SU529525A1 - Apparatus for improving commutator switching of an electric machine - Google Patents

Description

the crushing section of the core due to the voltage of the power condenser, which is switched on during the course of the mosg. Since this process takes place at a limited speed, the inductance of the connecting wires has practically no effect on the efficiency of the device. Since there is no resistor in the circuit designed to dissipate the energy of the capacitor, the energy loss in the device is reduced. The inclusion of inductance in series with the power source creates the conditions for the charge of a capacitor with minimal energy loss. FIG. 1 is a circuit diagram of the proposed device; Fig. 2 shows a part of the device operating with the right rotation of the machine and a conditionally positive current of load; Fig. 3 shows a part of a device operating with right-hand rotation and a negative load current; Fig. 4 is a part of the device operating with left-hand rotation and a positive load current; in fig. 5 — part of the device operating in left rotation and negative load current; FIG. 6 is a part of the device operating with right-hand and unfinished switching; FIG. 7 is a part of the device operating in left-hand rotation and incomplete switching. Main brush 1 and auxiliary brushes 2 and 3 of each scrap are mounted on a collector consisting of working plates 4, 5, 6, 7 and auxiliary (isolated) plates 8, 9, 10, Main brush 1 and auxiliary brushes 2 and 3 are connected to a three-phase reversing bridge 11, mounted on controlled thyristors 12-23, to the output of bridge 11, a capacitor 24 and chains from series-connected controlled thyristor 25, power supply 26 and inductance 27 are connected, Power supply 26 is controlled. The arrow in FIG. 1 conditionally shows the right direction of the collector, and the letter :) indicates the conditionally positive load current of the maschine. The terminal 28 of the power source of the machine is connected directly to the main drive 1, the auxiliary brushes 2 and 3 are smaller in width than the auxiliary plates 8–10 of the collector, and the brush 1 is larger than these collector plates. Fig. 1 shows the device at the moment when all the thyristors of bridge 11 and separate thyristor 25 are locked, the auxiliary wires 2 and 3 are de-energized, and the capacitor 24 is charged to a voltage approximately equal to the double voltage of the additional power source 26, Bounce Current from the working plate 5 through the brush 1 enters the terminal 28 when the collector moves to the right, the load current is positive. At the moment when the brush 3 has stable contact with the collector plate 6, control signals are sent to the thyristors 19 and 23. This moment is also reflected in FIG. 2. The remaining thyristors of bridge 11 are not shown, since at the moment they are not used. The diagram shows the currents Q and - i Q of parallel winding branches of the core and the current if, section after completing its switching with brush 1, Before turning on the thyristors 19 and 23, the current of the switched section has a direction opposite to the direction of current i 0 and is equal to the current - i cy Thyristors 19 and 23 open and start the discharge of the capacitor 24 through these thyristors and the winding section of the core connected to the plates 5 and 6, In the inductive-capacitive circuit, in the presence of small active resistances, the discharge of the capacitor 24 occurs according to a harmonic law. The circuit parameters are chosen so that the maximum discharge current is equal to the double current of the parallel winding branch of the core 2 I Q. After a quarter period of the harmonic, the voltage on the capacitor 24 drops to zero, and the discharge current becomes equal to the maximum, e, e. 2, i ci Therefore, the current i (of the switched section. At the same time, the current of the brush 1 varies from time to 2 I o to zero, and the brush 3 current from zero to 2 i, Q - 1. Voltage the capacitor 24 continues to change and becomes negative. When a negative voltage capacitor appears on the capacitor, a control signal is applied to the thyristor 14, which opens and shuns the capacitor 24 together with the thyristor 23, the thyristor 23 goes out, and the current of the capacitor 24 becomes zero. tJ - 2 i c flows from brush 3 through thyristors 14 and 19 to terminal 28 to When the brush 1 closes the insulated plate 9 and comes into contact with the working plate 6, shunt the brush circuit 3 with thyristors 14 and 19, the thyristors 14 and 19 extinguish, the current of the wire 3 drops to zero, and the current of the brush 1 grows from zero to value of 2t with 1, in this case the current of the plate 5 remains equal to the hopper, and the current of the section i Q - until the moment of brush 1 detachment from the plate 6 due to a sufficiently long constant ejection time. This state continues until ex brush 3 comes into contact with the next working plate 7 of the collector. The process is then repeated through thyristor 25 and inductance 27 from power supply 26 for the time that the thyristors of bridge 11 are locked. Blessings inductance 27 charge capacitor

occurs according to the harmonic law with almost no energy loss. The maximum voltage on the capacitor approaches the double voltage of the power source 26. Since the amplitude of the discharge current of the capacitor 24 depends on its initial voltage and must be equal to the double current of the parallel branch of the core winding, the voltage of the power source 26 is adjusted depending on the current machine load

With the right rotation of the core and the negative load current, the device operates as described using thyristors 13, 2O and 22 (see Fig. 3).

During the left rotation of the core and both directions of the load current, the device operates as shown in FIG. 4 and 5. The difference compared with FIG. 2 and 3 is that the active switching section is carried out through the auxiliary brush 2

At low speeds of rotation (compared to the nominal), it is possible that the current of the switched section, closed by the main brush 1 after the completion of the switching, is not maintained equal to the current of the parallel winding branch of the core to the moment when the ejection plate of this section loses contact with the brush 1 ( the time constant of the section during slow rotation is not large enough to keep the section current unchanged). Sparking the main brush 1 is then provided by connecting the switched section through part of the bridge 11 to an uncharged capacitor 24. In FIG. 6 shows the moment when the brush 1 leaves plate 4 at a non-zero current of this plate. The rotation of the core is right, and the load current is positive. Control signals are applied to the thyristors 12, 16 of bridge 11. After opening these thyristors, the current of the collector plate 4 closes through the brush 2, the thyristors 12 and 16, and the capacitor 24. When the voltage on the capacitor 24 increases, the current

the brush 2 drops from the initial value to zero and it comes off the plate 4 without current and sparking. The capacitor 24 is then charged from the power source 26 to the voltage required to switch the next section. When the load current is negative, the thyristors 13 and 15 are turned on. For the left rotation of the core, the brush 3 and the thyristors 13, 17 and 14, 16 of bridge 11 are used (see Fig. 7).

The control of the thyristors of the bridge 11 is carried out from the control system, the measuring unit of which determines the direction of the load current, the direction of rotation and the position of the brushes 1-3 relative to the collector. The power supply control system 26 measures the load current of the machine at an absolute magnitude.

Claims (3)

1. USSR author's certificate No. 230949, cl. H 02 to 13/14, 1964. 2. USSR author's certificate number 130960, cl. H 02 to 13/14, 1957. 3. USSR author's certificate number 406272, cl. H 02 to 13/14, 1972. L 25 14 28 27 1 eleven FIG. 2 U, c, a. iff eleven , Shchig. FIG. 5 x. Ul tc five 21  . -tflj . one 0i-o : 24 25