RU2583837C1 - Integrated high-temperature starter-generator and control method thereof - Google Patents

Abstract

FIELD: electronic equipment; engines and pumps.

SUBSTANCE: invention relates to electrical engineering, namely, to aircraft engine start and power supply to onboard system of aircraft. Starter-generator, rotor shaft of which is common to shaft of gas turbine engine, wherein on shaft there are permanent magnets with alternating polarities and different allowable operating temperature, and in stator slots located pole switching winding. Method of controlling integrated starter-generator consists in reduction of number of active poles in mode of operation of generator, thus reducing frequency of generated current, and in mode of operation of starter in increasing number of active poles, while providing sufficient starting torque, with automatic demagnetisation under temperature effect or are magnetized with permanent magnets on rotor depending on operating mode of starter-generator.

EFFECT: providing stable operation of integrated starter-generator in temperature mode to 450 °C due to automatic reduction of number of poles in case of allowable operating temperature exceeding and pass into generator mode and vice versa, increasing number of poles with reduction of operating temperature below permissible and pass in mode of starter.

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Description

The invention relates to the field of aircraft manufacturing, in particular to devices for starting an aircraft engine and powering the aircraft's onboard system.

Known starter-generator [Utt V.E. Electric equipment of cars. - M .: Transport, 1995. - 303 p.], Consisting of a DC collector motor, a mechanical transmission and an alternating current generator with a rectifier and a field winding on the rotor, connected via contact rings to the generator voltage control device, and mechanically connected to the shaft engine through a belt drive. The rotor of the collector motor in the starter mode of operation is mechanically connected to the flywheel of the shaft of the internal combustion engine.

The disadvantages of this device are the complexity of the design, consisting of two electrical machines, and the presence of a mechanical gearbox with a belt drive. Another drawback is the presence of movable contacts — a brush-collector assembly and slip rings, which reduces the reliability of the electric machine as a whole and increases energy losses.

A device is known for a two-speed synchronous motor with permanent magnets [USSR copyright certificate No. 201522, H02K 21/14, 01/01/1967]. The stator of the motor is a stator of a traditional AC machine, in the grooves of which there is a distributed pole-switchable winding. The rotor of the motor has two pole systems formed by permanent magnets, each of which corresponds to a certain number of poles of the stator winding and they are located side by side on the same motor shaft.

The disadvantage of this device is the high overall dimensions of the engine, due to the presence of several pole systems of the rotor.

A device is known [RF patent No. 2321765, H02N 11/00, 04/10/2008], consisting of a two-phase valve-induction machine with electromagnetic asymmetry and the power part of the control system. The main winding of each of the two phases is connected to the power source through one inverter transistor, and each of the recovery windings of the two phases is connected to the power source through one inverter diode.

The disadvantages of this device are high weight and size indicators, as well as a complex power system of an electric machine, which increases the energy loss on the excitation of the starter.

The closest in technical essence and the achieved result is a device [US patent No. 8269390 B2, 09/18/2012], which is a starter-generator containing a shaft on which permanent magnets are mounted, a stator magnetic circuit on which the windings are located, and a rectifier control system unit elements. Permanent magnets of various types are located on the shaft: Nd-Fe-B, Al-Ni-Co and Fe-Cr-Co. These magnets have different values of coercive force from 100 kA / m to 950 kA / m. When the starter-generator is operating, the armature reaction field created by the current flowing in the stator winding acts on the permanent magnets located on the shaft, as a result of which the magnets with the minimum values of the coercive force are demagnetized and thus the additional poles are disconnected.

The disadvantage of this device is the temperature limitation of the operation mode due to the permanent magnets used in this device from Nd-Fe-B alloy, which have an operating temperature of up to 180 degrees.

The objective of the invention is the expansion of the functionality of the starter generator due to its integration in a gas turbine engine; simplification of its control method by automatically changing the number of active poles of the starter generator, depending on the operating mode of the gas turbine engine without additional electronics.

EFFECT: stable operation of the starter generator as part of a gas turbine engine in the temperature regime up to 450 ° C due to automatic reduction of the number of poles on the shaft when its temperature is increased associated with the transition to generator mode, and vice versa, an increase in the number of poles during cooling and transition to starter mode.

The problem is solved, and the technical result is achieved by the fact that in the starter-generator containing the shaft on which the permanent magnets are mounted, the stator magnetic circuit on which the windings are located, the rectifier control system unit, according to the invention, a pole-switched winding is located in the stator slots, while the shaft of the starter generator and the gas turbine engine is made uniform, and permanent magnets with alternating polarities and various permissible operating temperatures are installed on the shaft ramie.

The problem is solved, and the technical result is also achieved by the method of controlling the starter-generator, according to which the number of active poles is reduced in the operating mode of the generator, thereby reducing the frequency of the generated current, and in the mode of operation by the starter, the number of active poles is increased, while providing a sufficient starting moment, during automatic demagnetization or magnetization of poles under the influence of temperature, depending on the operating mode of the starter-generator.

The invention is illustrated by drawings. In FIG. 1 shows a general view of a starter generator integrated in a gas turbine engine. In FIG. 2 shows a starter-generator in longitudinal section.

The proposed device (Fig. 1) contains a gas turbine engine 1, on the shaft 2 of which the starter-generator 7 is installed, permanent magnets 3 are also located on the shaft, in the stator 4 of the starter-generator 7 there is a pole-switched winding 6 for voltage stabilization, the terminals of the pole-switched winding are connected to control system 5.

The proposed device operates as follows: the starter-generator 7 accelerates the shaft 2 of the gas turbine engine to the starting speed of rotation, upon reaching which the air flow and pressure are created in the combustion chamber to reliably ignite the fuel and bring the turbine into operation, i.e. at the stage of fuel ignition, the air temperature of the starter generator is equal to the ambient temperature (up to + 50 ° C in tropical climates).

An example of a specific implementation of the method

To start an aircraft engine of the GTD-350 model, a high starting torque M = 240 N · m is required. Since the starting torque M is related to the rotational speed n by the ratio:

where P _nom - rated engine power, kW;

and the rotation frequency is related to the number of pole pairs p by the ratio:

where f is the current frequency, Hz;

an increase in the number of pole pairs will create a greater starting torque. Given this, a large number of pole pairs are used in the design of the starter-generator shaft, which are alternating permanent magnets of the SmCo5 and Sm2Co17 alloys. These magnets have different operating temperatures, for example, SmCo5 alloy has a limit of 250 ° C, and Sm2Co17 to 550 ° C. Thus, when the starting speed of rotation of the turbine is reached, the fuel-air mixture ignites, the turbine starts to work, i.e. develop torque, and the ambient temperature rises. In this case, the starter-generator and turbine jointly untwist the shaft of the gas turbine engine. With increasing gas temperature, the rotational moment developed by the turbine increases, and the moment developed by the starter-generator, and at a certain moment the starter-generator switches to the generator mode, decreases due to an increase in the temperature of permanent magnets and windings. As you know, in the generator mode, the temperature of the starter generator rises to 350 ° C, because of this, some of the permanent magnets from SmCo5 alloy lose their magnetic properties, which leads to the fact that the number of poles of the starter generator is reduced, which reduces the current frequency, generated by the generator to the desired value.

Thus, this starter-generator, depending on the operating mode of the aircraft engine, changes its pole system to the optimal one.

So, the claimed invention provides maximum output energy characteristics in all operating modes.

Claims (2)

1. A starter-generator, comprising a shaft on which permanent magnets are mounted, a stator magnetic circuit on which the windings are located, a rectifier element control system unit, characterized in that a pole-switched winding is located in the stator slots, while the shaft of the starter-generator and gas turbine engine permanent magnet magnets with alternating polarities and various permissible operating temperatures. 2. The method of controlling the starter-generator, according to which the number of active poles is reduced in the operating mode of the generator, thereby reducing the frequency of the generated current, and in the mode of operation by the starter, the number of active poles is increased, while ensuring a sufficient starting moment, when the demagnetization is automatic under the influence of temperature or magnetization of the poles depending on the operating mode of the starter generator.

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