The synchronous-machine rotor according to the invention is laminated, cylindrical and not provided with a squirre cage, having further slots in its broad teeth, in which a polyphase attenuator of a pole number identical with that of the exciting winding and uniformly distributed along the rotor periphery is accommodated and connected through a Graetz rectifier to the terminals of the field winding located as bottom layer in the slots outside the broad teeth below said amortisseur.

Single-phase synchronous generators provided with capacitor-loaded split- phase winding and fitted with a synchronous-machine rotor proposed by the invention can advantageously be used as generators of universal emergency power supply units serving, especially, for supplying motors, welding transformers on other inductive/resistive loads.

Prior Art One of the nearest prior art is DE 33 07 664 proposing an"Improved single- phase synchronous generator"According to said publication the negative- phase sequence component of armature excitation-termed"inverse excitation"-a pulsating direct current is induced through the blocking diode in the field winding not equipped with an amortisseur cage, the mean value of said pulsating current being proportional to the armature excitation, so the

generator is compounded. In no-load condition, the generator is auto-excited under the mutual effect of the remanence of the rotor and the capacitor- loaded split-phase winding.

However, with rising inductive current and reducing power factor, also the a. c. magnetic conductivity of the field winding diminishes, together with the efficiency of rectification, so the increase of the negative phase-sequence component of the field current will not be followed by the field current, thus the generator voltage will decrease. Consequently, no such single-phase synchronous, generator exists as yet that would be capable of maintaining its voltage within a narrow range around the rated value without brushes and exciter machine, both under growing inductive and resistive load, without being equipped with a voltage regulator.

Summarv of the Invention The invention is based on the recognition that the amortisseur can be utilized not only to prevent appearance of upper-harmonic excitation currents, but also to generate the required magnitude of field current, if instead of a squirre cage a polyphase amortisseur of pole number equal to that of the field winding arranged in the laminated, cylindrical synchronous- machine rotor is connected through a Graetz rectifier to the field winding, since the inverse excitation, together with the amortisseur will operate as an unsaturated exciter supplying, through said rectifier, the field current proportional in magnitude to the negative phase-sequence component of the armature reaction, ensuring thereby the capability of the generator of maintaining the output voltage within narrow limits.

The damping effect manifests itself as well, since it can be ensured that the field current of the amortisseur be of direction and magnitude opposite to of that produced by the inverse excitation.

In order to achieve the set aim the polyphase amortisseur of pole number equal to that of the field winding is accommodated in the cylindrical, high- remanence, laminated rotor close to the air gap and distributed as uniformly as possible along the periphery, and is connected to the field winding through the Graetz rectifier. It shall be dimensioned so that the armature reaction developing in the amortisseur be approximately opposed to the direction and magnitude of inverse excitation, and to make the current densities of the field winding acceptable at the permissible highest and most inductive load. The field winding shall be wound to have high number of turns and to make the electric time constant of the amortisseur considerably lower than that of the field winding. In one possible embodiment of the synchronous-machine rotor complying with the invention, the polyphase amortisseur in the cylindrical laminated body of the rotor consisting of cold- rolled thin sheets is a three-phase star-connected winding, one phase of which is arranged in the narrow slots stamped into the wide teeth, while the other two phases are accommodated in the wide slots of outside the broad teeth close to the slot mouths, and are connected, through the three-phase diode bridge mounted to the rotor to the terminals of the field winding located beneath the amortisseur and wound first into the slots outside the broad teeth. It is ensured by proper dimensioning of the amortisseur and field winding and of the iron parts that this synchronous machine rotor combined with a stator identical to the stator of a conventional split-phase synchronous generator mentioned further above and having a rotor of sheet length and diameter identical with that of the proposed design-provided with a smaller capacitor-is capable of achieving the same magnitude of apparent power output, producing an excitation maintaining constant output voltage not only at resistive, but also at varying inductive loads.

Brief Descrintion of the Drawinas The invention will be described in the following with reference to a preferred embodiment.

Figure 1 is a simplified drawing of a sheet of a possible embodiment of the synchronous-machine rotor complying with the invention, completed with the outlines of a stator pertaining to it.

Figure 2 is the connection diagram of a possible embodiment of the synchronous-machine rotor complying with the invention, completed with the connection diagram of a stator pertaining to it.

Description of the Preferred Embodiments The possible embodiment shown as an example is a cylindrical, laminated synchronous-machine rotor without squirre cage, containing a twisted-in three-phase amortisseur connected through a diode rectifier bridge to the field winding.

In this embodiment the three-phase amortisseur T2 occupying the narrow slots 5,6 located in the broad teeth 1,2 and approximately uniformly distributed along the rotor periphery, is connected to terminals K1, K2 of the field winding T1 placed into the bottom of the wide slots 3,4 outside the broad teeth 1,2 through the Graetz rectifier 7. The phase windings F1, F2 of amortisseur winding T2 are located in the upper layer of wide slots 3,4 and phase winding F3 is accommodated in narrow slots 5,6.

Assembling the synchronous machine rotor this embodiment with a properly dimensioned stator 11 provided with main phase 8 and split phase 9 fitted with capacitor 10, the voltage U1 remains within a narrow range close to the rated value even under an inductive-resistive load fed from the of main phase 8.

When the generator fitted with a rotor complying with the invention and with a stator described above is driven by an external force, voltage is induced in main phase 8 and split phase 9 under the effect of remanence, on increasing the speed. In no-load condition of the main phase 8, a capacitive

current starts flowing in the split phase 9 due to capacitor 10, by which a pulsating field is induced in the rotor. By this field current, on the one hand, rotor excitation is induced in the rotor rotating together with latter, producing excitation of the generator and on the other hand, an"inverse"fieid rotating in opposite sense and of double rotational speed with the respect to the rotor speed is produced by which a voltage is induced in its windings T1 and T2. When in the amortisseur T2 of lower electric time constant the line voltage sufficiently exceeds the voltage induced in amortisseur winding T2 of higher time constant, a current starts to flow through the Graetz rectifier 7. By this current, due to said bridge connection, a field of equal magnitude and of a direction opposite to that induced by the inverse excitation is produced, counterbalancing and attenuating the effect of the former. Hence, after build-up of this attenuating current in field winding T1, the induced voltage gradually diminishes. After the decay of transients a smoothed direct current of magnitude proportional to the inverse field current will flow through Graetz rectifier 7 in the high-inductivity field winding T1. As soon as the voltage induced by the field current magnetizing in the direction of the remanence becomes sufficiently high to amplify the above process, the fieid of the generator will build up. When an inductive-resistive load is connected to the main phase 8 after build-up of the field, an inverse excitation proportional to the load is produced. By this excitation a current directly proportional with the field is produced in amortisseur T2. Said current, flowing fed through the Graetz rectifier 7, will be of a magnitude necessary for maintaining the voltage within required limits within the specified range of loads, when properly dimensioned.

The outstanding properties of the single-phase synchronous generator- referred to as synchronous dynamo in the following-complying with the invention, provided with a synchronous-machine rotor, with a capacitor- loaded split phase, with a main phase and being of brushless construction and capable of maintaining its output voltage within a specified range without voltage regulator, render it suitable for being used as portable

emergency power source, especially in cases when loads absorbing also a reactive current are to be supplie.

The main advantage of the synchronous-machine rotor complying with the invention-contrary to the most up-to-date synchronous-machine rotor known so far, provided with capacitor-loaded field winding-is its capability of effectively maintaining the output voltage of the main phase of the generator without any external intervention or voltage regulator when feeding either a resistive or an inductive load.

A particular advantage of the synchronous dynamo fitted with the proposed rotor is its very good dynamic performance complementing its excellent static characteristics, rendered possible by the achievable extremely low value of time constant of the field-circuit feedback.

Due to these static and dynamic characteristics a most favorable portable power source can be provided by it, which is suitable for supplying single- phase welding transformers and single-phase motors having very low starting and service power factors.

List of reference symbols T1 Field winding T2 Polyphase amortisseur F1, F2, F3: T2 Phase windings of the plyphase amortisseur K1, K2: T1 Amortisseur terminals 1,2: Broad teeth 3.4: Wide slots 5,6: Narrow slots 7: Graetz rectifier 8: Main-phase winding 9: Split-phase winding 10: Capacitor 11: Stator 12: Inductive/resistive load of main-phase winding 8 U1: Voltage of main-phase winding 8.