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445 results on '"Munk-Nielsen, Stig"'

2. Analysis of Volt-Second Error for Medium Voltage SiC MOSFET Power Modules

Author

Nielsen, Morten Rahr, Zhao, Hongbo, Bech, Michael Moller, and Munk-Nielsen, Stig

Abstract

This article presents an analytical derivation of the volt-second error caused by converter nonlinearities such as dead time and the finite switching speeds of the emerging medium voltage silicon-carbide MOSFETs. The analytical model considers the transient behavior of the MOSFETs, the gate-driving circuitry, and the intrinsic parasitic capacitances of the MOSFETs and the power module. The importance of compensating converter nonlinearities has been revived with the utilization of wide bandgap semiconductor devices as the increased switching frequency penalizes the relative impact of dead time squared in motor drive applications. The first-order analytical model is validated with experimental and simulated results of switching events of a 10 kV silicon-carbide MOSFET power module. In addition, the analytical model is utilized to map out the individual contributions from each time period of the switching event.

Published
2024
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3. Startup Analysis and Design of Self-Powered Auxiliary Power Supply in Input-Series System With Small Submodule Capacitance

Author

Wang, Rui, Jorgensen, Asger Bjorn, Liu, Wentao, Zhao, Hongbo, Nee, Hans-Peter, and Munk-Nielsen, Stig

Abstract

For filling higher input voltage requirement, the input-series system based on attainable power devices is prevalent in industry. Specifically, its auxiliary power supply (APS) is self-powered from submodule (SM) capacitance on medium/high voltage occasions, for easing the common mode noise and insulation problems as well as facilitating the modular design. But in the meanwhile, the APS startup problem is brought into practice. This article points out that the out-of-sync issue of APSs during the startup process is considerable since it causes a severe voltage oscillation in the input-series system with small SM capacitance, which is rarely reported before since this adverse influence is neglectable in the common system with large SM capacitance. Therefore, for the first time, the impact of the parameters on voltage oscillation is assessed in this article, which is based on a half-bridge converter equipped with designed self-powered gate drivers as a target input-series system. After establishing an analytical model, the safety and stability criteria for oscillation are identified, followed by the simulation verification. Further, a two-stage startup scheme and hardware design are proposed to ease the voltage oscillation without the penalty of matching passive component parameters. Finally, the corresponding results from experiments are provided to verify the effectiveness.

Published
2024
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4. Adaptive Anti-Saturation Control Design of Transformers in Converter-Based Grid Emulators

Author

Li, Zejie, Zhao, Fangzhou, Hans, Florian, Munk-Nielsen, Stig, Wang, Xiongfei, Li, Zejie, Zhao, Fangzhou, Hans, Florian, Munk-Nielsen, Stig, and Wang, Xiongfei

Abstract

Transformer saturation is a common issue in megawatt converter-based grid emulators (GEs) when emulating grid faults. This problem necessitates the use of anti-saturation control (ASC) with GEs. However, conventional ASC methods tend to distort the emulated grid voltage or even interact with the voltage control (VC) of GEs, causing instability in the system. This article, thus, proposes an adaptive ASC method and superimposes its output command to both modulation and VC references, which not only alleviate transformer saturation with the lower output voltage distortion, but mitigate its adverse interaction with the VC of converter-based GEs. Experimental results confirm the effectiveness of the adaptive ASC., QC 20240819

Published
2024
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5. Medium-Voltage Megawatt Power-Electronic-Based Grid Emulators : Testing Capability Requirements and Dynamics Challenges-A Review

Author

Li, Zejie, Zhao, Fangzhou, Wang, Xiongfei, Munk-Nielsen, Stig, Geske, Martin, Grune, Rayk, Andersen, Daniel Bo Ronnest, Rodriguez, Miguel Garnelo, Li, Zejie, Zhao, Fangzhou, Wang, Xiongfei, Munk-Nielsen, Stig, Geske, Martin, Grune, Rayk, Andersen, Daniel Bo Ronnest, and Rodriguez, Miguel Garnelo

Abstract

Power-electronic-based grid emulators are emerging as a promising way to test the grid-code compliance of renewable energy resources. Yet, the ever-increasing power and voltage levels of device under test (DUT) pose new requirements and challenges to power-electronic-based grid emulators. This article first gives an overview of testing capability requirements based on the recent grid codes and standards and then discusses the resulted dynamic interactions and solutions for power-electronic-based grid emulators. Perspectives on the open issues and emerging trends of grid emulators are finally shared., QC 20240626

Published
2024
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30. Power-Hardware Design and Topologies of Converter-Based Grid Emulators for Wind Turbines

Author

Li, Zejie, Wang, Xiongfei, Zhao, Fangzhou, Munk-Nielsen, Stig, Geske, Martin, Grune, Rayk, Bo Ronnest Andersen, Daniel, Garnelo Rodriguez, Miguel, Li, Zejie, Wang, Xiongfei, Zhao, Fangzhou, Munk-Nielsen, Stig, Geske, Martin, Grune, Rayk, Bo Ronnest Andersen, Daniel, and Garnelo Rodriguez, Miguel

Abstract

Power-electronic-based grid emulators (GEs) emerge as a favorable method for testing grid-code compliances of wind turbines (WTs), thanks to their full controllability and improved efficiency. To accommodate the increasing power and voltage levels of WTs, scalability becomes a critical requirement for the topologies of converter-based GEs. This article identifies first the power rating of future GEs based on the system architecture and the evolution of WTs, followed by evaluating converter topologies of GEs for high scalability. Design considerations of power semiconductor devices, step-up transformers, dc chopper, and dc capacitors are also discussed for existing and prospective GEs., QC 20240703

Published
2023
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31. Issues of Impedance Emulation of Converter-Based Grid Emulator for LVRT Test

Author

Li, Zejie, Zhao, Fangzhou, Chen, Xingxing, Munk-Nielsen, Stig, and Wang, Xiongfei

Subjects
Transient impedance, virtual admittance, low-voltage ride-through, virtual impedance
Abstract

A simultaneous change of voltage magnitude and grid impedance may occur during grid faults. To reproduce such impedance variation by converter-based grid emulators, the virtual impedance (VI) control and the virtual admittance (VA) control are two typical approaches. Their dynamics when used with the L-filtered grid emulator are evaluated in this paper. Two major issues, i.e., the inaccuracy of emulated low-frequency (< 50Hz) impedance by the VI control, and the adverse interactions between VA control and its inner current control. Simulation and experimental results of an L-filtered voltage source inverter confirm the correctness of analysis.

Published
2023
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32. Loss Imbalance in SiC Half-Bridge Power Module

Author

Kjærsgaard, Benjamin Futtrup, Aunsborg, Thore Stig, Jørgensen, Jannick Kjær, Dalal, Dipen Narendra, Takahashi, Masaki, Jørgensen, Asger Bjørn, Zhao, Hongbo, Munk-Nielsen, Stig, and Rannestad, Bjørn

Abstract

Capacitive parasitic couplings in power electronics systems are gaining increased attention due to the emergence of the wide bandgap devices, with the main challenges being faster switching speeds and increased operating voltage capabilities causing increased voltage slew rate (dv/dt). The high dv/dt induces capacitive displacement currents through the channel of the power semiconductor devices, effectively reducing the switching speed, resulting in an increase in the Volt-Ampere integral, incurring surplus switching energy dissipation. This paper highlights that the parasitic power module gate high side capacitance should be analyzed in parallel to the high-side gate-drain capacitance and thus contributing to the “equivalent” high-side Miller capacitance, slowing down the switching speed of the high-side device compared to the low-side device in the half-bridge power module. Effectively this causes an imbalance in switching energy dissipation between high-side and low-side devices. A combined physics based and behavioural based digital twin simulation is used to evaluate high-side and low-side switching energy dissipation through double pulse testing. Simulations identify a significant increase in turn-on energy on the high-side device compared to the low side device, due to the equivalent high-side Miller capacitance increase. Possible reasons for why such significant deviation in switching energy dissipation between the high-side and low-side devices is unprecedented, are shared from the authors perspectives.

Published
2023
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33. Embedded Current Sensor for SiC Die Current Measurement

Author

Meinert, Janus Dybdahl, Beczkowski, Szymon Michal, Kubulus, Pawel Piotr, Munk-Nielsen, Stig, and Jørgensen, Asger Bjørn

Abstract

A common challenge when designing compact fast switching multichip power modules based on wide bandgap semiconductors is imbalanced current sharing between the parallel dies. The issue arises in asymmetric layouts where different parasitic inductance values will be present in the individual power or gate loops for the parallel connected dies. Experimental verification of the current sharing between the dies in a multichip power module is limited by the lack of current sensing strategies suitable for performing accurate drain current measurements of each individual die. This paper proposes a two-stage current sensor consisting of a customizable current transformer and a Pearson current monitor. The current transformer can be embedded into a multichip power module with its core encircling a single die to provide measurements of the die’s drain current. The concept is verified with a double pulse test performed at 200 V and 17.7 A of an asymmetric power module with four parallel connected silicon carbide dies. The measured die currents are compared to the total switch current measured with a 30MHz Rogowski coil where the current imbalance due to the asymmetric layout is clearly seen.

Published
2023
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35. Discovery of Loss Imbalance in SiC Half-Bridge Power Modules – Analysis and Validations

Author

Kjaersgaard, Benjamin Futtrup, Liu, Gao, Aunsborg, Thore Stig, Dalal, Dipen Narendra, Jorgensen, Jannick Kjaer, Rannestad, Bjorn, Zhao, Hongbo, and Munk-Nielsen, Stig

Abstract

It is commonly assumed that power semiconductor switching losses are the same for high-side and low-side devices in a half-bridge power module. However, this article reveals that the high-side SiC mosfet in a medium-voltage power module exhibits over 40% higher switching energy compared with the low-side SiC mosfet. The loss imbalance is attributed to the parasitic high-side gate capacitance in the power module, which contributes to the equivalent high-side Miller capacitance. A physics-based switching energy dissipation model is, therefore, proposed, distinguishing between low-side and high-side switching energy dissipation. Double pulse testing demonstrates that high-side switching energy dissipation increases by 5 mJ per 2.5-pF increment in the equivalent Miller capacitance, aligning closely with the analytically calculated increase of 6 mJ per 2.5 pF. Continuous power module testing shows a 10 $\mathrm{^{\circ }}$C increase in high-side junction temperature. The findings from this article offer crucial insights into research, design, and manufacturing of half-bridge modules enabled by SiC mosfets.

Published
2024
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47. Parasitic Capacitive Couplings in Medium Voltage Power Electronic Systems - an Overview

Author

Kjaersgaard, Benjamin Futtrup, primary, Liu, Gao, additional, Nielsen, Morten Rahr, additional, Wang, Rui, additional, Dalal, Dipen Narendra, additional, Aunsborg, Thore Stig, additional, Jorgensen, Jannick Kjaer, additional, Yan, Zhixing, additional, Jacobsen, Jonas, additional, Wu, Rui, additional, Bech, Michael Moller, additional, Rannestad, Bjørn, additional, Munk-Nielsen, Stig, additional, and Zhao, Hongbo, additional

Published
2023
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50. Passivity-Based Co-Design of Active Damping and Voltage Controller for Converter-Based Grid Emulator

Author

Li, Zejie, Zhao, Fangzhou, Munk-Nielsen, Stig, and Wang, Xiongfei

Subjects
relative passivity depth, voltage controller, Passivity, co-design, active damping
Abstract

To test grid compliances of devices under test (DUT), this paper proposes a passivity-based co-design method for the active damping (AD) and ac voltage controller (VC) used with a converter-based grid emulator. In the approach, a relative passivity depth (RPD) index is introduced to quantify the impact of AD and VC on the impedance passivity. Different from conventional passivity indices, the RPD is independent on the filter plant parameter, and thus enables a more robust co-design of AD and VC. An experimental prototype based on an L-filtered voltage source inverter is tested to validate the effectiveness of proposed method.

Published
2023
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