Development of an FPGA based Matrix Converter for More Electric Aircraft Applications

The major challenge in the aerospace industry represents the design of technologies and electrically powered systems to improve the performances of tomorrow`s aircraft. In the last 30 years significant researches are made to increase the overall reliability, availability, efficiency, maintainability and operational costs for the next generation of aircrafts. The general requirements of these power circuits are: the system must be fault tolerant with ability to continue operating properly (possibly at a reduced level) in case of a failure, the systems must have small size, low weight and must work in harsh conditions such as high temperature, humidity, vibrations and low maintenance. Matrix Converter is an “all silicon” solution which can direct connect an AC source to an AC load without the need of DC-link electrolytic capacitor. This AC to AC topology is a very promising alternative topology which can replace the actual two step power conversion solution, AC to DC to AC. The advantages of this topology are related to the lack of DC-link electrolytic capacitor, high output voltage quality, high input current quality, power factor control, high dynamic response, four quadrant operation, low current and low voltage stress of bidirectional switches. Despite these advantages, their market penetration is quite low, mainly due to their poor voltage transfer ratio, complexity in terms of structure and control, higher sensibility to input disturbances and its load parameter dependent. The main goal of this work is to design and implement a MC topology which can be used for aircraft applications. The thesis is divided into 6 chapters and in the end are presented the conclusions, appendices and references. In Chapter 1 the research starts with the presentation of the actual electrical system of an aircraft Boeing 787 and continues with the presentation of possible topologies which can be true fault tolerant. Next, a comparison is made between the most suitable topologies which can be used in AC to AC power conversion (MC and V-BBC) from the power components needed point of view for a three-phase load. The Chapter 2 is dedicated to MC study and analysis. Within this part, are presented the most used MC topology structures (DMC and IMC). An important part of the study is focused on bidirectional switches arrangement, safe commutation methods for bidirectional switches and control methods which can be applied. Next, in Chapter 3 the study continues with MC input filter design. MC is a direct AC to AC power conversion and because of this, special protection circuits are designed. An important part of the chapter is accorded to power switches selection and currents, voltages and temperature measurement circuits. In Chapter, 4 the DMC is simulated for two different control methods, 2L-PWM and DSVM. The simulations are made for two types of source frequencies, 50Hz and 400Hz on a RL load. Chapter 5 contains the electrical circuit schemes and the layout of the DMC “Main Board” and “Driver Board” which are used in prototype realization. Chapter 6 is divided into experimental test results for individual components and experimental results of DMC with DSVM algorithm for both source frequencies, 50Hz and 400Hz. Finally, at the end of the thesis are presented the conclusions drawn from this research and recommendations for future work which must be done to improve the waveforms quality. In the appendices sections is presented the code used in Matlab-Simulink for both simulations and also the LabVIEW implementation of the DSVM algorithm. Keywords: aerospace industry, power conversion, more electric aircraft, matrix converter, current commutation, direct space vector modulation, clamp circuit.