Behavioral IGBT Modeling for Predicting High Frequency Effects in Motor Drives

A first-order behavioral IGBT/gate drive model is proposed together with a procedure for deriving all model parameters. Despite the simplicity of the proposed model, comparison of model predictions with hardware measurements demonstrate the model to be accurate in predicting turn-on and turn-off transients

Wide-Bandwidth Multi-Resolutional Analysis of a Surface-Mounted PM Synchronous Machine

Advances in power semiconductor devices have led to inverters with unprecedented voltage edge rates. This has decreased inverter switching losses and enabled the use of increasingly higher switching frequencies. However, faster edge rates and higher switching frequencies increase electromagnetic compatibility (EMC) problems, machine insulation stress, bearing currents, and other aspects of system design. Typical computer simulations used to design and evaluate proposed electric drive systems cannot be used to predict these high-frequency effects. A wide-bandwidth multi-resolutional analysis that allows designers to anticipate and quantify high-frequency effects is detailed in this paper. The approach is specifically applied to permanent magnet synchronous machine drives, and is validated experimentally

Differential Signalling in PCBs: Modeling and Validation of Dielectric Losses and Effects of Discontinuities

This paper focuses on differential signal transmission above ground planes with gaps, taking into account the dielectric and conductive losses of the substrate. An equivalent lumped-circuit is proposed and its suitability is investigated by comparing the obtained numerical results with the measured data. Furthermore the differential to common mode conversion of the waves, while crossing the gap, is theoretically analyzed and experimentally verified

Efficient Modeling of Discontinuities and Dispersive Media in Printed Transmission Lines

The finite-difference time-domain method is applied to the analysis of transmission lines on printed circuit boards. The lossy, dispersive behavior of the dielectric substrate is accurately accounted for by means of several algorithms whose accuracy is discussed and compared. Numerical results are validated by comparisons with measurements and an equivalent circuit of slot in the ground plane is proposed

Physics-Based Modeling for Determining Transient Current Flow in Multi-Layer Pcb Pi Designs

A physics-based modeling methodology for determining the transient current flow path in multi-layer PI designs is given in this paper using a commercial board with a complicated structure as an example. Board structure analysis is done first to provide a physical basis of post-layout analytical and equivalent circuit modeling. A match of the PDN impedance between commercial tool simulation, post-layout analytical calculation, and the physics-based equivalent circuit modeling was achieved to support the model for the transient simulation. By analyzing the current response in all the vias, a clear representation of transient current flow across all via segments can be given layer-by-layer. The maximum current density in vertical vias can also be extracted in this process, providing a reference for preventing transient overcurrent design

Identifying an EMI Source and Coupling Path in a Computer System with Sub-Module Testing

EMI in a workstation server resulting from CPU clock harmonics was investigated. Mechanisms by which noise is coupled off the CPU PCB module were diagnosed from studies and measurements on the CPU PCB alone. A model was then developed. Modifications were made and tested in the fully functional system to support the model

Analysis of the Genome and Mobilome of a Dissimilatory Arsenate Reducing Aeromonas sp. O23A Reveals Multiple Mechanisms for Heavy Metal Resistance and Metabolism

Aeromonas spp. are among the most ubiquitous microorganisms, as they have been isolated from different environmental niches including waters, soil, as well as wounds and digestive tracts of poikilothermic animals and humans. Although much attention has been paid to the pathogenicity of Aeromonads, the role of these bacteria in environmentally important processes, such as transformation of heavy metals, remains to be discovered. Therefore, the aim of this study was a detailed genomic characterization of Aeromonas sp. O23A, the first representative of this genus capable of dissimilatory arsenate reduction. The strain was isolated from microbial mats from the Zloty Stok mine (SW Poland), an environment strongly contaminated with arsenic. Previous physiological studies indicated that O23A may be involved in both mobilization and immobilization of this metalloid in the environment. To discover the molecular basis of the mechanisms behind the observed abilities, the genome of O23A (∼5.0 Mbp) was sequenced and annotated, and genes for arsenic respiration, heavy metal resistance (hmr) and other phenotypic traits, including siderophore production, were identified. The functionality of the indicated gene modules was assessed in a series of minimal inhibitory concentration analyses for various metals and metalloids, as well as mineral dissolution experiments. Interestingly, comparative analyses revealed that O23A is related to a fish pathogen Aeromonas salmonicida subsp. salmonicida A449 which, however, does not carry genes for arsenic respiration. This indicates that the dissimilatory arsenate reduction ability may have been lost during genome reduction in pathogenic strains, or acquired through horizontal gene transfer. Therefore, particular emphasis was placed upon the mobilome of O23A, consisting of four plasmids, a phage, and numerous transposable elements, which may play a role in the dissemination of hmr and arsenic metabolism genes in the environment. The obtained results indicate that Aeromonas sp. O23A is well-adapted to the extreme environmental conditions occurring in the Zloty Stok mine. The analysis of genome encoded traits allowed for a better understanding of the mechanisms of adaptation of the strain, also with respect to its presumable role in colonization and remediation of arsenic-contaminated waters, which may never have been discovered based on physiological analyses alone

An Impact of Layer Stack-up on EMI

Investigation of a server shows the heatsink of the CPU module as a primary component of the EMI coupling path. In order to identify the specific noise source and coupling path to the heatsink, a series of experiments were defined to provide support for one source and eliminate others. Based on experiments with two different versions of the CPU module, a stack-up related design guideline is proposed: a ground layer should be the first entire plane (as opposed to Vcc) on the active component side of the board. If there are known IC sources that switch significant currents with the outputs unloaded at nanosecond rise and fall times on both sides of the board, then ground should be the first entire plane on both sides of the board when feasible

An EMI Estimate for Shielding-Enclosure Evaluation

A relatively simple, closed-form expression has been developed to estimate the EMI from shielding enclosures due to coupling from interior sources through slots and apertures at the enclosure cavity modes. A power-balance method, Bethe\u27s (1944) small-hole theory, and empirically developed formulas for the relation between radiation, and slot length and number of slots, were employed to estimate an upper bound on the radiated EMI from shielding enclosures. Comparisons between measurements and estimated field strengths suitably agree within engineering accuracy

Effects of Gapped Groundplanes and Guard Traces on Radiated EMI

Designers sometimes employ gapped reference planes to isolate analog and digital signals, and separate quiet and noisy ground structures by providing a series impedance. Guard traces are also used to reduce unwanted coupling to adjacent traces, which can lead to signal integrity or EMI problems. This study investigates the impact of gaps and guard traces on radiated EMI. A simple microstrip circuit was constructed to experimentally analyze the effects of groundplane gaps and guard traces