US1932667A - Voltage regulating system - Google Patents

Description

31, 1933. H. A. w. KLINKHAMER VOLTAGE REGULATING SYSTEM Filed May 14. 1930 I YT INVENTOR nsumzm A.W. K mxnmen BY 7 I w -z/-/L/ ATTORNEY Patented Oct. 31, 1933 UNITED STATES VOLTAGE REGULATING SYSTEM Hendrik Abraham Wijnand Klinkhamer, Eindhoven, Netherlands, assignor to Radio Corporation of America, a corporation of Delaware Application May 14, 1930, Serial No. 452,219, and in the Netherlands June 1, 1929 4 Claims.

This invention relates broadly to a voltage regulating system and more particularly to systems for converting widely varying alternating voltage into a slightly varying alternating voltage.

While the present invention is described in connection with and is found to be particularly useful in conjunction with electrical apparatus employing space discharge devices it is to be clearly understood that its teachings may in fact be utilized wherever a constant voltage is desirable.

Heretofore it has been the custom to regulate voltages by utilizing a highly saturated transformer the primary of which includes a seriesconnected inductance.

According to the present invention, the consumption voltage is drawn from the windings of a highly saturated transformer the primary of which is connected through a series-connected capacity to a source of widely varying current, a second capacity being connected in parallel to the primary of the transformer.

The advantage shown by an arrangement according to the present invention over the heretofore utilized circuit arrangements will be more clearly understood by reference to the following detailed specification when read in connection with the accompanying drawing in which:

Fig. 1 illustrates a substitution diagram of a known voltage regulating system;

Fig. 2 illustrates a substitution diagram of a voltage regulating system constructed in accordance with my invention;

Fig. 3 illustrates diagrammatically a switchover arrangement in connection with my invention; and,

Fig. 4 is a diagrammatic illustration of a possible arrangement incorporating my invention in a rectifier circuit.

In Fig. 1 P1 and P2 designate the supply voltage and the load voltage respectively and X1 designates the primary inductance. The secondary impedance is conceived as a part of the load resistance and need not therefore be inserted in the diagram. X designates the magnetization reactance which in consequence of high saturation is dependent upon the current flowing through so that X decreases when the current increases.

The substitution diagram shows that the presence of the primary impedance X1 is a requisite condition, since for 331:0, P2 would be equal to P1 so that the arrangement would not suit the purpose.

In order to obtain a suflicient effect it is indispensable to make $1 sufficiently large by artificially increasing the primary leak or by connecting in series an unsaturated choke coil. Whenever cost or space play a part, this solution is inconvenient. Moreover, in particular cases, for example, when housing in radio-sets,

a powerful leakage field is inadmissible in view of disturbances.

In addition, this arrangement is not efficient for the effect aimed at, as will be appreciated from the following considerations:

Generally, the arrangement will be most efficient at a maximum saturation, butthis has a limitation in the occurrence of an excessive proportion of higher harmonics and in the heating of the iron. It is therefore well-known at which point of the magnetization curve it will be necessary to operate the transformer. As, in addition, the relative deviation of P2 admissible in the operating zone is to be regarded as given, the relative deviation of a: is thereby determined. From this the relative deviation of P1 which can be admitted in order that the deviation admissible for P2 may not be surpassed can be de' duced. For this deduction I may confine myself to the case of the load resistance being great relatively to the magnetization reactance. In this case the supply voltage is equal to I P,;P By inserting the limit values so; (1+v) of x, I find for the maximum relative deviation w from its mean value Plg which can be admitted for P1 (if in first approximation P2 is looked upon as constant) The object is to render possible maximal deviations of the supply voltage, and consequently to attain a maximum value of w. From the formula it is apparent that even when an infinitely large choke coil that is to say x1= is used, w does nevertheless not exceed 1;, consequently The circuit arrangement above indicated has a further serious disadvantage. As the series-connected choke coil does not allow higher current harmonics to pass, the current is essentially sineshaped (assuming the supply voltage to be sineshaped). Consequently, the effective value of of the load voltage P2 contains in full size all the higher harmonics generated by reason of saturation in the transformer winding. As these higher harmonics are more prominent according as the saturation increases, the desired effect of the arrangement is thus partially annulled and in reality the value of w above calculated is not attained at all.

The invention obviates all the said disadvantages by using instead of a choke coil condensers which are connected as shewn in the principle diagram of Figure 2. To start with, the case of the capacity on being=0 may be considered. The admissible relative deviation in from the supply voltage is found by substituting in the formula deduced before x, for an, where IL I CW otherwise for part of the desired variation zone in which I is allowed to vary from :r (1+v) to m n-v) the condition is no condition of balance. Thus from the above formula is found When comparing this with the maximum obtainable of- 10 which was found for the circuit arrangement comprising a series connected choke coil, via

it is obvious that in the circuit arrangement of the invention a very much greater variation zone of the supply voltage Pi is admissible, for v is small in comparison with unity.

The limit value for C1 following from the said condition of balance requires but a comparatively small condenser, the dimensions and cost of which are much lower than those of a choke coil of the order of magnitude adapted for the first circuit arrangement.

1!, in addition, the ohmic resistances of the circuit arrangement, the iron losses and the secondary load are taken into account, the case is slightly more complicated but nevertheless the considerations given are substantially correct. The limit value becomes slightly displaced so that as a condition of balance it may, for example, be stated that the capacitance of the condenser should exceed of the maximum value of the magnetization resistance of the transformer in operation.

In addition, an important advantage of the arrangement according to the invention consists in that higher harmonics which are due to high saturation of the transformer core hardly penetrate into the secondary part of the circuit arrangement as they are short-circuited by the series connected condenser C1 through the supply and by the parallel condenser C2 directly. Thus, the output current is only little different from the sine-shape and the difiiculties arising in the circuit arrangement comprising a series-connected choke coil do not occur.

The general case of the circuit arrangement in which C2 is difierent from zero and which is shewn in Figure 2 is important in practice in view of the possibility of attaining a further considerable extension of the admissible variation zone of the supply voltage Pl by the use of a switch-over arrangement as shewn in Figure 3. The condensers having a plug, designated by a black point, in the under row are connected in parallel to the primary winding of the transformer, the others are connected in series therewith. In this circuit arrangement the sum of the capacities C1 and C2 is continually the same, which ensures that the curve showing the relation between the voltages P1 and P2 maintains its shape but that the Pi coordinates are all multiplied by the same constant.

Figure 4 shows an example of using the arrangement of the invention in connection with a rectifier apparatus which (as is well known) without such an arrangement is extremely sensitive to small variations of the supply voltage. As the saturated transformer, the transformer which is already provided in the well known construction may be used without any alteration.

The low dimensions of the required condensers C1 and C2 have in this case the practical advantage of permitting the said condensers to be housed in existing constructions, and the absence of magnetic leakage fields (such as may occur in the use of choke coils) is to be looked upon as an advantage in view of the possibility of humming disturbances occurring by induction in the other parts of the circuit arrangement. Using the arrangement according to the invention with high tension supply units or radio-receiving sets ensures not only that the latterare independent of fluctuations in the supply voltage but also that they are adapted to be connected to any existing alternating current circuits. Thus it is no longer necessary for the manufacturer to keep in stock a series of different constructions for voltages increasing by 5%, as is the practice nowadays, but a universal apparatus is obtained which serves for any voltage.

As a secondary advantage may be mentioned that the apparatus does not burn out when erroneously connected to a direct current supply, as in this case the series-connected condenser will prevent the passage of current.

What I claim is:

1. In a system of the kind described, a source of voltage and a utilizing circuit, means for coupling said source to said utilizing circuit comprising a capacitive reactance and an inductive reactance in series, said inductive reactance comprising means having saturation effects, and capacitive reactive means connected across said inductive reactance, the total impedance of said arrangement being adapted to increase with increasing applied voltage.

2. In a system for supplying a utilizing circuit with substantially constant voltage alternating current, a source of voltage, a transformer having highly saturated core, the primary winding of said transformer being connected through a capacity to said source and a second capacity shunted across said primary winding.

3. In a system of the kind described a source of current, a utilizing circuit, a saturated cou pling means for connecting said source to said circuit, said coupling means being connected to said source through a capacity, and a second capacity shunted across the source side of said coupling means.

4. In a system for supplying a utilizing circuit with substantially constant potential alternating current, means having saturation effects for coupling said source to said circuit, said means having an inductance which varies with the intensity of current flowing therethrough, a capacity for connecting said coupling means to said source and a second capacity shunted across said coupling means for controlling the degree of variation of the inductance thereof with the intensity of flow of current.

HENDRIK ABRAHAM WIJNAND KLINKHAMER.

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