DE694794C - Circuit for single-phase alternators with self-excitation by capacitors - Google Patents

Description

GERMAN EMPIRE

ISSUE AI
AUGUST 8, 194Q

REICH PATENT OFFICE

PATENT LETTERING

CLASS 21 d 2 GROUP

L 87556 VIII dl 2

Patented in the German Empire from February 21, 193s Patent issued July 11, 1940

It is known to generate alternating currents by capacitors, <those connected to the induced winding are to be excited. if in this case 'the capacitors are also used for the delivery of useful current at the same time Winding are connected, this results in an additional load; For example, if 10 A of useful current (induction-free) and 10 A would be supplied

to excitation current (90 ⁰ leading) 'the winding with 10 ] / ~ 2 = 14, ι A be loaded. It has therefore been proposed to provide different, expediently spatially, ie also phase-shifted winding phases and to use the excitation capacitors Mir to not deliver useful current. To connect strands. Since, however, in machines of this type the real excitation power is quite large in relation to the effective active power

ao is, so would 'the one only used for excitation Winding .a significant part of the changing room claim, which leads to an unfavorable utilization of the machine.

In order to achieve better utilization, the single-phase load is applied to any two terminals, e.g. B. V and W, the Ständerwick- ^v averaging of the power generator, the "shifted manner of a three-phase machine with three 120 ⁰ Wicklungssträingen executed and connected in star or delta configuration and connected to the terminals U, V, W is provided. A capacitor C ₁ , the capacity of which is such that it generates the nominal voltage when idling, is connected to two other terminals, e.g. U and V. As will be shown, an even load on all three winding strands can now be achieved achieve full load on the machine according to the invention in that the load l another capacitor C ₂ is connected in parallel, which gives her 'a leading phase shift with respect to the terminal voltage.

In Fig. Ιa an example of the circuit used is shown, while Fig. Ib shows the resulting current diagram. As can be seen, the stator winding has three phase windings offset by 120 ⁰ U, V, W; the serving for the excitation capacitor C ₁ is connected to terminals LJ and V 'the payload R is connected in parallel with the capacitor C _2, to the terminals V and W. Therefore, the strand is 0-U (only voreileindem reactive current excitation current ) flowed through, the strand 0-W from the useful current, which has _{a slight lead due to the capacitor C 2} 'and the strand 0-V from the resultant of both currents.

In Fig. Ib, UV and VW are the vectors of the voltages between UV and VW. Vi ₁ is the vector of the through capacitor C ₁

'*) The patent seeker stated as the inventor:

Leo student in Berlin-Lichterfelde.

'IJIIiII

flowing current Z ₁ , which leads the voltage UV by 90 °, while VZ ₂ the in the resistor /? and the capacitor C ₂ is the current flowing Z ₂ whose phase advance is assumed to its voltage VW to 30 °. Z ₁ and Z ₂ are combined to form the resulting current J _r , which flows through the winding track OV . It is immediately clear that for the case Z ₁ = Z ₂ also Jr = J ₁ = J ₂ ; the machine then works like a three-phase machine with equally loaded phases, ie under the most favorable operating conditions, despite the fact that it only delivers single-phase useful current. In practice, this also occurs in that the magnetic hum, which is unavoidable with single-phase loading, disappears with the switching method according to the invention.

For comparison, Fig. 2a and 2b show the relationships that would result in a different switching mode. As can be seen, the currents Z ₁ and Z ₂ are in phase with one another, so they add up algebraically, so that twice the current would flow in the branch OU than in the other two branches. As a result of the phase equality of the three currents, the machine would work as a pure single-phase machine with correspondingly higher losses.

Claims (1)

Claim: Circuit for single-phase alternators with self-excitation by capacitors, the stator winding consists of three ^{winding phases shifted by 120 0} , which are connected like a three-phase machine in star or delta and the load between two phases, e.g. B. V and VV, is connected, characterized in that pin part of the exciting capacitors (C ₁ ) to the phases U and V, another part (C ₂ ) connected in parallel to the load to the phases V and W and 'the phase sequence is chosen so that the three winding phases of the machine are traversed by approximately the same currents at full load. For this purpose ι sheet of drawings