Stray Inductance Research Articles

Impact of the Physical Layout of High-Current Rectifiers on Current Division and Magnetic Field Using PEEC Method

This paper addresses some problems linked to the physical layout of high-current rectifiers: paralleling components, magnetic field close to the rectifier, and also the validation of the physical layout at reduced current. Even if the impact of cabling stray inductance is well known, some new tools and methodology are available today to design quicker and safer physical layout of such high-current rectifiers.

脉冲激光器大电流窄脉冲驱动设计

The principle of high power MOSFET generating high-current narrow-width pulses to drive laser diode is theoretically analyzed, and the formula of MOSFET gate drive current and the estimation formula of MOSFET drive rise time are obtained. The key factors which influence the laser diode(LD) power supply current width, amplitude and oscillation are summarized through simulation. Theory and simulation show that components stray inductance, circuit routing inductance and load inductance influence the drive current greatly. Experiment results show that the MOSFET switch-on time is about 2 ns at the drain-source voltage of 200 V. The LD drive power supply’s pulse current possesses a rise-time less than 10 ns, with the pulse width, amplitude and frequency ranging in 15～100 ns， 0～50 A and 0～5

Power Electronics Design Laboratory Exercise for Final-Year M.Sc. Students

This paper presents experiences and results from a project task in power electronics for students at Chalmers University of Technology, Goteborg, Sweden, based on a flyback test board. The board is used in the course Power Electronic Devices and Applications. In the project task, the students design snubber circuits, improve the control of the output voltage, improve the gate drive of the main MOSFET transistor and study the influence of stray inductance. The project goals (the circuit improvements) are given, but the procedure for solving the problems and obtaining the results is not specified. Instead the students have to make their own specification in order to reach the goals. ldquoToolsrdquo that are given to the students are the hardware, measurement equipment, an example of the circuit in the circuit simulation software PSpice, and lastly lectures covering the material needed in order to attain the project goals. The project design builds on the ideas from the CDIO (Conceive, Design, Implement, Operate) initiative, where students are encouraged to consider the complete process structure. The result found was a substantial engagement by the students, who had both positive and negative reactions. The negative reactions were mainly that the project specification was too vague, in other words in the (C=Conceive)-phase of the CDIO structure. Further, the teachers observed increased learning, which also was noticeable for the students performing their M.Sc. thesis within the power electronics design area. Finally, it was found that a final written exam is definitely still needed to assess students adequately in the course.

VSC-Based D-STATCOM With Selective Harmonic Elimination

This paper describes the design, implementation, and performance of a medium-size distribution-type static synchronous compensator (D-STATCOM) with the simplest two-level three-leg voltage-source converter (VSC) topology. Reactive-power control is achieved by phase-shift-angle control, and VSC harmonics are eliminated by selective harmonic elimination method (SHEM). VSC has been designed at the highest low-voltage level of 1 kV and connected to a medium-voltage (MV) bus through a low-pass input filter and Delta/Y-connected MV/1-kV coupling transformer. At the MV side of D-STATCOM, line-current harmonics are minimized to comply with the IEEE Std. 519-1992 for the weakest supply conditions by applying 8-angle TLN2 elimination technique. This necessitates switching the water-cooled high-voltage insulated-gate bipolar transistor (HV-IGBT) modules at 850 Hz, thus eliminating 5th, 7th, 11th, 13th, 17th, 19th, 23rd, and 25th voltage harmonics at the input of VSC. By carefully designing the laminated bus system and selecting minimum stray-inductance dc-link capacitors directly mountable on the laminated bus, stray inductance of the commutation path is brought to a nearly absolute minimum of 60 nH, thus maximizing the utilization of wire-bond single-side cooled HV IGBTs and eliminating the need for resistor-capacitor-diode (RCD) clamping snubbers. The performance of SHEM, together with the phase-shift-angle control, has been tested in the field on a 0-1780-kVAr capacitive 6.3-kV VSC-based D-STATCOM (-750/+900 kVAr VSC) prototype. Field-test results show that SHEM, together with phase-shift-angle control, leads to optimum switching frequency and device utilization for HV IGBTs and high system performance at the expense of slower response as compared to the other known control techniques.

Electromagnetic Considerations for Designing Double-Sided Power Modules

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Double-sided power modules are particularly attractive due to their high thermal performance. Thanks to the stacking of two direct bond coppers, very low stray inductances may be expected, particularly because of the proximity of the two rear metalizations. On the other hand, capacitive effects may be increased. In this paper, the complete electromagnetic behavior of double-sided power modules is studied, regarding both internal coupling and unwanted electromagnetic compatibility emissions. Some layout and active solutions are proposed to reduce common-mode emissions. </para>

Improved Switching Characteristics of Fast Power MOSFETs Applying Solder Bump Technology

The impact of a reduced package stray inductance on the switching performance of fast power MOSFETs is discussed applying advanced 3D packaging technologies. Starting from an overview over new packaging approaches, a solder bump technology using a flexible PI substrate is exemplarily chosen for the evaluation. Measurement techniques to determine the stray inductance are discussed and compared with a numerical solution based on the PEEC method. Experimental results show the improvement of the voltage utilization while there is only a slight impact on total switching losses.

Improvement of diagnostic techniques and electrical circuit in azo dye degradation by high voltage electrical discharge

Fast electrical diagnostics and improvement of electrical circuits for methyl orange (MO) degradation by high voltage pulsed electrical discharge were investigated. To eliminate electromagnetic radiation, several effective methods were employed. RG 218 coaxial cable was substituted for the common transmission lines to transmit high voltage pulses, and multi-lines in parallel were earthed to avoid electromagnetic interference and, additionally, to reduce the stray inductance of the electrical circuit and increase the pulse rise rate to reduce the energy losses in the transmission system. The problem of the differences in the bandwidths of voltage and current probes causing an error in the calculation of energy dissipation was avoided by reducing the bandwidths of voltage and current measurements to the same value. The real discharge current was obtained by subtracting the capacitive current from the total current. The energy per pulse obtained in the reactor before and after improvement of the diagnostics and electrical circuit were 15.5 mJ and 26.8 mJ, respectively, and the energy efficiencies of MO degradation were 1.34 × 10 −9 mol/J and 1.95 × 10 −9 mol/J, respectively.

短波ＡＭ送信機用高効率電力増幅器の開発

This paper describes development of a High efficiency HF power amplifier. We fabricated a new wideband power amplifier operating at short wave band (3 MHz-26 MHz) using class-E amplifier and obtained a high output power efficiency of 74% at 25.5 MHz that is a target performance by controlling the shunt capacity for wideband operation. In addition, the low loss characteristic of about 0.4 dB and under and wideband characteristics was obtained by employing the balun using the transformer with coaxial cables and output circuit combiner tuned including stray capacitance and inductance.

Performance Evaluation of Switch Devices Equipped in High-Power Three-Level Inverters

The feature of the integrated gate-commutated thyristors (IGCTs) makes them have excellent performance in high-voltage high-current field. The high integration of drives and devices makes it very convenient to use them. In order to examine the dynamic characters of switch devices in high-power three-level inverter, an experimental test for IGCTs and diodes equipped in inverter is proposed and described in detail. The characteristics of switch devices are compared and evaluated experimentally. The relation between the devices' switching behavior and the other elements in the inverter, such as the inverter's structure, the topology position of devices, the stray inductances in commutating loops, etc., are analyzed. Moreover, the busbar structure is improved, and the key pulsewidth-modulation parameter of the inverter is determined. Finally, the advantages of the experiment are summarized in the conclusion.

Experimental and Numerical Analysis of Stray Field From Transformers

We present an assessment of a numerical methodology for evaluating stray fields from transformers by direct comparison with experimental results. The methodology can help to ensure compliance with the limits imposed by national and international laws and regulations on the levels of magnetic fields. We conducted validation experiments on a 1000-kVA cast-resin transformer. All measurements were performed in an anechoic room, in short-circuit conditions, along different directions in space. We compared two different numerical methods, based on linear and nonlinear 3-D finite-element methods, respectively, with the experimental results. Agreement with the measurements was very good. Numerical tools can be considered a valid alternative to measurements for the analysis of the stray magnetic induction field and for the design of shielded devices.

Simulation of 3-Staged MPC Using Custom Characteristics of Magnetic Cores

A low inductance circuit has been fabricated in order to obtain shorter time to saturation during core unsaturation and current pulses with shorter widths during core saturation. B-H curves have been derived from the measured voltage and current waveforms. Characteristics of the magnetic core for pulsed-power generators have been investigated and the Electromagnetic Transient Program (EMTP) simulation has been carried out in order to determine the effects of leakage current on the energy efficiency of a 3-staged magnetic pulse compressor (MPC). As results, the derived B-H curves show the following characteristics: a high ratio of unsaturated to saturated permeability (mu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">un</sub> /mu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> ), a maximum flux swing of about 2.55 T, a high ratio of remanent flux density to saturation magnetic flux density (B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> /B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) and low core loss. And, it is found that mu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">un</sub> increases with time to saturation and that mu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> is strongly influenced by the stray inductances of the core. By applying custom characteristics to each stage in EMTP simulation, more practical energy transfer in MPC is obtained.

Shielded-Loop-Type Onchip Magnetic-Field Probe to Evaluate Radiated Emission From Thin-Film Noise Suppressor

A silicon integrated RF magnetic field probe has been designed and microfabricated using CMOS-silicon-on-insulator (SOI) technology with a 0.15-mum design rule on a high-resistivity silicon substrate. The size of the coil window was 180times180 mum <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Coil and electrodes were separated by a 530-mum-long stripline so as to avoid stray voltage induction at the electrode portion. This probe was applied to evaluate the radiated emission from a thin-film electromagnetic noise suppressor. It was clarified and shown that the field intensity was suppressed by 4.0 dB at the center of the signal line at 1 GHz

Analysis of Electromagnetic Coupling and Current Distribution Inside a Power Module

Due to high-current commutation speed, it has become necessary to minimize stray inductances to reduce over-voltage. This is a great challenge for the power-converter designer. Integration of converters into ever smaller packages decreases stray inductance considerably but, at the same time, increases other phenomena (thermal issues and electromagnetic-compatibility disturbances) capable of decreasing reliability and efficiency of the system. This paper presents a generic equivalent cabling model and examines the impact of parasitic inductance on current-distribution imbalance. This paper could, therefore, be used in thermal analysis in order to better understand the influence of packaging.

Simulation and Optimization of Diode and Insulated Gate Bipolar Transistor Interaction in a Chopper Cell Using MATLAB and Simulink

Recently, a simulation method for power electronic devices has emerged, which has high accuracy and short run times based on a Fourier model of the device physics. This paper describes the use of the Fourier models for diodes and insulated gate bipolar transistors (IGBTs) and implementation in MATLAB and Simulink in a formal optimization strategy. In particular, this paper investigates coupled circuit, diode, and IGBT behavior. Conclusions are drawn concerning device loading and circuit design, particularly the role of stray inductance.

HF Characterization and Nonlinear Modeling of a Gapped Toroidal Magnetic Structure

The frequency dependent characteristics of a gapped toroidal structure are extracted empirically over a bandwidth that exceeds 30 MHz. The analysis is complicated due to non-linear flux distributions, magnetic properties of the core material, leakage inductance, stray capacitances and eddy currents in the windings. A permeance model of the core is implemented to model the magnetic circuit. The model includes a linear lumped element equivalent circuit to approximate the non-linear complex permeability of the core, which was measured empirically. Stray capacitance and inductance of the winding are also modeled. A gyrator is used to couple the electric and magnetic models for circuit simulation. The measured and simulated results of open-circuit impedance from the secondary winding and the transimpedance gain (V/A) of the current sensor are compared and discussed

Voltage Distribution Analysis of 500-kV DC Transmission-Line Voltage Divider Under Impulse Voltages: Stray Parameter Extraction

It is essential to extract the stray parameters accurately and efficiently in analyzing impulse responses of a power apparatus. In this paper the stray capacitances and stray inductances of a 500-kV dc transmission-line voltage divider are extracted by the hybrid finite element-analytical approach, and the corresponding equivalent circuit for analyzing the impulse voltage response of the voltage divider is established. According to the discussion of the results of the extracted stray parameters of the voltage divider, reasonable simplification of the equivalent circuit of the voltage divider is made. In addition, the influence of the insulating housing and the electrical insulation oil on the stray capacitances of the voltage divider is discussed.

Impedance criterion for power modules comparison

It is well known that power modules must exhibit as low as possible stray inductance. However, the total inductance of a power module is not the only parameter to indicate the electrical quality of the packaging. In this paper, mathematical criteria will be given, which will allow the evaluation of power modules interconnects with regard to several objectives: equal current constraints among the different paralleled dies, power-drive, and even drive-drive interactions.

Challenges in Using the Latest Generation of IGBTs in Traction Converters

SummaryThe voltage class 6.5kV was the last step to now cover completely the whole range of voltages for traction starting with 1.7kV and 3.3kV. This lead to the general introduction of the IGBT across the whole power range of traction. In first IGBT generations the Non Punch Through design dominated here. The latest generation of IGBTs feature characteristics like field-stop design or trench design. Thus high cosmic ray withstand capability can be combined with low VCesat.For the high-power high-voltage application as used in traction, the introduction of the field stop leads to a significant change in the switching behavior compared to the conventional NPT-design. It will be shown how the IGBT and diode turn-off characteristics change and how sensitive it is to parasitic circuit characteristics. Especially in high-power circuits with relatively large stray inductances, this is a device and application challenge. Further more it will be shown that the IGBT overvoltage during turn-off transients can be controlled only by using a highly dynamic gate driver. Since no active control ofthe diode turn-offis possible, the peak-voltage must be limited by appropriate circuit and device design. For new generations of IGBT and diode, this behavior should be considered carefully by the semiconductor development.

Direct integration of GaAs HEMTs on AlN ceramic substrates using fluidic self-assembly

Direct integration of AlGaAs/GaAs HEMTs on AlN ceramic substrates has been demonstrated based on the fluidic self-assembly (FSA) technology. The FSA is a unique technology to arrange small device blocks (around a few tens of microns) onto the other substrates. With this technology the core part of the HEMT having no pad can be mounted on the ceramic substrate. The HEMT core can then be connected electrically with the circuit on a ceramic substrate using a planar wiring process. This eliminates large stray capacitance and inductance in the conventional technology. It has been demonstrated that the good FET characteristics are obtained even after FSA process.

Development of a charge-carrier drift velocity measurement system in diamonds by using a UV pulse laser

There are continuing efforts of developing faster FETs and diamond is one of the strong candidates as a base semiconductor. Since the upper-limit-frequency of diamond FETs determines saturated drift velocities of charge-carriers, we need to first characterize diamond to develop better FETs. It is, however, not easy to measure the velocities with response time of less than 20 ns. Therefore, we developed a drift velocity measurement system using a time-of-flight (TOF) technique with a UV laser with 100 ps pulse width. In order to realize response times faster than 20 ns, we employed a 50 Ω coaxial cable as a load, with which we could effectively reduce the stray capacitance and inductance, and also, suppress reflections in the signal which gives false signals. As a result, we can measure carrier-transit times shorter than 10 ns.