Influence of high switching frequencies employing wide band gap semiconductors on encoderless control schemes

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The social upheaval towards "renewable energies" demands the partial re-evaluation of known concepts. In power electronics, the influence of the use of "novel" semiconductor materials, such as silicon carbide and gallium nitride, is of great importance in order to achieve a further increase in energy efficiency. For low and medium power drives, silicon carbide switches will replace the silicon technology-based switches used nowadays. In addition to increasing energy efficiency, this also makes it possible to be used at ambient temperatures that cannot be achieved with silicon-based technology. One application would be electromobility. The high safety requirements in electromobility are often accompanied by redundancies in safety-relevant areas. An important component here is the position sensor required for the energy-efficient control of electrical machines. With position sensorless control, a redundancy can be achieved on software side or the physical encoder can be completely be replaced. In recent years, much attention has been paid to position sensorless control in fundamental research, especially in connection with all types of synchronous machines. So far, however, no research has been conducted into the use of semiconductor switches with a high switching frequency in conjunction with position sensorless control. We therefore propose to investigate this fundamentally. The aim is to investigate the position sensorless control of synchronous machines in conjunction with a silicon carbide inverter using a modern FPGA-based controller architecture. To make this possible, a silicon carbide-based inverter will be designed and built. This forms the basis of the investigations that will take place. Furthermore, the question of how the electrical machine can be optimized in order to suppress adverse influences of the increased switching frequencies will be investigated. The optimization and manufacturing of a machine will take place in cooperation with University of Stellenbosch, South Africa. The third aspect of the investigations is the algorithm of the position sensorless control itself. This is the main focus of the investigation. Among other algorithms, the "Arbitrary Injection" algorithm is also used. This was developed at the applicant's institute. This algorithm is characterized by its fundamental independence from the used measurement signal. After completion of the project, the majority of the questions described in more detail in the application will be examined. Furthermore, it is to be expected that knowledge can be gained that can generally be applied to position sensorless control.