FI88236B - FRAON EN FLERFAS-DIREKTOMRIKTARANORDNING MATAD TREFASMOTOR - Google Patents

Abstract

1. Three-phase motor (M) supplied by a multiphase direct converter arrangement for producing a rotary movement of its rotatable part (rotor) with respect to its fixed part (stator), the rotary field winding of which consists of two electrically separate coil systems (Wa1 , Wa2 , Wa3 ; Wb1 , Wb2 , Wb3 ), the coil pairs of which, forming the poles of the motor, are arranged in a geometrically coincident or mirror-symmetrical manner, characterised in that the converter arrangement is formed of three-phase current-full wave-converters (UR1, UR2, UR3), the connection (U1, V1, W1; U2, V2, W2; U3, V3, W3) of which on the input side are connected in paralled to a supply network (R, S, T) or to the secondary winding of a transformer (Tr) and the two three-phase current-coil systems (Wa1 , Wa2 , Wa3 ; Wb1 , Wb2 , Wb3 ) with their pole-forming coil paris are dimesioned such that each coil system takes on half the electrical energy and the one connections (Y1, Y2, Y3) on the output side of the converter arrangement are electrically connected with the connections (1a, 2a, 3a) of the one coil system (Wa1 , Wa2 , Wa3 ) and the other connections (Z1, Z2, Z3) of the converter arrangement are electrically connected with (Wb1 , Wb2 , Wb3 ).

Description

1 88236

Multi-phase motor fed by a multi-phase direct-change rectifier

The invention relates to a three-phase motor to which current is supplied via a multi-phase direct inverter.

5 For example, in the magazine "Elektrotechnische

Zeitschrift ", 1932 Heft 32, pages 761-786. Such multistage-15 rectifiers with thyristors are described in Möltge's book "Netzgefiihrte Stromrichter mit Thyristoren", 2nd edition, entitled "Direktumrichter", on page 311. The direct-to-rectifier shown in Figure 247 of the book, which consists of three AC-wave rectifiers with thyristors, has the disadvantage of all that for each of these exchanges:. the current-to-wave rectifiers must have their own • transformer. This is necessary because when three rectifiers are connected in parallel to a single secondary winding of the transformer, the can. "* control overshoot areas11a occur over the neutral wire;:: short-circuit currents that result in device overload.

This prevents muutajapuolen galvanic decoupling.

30 In addition, when inverters are used in parallel in the sole secondary winding of the transformer, strong • rectified inverter output voltage may be present at strong third harmonic overvoltage currents, which may also contribute to the 35 inverter overload. To prevent this, controlling the inverter to produce 2 88236 sinusoidal output voltages would be insufficiently loaded, i.e. operating at poor efficiency, and would unnecessarily increase mains-side overvoltage, which in turn would adversely affect the rated power of the 5 transformers.

The invention lies in the fact that the multi-phase direct exchange of mouth-defendant fed through the electric motor winding is made constant copper component with respect to the inverters can also be rectangular lähtöjännit-10 tea input side of the parallel connection of a single voltage source and is then increased to overshoot currents in the motor windings.

By means of the invention according to claim 1, this object is solved by avoiding direct galvanic interconnection of the inverters and replacing it by using a second motor circuit, so that relatively large transformer side losses can be avoided without significantly increasing the motor side losses. In this case, it is also possible to operate simultaneously, depending on the respective connection method, at a rectangular supply voltage which has a favorable effect on the rated power of the transformers, so that the current generated by the third harmonic is completely or almost completely attenuated. In addition, several inverter systems can be connected to the same transformer or to the same network without an intermediate transformer.

It is previously known from U.S. Pat. No. 3,624,472 to provide a three-phase induction motor with two complete, full-power rated three-phase windings, the parallel phase windings of which each form a three-phase terminal , to a half - wave inverter of a controllable three - phase inverter. 35 In this case, both AC windings must be dimensioned for full motor power. Thus, it is achieved that half of the total number of rectifiers in the 3 88236 inverter system can be made into controllable rectifiers and the other half into simple diode rectifiers. In addition, the motor-side galvanic isolation of the individual rectifiers 5 of the inverter system avoids misfire of the controlled rectifiers or short circuits in the inverter system caused by inductive reactions.

Additional features of the invention are characterized in the dependent claims.

The invention is described in more detail below by means of embodiments.

Figure 1 shows different embodiments of the main connection and Figures 2-7 of the device according to the invention.

In Fig. 1 only, the three-phase electric motor M shown schematically shows a three-pole, star-shaped alternating current winding with winding pairs Wa1, Wb1,

Wa2 '^ b2 ^ b3' The individual windings are then moved 120 ° relative to each other. Coils W., W. and W, cl I clZ ä j form one winding system and the windings, and form another winding system. Both winding systems are made as opaque as possible and electrically isolated from each other. In other words, hitherto the conventional rotary field winding of a three-phase motor is divided into two geometrically overlapping, equivalent, galvanically isolated winding systems. These winding systems are connected to the motor-side connections UR1, UR2 and -V 30 UR3 of the three-phase inverter so that both outputs of the individual inverters of the inverter system are connected to one of two winding systems that do not have an interconnection: a galvanic connection. In the present example, the second poles Y1, Y2 and Y3 of the inverter are connected ·: ··; 35 to terminals 1a, 2a and 3a of the second winding system and

____: second inverters Z1, Z2 and Z3 of the inverter motor M

4 88236 AC winding for connections to another winding system

Ib, 2b and 3b. In this case, both Ιο la to the motor-side connections 11a of each inverter have a 180 phase shift, while the inverters produce 120 ° or -5 surges. Thus, the phase shift of the currents flowing in both windings of one pole pair of one pole of the AC winding becomes 60 °. A single inverter primary side terminals U1, V1, W1; U2, V2, W2 and U3, V3, W3 are connected by commutation chokes, ®U2 '^ V2' ^ W2 ^ u3 '^ V3f ^ * w3 in parallel with the secondary winding of the transformer, the primary winding of the transformer of which is connected to the supply network RST.

By dividing one phase of each winding into two parts and connecting the two sub-windings of the different phases in series, it is achieved that the third-order overshoot currents at the rectangular output voltage of the frequency converter are reduced to 1/4 of the values present with known rectifier connections.

Figure 2 shows a circuit diagram in which both parallel winding systems are connected in a triangular shape. The two outputs Y, Z of each inverter are then connected to the terminals of both winding systems, whereby the currents flowing in each winding of both windings forming one twist-25 pair are in turn 60 ° out of phase with each other.

When a higher frequency is desired due to the reaction effect on the supply network, the circuit diagrams of Figures 1 and 2 can be multiplied by increasing the number of motors or AC windings shown in Figures 3 and 4 and consequently the number of inverters connected on the input side. to the sole transducer. Thus, both windings Wfl1, W & 2, Wa3 and Wb1, Wb2 and Wfa3 of Figures 3 and 4 are doubled by a single AC winding connected to the residue 5 88236 or triangle winding systems, Wc2 3a WC3 and parallel to them, windings Wd1, W ^ 2 and wd3, with a geometric displacement of 30 ° and a corresponding electrical phase shift 11a with respect to the other 5 inverters formed by the inverters UR4, UR5 and ΐΡ6 as well as the commutation chokes DU4-DW6 '

Figure 5 shows a modification of the device of Figure 1. In this circuit diagram, the star-shaped winding systems 10 are winding W., W, js W, as well as geometrically blocked so that the windings of one winding system are geometrically between the windings of another winding system and accordingly form a six-phase rotation. The electrical connections 15 correspond to the connections in Figure 1. This coupling can also, as already described, be multiplied so that, as shown in Fig. 6, a 12-cycle network reaction can be achieved in the same way with two inverters. The device of Fig. 5 (in a variant corresponding to Fig. 2) can also be used in the device of Fig. 6 (in a variant corresponding to Fig. 4) in delta connection.

Finally, Fig. 7 shows a variant of the device of Fig. 1 with three winding systems consisting of two windings. As in the star connection of Figure 1, there is a | 25 two parallel windings of each pole or phase are provided

Wa1 'Wb1' Wa2 'Wb2 Wa3' Wb3 on display · Both windings of adjacent poles or phases and different systems, Wb2, wa2 'Wb3 and Wa ^, W ^ i are connected in series connected to the output-UR1, UR2 or UR3 of each switching rectifier. terminals. With this connection, the individual inverters on the motor side 11a are galvanically isolated from one another. This has the same effect as the device described so far.

6 88236

It is self-evident that the connection diagrams shown in Figures 5 and 6, which have been made by connecting the winding systems in the shape of a star, can also be made by delta connection and lead to the same results.

5 In addition to the connection examples shown, other modifications are conceivable, such as a 4-phase system, which have in common that they are not immediately galvanically connected on the motor side.

Claims (3)

A three-phase motor (M) to which motor current from a multiphase directional device for generating a pivotal movement of the rotatable part (rotor) of the motor relative to its fixed part (stator), which three-field winding motor consists of two electrically etched coil systems ( wa 2, Wa 2 'Wa 3' Wbl 'Wb 2 whose incoming connections (UI, VI, W1; U2, V2, W2; U3, V3, W3) are connected in parallel to a supply network (R, S, T) or to a transformer (Tr) secondary winding, and to the two alternating current coil systems (Wg ^, W ^> wa3 'Wbl' Wb2 'Wb3 ^ met ^ s:' - the pole-forming coils are so dimensioned that each coil system assumes half the electrical power and that one of the connections (Y1, Y2, Y3 ) at the output side of the inverter device are electrically connected to the connector the wires (1a, 2a, 3a) of one of the coil system (Wai®a2 'a3 ^ OC3) of the terminals (Z1, Z2, Z3) of the inverter device are electrically connected to the terminals (Ib, 2b, 3b) p <S the second coil system (W ^, Wb3> · 2. The device according to claim 1, characterized in that one of the pole-forming coils of a pole in one coil system (e.g. Wa 3) forms a series connection with one of the pole-forming coils of the other coil system (e.g. ) for an adjacent pole, wherein the series connection is connected to and respectively. a connection coil (Y1, Z1; Y2, Z2; Y3, Z3) on an inverter (UR1, UR2, UR3), in that the currents flowing through the coils in a pole-forming coil have a phase shift of 60 °. 3. Apparatus according to claim 1 or 2, characterized in that the three-phase motor (M) has several circumferentially symmetrically arranged three-phase field windings consisting of each two coil system with the associated ones connected to the input side in parallel.