Analysis of Aircraft Alternating Current Machines with Enhanced Power Performance
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RAFT AND ROCKET ENGINE THEORY
Analysis of Aircraft Alternating Current Machines with Enhanced Power Performance A. Yu. Afanas’eva, *, A. A. Petrova, A. N. D. Almakkya, and A. A. Zainullina a
Tupolev Kazan National Research Technical University, ul. Karla Marksa 10, Kazan, Tatarstan, 420111 Russia *e-mail: [email protected] Received January 22, 2020; revised March 11, 2020; accepted June 25, 2020
Abstract—The distribution of magnetic induction in the working gap of an alternating current machine with enhanced power performance is investigated. The efficiency of the machine winding proposed is analyzed. The results obtained by the analytical and software methods are compared. DOI: 10.3103/S1068799820030216 Keywords: alternating current electric machine, combined winding, phase current, magnetomotive force, magnetic induction.
Important elements of the electrical equipment of aircraft are synchronous and asynchronous electric machines. Synchronous machines are used as primary sources of electricity as well as starter generators [1]. They are used in instrumentation electromechanical systems [2], in pumps, compressors, hydraulic and pneumatic systems, to drive wing high-lift devices and control surfaces [3], on unmanned aerial vehicles as traction engines [4]. Along with the requirements of high reliability and controllability, the high energy performance is important that links the useful power of an electric machine with its volume and mass as well as with the amount of electrical, magnetic, and mechanical losses. One of the ways to improve the harmonic composition of the magnetic field in the working gap is the application of a doubly fed winding. The main idea of such a winding is that it consists of two windings, one of which has the wye connection and the other—the delta connection. In this case, the phase shift between the phase and line voltages is 30 deg. In addition, the windings are circumferentially shifted by an angle of 30 el. deg, which makes it possible to obtain an air gap induction larger than the induction of one distributed winding. Figure 1 shows a doubly fed winding with a winding A, B, C of wye connection and a winding D, E, F of delta connection. The switching circuit (a) and the vector voltage diagram (b) are shown in Fig. 2.
18 1 2 3
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1
Fig. 1.
Phase A of the main winding is located in the lower halves of grooves 2, 11 and in grooves 3, 12. Phase D of the additional winding is located in grooves 1, 10 and in the upper halves of grooves 2, 11. It is seen that the centers of mass of these phases are displaced by 1.333 grooves or by 26.666 el. deg. Therefore, the first spatial harmonics of the magneto motive force (MMF) of windings are shifted by 3.333 el. deg. 526
ANALYSIS OF AIRCRAFT ALTERNATING CURRENT MACHINES
527
A UD A
D
N B B
UA
F UF
C
0
UB
UC C
E
UE Fig. 2.
Phase B of the main winding occupies the lower halves of grooves 8, 17 and grooves 9, 18, and phase C occupies the lower halves of grooves 14, 5 and grooves 15, 6. Phase E o
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