Method of determining the power of a synchronous generator for powering the asynchronous starter of prospective transport aircraft

Abstract

Based on the presented genesis of the development of aircraft manufacturing technologies since the middle of the 20-th century, a categorization into four levels based on the degree of electrification has been determined: classical (“old”) aircraft manufacturing technologies, progressive aircraft manufacturing technologies, aircraft with fully electrified equipment (FEE), and fully electric aircraft (FEA). As a prospective aircraft, an aircraft with an modernized progressive manufacturing technology is considered, the improved of which foresees replacement of the pneumatic starter with the electric one.
As an electric starter, asynchronous and synchronous electric machines for starting capacities from 100 to 220 kW should be considered promising. The use of direct current electric machines is limited due to the presence of a collector-brush unit in the design, which limits the starting currents. The maximum power of their use is up to 70 kW. Synchronous electric machines have their limitations. They consist in the absence of a natural starting moment, which is associated with design features. This shortcoming does not allow obtaining a wide range of starting torque in relation to the nominal one and requires the use of special starting devices when forming the input electrical parameters, which must take into account the temperature of its active parts.
An asynchronous electric machine should be considered the most promising for an electric starter in terms of its energy parameters and design. It has the necessary starting characteristics in the absence of a collector-brush assembly. Currently, the availability of new magnetic materials and semiconductor elements makes it possible to create electric launch systems based on an asynchronous electric machine with a capacity of up to 1 MW for VTA aircraft.
The use of an asynchronous electric machine as an electric starter implies a reduction in the number of nodes of the starting system, which makes it possible to increase the reliability of the system as a whole. The development of power transistors and thyristors made it possible to expand the use of an asynchronous electric machine as a starter or starter-generator.
When using an asynchronous electric machine as a starting device for a gas turbine engine, it becomes necessary to calculate the power that a synchronous generator must have for its reliable power supply.
The goal of this article is to propose a methodology for calculating the required power of the primary power source for the electric starter when creating an electric start system for gas turbine engines of future transport aircraft. The order of selecting the primary source of electrical energy needed to supply the direct action electric starter for aircraft of this type is outlined. Recommendations for practical application of the developed methodology are provided, alongside an outline of the direction for necessary further research.