The increasing shift towards more electric or all electric aircraft urgently necessitates dc/ac converter systems with high power density. Silicon Carbide (SiC) devices, known for their superior performance over traditional silicon-based devices, facilitate this increase in power density. Nonetheless, achieving optimal power density faces challenges due to the unique requirements and conditions of aircraft applications. A primary obstacle is optimizing the topology and parameters of the dc/ac converter system to achieve high power density while adhering to the stringent aerospace EMI standard DO-160 and bearing current limitations. Electric aircraft demand unmatched reliability, necessitating strict control over EMI noise and bearing currents. These considerations significantly impact the selection of topology and parameters to maximize power density. This dissertation assesses how dc voltage, topology, and switching frequency affect component weight, seeking an optimal mix to enhance power density. The methodology and conclusions are validated through a 200-kW motor drive system designed for electric aircraft. Moreover, traditional dc/ac systems are burdened by the weight and space occupied by separate current sensors and short-circuit protection circuits. This work introduces two innovative current sensors that integrate device current sampling with the functionality of traditional shunt resistors, AC hall sensors, and short-circuit protection circuits, thus improving system density and bandwidth. The first sensor, a PCB-based Rogowski coil, integrates with the gate driver and commutation loops, enhancing power density despite challenges in managing CM noise. The second sensor utilizes parasitic inductance in the power loop, with an integrator circuit and an adaptive compensation algorithm correcting errors from parasitic resistance, ensuring high bandwidth accuracy without needing parasitic resistance information. Variable operation conditions from motors pose another challenge, potentially leading to oversized inverters due to uneven loss distribution among switching devices, exacerbated at extreme operating points like motor start-up. This dissertation investigates the loss distribution in multi-level T-Type neutral point clamped (NPC) topology and proposes a novel loss-balance modulation scheme. This scheme ensures even loss distribution across switches, independent of power factor and modulation index, and is applicable to T-type inverters of any level count. Finally, thermal management and insulation at high altitudes present significant challenges. While power devices may be cooled using conventional liquid cooling solutions, components like AC and EMI filters struggle with complex geometries that can create hot spots or high E-field points, complicating filter design for high current applications. A comprehensive design and optimization methodology based on planar heavy-copper PCB design is proposed. By utilizing flexible 2D or 3D E-field shaping and maximizing thermal transfer from copper to ambient, this methodology significantly improves power density and ensures effective heat dissipation and insulation at altitudes up to 50,000 feet. / Doctor of Philosophy / The increasing shift towards more electric or all electric aircraft urgently necessitates dc/ac converter systems with high power density. Silicon Carbide (SiC) devices, known for their superior performance over traditional silicon-based devices, facilitate this increase in power density. Nonetheless, achieving optimal power density faces challenges due to the unique requirements and conditions of aircraft applications. A primary obstacle is optimizing the topology and parameters of the dc/ac converter system to achieve high power density while adhering to the stringent aerospace EMI standard DO-160 and bearing current limitations. Electric aircraft demand unmatched reliability, necessitating strict control over EMI noise and bearing currents. These considerations significantly impact the selection of topology and parameters to maximize power density. This dissertation assesses how dc voltage, topology, and switching frequency affect component weight, seeking an optimal mix to enhance power density. The methodology and conclusions are validated through a 200-kW motor drive system designed for electric aircraft. Moreover, traditional dc/ac systems are burdened by the weight and space occupied by separate current sensors and short-circuit protection circuits. This work introduces two innovative current sensors that integrate device current sampling with the functionality of traditional shunt resistors, AC hall sensors, and short-circuit protection circuits, thus improving system density and bandwidth. The first sensor, a PCB-based Rogowski coil, integrates with the gate driver and commutation loops, enhancing power density despite challenges in managing CM noise. The second sensor utilizes parasitic inductance in the power loop, with an integrator circuit and an adaptive compensation algorithm correcting errors from parasitic resistance, ensuring high bandwidth accuracy without needing parasitic resistance information. Variable operation conditions from motors pose another challenge, potentially leading to oversized inverters due to uneven loss distribution among switching devices, exacerbated at extreme operating points like motor start-up. This dissertation investigates the loss distribution in multi-level T-Type neutral point clamped (NPC) topology and proposes a novel loss-balance modulation scheme. This scheme ensures even loss distribution across switches, independent of power factor and modulation index, and is applicable to T-type inverters of any level count. Finally, thermal management and insulation at high altitudes present significant challenges. While power devices may be cooled using conventional liquid cooling solutions, components like AC and EMI filters struggle with complex geometries that can create hot spots or high E-field points, complicating filter design for high current applications. A comprehensive design and optimization methodology based on planar heavy-copper PCB design is proposed. By utilizing flexible 2D or 3D E-field shaping and maximizing thermal transfer from copper to ambient, this methodology significantly improves power density and ensures effective heat dissipation and insulation at altitudes up to 50,000 feet.

United States government data shows AWD EV production increasing over 376 % from 2020 to 2023. The literature highlights energy savings from mixed-type dual EM powertrains and optimization-based energy management strategies (EMS), compared to single-type dual-motors and rule-based control. Other trends include the adoption of silicon carbide (SiC) based inverter devices and 800 V systems. Axial-flux machines have seen increased traction, with implementations in Ferrari’s SF90 Stradale, Lamborghini’s Revuelto, and Mercedes-Benz’s acquisition of YASA Ltd. These findings motivated the study of dual-motor AWD EV thermally constrained energy management. Using McMaster Automotive Resource Centre’s (MARC’s) facilities, accurate modeling of powertrain components was pursued to contribute realistic results. Firstly, inverter device materials and voltage ratings were studied in a Chevrolet Bolt EV model. Experimental validation was conducted on 1200 V inverters, powering 160+ kW traction machines. The model’s loss error was mostly within 100 W of measured loss. An empirical loss model revealed the analytical model estimates range within 6 km. This work highlighted the benefits of 800 V DC buses and SiC inverters. Secondly, experimental characterization of a yokeless and segmented armature (YASA) axial flux machine, by YASA Ltd., was documented. Dynamometer tests covered a wide torque, speed, and DC bus voltage range. The Bolt EV was modeled with the YASA machine, comparing its performance to the stock machine. All data was compiled and published in an online open-source repository. Lastly, thermally constrained energy management of various control strategies for a dual-motor AWD EV model were compared. Over two drive cycles, an MPC strategy ranked best in selected performance metrics. During a racetrack drive cycle, the MPC strategy kept the thermally limited motor cooler 246 % longer than a rule-based strategy. This work highlighted MPC’s potential in reducing total lifetime thermal wear of a dual-motor powertrain’s thermally limited motor. / Thesis / Doctor of Philosophy (PhD) / This thesis presents the experimental dynamometer work behind the accurate modeling of electric powertrain components, specifically the electric machine (EM) and inverter. The analytical inverter model is experimentally validated using electric machines as loads. The electric machine model is constructed from its experimental characterization data. Together, these models form a near-completely experimental-based electric drive unit (EDU). From this foundation, a dual-motor all-wheel-drive (AWD) electric vehicle (EV) model is built for the purpose of evaluating various control strategies’ thermally constrained energy management abilities. The control methods are ranked with respect to key performance indicators (KPIs) over the course of two drive cycles. Results from these drive cycles point to the model predictive control (MPC) strategy achieving the control objectives with the best quantified KPIs. Most importantly, it was able to keep the powertrain's thermally limited motor cooler 246 % longer than the second-best performing control strategy, a rule-based method applying a torque-split ratio algorithm.

This thesis deals with modeling, simulation and implementation of Load Commutated SCR based current source Inverter (LCI) fed squirrel cage induction motor drive with sinusoidal voltage and sinusoidal current. In the proposed system, the induction motor is fed by an LCI. A three level diode clamped voltage source inverter (VSI) is connected at the motor terminal with ac chokes connected in series with it. The VSI currents are controlled in such a manner that it injects the reactive current demanded by the induction motor and the LCI for successful commutation of the SCRs in the LCI. Additionally, it absorbs the harmonic frequency currents to ensure that the induction motor draws sinusoidal current. As a result, the nature of the motor terminal voltage is also sinusoidal. The concept of load commutation of the SCRs in the LCI feeding an induction motor load is explained with necessary waveforms and phasor diagrams. The necessity of reactive compensation by the active filter connected at the motor terminal for the load commutation of the thyristors, is elaborated with the help of analytical equations and phasor diagrams. The requirement of harmonic compensation by the same active filter to achieve sinusoidal motor current and motor voltage, is also described. Finally, to achieve the aforementioned induction motor drive, the VA ratings of the active filter (VSI) and the CSI with respect to VA rating of the motor, are determined theoretically. The proposed drive scheme is simulated under idealized condition. Simulation results show good steady state and dynamic response of the drive system. Load commutation of the SCRs in the LCI and the sinusoidal profile of motor current and voltage, have been demonstrated. As in LCI fed synchronous motor drives, a special mode of operation is required to run up the induction motor from standstill. As the SCRs of the LCI are load commutated, they need motor terminal voltages for commutation. At standstill these voltages are zero. So, a starting strategy has been proposed and adopted to start the motor with the aid of the current controlled VSI to accelerate until the motor terminal voltages are high enough for the commutation of the SCRs in the LCI. The proposed drive is implemented on an experimental setup in the laboratory. The IGBT based three level diode clamped VSI has been fabricated following the design of the standard module in the laboratory. A generalized digital control platform is also developed using a TMS320F2407A DSP. Two, three phase thyristor bridges with necessary firing pulse circuits have been used as the phase controlled rectifier and the LCI respectively. Appropriate protection scheme for such a drive is developed and adopted to operate the drive. Relevant experimental results are presented. They are observed to be in good agreement with the simulation results. The effect of capacitors connected at the output of the LCI in the commutation process of the SCRs in the LCI is studied and analyzed. From the analysis, it is understood that the capacitors form a parallel resonating pair with filter inductor and the motor leakage inductance, which results in an undesired oscillation in the terminal voltage during each of the commutation intervals leading to commutation failure. So, in the final system, the capacitors are removed to eliminate any chance of commutation failure of the SCRs in the LCI. It is shown by experiment that the commutation of the SCRs takes place reliably in the absence of the capacitors also. The commutation process is studied and analyzed without the capacitors to understand the motor terminal voltage waveform of the experimental results.

This work is focused on single phase inverters, which are used for the conversion of the direct current to the alternating current and are nowdays used especially in systems of back-up power supply. The specific aim of this work is implementation of design hight power circuit of inverter include calculation of control algorithm. It describes the complete solution of power circuit. Next step is a analysis of problems concerning the digital control with help of signal processor which is used for solution of regulator structure. Check of the design and checkout of control algorithm is made in the form of simulation in the MATLAB Simulink. Debugged program algorithm is subsequently implemented into the signal microprocessor. The work results rate estimation functionality of inverter and solution of control algorithm.

Wechselrichter im Antriebsstrang von Elektrofahrzeugen verbinden Batterie und Motor miteinander. Bei konventionellen Wechselrichtern ist die Ständerspannung des Fahrmotors durch die Batteriespannung begrenzt. Dies ist vor allem bei hohen Drehzahlen nachteilig, da hier ein zusätzlicher feldschwächender Strom notwendig ist. Dieser Strom wiederum verursacht zusätzliche Verluste in der Maschine und der Leistungselektronik. Einen alternativen Ansatz bieten hochsetzende Wechselrichter. Die Begrenzung der Ständerspannung durch die Batterie entfällt. In der vorliegenden Diplomarbeit werden zwei hochsetzende Wechselrichter miteinander verglichen. Zunächst wird die Funktionsweise des Wechselrichters mit Hochsetzsteller und des ZSource-Wechselrichters erläutert. Danach werden Bauelemente für beide hochsetzende Wechselrichter ausgewählt. Anschließend werden die Verluste und das thermische Verhalten der ausgewählten Konfigurationen analysiert und mit Matlab simuliert. Abschließend werden der Wechselrichter mit Hochsetzsteller und der Z-Source-Wechselrichter bezüglich der Kriterien Wirkungsgrad, Zuverlässigkeit und Fertigungsaufwand miteinander verglichen. / Inverter in the drive train of electric vehicles connect the battery to the machine. Using conventional inverters, the stator voltage is limited by the battery voltage. This is mainly a disadvantage at a high speed, since an additional field weakening current is needed. This current produces extra losses in the electrical machine and the power electronics. DC/DC boosted inverters offer an alternative solution. A limitation of stator voltage through the battery does not occur. This diploma thesis is comparing two kinds of DC/DC boosted inverters. First the functionality of an inverter with boost converter and that of a Z-Sourceinverter are presented. Afterwards the electrical components for both inverters are chosen and are simulated using Matlab. Finally the results of the simulation are compared with respect to power effciency, reliability of the electrical components and the effort of production.

This dissertation aims at designing a three-phase voltage source inverter based on the SiC devices and mainly the SiC-MOSFET. The designed inverter offers a possibility to drive the power inverter with a very high efficiency, which can reach up to 99% for 16 kW rated power. The design is dedicated to the electric vehicle application, and it aims at • Providing a comparative study on some of the current discrete SiC devices in terms of the total losses and the thermal conductivity. In addition, a behavioral study of the effective channel mobility with temperature variation in the SiC MOSFET will be investigated. • Designing a gate driver which fits with the driving requirements of the SiC-MOSFET and provides a trade-off between the switching losses and the EMI behavior. • Designing a three-phase voltage source inverter with 16 kW rated power; the design includes minimizing the inverter losses and extracts the EMI model of the power inverter by considering the effects of the parasitic parameters; moreover a short guideline for selecting the heat-sink based on the static network is introduced. • Proposing a new and simplified carried-based PWM, this will reduce the harmonics in the output waveforms and enhance the utilization of the DC-link voltage. • Proposing a new strategy for compensating the dead-time effect in carrier based-PWM and to find out the proper dead-time level in VSI based on SiC –MOSFET. • Designing faults diagnosis and protection circuits in order to protect the power inverter from the common faults; overcurrent, short-circuit, overvoltage, and overtemperature faults.

Hysteresis current control has been widely used in power electronics with the advantages of fast dynamic response under parameter, line and load variation and ensured stability. However, a main disadvantage of hysteresis current control is the uncertain and varying switching frequency which makes it difficult to form an average-value model. The changing switching frequency and unspecified switching duty cycle make conventional average-value models based on PWM control difficult to apply directly to converters that are controlled by hysteresis current control. In this work, a new method for average-value modeling of hysteresis current control in boost converters, three-phase inverters, and brushless dc motor drives is proposed. It incorporates a slew-rate limitation on the inductor current that occurs naturally in the circuit during large system transients. This new method is compared with existing methods in terms of simulation run time and rms error. The performance is evaluated based on a variety of scenarios, and the simulation results are compared with the results of detailed models. The simulation results show that the proposed model represents the detailed model well and is faster and more accurate than existing methods. The slew-rate limitation model of hysteresis current control accurately captures the salient detail of converter performance while maintaining the computational efficiency of average-value models. Validations in hardware are also presented.

The primary objective of this thesis is to develop a process for fabricating integrated circuits based on thin-film transistors (TFTs) using zinc tin oxide (ZTO) as the channel layer. ZTO, in contrast to indium- or gallium-based amorphous oxide semiconductors (AOS), is perceived to be a more commercially viable AOS choice due to its low cost and ability to be deposited via DC reactive sputtering. In the absence of an acceptable ZTO wet etch process, a plasma-etching process using Ar/CH₄ is developed for both 1:1 and 2:1 ZTO compositions. An Ar/CH₄ plasma etch process is also designed for indium gallium oxide (IGO), indium gallium zinc oxide (IGZO), and indium tin oxide (ITO). Ar/CH₄ dry etches have excellent selectivity with respect to SiO₂, providing a route for obtaining patterned ZTO channels. A critical asset of ZTO process integration involves removing polymer deposits after ZTO etching without active layer damage. A ZTO process is developed for the fabrication of integrated circuits which use ZTO channel enhancement-mode TFTs. Such ZTO TFTs exhibit incremental and average mobilities of 23 and 18 cm²V⁻¹s⁻¹, respectively, turn-on voltages approximately 0 to 1.5 V and subthreshold swings below 0.5 V/dec when annealed in air at 400 °C for 1 hour. Several types of ZTO TFT circuits are realized for the first time. Despite large parasitic capacitances due to large gate-source and gate-drain overlaps, AC/DC rectifiers are fabricated and found to operate in the MHz range. Thus, they are usable for RFID and other equivalent-speed applications. Finally, a ZTO process for simultaneously fabricating both enhancement-mode and depletion-mode TFTs on a single substrate using a single target and anneal step is developed. This dual-channel process is used to build a high-gain two-transistor enhancement/depletion inverter. At a rail voltage of 10 V, this inverter has a gain of 10.6 V/V, the highest yet reported for an AOS-based inverter. This E/D inverter is an important new functional block which will enable the realization of more complex digital logic circuits. / Graduation date: 2009

<p>U tezi je prikazana analiza pogona sa šestofaznom asimetričnom<br />asinhronom mašinom koja se napaja iz šestofaznog invertora.<br />Predložen je novi način upravljanja šestofaznim invertorom kojim<br />su rešeni nedostaci do sada predloženih tehnika upravljanja a koji<br />se pre svega ispoljavaju kroz dva aspekta: nekontrolisano generisanje<br />dodatnih gubitaka i teška implementacija u komercijalno dostupne<br />digitalne kontrolere. Rezultati svih teorijskih analiza i navoda su<br />dokazani računarskim simulacijama i eksperimentalnim putem.<br />Eksperimentalna verifikacija je ostvarena korištenjem<br />laboratorijskog prototipa koji se temelji na dSPACE kontrolnom<br />sistemu.</p> / <p>Doctoral thesis shows the analysis of the dual three-phase induction machine<br />drive. A novel way of driving of the six-phase inverter is proposed. A<br />proposed method solves disadvantages of currently proposed driving<br />techniques which are manifested in two aspects: the uncontrolled generation<br />of additional losses and difficult implementation in commercially available<br />digital controllers. The results of theoretical analysis and the statements are<br />proven by computer simulation and experimentally. Experimental verification<br />is achieved using a laboratory prototype that is based on dSPACE control<br />system.</p>

Ce mémoire présente le travail de thèse réalisé auprès des laboratoires LAPLACE et SATIE ainsi que les services EDYNE3 et EDYYLIC d'AIRBUS OPERATIONS. Le sujet porte sur les problèmes CEM apparaissant dans les convertisseurs de puissance embarqués à bord des futurs avions plus électriques. Le manuscrit est composé de cinq parties. La première partie, d'introduction, traite de la problématique CEM avion, la deuxième de la modélisation des éléments de la chaine de conversion DC/AC étudiée. Le troisième est composé d'une étude comparative par simulation des différentes solutions. La quatrième partie traite de la réalisation de la solution choisie et enfin le cinquième et dernier chapitre de l'étude expérimentale de celle-ci. / The studies conducted during this thesis deals with conducted EMC problems of an inverter associated to its actuator. Accurate high frequency models of every element of the DC/AC converter and actuator have been realised from measures. Then a comparative study of different topologies of converters have been led from simulations in order to determine the best solution minimising EMC current. The selected inverter was realised and the experimental results were compared to simulations validating them. Finally, a comparison of EMC filters architecture led to choose a better solution in order to avoid the increasing of mass.