A Space Vector Modulation Scheme for Reduction of Dead-Time Effects on Common Mode Voltage of an Open End Winding Induction Machine

In recent times, the demand for high voltage and high current rating motor drives for electric vehicles applications has increased. These conditions place a great deal of stress on the semiconductor switches, which are usually based on silicon. Multilevel converters provide an alternative that reduces the stress on the switch and also improves the quality of the voltage output. On the other hand, 2-level power converters have proven to be reliable over a number of years. Therefore, they have been used as building blocks to achieve higher voltage and/or currents, by creating a multilevel effect to improve the quality of the voltage waveforms supplied to the motor. In this project, a power configuration with dual 2-level inverters supplying an Open End Winding Machine (OEWM) was studied. This thesis investigates the Space Vector Modulation (SVM) switching strategy for an open end winding machine, fed by dual 2-level inverters. One DC voltage source is employed to feed the both inverters. In addition, the problem of Common Mode Voltage (CMV) in this configuration was discussed in depth and the cause of this problem was explored. The existing SVM strategy to eliminate the CMV due to switching states was discussed in depth and it was modified in order to eliminate the effect of dead-time on the common mode voltages. The existing modulation strategy was adjusted to re-align the switching states according to the phase current direction in order to obtain a proper sequence. The proposed scheme is also applicable for n-level inverters. The performance of the system under the proposed strategy in terms of current and voltage quality was investigated and duly presented. The studies were conducted in MATLAB/Simulink software in the time-domain. Loss calculation using PLECS toolbox is also provided in this thesis

デュアルインバータ駆動オープン巻線誘導電動機の位相制御変調を用いた低負荷領域における高調波低減に関する研究

国立大学法人長岡技術科学大

Technical design of the phase I Mu3e experiment

The Mu3e experiment aims to find or exclude the lepton flavour violating decay μ→eee at branching fractions above 10−16. A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of 2⋅10−15. We present an overview of all aspects of the technical design and expected performance of the phase I Mu3e detector. The high rate of up to 108 muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements

Technical design of the phase I Mu3e experiment

The Mu3e experiment aims to find or exclude the lepton flavour violating decay at branching fractions above . A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of . We present an overview of all aspects of the technical design and expected performance of the phase I Mu3e detector. The high rate of up to muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements

Technical design of the phase I Mu3e experiment

The Mu3e experiment aims to find or exclude the lepton flavour violating decay $\mu \rightarrow eee$ at branching fractions above $10^{-16}$. A first phase of the experiment using an existing beamline at the Paul Scherrer Institute (PSI) is designed to reach a single event sensitivity of $2\cdot 10^{-15}$. We present an overview of all aspects of the technical design and expected performance of the phase~I Mu3e detector. The high rate of up to $10^{8}$ muon decays per second and the low momenta of the decay electrons and positrons pose a unique set of challenges, which we tackle using an ultra thin tracking detector based on high-voltage monolithic active pixel sensors combined with scintillating fibres and tiles for precise timing measurements.Comment: 114 pages, 185 figures. Submitted to Nuclear Instruments and Methods A. Edited by Frank Meier Aeschbacher This version has many enhancements for better readability and more detail

Design and Control of Power Converters 2019

In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc

Mu2e Technical Design Report

The Mu2e experiment at Fermilab will search for charged lepton flavor violation via the coherent conversion process mu- N --> e- N with a sensitivity approximately four orders of magnitude better than the current world's best limits for this process. The experiment's sensitivity offers discovery potential over a wide array of new physics models and probes mass scales well beyond the reach of the LHC. We describe herein the preliminary design of the proposed Mu2e experiment. This document was created in partial fulfillment of the requirements necessary to obtain DOE CD-2 approval.Comment: compressed file, 888 pages, 621 figures, 126 tables; full resolution available at http://mu2e.fnal.gov; corrected typo in background summary, Table 3.

Modulation and control strategies for multilevel five-phase open-end winding drives

Industrial and automotive trends clearly demonstrate an increased interest in medium- and high-power variable speed drives. Despite constant progress in the technology, the semiconductor characteristics are still the bottleneck in drive designs, due to their limitations to block high voltage (several kilovolts) and conduct high current (several hundreds of amperes per-phase). For this reason and numerous other advantages, solutions based on multilevel inverters and multiphase machines are considered in recent years. The open-end winding drives are an alternative approach for drives construction. This thesis investigates carrier based pulse width modulation schemes for five-phase open-end winding drives. Two drive topologies, with isolated dc-links of two inverters, are considered. The first one consists of two two-level inverters and a five-phase machine. The second topology utilises one three- and one two-level five-phase inverter. It is shown that the same drive structure can produce a different number of phase voltage levels, when different dc-link voltages of two inverters are in use. Hence, dc-link voltage ratio is considered as an additional degree of freedom. An open-end winding structure that comprises of two two-level inverters offers harmonic performance equivalent to three- and four-level single-sided supply. The second drive structure under analysis is able to produce four, five and six voltage levels, depending on utilised dc-link voltage ratio. Modulation schemes are classified in two categories. So-called coupled modulation schemes are developed under the assumption that open-end winding drives are equivalent to certain single-sided multilevel solutions. This enables the application of slightly modified modulation methods for multilevel inverters, to the open-end winding configurations. As a consequence, number of utilised voltage levels can be higher than the sum of two inverters’ number of levels. However, this boost in number of levels relies on simultaneous switching in two inverters’ legs connected to the same drive phase,which causes so-called dead-time spikes. The second group, referred to in this thesis as decoupled modulation schemes, rely on the separate modulation of two inverters, using voltage references obtained by splitting the overall phase voltage reference, proportionally to inverters’ dc-link voltages. Hence, this kind of modulation offers somewhat worse harmonic performance, when compared to coupled modulation schemes. Special attention is paid to the stability of dc-link voltage levels, which is one of the most important figures of merits of quality for multilevel drives. Using a novel analysis approach, it is demonstrated that utilisation of optimal harmonic performance offered by coupled modulation methods leads to unstable dc-link voltages, but only in the cases where dc-link voltage ratio is used for increment of available number of voltage levels. Decoupled modulation methods offer stable dc-link voltages, regardless of drive configuration. One of the drawbacks of the analysed open-end winding drives is the need for two isolated dc sources, which form dc-link voltages of two inverters. For that reason, a possibility to use only one dc-source in open-end winding drives with isolated inverters is considered. Analysis shows that both drive topologies can be operated using so-called bulk and conditioning inverter control, where bulk inverter is supplied from an active dc source, but operates in staircase mode, while conditioning inverter performs high-frequency pulse width modulation, in order to suppress low-order harmonic content. This kind of operation is investigated in details for two specific configurations in which two inverters never operate at the same time in PWM mode, when coupled modulation methods are used. Comparison of the results shows that topology which comprises from one three- and one two-level inverter is more suitable for this kind of control. Together with previously analysed configurations and modulation strategies, dynamic performance of this novel drive is tested under the closed-loop speed control. Experimental results show that open-end winding drives are suitable for a wide range of applications

Dark matter searches and study of electrode design in LUX and LZ

There is substantial evidence that over 80% of matter in the universe is dark matter – which is non-baryonic in nature and is thought to be composed of a new, slow-moving, stable particle not found in the Standard Model of Particle Physics. Its presence is inferred from gravitational effects on luminous matter from several independent observations, from the galactic to the cosmological scale. Weakly Interacting Massive Particles (WIMPs) are the leading candidate, which can explain all of the observed effects. LUX and LZ are dual-phase xenon time projection chambers (TPC), aiming to observe scattering of WIMPs from xenon nuclei. LUX has an active mass of 250 kg of liquid xenon, and took data at the Sanford Underground Research Facility in Lead, South Dakota, between 2013 and 2016. The first WIMP search run of 85 live days in 2013 set world-leading exclusion limits on the spin-independent WIMP-nucleon cross section. This was improved by a reanalysis of those data, and subsequently by a new run yielding 332 live days, which set a minimum exclusion limit of 2.2 × 10−46 cm2 for a 50 GeV WIMP (90% CL). In addition, the most stringent limit to date on the spin-dependent WIMP-neutron scattering cross section comes from the reanalysis of the 2013 dataset, with a minimum exclusion of 9.4 × 10−41 cm2 for a 33 GeV WIMP. LZ is a next generation experiment with a 7 tonne active mass to be deployed in the same location as LUX, expected to be 100 times more sensitive. Work presented in this thesis includes analysis of the 2013 LUX search data to produce the spin-dependent results, evaluating the detector response using a tritium β−source, and determining the 85Kr background from data. A study was carried out on spurious electron emission phenomena from thin cathodic wires under high electric fields, using LUX engineering data where the grid voltages were increased above nominal operating values; this led to new insights into the microscopic breakdown mechanisms which have affected these (and other) TPC detectors for decades. The detailed understanding of the electroluminescence response gained in LUX was applied to the design of the LZ electroluminescence region; detailed simulation work of electrode geometry was performed to assess the performance of several candidate designs.Open Acces