SU756575A1 - Current inverter for switching-over ac motor armature winding phases - Google Patents

Description

The invention relates to a converter technique.

Known current inverters for switching the phases of the armature winding of an AC motor, used in particular for powering traction valve motors of electric rolling stock. The output of inverters with natural commutation is that a substantial part of the reactive power of an electric machine is consumed for switching and not uses pulse voltage regulation.

Artificial phase-to-current switching increases the use of machine power and allows the use of pulsed voltage regulation. „

It is also known to switch the inverter current phase motor armature winding AC containing osnovnoy.tiristorny bridge i.most reverse current diode between raznoimen ^^ GOVERNMENTAL polarity direct current terminals which are incorporated winding inductance inductors _h, and the AC terminals of the bridge are combined | 2]. In this inverter occurs ..

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double energy conversion, which leads to increased electrical losses. Along with this, capacitors are used in the inverter for artificial switching, in which the mains energy is initially accumulated, and then used to switch the phases of the machine, which is also associated with an increase in electrical losses.

The purpose of the invention is the reduction of electrical losses in the Converter when the pulse voltage regulation.

This is achieved by the fact that in the proposed inverter the windings of the chokes are magnetically connected.

FIG. 1 shows the proposed current inverter when powered from a DC source) nafig. 2-5 - instant diagrams of his work; in fig. 6 and 7 are time diagrams of voltage and motor and current in

various elements of the inverter; in fig. 8 - the proposed current inverter when powered from an AC / OC source; · FIG. 9-11 - instant schemes of his work.

The inverter (see Fig. 1) contains the main thyristor bridge with keys

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1-6, Diodes 7-12 form a reverse current bridge. Phases 13-15 of the armature winding of an AC motor are connected to the combined AC terminals of these bridges. The magnetically connected windings 16 and 17 of the inductor inductance are connected between the DC terminals of these bridges, and the filter capacitance 18 is connected to the DC terminals of the diode bridge 7-12 of the reverse current.

When current flows through phases 13 and 15 of the armature motor winding and the inverter keys 1 and 6, as shown in the instantaneous circuit (see Fig. 2), voltage regulation is achieved by turning off switch 1 or 6. In the first case, the reactive energy of the chokes and the motor closes circuit: phase 13 and 15 of the engine - key 6 - winding 17 of the choke - diode 10 (see Fig. 3). In the second case, the circuit is formed using key 1, diode 9, winding 16 of the choke. In both cases, the energy of the magnetoswitch windings of the chokes, performing the function of a smoothing reactor, after switching off the keys is closed in the circuit of the motor winding. Such its construction facilitates the operation of keys.

When switching the current from phase 13 to phase 14 after turning off the key 1, the key 2 is turned on (see Fig. 4). The switching circuit is formed by the power source, the winding 16 of the choke, the key .2, the motor phases 14 and 13 and the diode 10 "When the switching is completed, the diode 10 is closed by the current of the motor phases 14 and 15 (see Fig. 5). .

FIG. 6 explains the operation of the circuit during the pulse-width regulation of the voltage when the engine is started. FIG. 7 explains the operation of the inverter at the highest position of voltage regulation. The frequency of regulation of the motor voltage is equal to the sum of the frequencies of regulation of the anodic and cathodic groups of shoulders of the main thyristor bridge and can be chosen high enough to ensure the switching of the phases of the armature motor winding at the maximum frequency of its rotation. At the highest positions of voltage regulation, almost complete use of the active materials of the smoothing reactor is ensured, i.e. magnetically connected windings 16 and 17 chokes.

The described inverter also implements the generator mode of the engine. To regulate the voltage of the generator, the arms of the bridge 7–12 include fully controlled keys, and diodes in the arms of the bridge 1–6. Thus, to transfer the engine to generator mode with output regulation

the voltages mentioned bridges change

in the scheme in some places. ,

Pulse regulation and artificial switching are also implemented in various schemes of a ^5th valve motor with an implicit DC link, for which the main thyristor bridge is made of controlled keys 1-6 and 19-24. (see Fig. 8). Magnet _D connected windings 16 and 17 chokes,

'0 performing the function of a smoothing reactor, connected through diodes 25-28 to the secondary windings 29 and 30 of the transformer, which is the source of alternating current.

15 The operation of the inverter in motor mode is illustrated by instant diagrams (see Fig. 9-11). When current flows around the phases 13 and 15 of the motor and with the voltage direction shown

20 by arrows, in the windings 29 and 30 of the transformer, an engine power circuit is formed, shown in FIG. 9. To interrupt power supply, keys 1 and 24 are turned off and simultaneously opened.

clock keys 4 and 21 for the formation of the circuit chokes - the engine (see Fig. 10). When turning on the keys 1 and 24, the inverter returns to its original state.

To switch the current from phase 13 to phase 14, instead of key 1, it opens

30 switch 2 (see Fig. 11) and a switching circuit is formed: transformer winding 29 - switch 2 - motor phases 13 and 14 - switch 4. Pulsed voltage regulation is carried out

35 by simultaneously switching bridges 1-6 and 19-24, as shown in FIG. 9, either. Their alternate switching is applied.

To realize the generator mode of the motor, the diodes 25-28 in the inverter shown in FIG. 8, are replaced by .thyristors.

Claims (1)

Claim A current inverter for switching phases 4 ^ of the armature winding of an alternating current motor, containing a main thyristor bridge and a reverse current diode bridge, between opposite-polarized DC terminals of which include windings of inductance inductors, ³⁰ and the AC terminals of these bridges are combined, characterized in that in order to reduce electrical losses during pulse voltage regulation, the windings of chokes 55 are magnetically connected.