Electric Vehicle Powertrain Integrated Charging

Batterieelektrische Fahrzeuge benötigen ein im Fahrzeug eingebautes Ladegerät, um die Energie aus dem Wechselstromnetz für die Gleichstrom- Batterie aufzubereiten. Integriertes Laden ist eine Methode der Integration von Ladefunktionalität in die Antriebsstrangkomponenten, welche während des Parkens außer Betrieb sind, mit dem Ziel, Kosten, Gewicht und Volumen des Ladegerät zu sparen. Das Laden ohne die Sicherheitsmaßnahme einer galvanischen Trennung im Ladegerät ist möglich mit zusätzlichen Maßnahmen gegen elektrischen Schlag, z.B. mit einer Fehlerstromerkennung und entsprechenden Trenneinrichtung. Im Stand der Technik wurden 33 integrierte Ladekonzepte gefunden und bezüglich Antriebsstrangnutzung, benötigte Komponenten, Drehmoment der elektrischen Maschine und Wirkungsgrad verglichen. Im Rahmen dieser Arbeit wird ein neues galvanisch getrenntes integriertes Ladekonzept beschrieben, mit dem Ziel, die Effizienz zu verbessern und gleichzeitig auftretendes Drehmoment in der Maschine zu vermeiden. Der Antriebsstrang wird als DC/DC-Wandler mit der elektrischen Maschine als Transformator im Stillstand genutzt. Berechnungen zeigen eine maximale Effizienz von 88%. Ansätze zur Verbesserung des Wirkungsgrads und zur Integration des Energieflusses im Bordnetz werden in dieser Arbeit vorgeschlagen und diskutiert. Allerdings muss der Rotorkäfig geöffnet werden, um ein Drehmoment während des Laden zu vermeiden. Dies stellt einen ähnlichen Aufwand dar wie die Darstellung eines separaten Ladegeräts. Somit ist dieses Konzept aus heutiger Sicht wegen niedriger Effizienz und hoher Kosten gegenüber einem separaten Ladegerät nicht konkurrenzfähig. Zwei Ladekonzepte ohne galvanische Trennung, die eine sechsphasige elektrische Maschine als in Serie geschaltete Hoch- und Tiefsetzsteller nutzen, werden im Rahmen der Arbeit vorgestellt und bezüglich der benötigten Komponenten, der Effizienz und des Drehmoments des Maschine ausgearbeitet. Die Antriebsstrangverluste werden für die Ladebedingungen mit Gleichströmen analysiert, basierend auf neuen Materialcharakterisierungen für die angewendete Belastung. Es wurden Wirkungsgrade bis zu 93% demonstriert und auch in theoretischen Berechnungen mit einer maximalen Abweichung von ±1% zum experimentellen Befund bestätigt. Zum Schutz gegen elektrischen Schlag bei nicht isolierten Ladekonzepten werden drei Konzepte für eine Fehlerstrommessung präsentiert und anhand von Messergebnissen analysiert. Siliziumkarbid-Inverter-Technologien zeigen in Kombination mit diesen Ladekonzepten Wirkungsgrade, die vergleichbar zu herkömmlichen separaten Ladegeräten sind, und weisen dabei deutlich geringere Kosten auf

A review on integrated battery chargers for electric vehicles

Electric vehicles (EVs) contain two main power electronics systems, namely, the traction system and the battery charging system, which are not used simultaneously since traction occurs when the EV is travelling and battery charging when the EV is parked. By taking advantage of this interchangeability, a single set of power converters that can perform the functions of both traction and battery charging can be assembled, classified in the literature as integrated battery chargers (IBCs). Several IBC topologies have been proposed in the literature, and the aim of this paper is to present a literature review of IBCs for EVs. In order to better organize the information presented in this paper, the analyzed topologies are divided into classical IBCs, IBCs for switched reluctance machines (SRMs), IBCs with galvanic isolation, IBCs based on multiple traction converters and IBCs based on multiphase machines. A comparison between all these IBCs is subsequently presented, based on both requirements and possible functionalities.This work has been supported by FCT - Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. T.J.C.S. is supported by the FCT scholarships SFRH/BD/134353/2017 and COVID/BD/151993/2021

Design of an electric drivetrain for the Formula Student-class vehicle

Hlavním úkolem této diplomové práce bylo navrhnout a postavit funkční prototyp frekvenčního měniče pro použití ve vozidlech týmu eForce FEE Prague Formula, soutěžícího v mezinárodní inženýrské soutěži Formula Student. Práce je členěna do několika kapitol, kdy je nejdříve prozkoumán již minule provedený vývoj v týmu. Dále je vystavěna potřebná teorie pro vývoj frekvenčního měniče. Další kapitola detailně popisuje provedený vývoj zařízení. Poslední kapitoly se věnují zhodnocení navrženého měniče. Diplomová práce také prozkoumala nové možnosti v měření fázových proudů, umožňující vysokou přesnost při zachování nízké ceny a kompaktních rozměrů. Celkovým cílem bylo navrhnout jednoduché a robustní zařízení s nízkou výrobní cenou. Ověřování návrhu bylo provedeno v laboratořích fakulty pro ujištění připravenosti navrženého měniče pro nasazení do vozidla. Práce bude pokračovat na vylepšování řídícího algoritmu a postupné integraci do týmových vozidel.This thesis' main objective was to design and develop a functional motor controller for usage in a Formula Student competition vehicle of the eForce FEE Prague Formula team. Work is split into several chapters. Exploring a drivetrain development progression in the team, presenting a needed theory for a motor controller development and giving a detailed overview of the designed device. The last chapters are dedicated to evaluation of the design. Thesis had explored a new methodology in a phase current sensing, providing a significant precision while allowing for a low cost and compact design. Overall aim was to create a simple, robust and cheap solution. Verification of the design was performed in the laboratory environment of the faculty in order to ensure preparedness for integration into the vehicle. Further work will focus on control strategy improvements and final integration into the team's vehicles

Vehicle electrification: technologies, challenges and a global perspective for smart grids

Nowadays, due to economic and climate concerns, the private transportation sector is shifting for the vehicle electrification, mainly supported by electric and hybrid plug-in vehicles. For this new reality, new challenges about operation modes are emerging, demanding a cooperative and dynamic operation with the electrical power grid, guaranteeing a stable integration without omitting the power quality for the grid-side and for the vehicle-side. Besides the operation modes, new attractive and complementary technologies are offered by the vehicle electrification in the context of smart grids, which are valid for both on-board and off-board systems. In this perspective, this book chapter presents a global perspective and deals with challenges for the vehicle electrification, covering the key technologies toward a sustainable future. Among others, the flowing topics are covered: (1) Overview of power electronics structures for battery charging systems, including on-board and off-board systems; (2) State-of-the-art of communication technologies for application in the context of vehicular electrification, smart grids and smart homes; (3) Challenges and opportunities concerning wireless power transfer with bidirectional interface to the electrical grid; (4) Future perspectives about bidirectional power transfer between electric vehicles (vehicle-to-vehicle operation mode); (5) Unified technologies, allowing to combine functionalities of a bidirectional interface with the electrical grid and motor driver based on a single system; and (6) Smart grids and smart homes scenarios and accessible opportunities about operation modes.Fundação para a Ciência e Tecnologia (FCT

High step up DC-DC converter topology for PV systems and electric vehicles

This thesis presents new high step-up DC-DC converters for photovoltaic and electric vehicle applications. An asymmetric flyback-forward DC-DC converter is proposed for the PV system controlled by the MPPT algorithm. The second converter is a modular switched-capacitor DC-DC converter, it has the capability to operate with transistor and capacitor open-circuit faults in every module. The results from simulations and tests of the asymmetric DC-DC converters have suggested that the proposed converter has a 5% to 10% voltage gain ratio increased to the symmetric structures among 100W – 300W power (such as [3]) range while maintaining efficiency of 89%-93% when input voltage is in the range of 25 – 30 V. they also indicated that the softswitching technique has been achieved, which significantly reduce the power loss by 1.7%, which exceeds the same topology of the proposed converter without the softswitching technique. Moreover, the converters can maintain rated outputs under main transistor open circuit fault situation or capacitor open circuit faults. The simulation and test results of the proposed modularized switched-capacitor DC-DC converters indicate that the proposed converter has the potential of extension, it can be embedded with infinite module in simulation results, however, during experiment. The sign open circuit fault to the transistors and capacitors would have low impact to the proposed converters, only the current ripple on the input source would increase around 25% for 4-module switched-capacitor DC-DC converters. The developed converters can be applied to many applications where DC-DC voltage conversion is alighted. In addition to PVs and EVs. Since they can ride through some electrical faults in the devices, the developed converter will have economic implications to improve the system efficiency and reliability

Hybrid Energy Storage Implementation in DC and AC Power System for Efficiency, Power Quality and Reliability Improvements

Battery storage devices have been widely utilized for different applications. However, for high power applications, battery storage systems come with several challenges, such as the thermal issue, low power density, low life span and high cost. Compared with batteries, supercapacitors have a lower energy density but their power density is very high, and they offer higher cyclic life and efficiency even during fast charge and discharge processes. In this dissertation, new techniques for the control and energy management of the hybrid battery-supercapacitor storage system are developed to improve the performance of the system in terms of efficiency, power quality and reliability. To evaluate the findings of this dissertation, a laboratory-scale DC microgrid system is designed and implemented. The developed microgrid utilizes a hybrid lead-acid battery and supercapacitor energy storage system and is loaded under various grid conditions. The developed microgrid has also real-time monitoring, control and energy management capabilities. A new control scheme and real-time energy management algorithm for an actively controlled hybrid DC microgrid is developed to reduce the adverse impacts of pulsed power loads. The developed control scheme is an adaptive current-voltage controller that is based on the moving average measurement technique and an adaptive proportional compensator. Unlike conventional energy control methods, the developed controller has the advantages of controlling both current and voltage of the system. This development is experimentally tested and verified. The results show significant improvements achieved in terms of enhancing the system efficiency, reducing the AC grid voltage drop and mitigating frequency fluctuation. Moreover, a novel event-based protection scheme for a multi-terminal DC power system has been developed and evaluated. In this technique, fault identification and classifications are performed based on the current derivative method and employing an artificial inductive line impedance. The developed scheme does not require high speed communication and synchronization and it transfers much less data when compared with the traditional method such as the differential protection approach. Moreover, this scheme utilizes less measurement equipment since only the DC bus data is required