## 1 Introduction  
Currently, in modern aviation, military (Lockheed Martin) and civil aviation (Airbus, Boeing), both in the field of military aircrafts JSF (Joint Strike Fighter) F-35 and F-22 Raptor, as well as civilian aircrafts (A-380 and A-350 XWB, B-787), according to the evolving trend of the more/all electric MEA/AEA aircraft (More/All Electric Aircraft), the dynamic development of on-board advanced electrical systems AAES (Aircraft Advanced Electrical Systems) can be observed. The above systems are characterized by advanced technological solutions in terms of two key components in the form of systems, namely the electro-energetic power supply system EPS (Electric Power System) and energy-electronic power system PES (Power Electronics Systems) and its main components, such as multi-pulse rectifiers, including 12-, 24- and 36-pulse, which were subject to detailed analysis in this paper. A representative of multi-pulse rectifiers in aviation is a transformer-rectifying device, popularly referred to as a TRU (Transformer Rectifiers Unit), used primarily in the absence of basic DC (Direct Current) sources (generator, integrated starter/generator unit) and ATRU (Auto-Transformer Rectifier Unit) on-board aircrafts. They are mainly used on aircrafts where the leading power system is a constant-frequency AC (Alternating Current) electro-energetic power supply system in the case of conventional aircrafts, and an on-board autonomous power system for alternating frequency AC in the case of advanced aircrafts compatible with the MEA/AEA concept. Changes in the on-board power supply in modern aviation exert a decisive influence on the dynamically developing concept of a more electric aircraft, including in particular the dominant role of innovative systems in the generation, processing and transmission of AC electricity on-board a modern aircraft. Referring to the analysis of the dominant role of an on-board AC power supply, it should be noted that in the case of advanced aircrafts in accordance with the MEA/AEA concept, the electrical network is based on VF (Variable Frequency) or integrated AC unit starter/alternator AS/G VF (Alternating Starter/Generator Variable Frequency). In the case of aircrafts in the field of \"More Electric\" or MET (More Electric Technology), advanced AC electric networks of elevated frequency in the range of 360-800 Hz are used in various types of industries (marine, automotive, renewable energy sources) and above all in aviation and space applications in which the key essence consists of converting conventional types of energy (electric, mechanical, hydraulic, pneumatic) to one kind of energy, namely electricity. Usually, especially in the case of classical aircrafts, the systems considered above are supplemented with DC electric networks, using voltages of different values, suited to the target receivers working on-board aircrafts [1,2]. The current state of the technology, especially of electronics and power electronics, allows for the reduction of a number of power systems to one system, namely to AC mains, leaving emergency sources based on accumulator batteries as the so-called final link of the on-board power supply of the modern aircraft. Through modern advanced systems such as electronic devices and power electronic elements, it is possible to design rectifier circuits matching one AC network to provide power to all receivers, regardless of the value and type of voltage (AC or DC). However, the problem with creating a uniform power system and the use of semiconductor converters requires a number of tests to obtain the appropriate PF (Power Factor), determined by the quotient of active power to maximum power found in the power supply system and the THD (Total Harmonic Distortion) signal aspect ratio. The power factor is an element of economic effect, and the essence of the shape coefficient of signals is the maintenance of electromagnetic compatibility.