RU2746149C1 - Method of short circuit protection of magnetoelectric generator - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electric machine engineering and can be used in magnetoelectric generators for short circuit protection. The method of short circuit protection of a magnetoelectric generator, wherein existence of a short circuit is determined by the values of temperature, current and voltage, wherein the method is characterized by a coil galvanically and thermally isolated from other coils of the magnetoelectric generator phase being disconnected from other winding coils and commuted to itself upon detecting inter-turn short circuit on the coil.

EFFECT: increased operational reliability of a magnetoelectric generator due to short circuit protection of turns.

1 cl, 2 dwg, 1 tbl

Description

The invention relates to the field of electrical engineering and can be used in magnetoelectric generators for short circuit protection

Known protection device against short circuit [RF patent No. 2399137C1, class. Н02Н 7/06, 26.12.2008], installed in the alternator to control the excitation current generated by the excitation winding of the alternator, containing a start switch electrically connected to the excitation winding and operating so that the on / off of the start switch corresponds to the transmission / cut-off of the excitation current; a sensor having a current input assembly and a current output assembly, respectively, electrically connected to a start switch and a ground potential, the sensor passing a drive current when the start switch is turned on; a amplification circuit comprising an input end and an output end, the input end being electrically connected to the current input assembly of the sensor.

The disadvantage of the analogue is the limited functionality due to the fact that the use of this device is impossible in magnetoelectric generators.

There is a known device for protecting an alternator from a short circuit in a redundant power supply system [RF patent No. 1017146, cl. Н02Н 7/06, 27.08.2004], containing a contactor for connecting generators to the buses, a block of current transformers in the stator winding circuit of the generator, a block of current transformers in the load circuit, semiconductor diodes according to the number of generator phases and an actuator whose input is connected to the output of a half-wave rectifier formed by diodes and back-to-back secondary windings of current transformer blocks, secondary windings of current transformer blocks, shunted by diodes, while in relation to the rectifier diodes, diodes shunting the windings of the current transformer block in the stator winding circuit of the generator are turned on according to, and the diodes , shunt windings of the current transformer block in the load circuit - opposite.

The disadvantage of the analogue is the limited functionality due to the fact that the use of this device is impossible in magnetoelectric generators.

A known method of protecting a magnetoelectric generator from short circuit [US patent No. 4950973, class. Н02Р 9/10, 08.21.1990], implemented by a device containing a generator with permanent magnets, the first, second and third output terminals, a protection unit containing the first, second and third pair of electrical contacts, and the first, second, third stator winding ... The first stator winding is electrically connected between the first pair of electrical contacts and the neutral point. The second stator winding is electrically connected between the second output terminal and the neutral point. The third stator winding is electrically connected between the third pair of electrical contacts and the neutral point. The third stator winding comprises means for opening and closing the first and second pair of electrical contacts in response to a control signal.

This analog has a number of disadvantages. Firstly, the stator winding has a low service life, which is due to the fact that in the event of a short circuit, the stator winding of the magnetoelectric generator is exposed to the entire short circuit current. Secondly, it has limited functionality due to the fact that the control signal is determined only by the value of the current strength.

A known method of protecting a magnetoelectric generator from short circuit, implemented by a protection device for a magnetoelectric generator [RF patent No. 2691735, cl. Н02К 1/14 (2006.01), September 17, 2018], containing a rotor, a stator magnetic circuit with a slotted, main winding and a toroidal, auxiliary magnetizing winding, which is electrically connected to a direct current source, and also electrically connected to an electrical resistance unit, which is electrically connected to the control system, and the control system is electrically connected to a multi-channel voltmeter, which is connected to the phases of the main winding. The toroidal, auxiliary bias winding is electrically connected to a rectifier, which is electrically connected to a three-phase inverter and control system. The three-phase inverter is connected to the starter of the aircraft's main engine. The control system controls the magnetoelectric generator through the switching keys. The main windings are also connected to the load through a multichannel voltmeter. The main winding and the toroidal, auxiliary bias winding have lead ends.

The disadvantages of the analog are limited functionality, the complexity of short-circuit protection, the need for a direct current source. In addition, the presence of a bias winding reduces the copper filling factor of the main winding, which leads to an increase in the current density of the main winding and, as a consequence, to an increase in losses in the main winding.

Closest to the claimed method is a method of controlling a system for protecting a magnetoelectric generator from short circuits [RF Patent No. 2644586, cl. Н02Н 7/06 (2006.01) 04/28/2017], according to which the presence of a short circuit is determined by the magnitude of the temperature, the magnitude of the current and the magnitude of the voltage, after detecting a short circuit on the phase winding of the generator, this winding is connected in series with the bias winding, the inductive resistance of the phase winding is increased and reduce the short-circuit current to the rated one, and then disconnect the magnetoelectric generator from the drive, with the possibility of providing protection against overheating of the magnetoelectric generator.

The disadvantages of the prototype are limited functionality, the complexity of short-circuit protection, the need for a bias winding. In addition, the presence of a bias winding reduces the copper filling factor of the main winding, which leads to an increase in the current density of the main winding and, as a consequence, to an increase in losses in the main winding.

The objective of the invention is to expand the functionality due to a change in the active resistance of the winding in the short circuit mode and, as a consequence, to increase the reliability of the magnetoelectric generator.

The technical result is an increase in the reliability of the magnetoelectric generator due to the protection against short circuit of the windings.

The problem is solved and the specified technical result is achieved by the fact that in the method of short-circuit protection of a magnetoelectric generator, which determines the presence of a short circuit in terms of temperature, current and voltage, according to the invention, after detecting a short turn-to-turn circuit in one of the coils, it disconnected from other coils, opening the keys connecting it to the load and closing the key shunting it.

The essence of the invention is illustrated by drawings. FIG. 1 shows a cross section of a magnetoelectric generator, FIG. 2 shows an electrical diagram of the connection of the short circuit protection method of the magnetoelectric generator.

An example of a specific implementation of the method.

As a material that implements the method, a magnetoelectric generator with a power of 60 W, a rotational speed of 3000 rpm, a nominal phase current of 1.21 A, a nominal phase voltage of 8 V, a six-phase toothed winding (single-layer) is used, the stator has 12 slots, the rotor has 14 poles. The phases of the winding are galvanically and thermally separated. Coil temperature in nominal operation 40 ° C.

The short-circuit protection device of the magnetoelectric generator contains (Fig. 1) a rotor 1, a stator magnetic core 2 with a groove winding 3, which is connected to the control system 4 and load 5. The groove winding 3 has phases For consisting of coils 6 (the number of coils depends on the type windings, the number of slots and poles), at the terminals of which the measuring unit 7 is installed, with which the voltage, temperature and current of the coils 6 are determined. After the measuring unit 7, three keys 8a, 86, 8b are placed (Fig. 2), and they are connected with load 5. Keys 8a, 86, 8b, and measuring unit 7 are connected to control system 4. To explain the principle of operation of the device, an emergency coil 6a is introduced.

The method of short-circuit protection of a magnetoelectric generator is implemented as follows: when the rotor 1 rotates, the magnetic field flux flows through the stator 2 magnetic circuit. In this case, according to the law of electromagnetic induction, an electromotive force (EMF) is induced in the main winding 3, the value of which depends on the number of turns in coils 6 and 6a, the rotor speed 1 and the magnetic field flux. When the rated load 5 is connected to the winding 3, the rated current of 1.21 A begins to flow in the coils 6 and 6a, the phase rated voltage of the winding is 3 - 8 V, the voltage of the coils is 6 - 8 V (since the phase consists of one coil). In the nominal operating mode, keys 8a and 8b are closed, 86 are open. In critical operating modes (turn-to-turn closure), when the voltage of the coil 6a, measured by the measuring unit 7, is 15% less than the calculated one, the current of the coil 6a, measured by the measuring unit 7, is 15% more or less than the calculated (nominal), and the temperature of the coil 6 is more than 1.3 times the design temperature, then the control system 4 disconnects keys 8a and 8b, and 86 closes. As a result, in the coil 6a, in which the turn-to-turn closure occurred, its active resistance is switched, thereby the currents in the emergency coil 6a are reduced, and the emergency coil 6a is electrically disconnected (disconnected) from the remaining coils 6 of the winding 3. Thus, during the turn-to-turn closure, the emergency coil 6a does not experience thermal destruction and does not introduce nonlinearities into the circuit of serviceable coils 6 and winding 3 as a whole. Table 1 shows the values of the currents in the nominal operating mode, with an interturn short circuit of the coil 6a and with an interturn short circuit in the coil 6a with shunting of this coil.

Table 1. Values of currents at turn-to-turn closure of the coil 6a

As can be seen from this table, when using the proposed method, the turn-to-turn closure current decreases from 165 A to 93 A, the winding temperature - from 150 ° C to 90 ° C.

So, the proposed method allows you to expand the functionality due to a change in the active resistance of the winding in the short circuit mode, to increase the reliability of the magnetoelectric generator and to protect the magnetoelectric generator from short circuits.

Claims (1)

A method of protection against a short circuit of a magnetoelectric generator, according to which the presence of a short circuit is determined by the magnitude of the temperature, the magnitude of the current and the magnitude of the voltage, characterized in that after detecting a short interturn circuit in one of the coils, it is disconnected from other coils, opening the keys connecting it to load, and close the key shunting it.

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