The development of aircraft power supply follows a certain pattern, soWhy will airplanes develop DC270V power system？ The editor of this article will gradually analyze and explore. In recent years, there has been significant development in the power system of airplanes as they increasingly rely on electricity, as shown in Figure 1. The voltage of 28VDC was a classic power system in the 1940s and 1950s. There are one or several DC batteries to support the basic load in emergency situations. The voltage is 200VAC to supply power to AC loads. The start-up of the 200VAC aircraft system with a constant frequency (CF) of 400Hz began in the 1990s, with the emergence of variable frequency generator sets and the analysis and management of their loads, as well as backup generators. The switching and distribution of the power system in this cannot be separated from the development of aviation contactors. Only with the emergence of larger payload devices can the development of power be a benign process.

Variable speed constant frequency aircraft appeared in 2000 and still include a constant DC bus of 270VDC as shown in Figure 1-a, which is used to supply power to AC loads; Used three-phase inverter. Due to the existence of the power system, these new variable-speed constant frequency systems contain a large number of harmonic converters. Passive filters that meet harmonic content standards [1] and active power filters use filters [2], [5]. The rated power generation of Boeing and Airbus has increased in the past decade, with Airbus A380 reaching 800kVA and Boeing B787 reaching 1400kVA, as shown in Figure 1-b. The different rated power of aircraft and the technologies used are listed in Table 1 [7]. These aircraft systems emphasize the following.

The 1-CSD/IDG power generation system is an engine driven device that, like traditional aircraft, has constant speed drive (CSD) as shown in Figure 2-a. Through hydraulic mechanical conversion at the source, it serves as the engine

The speed is constant, the generator frequency is constant at 400Hz, and the phase voltage is 115V AC. Due to the complexity of the hydraulic mechanical transmission system, the procurement and maintenance costs of the system are high. Only increasing power can continuously meet the increasing load of aircraft systems, and the Boeing 787 is also the first aircraft to exceed 1000kW. This is also a major reason for the increasing voltage of airplanes, and DC270V has also developed under these conditions.