SU1646033A1 - Synchronous electric drive - Google Patents

Description

one

(21) 4682980/07

(22) 04/27/89

(46) 04.30.91. Bul sixteen

(71) Physical-energetic and STI of the Academy of Sciences of the Latvian SSR

(72) V.P. Bezrukov

(53) 62: 83: 621.313.335.52 (088.8)

(56) Kovalyuk L.A. A specialized series of contactless synchronous motors for oilfield mechanisms. RNTS VNIIOEG. Machines and oil equipment, 1977, N-2, pp. 15-19.

USSR author's certificate M 1252891, cl. H 02 R 1/50, 1984.

(54) SYNCHRONOUS ELECTRIC DRIVE

(57) The invention relates to electrical engineering. The goal is to simplify the device. To this end, in a synchronous electric drive, the control unit (CU) of the adjustable rectifier is made on a four-winding control transformer 6, the first primary winding 9 of which is connected to the main winding circuit of the motor 1 of one phase, and the second primary winding 10 is connected to the alternating voltage source via distribution chain 11. The pins of the first secondary winding of the transformer 6 are bridged by a capacitor 14 and two diodes 21,20 connected in opposite directions. Between the point of the diodes 20, 21 and the common point of controlled valves 4.5 of the controlled rectifier, the dynistor 7 and the resistor 8 are connected in series, and the control electrode of each valve is connected to the corresponding output of the first secondary winding 12 through the diode 13 or 19. The conclusions of the second secondary The windings 15 are connected to the input of the bridge rectifier 16. The output of the bridge rectifier is loaded on the thyristor 17, the control electrode of which is connected to its anode through a resistor. The post rectifier with a thyristor forms a key that closes the leads of the transformer secondary winding and thus turns off the control unit for the duration of the start. The opening angle of the controlled valves changes as a result of the addition of currents in the primary windings of the transformer and the change in the phase of the voltage vector on a capacitor that supports the terminals of the second secondary winding 15. 1 Il.

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The invention relates to electrical engineering, in particular, to systems for automatically controlling the excitation current of contactless synchronous machines with fixed excitation windings, and can be used mainly in driving mechanisms having a cyclic load,

for example, to drive oilfield pumping units.

The aim of the invention is to simplify the device by simplifying the circuit of the control unit and the design of the control transformer.

The drawing shows a circuit diagram of a synchronous electric drive.

The synchronous electric drive contains an electric motor 1 with a crust winding, the phase terminals of which are connected to a source of alternating voltage, an excitation winding made in the form of two coils 2,3 arranged coaxially on the inductor magnet circuit, an adjustable rectifier on two controlled gates 4 , 5 s

20

25

thirty

a control unit consisting of a trans-to-rotor. Simultaneously

windings 9, 10 of the control transformer 6 and coil 2, 3 receive power.

The starting current in the electrical motor's core winding causes a sharp increase in the magnetic flux in the magnetic conductor of the control transformer 6, as a result of which the control electrode of the thyristor 17 is energized, the level of which is above the turn-on threshold of this thyristor and it opens. By turning on, the thyristor 17 shunts the winding 15, the current in which damps the magnetic flux in the magnetic conductor and the voltage at the terminals of the winding 12 does not reach the switch-on level of the 7.

Thus, the opening pulses are not applied to the controlled valves 4.5 and they remain closed for the entire duration of the start-up.

When the valves 4.5 are turned off, the current distribution in the coils 2.3 is such that the total value of the magnetomotive forces (VAT) of the excitation winding coils in this period is zero. As a result, there is no magnetic field in the raspberry and the rotor accelerates to the sub-synchronous rotation frequency under the action of asynchronous torque.

With an increase in the frequency of rotation of the rotor, the magnitude of the current in the core circuit of the winding decreases, resulting in a decrease in voltage in the winding 15 and the thyristor 17 closes. At this moment, the resulting magnetic flux in the control pipeline of the control transformer 6 increases and the voltage in the secondary winding 12 reaches the switching level of the dynistor 7.

The control pulses are formed by a capacitor 14, a driver 7 and a resistor 8. At the same time, the amplitude of the onpe-i control pulses

control format 6 and serially connected dinistor 7 and resistor 8, the first primary winding 9 of the transformer is connected in series to the single phase circuit of the electric motor 1, the terminals of the second primary winding 10 are connected to the alternating voltage source through the phase-rotating chain 11, one output of the first secondary winding 12 connected to one output of the diode 13 and the output of the capacitor 14, the second output of which is connected to the second output of the winding 12, and the terminals of the second secondary winding 15 are connected to the AC input of the bridge rectifier goal 16, the DC output of which is loaded on the thyristor 17, the control electrode of the thyristor 17 is connected to its anode through an adjustable resistor 18. In addition, three diodes 19-21 are additionally inserted into the device control unit, the output of the first additional diode 19 and free the output of the diode 13 in the control unit is connected to the control electrodes of one and the other controlled gates 4, 5, respectively; the same terminals of the second and third additional diodes 20, 21 are connected to the free output of the resistor 8, the free output The first and second additional diodes 19, 20 are connected to the first output of the first secondary winding 12, the free output of the third additional diode 21 is connected to the first output of this winding, and the free output of the dynistor 7, the same output terminals of the coils 2, 3 and controlled valves 4.5 connected together, the free leads of the one and the other coils 2,3 are connected to the free leads of the controlled valve 4,5 and are intended for

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1646033

connect to a variable voltage source.

The operation of the synchronous electric drive is as follows.

In the initial position, the terminals of the core winding of the synchronous motor 1 are disconnected from the source of alternating voltage and the machine rotor is stationary. During start-up, the three-phase voltage is applied to the terminals of the device A, B, C, O and the alternating current creates in the stator bore of the electric motor 1 a rotating magnetic field, which causes

it is made by the dipping voltage of the di-micropro 7, the value of the capacitor 14 and the reistor 8. The switching off of the drive 7 is ensured by the fact that the current in the circuit at the end of the half period passes through zero. Diodes 20, 21 serve to match the polarity of the voltage on the controlled gates 4,5 and the leads of the winding 12, and the diodes 13,19 are designed to protect the control transitions of these gates from the reverse voltage.

The switching on of the daschistor 7 in each half-period of the alternating voltage loses the pulse discharge of the capacitor 14 to the control electrode of the valves 4.5, which open and shunt the cat-lacquers 2,3. In this case, the periodic switching of the rectifier valves 16 leads to the fact that currents in the coils 2,3 begin to flow due to the voltage of the power source and the EMF of self-induction. The polarity of these currents remains unchanged in time, so the total SSS of the coils in the magnetic core forms a constant magnetic field of excitation. As a result, a synchronizing torque occurs in the machine and the rotor is pulled into synchronism.

In synchronous operation mode, the current in the excitation winding is a function of the bore on the machine shaft, and the voltage at the terminals of the control transformer winding 12 changes the phase in the windings 9, 10 and, accordingly, changes the opening angle gates 4,5.

The adjustment of the law of voltage regulation on the field winding with the revocation characteristic of a synchronous motor is carried out by changing the parameters of the phase-rotation chain 11 and the corresponding sub-number of turns of the windings 9.10.

The technical and economic effect of using the invention is expressed by the fact that the design of the device is simplified. This simplifies the circuit and eliminates the need to set up a node that generates pulses in the control unit to obtain a symmetric voltage on controlled valves; the design of the controlled rectifier is simplified, the number of controlled valves in the tank is equal to

0

five

d mind, while retaining the function of two half pernodal rectification of excitation current; the technology of preparing a control transformer is simplified by reducing the number of secondary windings.

Claims (1)

Invention Formula A synchronous electric drive containing an electric motor, the phase terminals of which the core winding is connected to an alternating voltage source, and the excitation winding is made in the form of two coils located on the inductor magnetic circuit, an adjustable rectifier on two packs. equal vents with a control unit made up of a transformer and a serial unit and resistor connected in series, the first primary winding of the transformer is connected to a single phase of the electric motor core winding, the outputs of the second primary winding are connected to the alternating voltage source through a phase inverter a chain, one output of the first e-winding winding is connected i: one output of the diode and one output of the capacitor, the second output of which is connected to the second output of the first secondary winding, and the outputs of the second secondary The second winding is connected to the AC input of a bridge rectifier, whose DC output is shunted by a thyristor, the control electrode of the thyristor is connected to its anode through an adjustable resistor, characterized in that, for the sake of simplicity, three diodes are added to the control unit, and the output the first additional diode and the free output of the aforementioned diode of the control unit are connected to the control electrodes of the controllable gates, the like-named terminals of the second and third additional diodes are connected to The free output of the first and second additional diodes is connected to the second output of the first secondary winding, the free output of the third additional diode is connected to the first output of this winding, and the free output of the dynistor, the like terminals of the coils and controlled valves are combined, while free outputs of one and the other coils five five 0 71646033 8 yens with free outputs of the corresponding valves and connected: to the power supply of one and the other to the control of the alternating voltage. About o-flo C o Editors Z. Khodakova Order 1554 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5  eleven YU ъ Compiled by V.Tarasov Tehred L. Oliynyk Proofreader T. Paliy Circulation 354 Subscription