| 1. |
- Abbas, Khizra, et al.
(författare)
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Autonomously Modulating Gate Drivers For Triangular-Current Mode (TCM) Zero-Voltage Switching (ZVS) Buck Converter
- 2023
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Ingår i: <em>Proceedings of 22nd International Symposium on Power Electronics, Ee 2023</em>. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a novel approach to designing autonomous gate drivers for soft-switched buck converters. The objective is to reduce switching losses, enhance converter efficiency, and reduce electromagnetic interference (EMI). The uniqueness of this converter is that the pulse-width modulation is performed autonomously on the gate driver. The gate driver makes quick decisions on switching times, capitalizing on the minimal time delay between measurements and switching. In the proposed buck converter configuration, the gate driver senses both the current and voltage across the switches to avoid delay. When a slightly negative voltage is detected across the switch, it rapidly turns on, resulting in a zero-voltage switching (ZVS). With an external snubber capacitor placed across the switches, the turn-off switching losses are zero (ZVS). Hence, both the turn-on and turn-off of the switch are soft. To enable the switch to turn off, a reference value of the switch current needs to be sent out to the gate driver using a galvanically isolated current sensor. Through this approach, the efficiency of the 7 kW buck converter has been calculated to exceed 99% without including the filter losses. Additional benefits include reduced switch stresses, diminished electromagnetic interference (EMI), and simplified thermal management.
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| 2. |
- Abbas, Khizra, et al.
(författare)
-
Autonomously Modulating Gate Drivers For Triangular-Current Mode (TCM) Zero-Voltage Switching (ZVS) Buck Converter
- 2023
-
Ingår i: Proceedings of 22nd International Symposium on Power Electronics, Ee 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- This paper introduces a novel approach to designing autonomous gate drivers for soft-switched buck converters. The objective is to reduce switching losses, enhance converter efficiency, and reduce electromagnetic interference (EMI). The uniqueness of this converter is that the pulse-width modulation is performed autonomously on the gate driver. The gate driver makes quick decisions on switching times, capitalizing on the minimal time delay between measurements and switching. In the proposed buck converter configuration, the gate driver senses both the current and voltage across the switches to avoid delay. When a slightly negative voltage is detected across the switch, it rapidly turns on, resulting in a zero-voltage switching (ZVS). With an external snubber capacitor placed across the switches, the turn-off switching losses are zero (ZVS). Hence, both the turn-on and turn-off of the switch are soft. To enable the switch to turn off, a reference value of the switch current needs to be sent out to the gate driver using a galvanically isolated current sensor. Through this approach, the efficiency of the 7 kW buck converter has been calculated to exceed 99% without including the filter losses. Additional benefits include reduced switch stresses, diminished electromagnetic interference (EMI), and simplified thermal management.
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| 3. |
- Abbas, Khizra, et al.
(författare)
-
Comprehensive Insight into the Operational Dynamics of TCM-Based Zero-Voltage Switching (ZVS) Two-Level Three-Phase Inverters for Electric Vehicle (EV) Motor-Drive Applications
- 2024
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Ingår i: 2024 IEEE Texas Power and Energy Conference, TPEC 2024. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a novel triangular-current mode (TCM), zero-voltage switching (ZVS) two-level three-phase inverter, specifically designed to enhance the performance of the electric vehicle (EV) drive system. The primary objective is to enhance the inverter efficiency by minimizing turn-on and turn-off switching losses while mitigating electromagnetic interference (EMI) by generating sinusoidal output waveforms. The distinctive feature of this inverter lies in its gate driver, which executes the current modulation scheme. Achieving ZVS during turn-on involves the gate driver sensing the switch voltage and turning it on at zero voltage, utilizing TCM. For turn-off ZVS, the gate driver monitors the switch current, turning it off when it exceeds a predefined reference value. With a carefully placed snubber capacitor, turn-off ZVS is achieved. The implemented current modulation scheme yields an efficiency exceeding 99% for a 10 kW power rating. The sinusoidal output waveforms not only enhance motor lifespan by safeguarding against sharp-edge voltages but also offer benefits like reduced switch stress and simplified thermal management.
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| 4. |
- Akbari, Saeed, et al.
(författare)
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Ceramic Additive Manufacturing Potential for Power Electronics Packaging
- 2022
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Ingår i: IEEE Transactions on Components, Packaging, and Manufacturing Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 2156-3950 .- 2156-3985. ; 12:11, s. 1857-1866
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Tidskriftsartikel (refereegranskat)abstract
- Compared with silicon-based power devices, wide band gap (WBG) semiconductor devices operate at significantly higher power densities required in applications such as electric vehicles and more electric airplanes. This necessitates development of power electronics packages with enhanced thermal characteristics that fulfil the electrical insulation requirements. The present research investigates the feasibility of using ceramic additive manufacturing (AM), also known as three-dimensional (3D) printing, to address thermal and electrical requirements in packaging gallium nitride (GaN) based high-electron-mobility transistors (HEMTs). The goal is to exploit design freedom and manufacturing flexibility provided by ceramic AM to fabricate power device packages with a lower junction-to-ambient thermal resistance (RθJA). Ceramic AM also enables incorporation of intricate 3D features into the package structure in order to control the isolation distance between the package source and drain contact pads. Moreover, AM allows to fabricate different parts of the packaging assembly as a single structure to avoid high thermal resistance interfaces. For example, the ceramic package and the ceramic heatsink can be printed as a single part without any bonding layer. Thermal simulations under different thermal loading and cooling conditions show the improvement of thermal performance of the package fabricated by ceramic AM. If assisted by an efficient cooling strategy, the proposed package has the potential to reduce RθJA by up to 48%. The results of the preliminary efforts to fabricate the ceramic package by AM are presented, and the challenges that have to be overcome for further development of this manufacturing method are recognized and discussed.
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| 5. |
- Akbari, Saeed, et al.
(författare)
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Low Inductive SiC Power Electronics Module with Flexible PCB Interconnections and 3D Printed Casing
- 2022
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Ingår i: 2022 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9789189711396
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Konferensbidrag (refereegranskat)abstract
- Silicon carbide (SiC) power devices are steadily increasing their market share in various power electronics applications. However, they require low-inductive packaging in order to realize their full potential. In this research, low-inductive layouts for half-bridge power modules, using a direct bonded copper (DBC) substrate, that are suitable for SiC power devices, were designed and tested. To reduce the negative effects of the switching transients on the gate voltage, flexible printed circuit boards (PCBs) were used to interconnect the gate and source pins of the module with the corresponding pads of the power chips. In addition, conductive springs were used as low inductive, solder-free contacts for the module power terminals. The module casing and lid were produced using additive manufacturing, also known as 3D printing, to create a compact design. It is shown that the inductance of this module is significantly lower than the commercially available modules.
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| 6. |
- Bhadoria, Shubhangi, et al.
(författare)
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Enablers for Overcurrent Capability of Silicon-Carbide-Based Power Converters : An Overview
- 2023
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Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers Inc.. - 0885-8993 .- 1941-0107. ; 38:3, s. 3569-3589
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Tidskriftsartikel (refereegranskat)abstract
- With the increase in penetration of power electronic converters in the power systems, a demand for overcurrent/ overloading capability has risen for the fault clearance duration. This article gives an overview of the limiting factors and the recent technologies for the overcurrent performance of SiC power modules in power electronics converters. It presents the limitations produced at the power module level by packaging materials, which include semiconductor chips, substrates, metallization, bonding techniques, die attach, and encapsulation materials. Specifically, technologies for overcurrent related temperatures in excess of 200°C are discussed. This article also discusses potential technologies, which have been proven or may be potential candidates for improving the safe operating area. The discussed technologies are use of phase-change materials below the semiconductor chip, Peltier elements, new layouts of the power modules, control and modulation techniques for converters. Special attention has been given to an overview of various potential phase-change materials, which can be considered for high-temperature operations.
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| 7. |
- Kostov, Konstantin, et al.
(författare)
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Conducted EMI from SiC BJT boost converter and its dependence on the output voltage, current, and heatsink connection
- 2013
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Ingår i: 2013 IEEE ECCE Asia Downunder - 5th IEEE Annual International Energy Conversion Congress and Exhibition, IEEE ECCE Asia 2013. - : IEEE. - 9781479904839 ; , s. 1125-1130
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Konferensbidrag (refereegranskat)abstract
- In comparison to their Silicon (Si) counterparts, the Silicon Carbide (SiC) power transistors have lower on-state resistance and higher switching speed, power and temperature ratings. These advantages make it possible to build smaller, lighter and more efficient power converters. Unfortunately, all these benefits come at the price of higher conducted and radiated electromagnetic interference (EMI). This paper investigates the conducted disturbances from a 6 kW boost converter with SiC bipolar junction transistors (BJTs). The results show that the conducted emissions at the input of the converter are approximately proportional to the output voltage, but almost independent on the load current. The effect of the heatsink on the conducted EMI was studied as well. It was found that using separate heatsinks for the diode and the BJT did not affect the level of conducted emissions significantly, but the way of connecting the heatsink does. A floating heatsink is bad from an EMI point of view, and in many cases it may not be allowed for safety reasons. When the heatsink is grounded, alone or together with the negative terminal, the common-mode noise increases the EMI measured at the positive line and decreases the EMI on the negative line. However, this appears only in the lower frequency range. At higher frequencies, connecting the heatsink in any way is better than letting it float. Therefore, the best option is to connect the heatsink to the negative line of the boost converter, and if grounding is required, it may be grounded as well. This may not be possible in systems where the negative voltage bus is at non-zero potential.
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| 8. |
- Kostov, Konstantin S., et al.
(författare)
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Combining diagonal connection and cancellation turn in electromagnetic interference filtering
- 2014
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Ingår i: IET Power Electronics. - : Institution of Engineering and Technology. - 1755-4535 .- 1755-4543. ; 7:3, s. 559-566
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a new printed circuit board (PCB) implementation of the diagonal connection is proposed. The two capacitors that are connected diagonally are laid out as close as possible and in such a way that their currents have opposite directions. The new layout combines the benefits of the so-called 'cancellation turn' with the benefits of the diagonal connection, without the need for additional PCB space and components. The experimental results show that the self-resonant frequency of the diagonally connected capacitors increased by 32%. Additionally, the coupling between the diagonally connected capacitors and a capacitor on the other side of the filter was reduced by 20-25 dB.
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| 9. |
- Kostov, Konstantin Stoychev, et al.
(författare)
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Impact of package parasitics on switching performance
- 2016
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Ingår i: Materials Science Forum. - : Trans Tech Publications Ltd. - 9783035710427 ; , s. 1057-1060
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Konferensbidrag (refereegranskat)abstract
- The package parasitics are a serious obstacle to the high-speed switching, which is necessary in order to reduce the switching power losses or reduce the size of power converters. In order to design new packages suitable for Silicon Carbide (SiC) power transistors, it is necessary to extract the parasitics of different packages and be able to predict the switching performance of the power devices placed in these packages. This paper presents two ways of simulating the switching performance in a half-bridge power module with SiC MOSFETs. The results show that the parasitic inductances in the power module slow down the switching, lead to poor current sharing, and together with the parasitic capacitances lead to oscillations. These negative effects can cause failures, increased losses, and electromagnetic compatibility issues.
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| 10. |
- Kostov, Konstantin S., et al.
(författare)
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The input impedance of common mode and differential mode noise separators
- 2013
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Ingår i: 2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013. - 9781479903351 ; , s. 1688-1695
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Konferensbidrag (refereegranskat)abstract
- This paper discusses the Δ-networks and other circuits designed to separate the conducted electromagnetic interference (EMI) into its common mode (CM) and differential mode (DM) components. The input impedances of CM/DM separators must be 50 Ω resistive in the measurement frequency band and they must be independent of the values of the noise signals and noise source impedances. The conditions for achieving such input impedances are derived. It is shown that many of the proposed separators, including the Δ-network suggested in the CISPR 16 standard, do not fulfill the input impedance requirement. This leads to unreliable CM and DM measurements, and consequently, to EMI filter oversizing and design by trial-and-error.
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