SU930553A1 - Electric machine excitation device - Google Patents

Description

(5) DEVICE FOR CONTROLLING THE EXCITATION OF THE ELECTRIC MACHINE

...- / I -. The invention relates to electrical engineering and can be used in control systems for direct current thyristor electrodes and, moreover, in control devices for the excitation of electric motors. Electric drives are known using thyristor pulse-width converters, which differ in capacitive switching method, structural power circuit, law and control method tl 3. However, the use of a thyristor pulse-width converter controlled by a pulse-width modulator as a separate motor excitation device is not advisable . The closest technical solution to the invention is a device for controlling the excitation of electric machines, containing 5 | General power sources assembled on two sets of transformer secondary windings are field windings and main thyristors connected to power sources 2. A disadvantage of the known device is that during each switching period many elements are forced to switch, which is cumbersome and not reliable enough. This significant drawback of the device becomes especially significant when the speed of the electric drive is controlled only in the first zone (by changing the voltage of the electric motor and the control of its excitation, which is necessary only for deceleration or reverse, essentially reduces to a change in the polarity of the excitation. The aim of the invention is to increase reliability. The goal is achieved by the fact that two auxiliary thyristors are additionally introduced into the device, each of which is included the first and second pairs of converting diodes, the diodes of each of which are connected by cathodes, and the anodes are connected to the terminals of the respective secondary windings, the transformer, the third and fourth pairs - the diodes of which are connected by anodes, and the cathodes are connected to the control electrodes of the corresponding auxiliary and main thyristors, two chains, each of which consists of a series-connected variable resistor and key,. the combined cathodes of the First pair of decoupling diodes are connected, With the combined anodes of the third pair of cyodes, and the combined cathodes of the second decoupling diodes are connected with the combined anodes of the fourth pair through the indicated chains. secondary windings 1, 2 transformers, excitation winding 3 and main thyristors k, 5 connected to: power sources, two auxiliary thyristors i, 7, each of which includes a pair of opposite It corresponds to the main one, the first pair of dissolving diodes 8, 9 of which the diodes are connected by cathodes, and the anodes are connected to the inputs of the secondary winding 1 of the transformer, the second pair of converting diodes 10 ,. 11, the cathodes of which are combined, and the anodes are connected to the terminals of the secondary winding 2 of the transformer, the third pair of connecting diodes 12, 13, and the fourth pair of connecting diodes 14, 15, the diodes of each

of which are connected by anodes, and the cathodes are connected respectively to the control electrodes of the thyristors k, 7, 6, 5.

The combined cathodes of the diodes 8, 9 and the combined anodes of the diodes 12, 13 are connected via series-connected variable resistor 16 and key 17, and the combined cathodes of diodes 10, 11 and the combined anodes of diodes I, 15 are connected via series-connected variable resistor 18 and key 19.

The device works as follows.

For a given direction of rotation of the drive and this one (according to the scheme, the operation of the circuit repeats as described.

Claims (2)

Invention Formula A device for controlling the excitation of an electric machine, comprising power sources assembled on two sets of transformer secondary windings, an excitation winding and main thyristors connected to power sources, characterized in that, in order to increase reliability, two auxiliary thyristors are added to it, each of which are connected antiparallel to the corresponding fundamental polarity of the excitation winding 3 of the electric motor, one of the keys 17 or 19 is closed. The excitation winding 3 is provided with a voltage rectified by a single-phase, full-wave (midpoint) circuit. At the same time, for one polarity of the excitation, thyristors k, 7 are periodically open (the key 17 in the thyristor control circuit is closed), and for the other, 6, 5 (if the key 19 is closed), the voltage required on the excitation winding 3 can be set (in including below nominal to 0.6) with the help of resistors 16, 18. Keys 17 and 19 can work both from a device made on contact elements {an ISH full-wave magnetic amplifier can be used, or from a device performed on logical elements. If, for example, O arrives at the input of the key 17, this means turning on the key 17 and closing the thyristors control circuit and 7- In the case of a command to brake (or reverse) the actuator, signal 1 appears at the input of the key 17 1 7 is turned off, and the signal O is received at the input of the key 19. The key 19 is turned on, the thyristors control circuits 6, 5 are turned on, providing the opposite polarity of the drive and the braking mode of the electric drive. At the end of the braking of the electric drive to the specified rotational speed, the command signal 1 applied to the input of the key 19 is removed and the key 19 is turned off. Then, the key 17 is again turned on to the thyristor, the first and the second pair of decoupling diodes, the diodes of each of which are connected by cathodes, and the anodes are connected to the terminals of the corresponding secondary winding of the transformer, the third and fourth pairs of converting diodes, the diodes of which are connected by anodes, and the cathodes are connected control electrodes of the respective auxiliary and main thyristors, two chains, each of which consists of a series-connected variable resistor and a key, the combined cathodes of the first pair in zy93 36 | Vayuschih diodes connected with anodes combined third diode pair and the second pair of combined cathodes decoupling diode - with merged anodes through said fourth pair of chains. Sources of information taken into account in the examination 1. TA Glazenko Pulsed semiconductor amplifiers in electric drives. ML, Energie, 1965.. 2. USSR author's certificate №, cl. H 02 R 9/1, 1968.