Current controls the motion of a manipulator. The manipulators at ABB are powered by a three-phase alternating current system where shunt resistors are utilised to measure the current to the motors. Magnetic field sensors are instead investigated to eliminate issues with power losses, the number of components and the cost of the shunt resistors. Since current produces a magnetic field, it can be measured without contact using a magnetic field sensor. However, employing non-contact magnetic field sensors in three-phase implementations introduces problems with stray magnetic fields due to the three traces being in close proximity to each other. This magnetic crosstalk will influence the sensors, hence the current measurement for each trace. In this thesis separating this influence of the magnetic fields is done through a software approach. Initially, two magnetic field sensors, a tunnel magnetoresistance sensor and a Fluxgate sensor, were tested and evaluated to gain knowledge and understanding. From the different tests, it was decided to continue with the Fluxgate sensor. Further, a partial least-squares regression was constructed to separate the magnetic field and predict the current in each trace from the Fluxgate sensor output. From a simulation created, the current could be predicted with an error of approximately 1 nA, meaning less than 0.1% when considering a simulated linear model of the Fluxgate sensor.

A DC power distribution system (PDS) of a transport aircraft was modeled and analyzed using MATLAB/Simulink software. The multi-level modeling concept was used as a modeling approach, which assumes modeling subsystem of the PDS at three different levels of complexity. The subsystem models were implemented in Simulink and combined into the whole PDS model according to certain interconnection rules. Effective modeling of different scenarios of operation was achieved by mixing subsystem models of different levels in one PDS model. Linearized models were obtained from the nonlinear PDS model for stability analysis and control design. The PDS model was used to examine the system stability and the DC bus power quality under bidirectional power flow conditions. Small-signal analysis techniques were employed to study stability issues resulting from subsystem interactions. The DC bus stability diagram was proposed for predicting stability of the PDS with different types of loads without performing an actual stability test based on regular stability analysis tools. Certain PDS configurations and operational scenarios leading to instability were identified. An analysis of energy transfer in the PDS showed that a large energy storage capacitor in the input filter of a flight control actuator is effective for reduction of the DC bus voltage disturbances produced by regenerative action of the actuator. However, energy storage capacitors do not provide energy savings in the PDS and do not increase its overall efficiency. / Master of Science

Submitted by ALESSANDRO LUCINDO DA LUZ null (aledaluz@hotmail.com) on 2018-01-10T01:24:32Z No. of bitstreams: 1 Operacao flexivel conversores_ALuz.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-01-10T11:41:48Z (GMT) No. of bitstreams: 1 luz_al_me_bauru.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) / Made available in DSpace on 2018-01-10T11:41:48Z (GMT). No. of bitstreams: 1 luz_al_me_bauru.pdf: 10997918 bytes, checksum: 18fe1f6d3eba73d11bf63fab8cf0a0be (MD5) Previous issue date: 2017-11-13 / Este trabalho de mestrado descreve uma estratégia de operação multifuncional e flexível aplicado a conversores trifásicos CC-CA (inversores) conectados à rede de distribuição de energia elétrica. A estratégia proposta é capaz de injetar potência ativa na rede e compensar correntes de distúrbios (reativos, desbalanço e harmônicos) simultaneamente. O maior objetivo desta operação flexível é de melhorar a Qualidade de Energia Elétrica em um ponto de acoplamento comum (PAC) permitindo a compensação total ou parcial destes distúrbios ou fatores que degradam a Qualidade de Energia Elétrica. O fator de potência é o principal fator de qualidade a ser observado e ele é calculado através da Teoria da Potência Conservativa – CPT. Entretanto, com base no fator de potência medido pelo lado da rede de distribuição e o fator de potência desejado, um coeficiente de compensação – k é calculado para o ajuste das correntes de compensação dos distúrbios que geram a potência não ativa. / This paper depicts a multifunctional and flexible control strategy applied in three-phase inverters, which are connected to the distribution network. The proposed strategy is able to inject active power into the electrical grid and compensate current disturbances (reactive, harmonics and unbalance) simultaneously. The main goal of this flexible strategy is to improve the Power Quality at the point of common coupling (PCC) allowing full or partial compensation of disturbances. Power factor is the main quality index observed and it is calculated according to Conservative Power Theory - CPT. Therefore, based on the power factor measured in the grid side and the desired value for the power factor, a compensation coefficient - k is calculated continuously adjusting the amplitude of the compensation current.

Zur Entwicklung eines effizienten Verfahrens zur CO2-Hydierung im Dreiphasensystem erfolgten in dieser Arbeit Untersuchungen zur Optimierung des Katalysatorsystems, zum Screening nach neuen geeigneten Lösungsmitteln und zum Einfluss der Prozessführung. Durch Variieren des Trägersystems und der Präparationsmethode ergaben sich sieben Kupferkatalysatoren, welche sich in ihren Eigenschaften und ihrer katalytischen Aktivität unterschieden. Zudem gelang die Immobilisierung von Kupferkatalysatoren auf Aluminiumoxid und auf Glas. Es wurde eine kontinuierliche Anlage mit Rieselbettreaktor entwickelt und in Betrieb genommen, welche die Durchführung der CO2-Hydrierung in Gasphase und im Dreiphasensystem bei bis zu 90 bar ermöglicht. Im Batchversuch zeigte sich der Einfluss der Lösungsmittel auf die Effizienz des Katalysators. Vielversprechende Lösungsmittel wurden dann zur Methanolsynthese im kontinuierlichen Prozess eingesetzt, um den Einfluss der Prozessbedingungen zu untersuchen.