT markedly. Conclusion Thus, complete APs could propagate along a network of 100 cardiac muscle cells even when no gj-channels were present between the cells. Insertion of transverse gj-channels greatly speeded propagation through the 10 × 10 network when there were also many longitudinal gj-channels.
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effect of transverse gap junction channels on transverse propagation in an enlarged Pspice Model of cardiac muscle
Theoretical Biology and Medical Modelling, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Background In previous Pspice Modeling studies of simulated action potentials (APs) in parallel chains of cardiac muscle, it was found that transverse propagation could occur between adjacent chains in the absence of gap-junction (gj) channels, presumably by the electric field (EF) generated in the narrow interstitial space between the chains. Transverse propagation was sometimes erratic, the more distal chains firing out of order.
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Effect of transverse gap-junction channels on transverse propagation in an enlarged Pspice Model of cardiac muscle
Theoretical Biology and Medical Modelling, 2006Co-Authors: Lakshminarayanan Ramasamy, Nicholas SperelakisAbstract:Background: In previous Pspice Modeling studies of simulated action potentials (APs) in parallel chains of cardiac muscle, it was found that transverse propagation could occur between adjacent chains in the absence of gap-junction (gj) channels, presumably by the electric field (EF) generated in the narrow interstitial space between the chains. Transverse propagation was sometimes erratic, the more distal chains firing out of order. Methods: In the present study, the propagation of complete APs was studied in a 2-dimensional network of 100 cardiac muscle cells (10 × 10 Model). Various numbers of gj-channels (assumed to be 100 pS each) were inserted across the junctions between the longitudinal cells of each chain and between adjacent chains (only at the end cells of each chain). The shunt resistance produced by the gj-channels (Rgj) was varied from 100,000 MΩ (0 gj-channels) to 1,000 MΩ (10 channels), 100 MΩ (100 channels) and 10 MΩ (1,000 channels). Total propagation time (TPT) was measured as the difference between the times when the AP rising phase of the first cell (cell # A1) and the last cell (in the J chain) crossed 0 mV. When there were no gj-channels, the excitation was transmitted between cells by the EF, i.e., the negative potential generated in the narrow junctional clefts (e.g., 100 A) when the prejunctional membrane fired an AP. For the EF mechanism to work, the prejunctional membrane must fire a fraction of a millisecond before the adjacent surface membrane. When there were many gj-channels (e.g., 100 or 1,000), the excitation was transmitted by local-circuit current flow from one cell to the next through these channels. Results: TPT was measured as a function of four different numbers of transverse gj-channels, namely 0, 10, 100 and 1,000, and four different numbers of longitudinal gj-channels, namely 0, 10, 100 and 1,000. Thus, 16 different measurements were made. It was found that increasing the number of transverse channels had no effect on TPT when the number of longitudinal channels was low (i.e., 0 or 10). In contrast, when the number of longitudinal gj-channels was high (e.g., 100 or 1,000), then increasing the number of transverse channels decreased TPT markedly.
Hong Li - One of the best experts on this subject based on the ideXlab platform.
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a non segmented Pspice Model of sic mosfet with temperature dependent parameters
IEEE Transactions on Power Electronics, 2019Co-Authors: Hong Li, Xingran Zhao, Zhengming Zhao, Trillion Q ZhengAbstract:A non-segmented Pspice Model of silicon carbide metal-oxide semiconductor field effect transistor (SiC mosfet ) with temperature-dependent parameters is proposed in this paper, which can improve the Model's convergence and temperature characteristics. The non-segmented equations and the parameter-extraction method for the proposed SiC mosfet Pspice Model are introduced first. Simulation and experiment results are given to verify the correctness of the Model while considering the temperature-dependent parameters. The static characteristics of the Model are verified by comparing the simulation curves with the static characteristic curves in the SiC mosfet 's datasheet, and its dynamic characteristics are verified by comparing the simulation results with experimental results under different ambient temperatures (25, 75, and 125 °C) based on a double-pulse test platform. Moreover, the proposed non-segmented Model, the conventional segmented Model, and the Model from the manufacturer are adopted and simulated in a full-bridge inverter. The simulation results show better convergence of the proposed non-segmented Model. Therefore, an accurate and practical simulation Model of SiC mosfet is provided for circuit design in this paper.
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a non segmented Pspice Model of sic mosfets
Conference of the Industrial Electronics Society, 2017Co-Authors: Hong Li, Xingran ZhaoAbstract:To solve the simulation convergence problem of Silicon Carbide metal-oxide semiconductor field effect transistor (SiC MOSFET) Models, this paper proposes a non-segmented Model for SiC MOSFETs, which uses non-segmented, smooth continuous equations to describe the static and dynamic characteristics of SiC MOSFET. Further, the static characteristic of SiC MOSFET obtained by the non-segmented Model is verified by comparing the simulation curves with the static curves provided in datasheet, and the dynamic characteristic is verified by comparing the simulation rise time and fall time of voltage with the datasheet based on the double pulse simulation circuit. The accuracy and good convergence of non-segmented Model provide a good way to research the power converters with SiC MOSFETs by simulation way.
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IECON - A non-segmented Pspice Model of SiC MOSFETs
IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society, 2017Co-Authors: Hong Li, Xingran ZhaoAbstract:To solve the simulation convergence problem of Silicon Carbide metal-oxide semiconductor field effect transistor (SiC MOSFET) Models, this paper proposes a non-segmented Model for SiC MOSFETs, which uses non-segmented, smooth continuous equations to describe the static and dynamic characteristics of SiC MOSFET. Further, the static characteristic of SiC MOSFET obtained by the non-segmented Model is verified by comparing the simulation curves with the static curves provided in datasheet, and the dynamic characteristic is verified by comparing the simulation rise time and fall time of voltage with the datasheet based on the double pulse simulation circuit. The accuracy and good convergence of non-segmented Model provide a good way to research the power converters with SiC MOSFETs by simulation way.
