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8. Autonomous Gate Drivers Tailored for Triangular Current Mode-Based Zero-Voltage Switching Two-Level Three-Phase Inverters for Electric Vehicle Drive Systems.

Author

Abbas, Khizra and Nee, Hans-Peter

Subjects
*ZERO voltage switching, *ELECTRIC inverters, *MOTOR vehicle driving, *AUTONOMOUS vehicles, *ELECTROMAGNETIC interference, *ELECTRIC vehicles, *POWER density
Abstract

The demand for highly efficient and dynamic electric vehicles (EVs) has increased dramatically. The traction inverter, a pivotal component in an EV powertrain, plays a crucial role. This study is dedicated to designing a traction inverter with focus on achieving high efficiency and elevated power density and mitigating electromagnetic interference (EMI) issues. To realize these objectives, autonomous gate drivers (AGDs) are proposed and designed using LTspice simulation software. The aim is to achieve zero voltage switching (ZVS) at both turn-on and turn-off through the utilization of triangular current mode (TCM) control on the gate driver. The AGDs implement a current modulation scheme by sensing the current and voltage and generating gate-source voltage signals with minimal delays. The implemented current modulation scheme by the AGDs results in an efficiency exceeding 99% for a 10 kW power rating. The sinusoidal output waveforms not only contribute to extending the motor lifespan by mitigating sharp-edge voltages but also bring advantages such as reduced switch stress, decreased EMI, and simplified thermal management. [ABSTRACT FROM AUTHOR]

Published
2024
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12. 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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18. Accurate Condition Monitoring of Semiconductor Devices in Cascaded H-Bridge Modular Multilevel Converters

Author

Asoodar, Mohsen, Nahalparvari, Mehrdad, Zhang, Yi, Danielsson, Christer, Nee, Hans Peter, and Blaabjerg, Frede

Subjects
reliability, Cascaded H-bridge, online monitoring, health estimation, modular multilevel converter (MMC), flexible ac transmission systems (FACTS), semiconductors, condition monitoring (CM)
Abstract

This article presents an online condition monitoring (CM) scheme for semiconductors used in modular multilevel converters (MMCs) that comprise cascaded H-bridge submodules. The CM algorithm is based on detecting changes in the on-state resistance of the semiconductors over time. The proposed method is shown to successfully perform a curve tracing of semiconductors in MMCs while the semiconductor junction remains at a temperature that is readily measurable and undergoes minute changes during the measurement process. The on-state resistance value is estimated from the measured on-state voltage drop of the semiconductors and the measured arm current. Measuring the on-state resistance at known temperatures allows for separating temperature-dependent variations of the on-state resistance from age-dependent variations of this parameter. Suitable methods for reducing the effect of noise on the curve-traced data are proposed, and a recursive least square estimator is used to extract the optimum on-state resistance from the traced vCE-iC curve. Simulation results show that the proposed scheme can accurately determine the on-state resistance of semiconductors at a known temperature and under various levels of measurement noise. Moreover, experimental results on a low-power prototype show that the proposed scheme is applicable in practice, and provides similar online curves to what a commercial curve tracer can produce offline. The experimental verification has been conducted under constant load conditions; however, the proposed methods can be used under any variable load condition as well.

Published
2023

31. Wireless Communication in Modular Multilevel Converters and Electromagnetic Interference Characterization

Author

Ciftci, Baris, Gross, James, Augustin, Tim, Wang, Xiongfei, Norrga, Staffan, and Nee, Hans-Peter

Subjects
multilevel converters, Other Electrical Engineering, Electronic Engineering, Information Engineering, 5G mobile communication, Annan elektroteknik och elektronik, circuit breakers, wireless communication, electromagnetic interference
Abstract

The wireless control of modular multilevel converter (MMC) submodules was recently proposed. The success of the control depends on specialized control methods suitable for wireless communication and a properly designed wireless communication network in the MMC valve hall while aiming for low latency and high reliability. The wireless communication in the hall can be affected by the electromagnetic interference (EMI) of MMC submodules, voltage and current transients. In this article, firstly, a wireless communication network based on 5G New Radio is designed for an example full-scale MMC valve hall. After that, the radiated EMI characteristics of the MMC submodules with different voltage and current ratings and two dc circuit breakers are measured. The effects of EMI on wireless communication in the multi-GHz frequency band are tested. The interference from the components is confined below 500 MHz, and the wireless communication with 5825 MHz center frequency is not affected by the interference. QC 20220502

Published
2022

32. Wireless Control of Modular Multilevel Converter Submodules With Communication Errors

Author

Ciftci, Baris, Harnefors, Lennart, Wang, Xiongfei, Gross, James, Norrga, Staffan, and Nee, Hans-Peter

Subjects
Other Electrical Engineering, Electronic Engineering, Information Engineering, resonant controller, modular multilevel converter (MMC), wireless control, Annan elektroteknik och elektronik, prototype, Autonomous control
Abstract

Wireless control of modular multilevel converter (MMC) submodules can benefit from different points of view, such as lower converter cost and shorter installation time. In return for the advantages, the stochastic performance of wireless communication networks necessitates an advanced converter control system immune to the losses and delays of the wirelessly transmitted data. This paper proposes an advancement to the distributed control of MMCs to utilize in wireless submodule control. Using the proposed method, the operation of the MMC continues smoothly and uninterruptedly during wireless communication errors. The previously proposed submodule wireless control concept relies on implementing the modulation and individual submodule-capacitor-voltage control in the submodules using the insertion indices transmitted from a central controller. This paper takes the concept as a basis and introduces to synthesize the indices autonomously in the submodules during the communication errors. This new approach allows the MMC continue its operation when one, some, or all submodules suffer from communication errors for a limited time. The proposal is validated experimentally on a laboratory-scale MMC. QC 20220627

Published
2022

33. An overview of stability challenges for power‐electronic‐dominated power systems: The grid‐forming approach.

Author

Shakerighadi, Bahram, Johansson, Nicklas, Eriksson, Robert, Mitra, Pinaki, Bolzoni, Alberto, Clark, Angel, and Nee, Hans‐Peter

Subjects
ELECTRIC power distribution grids, SIMULATION software, TEST systems, ELECTRIC transients, UNIVERSITY research
Abstract

Inverter‐based generators (IBGs) are becoming popular in modern power systems. When the penetration of IBGs is increasing in power systems, new stability, protection, and monitoring challenges are introduced in the grid. Grid‐forming (GFM) control of converters is seen as a promising solution for future power grids to overcome particular stability challenges. Here, the technical challenges of the GFM‐based IBGs are reviewed from the point of view of TSOs and academic research. The properties of different GFM methods are studied for different GFM‐based IBGs for a single grid‐tied IBG and using the IEEE 9‐bus test system. Simulation results are provided by using the PSCAD‐EMT simulation software. [ABSTRACT FROM AUTHOR]

Published
2023
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50. Characterization of Gate-Oxide Degradation Location for SiC MOSFETs Based on the Split C–V Method Under Bias Temperature Instability Conditions

Author

Cai, Yumeng, Chen, Cong, Zhao, Zhibin, Sun, Peng, Li, Xuebao, Zhang, Manhong, Wang, Hui, Chen, Zhong, and Nee, Hans-Peter

Abstract

Gate-oxide degradation has been one of the major reliability challenges of SiC mosfets. Comprehensive and accurate localization of gate-oxide degradation under bias temperature instability (BTI) conditions is important to improve the device reliability. The split C–V [gate–source capacitance CGS (vG) and gate–drain capacitance CGD (vG)] method is proposed in this article to locate gate-oxide degradation. Moreover, a BTI automated characterization system integrated I–V and split C–V test is presented. The effect of gate-oxide degradation on threshold voltage and split C–V under dc and ac BTI conditions is investigated and the degradation location is analyzed. Furthermore, the degradation simulation is conducted with technology computer aided design (TCAD) to reveal the mechanism. The results show that the different parts of split C–V can characterize degradation location, the type, and energy level of traps. The acceptor traps near valence band and donor traps near conduction band cause gate-oxide degradation above the channel and junction field effect transistor (JFET) region in positive bias temperature instability (PBTI) and Negative Bias Temperature Instability (NBTI), respectively. In ac BTI, the gate-oxide degradation at the channel region is independent of vG polarity, while the opposite is true above JFET region. These findings help to improve the long-term operation reliability of gate oxide from the perspective of chip design and application.

Published
2023
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