DE1613409A1 - Circuit arrangement for the excitation of direct current generators or motors - Google Patents

Description

Circuit arrangement for the excitation of DC generators or motors The invention is concerned with a circuit arrangement for the excitation of DC generators, in particular for the continuous change of the four-quadrant drives controlled by LeonarigGacy9toron, mediated by the Pür-regulated four-quadrant drives. If the Drohsehl is to be modified by means of a circuit carried out in the circuit, this indication is supplied by an assigned Leonard generator. It is now the object of the present invention to measure the voltage of such a generator (Leonardgeneratora) for the purpose of influencing the speed of the downstream. to be able to change killed Gläichotrommotorn in a simple manner. It is known to take the excitation voltage from a generator for the DC power supply to consumers from a DC network and to change the excitation voltage by means of controllable resistors. It is also known to take the required direct current from the local AC power supply via a rectifier for the direct current supply of the exciter winding to the generator, with controllable resistors again being used to change the exciter direct currents. Such an assumption is associated with the disadvantage that considerable voltage drops can occur at the Ragelwideretand and a not inconsiderable loss of power in the pathogen occurs. In order to counter this deficiency, "it is customary and known to work in the DC exciter circuit without using a control resistor and instead insert controllable rectifiers (thyrintors or transistors) into the exciter current circuit, which - through appropriate control - ensure that the generator works in a suitable manner is excited according to size and direction. By controlling the semiconductor elements int a continuous change of the field excitation and thus a corresponding regulation of the output voltage of the Gleichatrongeneratorsn possible. A low-cost circuit for feeding the exciter winding of Leonardieneratoren with thyrintors from dba Wochseletronnetz should get by with the smallest possible number of thyristors. The simplest thyristor circuit is the single-coil circuit, whereby a thyristor is available for each current direction because of the required reversal of the current direction for the generator field. However, such a circuit initially has the disadvantage that the magnetic energy given to the excitation winding is dissipated again in each network period. Technically sensible operation is therefore not possible because the output voltage of the generator changes periodically between the remanent voltage and a certain maximum value. It is known to counteract this deficiency by using two excitation windings, each with a free-wheeling valve (diode) connected in parallel to the winding.

The »invention goes a different way. To solve the tasks set, The invention provides the generator according to the invention two magnetically with each other Coupled Kldwieklungen assigned, one of which periodically from the feeder stream excitable the other is short-circuited. In the circuit arrangement according to According to the invention, the winding, which can be excited by the supply current, is via controllable rectifiers in anti-parallel connection either only during the positive or only during the negative half-wave or excited during part of the respective half-wave.

The invention is subsequently based on an exemplary embodiment in schematic representation nI # explained here.

The Pigur illustrates the direct current generator Gg which is driven by the motor M. The generator feeds the consumer V via its output terminals 5 and 6. The output voltage is UG «The generator G has two magnetically coupled field windings Wl and W2, of which the winding W2 is short-circuited. The winding Wl is taken from the local alternating electricity network whose terminals are labeled 1 and 2, supplied with direct current via controllable semiconductor rectifiers (thyristors) Nl or * »2. The semiconductor rectifier Nl or N2 is controlled from a control circuit, which is not illustrated in detail and is not essential to the invention, via terminals 3 and 4. The control works in the usual way in such a way that either the rectifier NI in every positive half-wave of the feed week or during the respective negative half-cycle of the Speinewechseletrome the rectifier N2 is controlled permeable. The control device can be designed in such a way that the corresponding thyristor N1 or N2 is controlled only during part of such a half-wave.

It is initially assumed that the short-circuit winding W2 is not present and that the thyristor Nl is triggered in the event of the positive half-wave of the AC supply voltage UX applied to the terminals 19 2. A current i then flows in the field voltage Wl of the generator G. With the zero throughput of the feeding alternating voltage ül, and with the transition to the negative half-wave, a deletion of the thyrietor NI would be desirable. The valve Nl, however, remains ignited until the current in the field winding Wi is completely reduced again and i becomes zero (inverter operation). If, on the other hand, the illustrated short-circuit winding W2 is present, it prevents a slight change in current and maintains the field excitation in the negative voltage half-wave of the supply alternating current and also ensures that the controlled valve Nl can be extinguished practically at the beginning of the negative voltage half-wave, the excitation flow i Wl commutates thus from the winding Wi to the winding W2. This short-circuited auxiliary winding also reduces the 50 Hz ripple of the exciter flux in the desired manner.

If the polarity of the output voltage U is to be reversed at the consumer V, it is only necessary to reverse the excitation current. This can happen in that instead of the thyristor Ni, the thyristor »2 is always activated during the negative half-cycle of the alternating supply voltage U, #. The commutation of the excitation flux from the feed winding Wl.

on the short-circuit winding W2 takes place in a corresponding manner Way.

The illustrated anti-parallel connection of the controllable rectifiers (thyristors Nl and N2) is insensitive to interference. Although the current I is inversely with Halbwellenwecheel, no interference occurs by WecUselrIchterbetriebe Kreisstron o. The like. On, the wire cross-section and d-io Windmiezähl the Poldhilfswicklung WZ directed SiCB on the required for the smoothing of the Erregerflussee Glättungezeitkonntanten. The short-circuit winding W2 can hold all stator poles of the machine environmentally. However, it is advantageous to short-circuit each winding separately around one pole. It is possible to manufacture the coil body for the excitation winding W2 from conductive material in order to be able to easily implement a short-circuit winding in this way.

Claims (2)

Circuit arrangement for the excitation of direct current machines, in particular for the continuous change of the field excitation of Leonard generators by means of expensive rectifiers from the alternating current network # characterized in that the generator (G) is assigned two magnetically coupled field windings (W1, W2), one of which is periodically excited by the supply current while the other (W-2) is closed for a short time. 2. A circuit arrangement according to claim 1, characterized in that the excitable the supply current winding (W1) via controllable Alike hrichter (Nlt N2) either only during the positive or only during the negative half-wave or a part-of JE weiligen half-wave is auferragt . 34 Circuit arrangement according to Claim 1, characterized in that the short-circuit winding (W2) is carried out separately for each stator pole of the DC machine.