Stray Inductance Research Articles

Wide Bandgap 소자의 안정적 구동을 위한 하드웨어 최적 설계 및 구현

In this paper, the GaN FET based phase-shift full-bridge dc-dc converter design is implemented. Switch characteristics of GaN FET were analyzed in detail by comparing state-of-the-art Si MOSFET. Owing to the low conduction resistance and parasitic capacitance, it is expected to GaN FET based power conversion system has improved performance. However, GaN FET is vulnerable to electric interference due to the relatively low threshold voltage and fast switching transient. Therefore, it is necessary to consider PCB layout to design GaN FET based power system because PCB layout is the main reason of stray inductance. To reduce the electric noise, gate voltage of GaN FET is analyzed according to operation mode of phase-shift full-bridge dc-dc converter. Two 600W phase-shifted full-bridge dc-dc converter are designed based on the result to evaluate effects of stray inductance.

Development of an ANN-Based Pressure Transducer

This paper presents the development of an artificial neural network (ANN)-based improved inductive signal conditioning circuit for pressure transducer with bellow as sensor. A bellow is an elastic-type mechanical pressure sensor. The deflection of the bellow due to applied pressure must be translated into an efficient electrical signal for continuous monitoring, wireless transmission, and digital readout. A ferromagnetic wire attached to the bellow as a part of an inductive coil arrangement, gets deflected due to applied pressure, thereby changing the self inductance of the coil. An op-amp inductive signal conditioning circuit (OISCC) is designed to produce voltage proportional to changes in self-inductance, but the OISCC voltage versus applied pressure exhibits a considerable nonlinearity error due to stray inductances and component drifts. The ANN modeling estimates and compensates the nonlinearity of OISCC. An embedded unit is used for implementation of ANN learning process. The pressure transducer with significant stability has exhibited high linearity and sensitivity of ±0.35% and 10 mH/psig, respectively, in the measuring range of 0–70 psig. The design and experimental aspects of the technique are reported.

Development of an intelligent pressure measuring technique for bellows using radial basis function neural network

This paper presents the implementation of an intelligent pressure transmitter to measure pressure using a bellow sensor. In industrial applications, the deflection of the bellow due to applied pressure must be translated into an efficient electrical readout for monitoring, transmission and control. An inductive pick-up is used to convert the deflection of the bellow into the change in self-inductance of a coil. The signal conditioning circuit designed for the bellow sensor with the inductive coil is an inductance to voltage conversion circuit (ITVCC). The stray inductances, component tolerances and ambient factors introduce errors in the output of the ITVCC. The voltage–pressure relation exhibits a considerable nonlinearity and limits the measurement to local operations. In this aspect, we propose an artificial neural network (ANN) using a radial basis function to estimate and compensate the nonlinearity of the ITVCC. The intelligence of ANN modeling is incorporated into an embedded plug-in-module (EPIM). The output voltage of the EPIM is converted into a 4–20mA current signal for further processing. The performance of the proposed technique is experimentally verified. The nonlinearity expressed as maximum deviation from the desired response is within ±0.6% of full scale reading. The design aspects, simulation analysis and experimental results of the technique are reported.

Investigation of an overvoltage protection for fast switching silicon carbide transistors

Transistors made of wide band-gap materials such as silicon carbide (SiC) offer the opportunity of much faster switching, and, hence, lower switching losses compared with silicon (Si) devices. To utilise the full potential of SiC-devices the influence of stray inductances and capacitances on the switching behaviour has to be minimised. Stray inductances result in overvoltages possibly destroying the transistor at turn-off. These overvoltages can be avoided by protective circuitries such as active clamping or dynamic voltage rise control without sacrificing the fast switching. Such circuitries are well-known from Si-transistor drivers and are used in cases where stray inductances cannot be reduced any further. All investigations of the overvoltage reduction by the dynamic voltage rise control (DVRC) were performed for one SiC-BJT and two SiC-MOSFETs from different manufacturers. If the DVRC would behave in a similar way such as for silicon IGBTs, the benefit would be huge: Overvoltages would be reduced and the switching speed could be increased. However the influence of parasitic components has to be considered for the protective circuitry as well.

Analysis of nanosecond breaking of a high-density current in SOS diodes

Effect of a sharp (nanosecond) breaking of the reverse current with a density on the order of 103–104 A/cm2 in a silicon diode upon switching from direct to reverse bias voltage (so-called silicon opening switch, or SOS effect) is widely used in nanosecond technologies of gigawatt powers. For detailed analysis of the SOS effect, we constructed a special setup with small stray inductance, which makes it possible to test single SOS diodes with a working area of 1–2 mm2 in a wide range of current densities. Our experiments show, in particular, that the numerical model of the SOS effect developed at the Institute of Electrophysics, Ural Branch, Russian Academy of Sciences successfully described the experimental results. It is also shown that the charge extracted from the diode structure by the reverse current exceeds the charge introduced by a direct current pulse by not more than 10%, indicating a relatively small role of ionization processes. The possibility to carry out experiments on single samples with a small surface area allows us to study the SOS effect and considerably facilitates investigations aimed at the perfection of the design of SOS diodes.

Comparative evaluation of the short-circuit withstand capability of 1.2 kV silicon carbide (SiC) power transistors in real life applications

In this paper, the response of the new generation silicon carbide (SiC) power transistors under short-circuit faults is examined. The study is focused on real life applications, where a large stray inductance is typically part of the main power loop. Three types of short-circuits are experimentally investigated and the effect of the stray inductance in each case is recorded. A comparative analysis regarding the performance of the SiC junction field effect transistors (JFETs) and SiC metal oxide field effect transistors (MOSFETs), along with the latest technology silicon (Si) MOSFETs is carried out. Maximum instantaneous power, critical energy and saturation current are the main criteria for evaluating the robustness of each power device. A destructive test is performed in order to obtain the short-circuit withstand capability and the failure mechanism of each semiconductor.

Study on Oscillations During Short Circuit of MW-Scale IGBT Power Modules by Means of a 6-kA/1.1-kV Nondestructive Testing System

This paper uses a 6-kA/1.1-kV nondestructive testing system for the analysis of the short-circuit behavior of insulated-gate bipolar transistor (IGBT) power modules. A field-programmable gate array enables the definition of control signals to an accuracy of 10 ns. Multiple 1.7-kV/1-kA IGBT power modules displayed severe divergent oscillations, which were subsequently characterized. Experimental tests indicate that nonnegligible circuit stray inductance plays an important role in the divergent oscillations. In addition, the temperature dependence of the transconductance is proposed as an important element in triggering for the oscillations.

Characterization and Implementation of Dual-SiC MOSFET Modules for Future Use in Traction Converters

Silicon (Si) insulated-gate bipolar transistors are widely used in railway traction converters. In the near future, silicon carbide (SiC) technology will push the limits of switching devices in three directions: higher blocking voltage, higher operating temperature, and higher switching speeds. The first silicon carbide (SiC) MOSFET modules are available on the market and look promising. Although they are still limited in breakdown voltage, these wide-bandgap components should improve traction-chain efficiency. Particularly, a significant reduction in the switching losses is expected which should lead to improvements in power–weight ratios. Nevertheless, because of the high switching speed and the high current levels required by traction applications, the implementation of these new modules is critical. An original method is proposed to compare, in terms of stray inductance, several dc bus-bar designs. To evaluate the potential of these new devices, a first set of measurements, based on a single-pulse test-bench, was obtained. The switching behavior of SiC devices was well understood at turn-off and turn-on. To complete this work, the authors use an opposition method to compare Si-IGBT and SiC-MOSFET modules in voltage source inverter operation. For this purpose, a second test-bench, allowing electrical and thermal measurements, was developed. Experimental results confirm the theoretical loss-calculation of the single-pulse tests and the correct operation of up to three modules directly connected in parallel. This analysis provides guidelines for a full SiC inverter design, and prospects for developments in traction applications are presented.

Dynamic Voltage Rise Control (DVRC) Applied to SiC Bipolar Junction Transistors

Considering the development of faster power electronic switches, especially silicon carbide (SiC) devices, parasitic elements, such as stray inductances and capacitances, become more and more crucial. Overvoltages caused by stray inductances in combination with fast switching transients can destroy the devices at turn-off. In this paper the implementation of the DVRC circuit for silicon carbide bipolar junction transistors (BJTs) is investigated. The DUT was Fairchild`s FSICBH057A120 (VCES = 1200 V, Ron = 57 mΩ).

Power semiconductor and packaging trends in vehicle electrification

Since road traffic currently contributes 23% to CO2 emission, the European Union forces car makers to reduce the average CO2 emission of their fleet to 95g CO2/km by 2021. This can only be achieved by electrification of vehicles. It is obvious that the market requires electrified vehicles to be comparable to combustion engine cars in price, driving range, maintenance effort, lifetime and safety. The main inverter, also called HPCU (hybrid control unit), with the power module as its core component plays a key role because it is a major lever for CO2 reduction. The strict rules of the EC requires future power modules with highest power density, high voltage and high current rating, high temperature capability and cooling, sufficient lifetime, low weight and small size. The article describes how Infineon will meet the requirements of power modules for the coming years. On the power semiconductor technology side, a new IGBT generation will be introduced as well as a very thin IGBT technology. On the packaging side, two new packages will be introduced: a very compact low-cost generator module, and a high power motor module with significant improvements in power density and size, cost, stray inductance and efficiency. It will also be discussed how to further increase the robustness of such packages to allow operation at even higher operating temperatures. An insight into wide bandgap power semiconductor switches will also be given. The new technologies will reduce Vce and switching losses at the same time and thereby increase inverter efficiency and power density.

Analytical Modeling of Switching Energy of Silicon Carbide Schottky Diodes as Functions of <italic>dI <inline-formula><tex-math notation="LaTeX">$_{\bf DS}$</tex-math></inline-formula>/dt</italic> and Temperature

SiC Schottky Barrier diodes (SiC SBD) are known to oscillate/ring in the output terminal when used as free-wheeling diodes in voltage-source converters. This ringing is due to RLC resonance among the diode capacitance, parasitic resistance, and circuit stray inductance. In this paper, a model has been developed for calculating the switching energy of SiC diodes as a function of the switching rate ( dI $_{\rm DS}/dt$ of the commutating SiC mosfet ) and temperature. It is shown that the damping of the oscillations increases with decreasing temperature and decreasing dI $_{\rm DS}/dt$ . This in turn determines the switching energy of the diode, which initially decreases with decreasing dI $_{\rm DS}/dt$ and subsequently increases with decreasing dI $_{\rm DS}/dt$ thereby indicating an optimal dI $_{\rm DS}/dt$ for minimum switching energy. The total switching energy of the diode can be subdivided into three phases namely the current switching phase, the voltage switching phase, and the ringing phase. Although the switching energy in the current switching phase decreases with increasing switching rate, the switching energy of the voltage and ringing phase increases with the switching rate. The model developed characterizes the dependence of diode's switching energy on temperature and dI $_{\rm DS}/dt$ , hence, can be used to predict the behavior of the SiC SBD.

Influences of Device and Circuit Mismatches on Paralleling Silicon Carbide MOSFETs

This paper addresses the influences of device and circuit mismatches on paralleling the silicon carbide (SiC) MOSFETs. Comprehensive theoretical analysis and experimental validation from paralleled discrete devices to paralleled dies in multichip power modules are first presented. Then, the influence of circuit mismatch on paralleling SiC MOSFETs is investigated and experimentally evaluated for the first time. It is found that the mismatch of the switching loop stray inductance can also lead to on-state current unbalance with inductive output current, in addition to the on-state resistance of the device. It further reveals that circuit mismatches and a current coupling among the paralleled dies exist in a SiC MOSFET multichip power module, which is critical for the transient current distribution in the power module. Thus, a power module layout with an auxiliary source connection is developed to reduce such a coupling effect. Finally, simulations and experimental tests are carried out to validate the analysis and effectiveness of the developed layout.

Accurate Analytical Modeling for Switching Energy of PiN Diodes Reverse Recovery

PiN diodes are known to significantly contribute to switching energy as a result of reverse-recovery charge during turn- off . At high switching rates, the overlap between the high peak reserve-recovery current and the high peak voltage overshoot contributes to significant switching energy. The peak reverse-recovery current depends on the temperature and switching rate, whereas the peak diode voltage overshoot depends additionally on the stray inductance. Furthermore, the slope of the diode turn- off current is constant at high insulated-gate bipolar transistor (IGBT) switching rates and varies for low IGBT switching rates. In this paper, an analytical model for calculating PiN diode switching energy at different switching rates and temperatures is presented and validated by ultrafast and standard recovery diodes with different current ratings. Measurements of current commutation in IGBT/PiN diode pairs have been made at different switching rates and temperatures and used to validate the model. It is shown here that there is an optimal switching rate to minimize switching energy. The model is able to correctly predict the switching rate and temperature dependence of the PiN diode switching energies for different devices.

The Impact of DC-power Layout on Stray Inductance of Bridge Arm in Power Converters

In high power converter design, low-inductance busbar connecting DC capacitors and power devices is the main concern to improve the quality of the whole power electronics system. There are several facts which affect the stray inductance of bridge arm. This paper mainly analyzes the influence of DC-power layout on the stray inductance taking a subway traction converter as example. The Psim9.0 software was used to calculate the stray inductance. The conclusion is that DC-power connection should be put different side from DC capacitance because lower stray inductance can be obtained than that of the same side. The simulation and experimental results are given to illustrate the effectiveness.

Accurate measurement of original current pulses because of positive corona in the coaxial cylindrical arrangement

Current pulse because of positive corona discharge is a main source of radio interference (RI). An accurate measurement of the original corona pulse is necessary to study corona-generated RI. However, the corona pulse is likely to be distorted by either LC oscillation or reflection. In this study, an experiment system with single corona source is built which can provide a nearly free-reflection path for the current pulses, and measurements are carried out in the system. The magnitude of the measured waveform is close to one half of the original pulse, which proves the accuracy of the measurement method. In order to obtain the original current pulse, a comprehensive model for the current pulses’ path, taking the stray capacitance and stray inductance into consideration, is established. Based on the model, an inversion method to derive the original pulse is proposed. In combination with the obtained original pulse, the model gives the calculated results for other experimental conditions. The calculated results agree well with the measured results, which provide solid validation for the accuracy of the measurement. Another advantage of the proposed measurement method is that the long cables enable the accurate measurements to be achieved under any terminal conditions.

Firing thyristors with negative firing angle using multilevel current reinjection concept: an experimental evaluation

Thyristor based multilevel current reinjection (MLCR) current source converter (CSC) provides self-commutation capability to thyristors. It also has high quality line current waveform by accurately shaping the DC bus current using an auxiliary reinjection bridge. However the theoretical and PSCAD/ETDC simulation analysis do not take into account the inevitable stray capacitances and inductances which may influence the thyristor turn-on/off and the simulation switching model may not represent the switching characteristics of the main bridge thyristors fully or accurately. Questions have been raised about the ability to achieve self-commutation with thyristors and the possibility of operating thyristors with negative firing angles. Therefore, it is necessary to experimentally verify whether neglecting the real-world artefacts actually impedes the performance of thyristor based MLCR CSC. The experimental results presented in this paper prove that the auxiliary reinjection circuit can force the thyristor to commutate independently from their respective line-to-line voltages and thyristor converter can operate with a negative firing angle.

Dynamic Characterization of Parallel-Connected High-Power IGBT Modules

In high-power converter design, insulated gate bipolar transistor (IGBT) modules are often operated in parallel to reach high output currents. Evaluating the electrical and thermal behavior of the parallel IGBTs is crucial for the design and reliable operation of converter systems. This paper investigates the static and dynamic characterization of parallel IGBTs and the influence of the electrical parameters on the IGBT behavior. Si-based IGBT power modules with voltage rating of 4.5 kV and current rating of 1 kA are used for the experimental evaluation of module parallel connections. Parallel-connected modules have been driven by several commercial IGBT gate units at various dc-link voltages and current levels and with different temperatures. The tested IGBT gate units show good current sharing performance between the two parallel modules. Other important influencing factors such as busbar design layout, stray inductance variation, and gate driving are also investigated for parallel connections of IGBT modules. Finally, the switching energy of the parallel modules is extracted for IGBTs and diodes under different conditions.

Embedded Power Modules – A new approach using Power Core and High Power PCB

Power electronics packaging applications has strong demands regarding reliability and cost. The fields of developments reach from low power converter modules, over single or multichip MOSFET or IGBT packages, up to high power applications, like needed e.g. for solar inverters and automotive applications. This paper will give an overview about these applications and a description of each ones demand. The spectrum of conventional power electronics packaging reaches from SMD packages for power chips to large power modules. In most of these packages the power semiconductors are connected by bond wires, resulting in large resistances and parasitic inductance. Additionally bond wires result in a high stray inductance which limits the switching frequency. The embedding of chips using Printed Circuit Board (PCB) technology offers a solution for many of the problems in power packaging. This paper will show today's available power packages and power modules, realized in industrial production as well as in European research projects. All technologies which are used are based on PCB materials and processes. Chips are mounted to Cu foils, lead frames, high power PCBs or even ceramic substrates, embedded by vacuum lamination of laminate sheets and electrically connected by laser drilling and Cu plating. A new approach for embedded power modules will be presented in detail. In this project, different application fields are covered, ranging from 50 W over 500 W to 50kW power modules for different applications like single chip packages, over power control units for pedelec (Pedal Electric Cycle), to inverter modules for automotive applications. This approach will focus on a power core base structure for the embedded semiconductor, which is then connected to a high power PCB. The connection to the embedded die is realized by direct copper connection only. The technology principle will be described in detail. Frist manufactured demonstrators will be presented. The presented new approach for the realization of a power core structure offers new possibilities for the module manufacturing, avoiding soldering or Ag sintering of the power semiconductors and the handling of thick copper substrates during the embedding process.

Reduction in overvoltages and dynamic power losses in power switches of multilevel voltage inverters

A number of the circuit and design decisions that provide a reduction in overvoltage and dynamic power losses in power switches of multilevel voltage inverters with clamping diodes is considered. It is shown that the integral or unpackaged version is the most effective method for a reduction in the stray inductance in the multilevel circuit, which is the general cause for occurrence of dynamic overvoltage. To reduce dynamic losses of power, a method for resonant commutation on fronts, which provides commutation of switches in the multilevel circuit at zero voltage (SZV) and zero current (SZC), is proposed. The resonant switching method as applied to the multilevel circuit simultaneously solves a problem of dynamic overvoltage by means of limitation for the rate of voltage rise in the SZV mode or the mode of preliminary fault of energy stored in the inductance of the switching circuit in the SZC mode.

Effects of Stray Inductance on Hard-Switched Switched Capacitor Converters

Switched capacitor (SC) converters are becoming quite popular for use in DC-DC power conversion. The concept of equivalent resistance in SC converters is frequently used to determine the conduction losses due to the load current. A variety of methodologies have been presented to predict the equivalent resistance in hard-switched SC converters. These works, however, did not consider the effect of stray inductance on equivalent resistance. Current power converter design practices favor higher switching frequencies, moving hard-switched SC converters into operating areas in which stray inductance affects converter performance. This paper presents an analytic equation that can be used to evaluate the effects of stray inductance on the equivalent resistance of switched capacitor converters. The concepts proposed here are verified by both digital simulation and a prototype converter. The equations presented can be used to evaluate the effects of stray inductance on SC converter performance, thereby helping designers set a maximum operating frequency to limit its effect.