US2552952A - Magnetic amplifier - Google Patents

Description

y 1951 P. GACHET ETAL 2,552,952

MAGNETIC AMPLIFIER Filed July 15, l948 FIGJ.

1 I INVENTORS H6 2 PAUL-JOSEPH AUGIER DE MONTGREMIEP PAUL GACHET AGENT Patented May 15, 1951 H. =MAGN'ETIC AMPLIFIER Paul Gache't; fvincennes, and Paul Joseph Augier deMontgremienVanves, France, assigners to YvesgRocard, ParisgFrance Applicationiluly 15, 1948, Serial No. 38,935 In France March 12, 1948 -12Claims. 1

Our invention relates to magnetic amplifiers, and more particularly .to magneticvamplifiers in which two similar transductors are provided; It is well known in the art that :such transductors when connectedin parallel. teen-alternating current source will supply'equaLoutput currents onless they are unbalanced by changing thegsaturations of their magnetic structures inopposite senses by means of a directcurrent, the fcontrol current. The. change initherel'ation-of the output currents is a multiple onamplification of the change in control current.

It isan-object'of our. invention to: improve 'the range of such magnetic amplifiers.

It is another objectof our invention tozenable such amplifiers to 'yie1d;higher outputs.

It is also an object of our invention to render such magnetic amplifiers more e'flicient.

It is a further object of'our invention to provide magnetic amplifiers which are compact in construction and allow a considerable-reduction of metal weight in 'comparison tovknown amplifiers of similar output.

Other objects and advantageswill be-apparent from a consideration of the-specification and claims.

According to our invention, .magneticxamplifiers are improved by providing the :transductors with additional windings influencing the saturations of their magnetic materials, .said windings being energized by currents bearing .certainrelations to the currents flowing in themain windings of the transductors and serving to 'aid the .unbalancing effect of the control current.

Our invention will bebetter understood-from the following detailed description, withreference to the accompanying drawing illustrating byway of example two embodiments of. the same- In the drawings- Fig. 1 is a wiring, diagram otamagnetic amplifier according to our invention,.-and

Fig. 2 is a modification of the diagram. shown .in Fig. 1.

Referring now to thedrawings andiflrstto Fig.

1, the amplifier shown in the diagram :comprises the. leads 'joiningthe source I to the winding fi. It will be understood that the alternatingcur- .rent flowing in. the winding 6 depends on the state of saturation of the material of the magnetic structure. In the transductor shown in the diagram this saturation is controlled by .a plurality of windings in which direct current .flows. All these windings are provided in pairs, one winding of each pair on-each of the outer legs I and 2, respectively, and each two windings belonging to the same pair are-connected in series and are wound in such a manner that any alternating electrornotive forcesinduced :in them by the alternating current flowing in winding 6 will-cancel each other. Altogetherthere-are three pairs of direct current windings inuthe transductor as will be more'iully described-.hereinafter.

The first pairof direct current windings iland I0 is fed from a direct current source II supplying what may be termed the contro current. This is a current which can be varied'at will by the operator or may be supplied by some controlling device of a type well known'in the art. It should benoted that no alternating current will be sent back into the direct current source I I because, as mentioned above, the control windings?! and Marc wound in such a sense thatany electromotive forces induced in them cancel each other. It should also benoted that the-windings 9, II! are connected in series with the corresponding-windings 9', IE of the transductor T2 so-that the same control current controls the saturation of the material in both transductors. By means of a suitable arrangement of the windings 9'; Ill it is achieved that the saturation of/the material is affected in opposite senses in the two transductors so that according to the direction of the control current either thezinductance of T1 will be increasedgand that of Tzdecreased or that of Trdecreased and that of T2 increased.

The main winding 6 and the series-connected rectifier a of the transductor T2 are connected in parallel to the correspondingparts oftransductor T1.

Each transductor is provided..with.a. second pair of windings I2, I3 and I2, I3',respectively, which will be termed cross-reaction? windings for a .reason to be. explainedv presently.v Rectifiers I4, I4 are connected across portions of: the main-windings-fi, 6'. respectively, the connections beingmade by means ofjsliding .tapxcontacts IE, 15;,andthroughcondensers I6, I 6', respectively. Aswill be; seen from. the diagram, the windings I2, I3 of transductor T1 are;energizedgfromarectifier I4 of transductor T2, and conversely the windings I2, l3 of T2 drawn their current from rectifier I4 of T1. Thus the current flowing in I2, I3 will be in direct proportion to the voltage at the input of rectifier I4, i. e. to that which ap pears across winding 6', whereas the current in I2, I 3 is in direct proportion to the voltage across winding 6. It will be thus understood that there is a cross-reaction between the two transductors. A decrease of the inductance of T1 gives an increase of the current in winding 6. the voltage across this winding is equal to the product of the intensity of the current in 6, by the impedance of this winding.

Both terms vary in opposite senses but it can be seen that impedance decreases faster than corresponding intensity increases.

A decrease in the inductance of T1 gives a decrease in the voltage across winding 6, i. e. gives a decrease in the current that flows in the crossreaction windings I2, I3 and in turn gives an increase of inductance of T2 i. e. reduces the current in 6. Conversely, a decrease of inductance of T2 will increase that of T1 which in turn will decrease the inductance of T2 even further. Thus it will be understood that the cross-reaction windings greatly enhance the unbalancing effect of the control current. By feeding the rectifiers I4, I4 in an autotransformer connection from portions of the main windings ES, 6 through condensers IE, IS, respectively, the range and the efficiency of the device are greatly improved.

Rectifier 8 supplies to a resistance Il' a direct current i1 proportional to the alternating current flowing in winding 6, and similarly rectifier 8 feeds a resistance I1 with a direct current 22 proportional to the alternating current flowing in winding 6'. I 'l and H are parts of the output circuit of the amplifier and may, for instance, be exciting windings of a reversible motor which will reverse its sense of rotation according as i1 or 12 is larger.

Each transductor is provided with a third pair of direct current windings, viz. I8, IQ for T1 and I8, I9 for T2. These windings are connected in series With one another and with the resistances H and H and also with an adjustable resistance 20, which preferably is rather large in comparison to the resistances I1 and I1. Thus the wndings I8, I9, I8, I9 will be flowed through by a current which is directly proportional to the difierence i1i2 and the intensity of this current can be adjusted at will by a suitable adjustment of resistance 20. Bearing in mind that the windings are arranged on their respective transductors so as to affect the inductances of the latter on opposite senses, it will be understood that these windings also serve to enhance the unbalancing effect of the control current.

H is a resistance which may be provided, if desired, in the connection between windings I9 and I8.

The operation of the amplifier is as follows: As long as no control current is supplied, equal currents flow in I? and I1 owing to the symmetry of the transductors T and T2. When a control current in a certain direction is supplied, the

transductors will be unbalanced, the inductance of one transductor, say T1, being decreased and that of T2 increased, owing to the opposite effects of the windings 9, I I] and 9, It on the saturation of the magnetic material. Thus the currents in 6 and 6 will tend to become different and this effect is greatly enhanced by the cross-reaction between the two transductors and the efiect of the difference current flowing in the windings I8, l9 and I8, I9. Thus a relatively large direct current will flow in resistance I! and a much smaller one in resistance I'I'. When now the direction of the control current is reversed, the current in resistance I 1' will be much larger than that in I! and it will be seen that, .for instance, a motor in which I! and I1 are exciting windings may be reversed by a relatively weak control current. It will also be understood that the current flowing in resistance 2| will reverse its direction whenever the control current is reversed.

The modification of the amplifier shown in Fig. 2 is essentially the same as that illustrated in Fig. 1 except that the rectifiers 8 and 8' are not directly connected in series with the windings 5 and 6', respectively, but through transformers. As will be seen from the diagram, the primary 22 of a transformer is connected in series to winding 6, and correspondingly primary 22 to winding 6'. The secondary winding 23 of the transformer has its circuit completed by the rectifier 8, and similarly rectifier 8 is connected to the secondary 23' of the other transformer. Resistance 20 of the amplifier according to Fig. lcan be dispensed with here, any adjustment of the difierence current being made possible by providing sliding contacts 24, 24 engagin resistances I1, I'I', respectively.

The operation of the amplifier shown in Fig. 2 is exactly the same as that of the amplifier described hereinabove.

It will be appreciated that modifications of the disclosed embodiments of our invention are possible without departing from the spirit of the invention or the scope of the appended claims.

What we claim is:

1. A magnetic amplifier which comprises: a first transductor including a first saturable magnetic core structure having a first A. C. winding wound thereon, a second transductor including a second saturable magnetic core structure having a second A. C. winding wound thereon, a series connection comprising said first A. C. winding and a first impedance, a series connection comprising said second A. C. windin and a second impedance, means for connecting said series connections in parallel with a source of alternating current, a first saturation winding wound on said first core structure, means for applying a direct current through said first saturation winding proportional to the magnitude of the voltage across said second A. C. winding, a second saturation winding wound on said second core structure, means for applying a direct current through said second saturation winding proportional to the magnitude of the voltage across said first A. C. winding, a control winding wound on each of said core structures, and means for connecting said control windings to a source of variable D. C. control current so that a variation in control current causes an increase in the magnetic saturation of one core structure and a decrease in the magnetic saturation of the other core structure, all of said windings being so wound that substantially no alternating current is induced by said A. C. windings in the outputs of said control and said saturation windings.

2. A magnetic amplifier as in claim 1, and a load controlled by the difference in current flow-- ing through said first and said second impedances, respectively.

3. A magnetic amplifier as in claim 2 wherein said means for applying a direct current through said first saturation winding comprises a rectifier connected across at least a portion of said second A. C. Winding, and means connecting the D. C. output of said rectifier to said first saturation winding.

4. A magnetic amplifier as in claim 3 wherein said means for applying a direct current through said second saturation winding comprises a second rectifier connected across at least a portion of said first A. C. winding, and means connecting the D. C. output of said second rectifier to said second saturation winding.

5. A magnetic amplifier as in claim 4 including a third and a fourth saturation winding wound on said first and second core structures, respectively, in opposite electrical direction to the control winding on the same core structure, and means for passing a direct current through said third and said fourth saturation windings proportional to the magnitude of the difference in A. C. current passing through said first and said second impedanccs, respectively.

6. A magnetic amplifier which comprises: a first transductor including a first saturable magnetic core structure having a first A. C. winding wound thereon, a second transductor including a second saturable magnetic core structure having a second A. C. winding wound thereon, a series connection comprising said first A. C. winding and a first rectifier, a series connection comprising said second A. C. winding and a second rectifier, means for connecting said series connections in parallel with a source of alternating current, a first saturation winding wound on said first core structure, means for applying a direct current through said first saturation winding proportional to the magnitude of the voltage across said second A. C. winding, a second saturation winding wound on said second core structure, means for applying a direct current through said second saturation winding proportional to the magnitude of the voltage across said first A. C. winding, 2. control winding wound on each of said core structures, means for connecting said control windings to a source of variable D. C. control current so that a variation in control current causes an increase in the magnetic saturation of the other core structure, a first impedance connected across the D. C. output of said first rectifier, a second impedance connected across the D. C. output of said second rectifier, a third and a fourth saturation winding wound on said first and second core structures, respectively, in opposite electrical direction to the control winding on the same core structure, and means for passing a current through said third and said fourth saturation windings proportional to the difference in voltage across said impedances, all of said windings being so wound that substantially no alternating current is induced by said A. C. windings in the outputs of said control and said saturation windings.

7. A magnetic amplifier as in claim 6, and a load connected between said first and said second impedances.

8. A magnetic amplifier as in claim 6 Wherein said means for passing a current through said third and fourth saturation windings comprises means connecting said third and said fourth saturation windings in series between said first and said second impedances.

9. A magnetic amplifier as in claim 1 which includes a third and'a fourth saturation winding wound on said first and second core structures, respectively, in opposite electrical direction to the control winding of the same core structure, a first rectifier connected across said first impedance, a first resistance connected across the D. C. output terminals of said first rectifier, a second rectifier connected across said second impedance, a second resistance connected across the D. C. output terminals of said second rectifier, and means for applying a current through said third and said fourth saturation windings proportional to the diiference in potential across said first and said second resistances, respectively.

10. A magnetic amplifier as in claim 9, and a load connected between said first and second resistances.

11. A magnetic amplifier as in claim 10, wherein said means for passing a current through said third and said fourth saturation windings comprises means connecting said third and said fourth saturation windings in series between said first and said second resistances.

1'2. A magnetic amplifier as in claim 11 wherein said first and said second impedances comprise transformers each having its input terminals in series with the respective A. C. winding and having its output terminals connected across the respective rectifier.

PAUL GACHET. PAUL JOSEPH AUGIER. on

MONTGREMIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,914,220 Sorensen June 13, 1933 2,247,983 Barth July 1, 1941 2,338,423 Geyger Jan. 4, 1944

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