SU811418A1 - Dc electric machine with power-diode mechanical switching device - Google Patents

Description

one

The invention relates to electrical machines, in particular, to direct current machines with additional devices for improving switching.

An electrical machine with a valve-mechanical switch (IUD) is known, containing a mechanical collector, in contact with it, a group of braids connected to the power supply terminals via controlled semiconductor valves, designed for full current w, current breakouts. In this machine, the switching is carried out without additional poles using capacitive electrical energy storage devices 1.

The disadvantage of such a machine is its complexity.

Also known is an electric machine with IUD, containing main brushes and auxiliary, connected to the corresponding terminals of the power source through controllable gates, and a capacitor connected to controllable gates, in parallel with which a chain of series-connected controllable valve, auxiliary source and linear Drossel 2.

This machine is closest to the invention in its technical essence and the achieved result.

Its disadvantage is the splitting of the structure.

The aim of the invention is to simplify the design of the electric machine.

This goal is achieved by connecting two anti-parallel-connected controlled valves between a valve connected to an additional brush and a condenser.

FIG. 1 shows a circuit diagram of the proposed DC machine; in fig. 2-diagrams of the discharge current and voltage on the capacitor; in fig. 3 - current diagram in the switched section of the winding box.

For simplicity, only one brush group and the associated semiconductor elements and switching device are connected to the positive terminal of the source. The remaining brush groups, the number of which is equal to the number of poles of the machine (2p), have a similar pattern.

The machine contains a core winding 1 connected to a mechanical collector 2 with conductive 3 and 4 and insulating 5-7 plates, contacting groups of brushes, each of which consists of a main contact 8 connected directly to a power supply terminal and two auxiliary brushes 9 and 10, connected to the same source terminal through control valves 11 and 12, are required and the sequence of switching on and off of which is provided by the switching device 13 and the control device 14.

The switching device consists of a capacitor 15 and a series-reversing node connected to it from two anti-parallel connected thyristors 16 and 17. For charging the switching capacitor in transient modes, a special circuit is used in the circuit, consisting of a thyristor 18, an auxiliary power source 19 and Line Drossel 20.

When the machine is working, sliding contacts move along the working surface of the collector from left to right. In the initial state, the load current flows from the clamp of the power source through the main contact 8, the conductive plate 3, through the winding 1 of the core and through the corresponding sliding contacts connected to the clamp of the source of opposite polarity. All thyristors are locked, the capacitor is charged before f / o flow, the polarity of which is indicated in FIG. 1 without brackets. In the position where the ramping edge of the main contact 8 continues to contact with the insulating plate 6, or at time ti (Fig. 2), control signals are sent to the device 14 to turn on the thyristor 16. At the same time, the capacitor 15 begins to discharge through the winding section, connected to plates 3 and 4 along the contour 15-16-10-4-section, 3-9-15. At time 2 (Fig. 2), the discharge current of the capacitor tp reaches a value approximately equal to the current in the parallel branch of the winding of the core, and the voltage across the capacitor changes polarity and becomes equal to Ui. The control unit at this moment includes the key thyristor 12, which "picks up the discharge current of the capacitor 15 and shunts the switched section. The capacitor discharge current decreases to zero, and the switching thyristor 16 is locked. The load current flows from the power supply terminal through two parallel circuits — through the key thyristor 12, pin 10, plate 4 to the core winding and through the main contact 8 and plate 3 to the winding. If at time 4 the discharge current of the capacitor reaches the value of the current of branch IB. as shown in FIG. 2, after the thyristor 16 is turned off, the current in the switched section becomes zero (Fig. 3).

As the frontier edge of the main contact 8 goes to the conductive plate 4, the current of the key thyristor 12 and the auxiliary contact 10 connected with it decreases due to the fact that part of the current

contact 10 goes to contact 8. The auxiliary contact 10 goes from the conductive plate 4 to the insulating 7 without sparking, since the conductive circuit 12, 10 is shunted by the low-voltage contact resistance of the main contact 8. The key thyristor 12 is turned off in a natural way when auxiliary contact 10 is included

in full contact with the insulating plate 7.

At the time ts (Figs. 2, 3), the escaping edge of the main contact 8 begins to move from the conducting plate 3 to

isolating 6. At this moment, control signals are supplied from the control circuit 14 to turn on the key thyristor 11, which together with the auxiliary contact 9 forms a shunt circuit

The intercepting current of the main contact 8 at the moment of the end of its contact with the conductive plate 3. Thus, the sparking at the incident edge of the main contact is eliminated. After the time delay Atg, which is provided by the circuit 14, turns on the thyristor 17, which connects the capacitor 15 to the conducting thyristor 11, the discharge current of the capacitor flows through the circuit 15-11-12-17-15.

At the moment of equality of the discharge current of the capacitor to the direct current through the thyristor 11, the latter is turned off, and the current passing through the thyristor 11 is transferred to the shunt circuit formed by the conducting thyristors 12 and 17 and the capacitor 15. As the capacitor recharges from time 1z in the switched section associated with the plates 3 and 4, the process of reversing the current continues, which ends at time 4 (Figs. 2, 3)). At the same time, the charge current of the capacitor 15 decreases to zero, and the thyristors 12 and 17 are turned off. Further, the switching processes in the circuit are repeated.

Claims (1)

Invention Formula Electric direct current machine with a valve-mechanical switch containing a mechanical collector with conductive and insulating plates, in contact with them different polar groups of brushes, each of which is connected to one power supply terminal and contains the main and two additional brushes located on opposite sides connected to the power supply terminal through controllable gates, and a capacitor connected to controllable gates in parallel with which a chain of sequentially connected controllable valve is connected, auxiliary source and linear throttle, so that, in order to simplify