US2150386A - Harmonic producer - Google Patents

Description

March 14, 1939.. J. M. MANLEY 2,150,386

HARMONIC PRODUCER Filed Sept. 30, 1957 2 Sheets-Sheet l /6 000 m0 EVEN l0 "mum/n;

FILTERS i, FIG? D I 4 V n n n A J zil FIQ 3 7i 7%; 3 377- 5 l n n V77 V n A t,

IN VE N TOR JM. MANLEV JW I ATTORNEY March 14,1939. J MANLEY 2,150,386

HARMONIC PRODUCER Filed Sept. 30, 1937 2 Sheets-Shem- 42 /.0 Q00 X EVEN y 000 EVEN q 2. FIGS- 3 g E E n t I p 0 I z z'r jl a F/G.4 B

INVENTOR JM. MANLE) ATTORNEY Patented Mar. 14, 1939 UNITED STATES HARMONIC PRODUCER Jack M. Manley, East Orange, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application September 30, 1937, SerialNo. 166,519

'7 Claims. This invention relates to harmonic generators I and more particularly to harmonic generatorsof the magnetic type utilizing a direct current bias to produce both odd and even harmonics and to accentuate a preselected harmonic.

In the copending application of L. R. Wrathall. Serial No. 77,989, filed May 5, 1936, and assigned to applicants assignee; a system utilizing a saturable-core coil is described for producing a series of relatively sharp pulses having a uniform time spacing therebetween and whereby a range of odd harmonics is produced. The present invention cotemplates the provisions of applying a direct current bias to the saturable-core coil to shift each of the pulses by a predetermined amount depending on the magnitude of the bias. This shift of the pulses provides a wave form such that both odd and even harmonics are produced in the output circuit. Also, the bias may be so proportioned that the amplitude of an even harmonic is produced with a maximum value while the amplitudes of the odd harmonics lying adjacent thereto are suppressed or that the amplitude of an odd harmonic is produced with a maximum value while the amplitude of the even harmonics lying adjacent thereto are suppressed. A harmonic having a maximum amplitude relative to the suppressed amplitudes of adjacent harmonics is useful in certain systems for synchronizing purposes, particularly in systems where the synchronizing harmonic is changed from time to time over a range of odd and even harmonics.

It is an object of this invention to simultaneously produce odd and even harmonics.

It is another object of this invention to accentuate the amplitude of a preselected harmonic while at the same time suppressing the amplitudes of the harmonics lying adjacent thereto.

It is a further object of this invention to produce a certain range of both odd and even harmonies having uniformly large amplitudes.

The invention will be more readily understood from the following description taken together with the accompanying drawings in which:

Fig. 1 is a diagrammatic circuit illustrating the preferred form of the invention;

Fig. 2 shows a wave form resulting from the operation of Fig. 1 without bias; and

Figs. 3, 4 and 5 illustrate the operation of Fig. 1 with bias in accordance with the invention.

Referring to Fig. 1, an alternating current source l0 applies a fundamental wave through a tuned circuit II to the primary of a saturablecore coil l2. A secondary or output circuit l3 for the coil comprises a condenser l4, coupling transformer l5 and a group [6 of odd and even harmonic-selective filters. As described in the aforementioned copending application of L. R. Wrathall the constants of the output circuit are so proportioned as to produce a series of alternating pulses, each of brief duration and representing the discharge of condenser i4 through. a substantially resistive output circuit. These pulses illustrated in Fig. 2 have a uniform time spacing therebetween and occur periodically with the period of the fundamental wave to produce in the output circuit a group of odd harmonics having uniformly large amplitudes. Curve A in Fig. 4 shows the magnetization characteristic of the saturable-core of the coil 12 as the fundamental current I: is impressed thereon to eiiect the wave form illustrated in Fig. 2. In curve A of Fig. 4, it is seen that the inductance of the coil I2 is a maximum for the positive half-cycle between the points C and D, and again a maximum for the negative half-cycle between the points E and F.

In the present invention a source ll of direct current is applied to the saturable-core coil through a choke coil [8 and an adjustable resistance l9. This direct current bias serves to shift the magnetization characteristic of the saturable-core coil shown by curve A of Fig. 4 to that illustrated by curve B of Fig. 4 by an amount b that depends on the magnitude of the direct current voltage.

The wave shape shown in Fig. 3 and resulting from the magnetization characteristic curve B produces in the output circuit both odd and even harmonics whose range is substantially the same as that produced by the wave shown in Fig. 2. The amount of the pulse shift in pt can be readily determined from the following equation:

tude of the magnetization force of the wave Ir. The equation is approximately correct if b 1 r e It is to be understood that the relative heights of the peaks of the pulses illustrated in both Figs.

2 a,1so,aas

2 and 8 are substantially identical. This is true since the shape of the pulse is determined by the constants of the saturable-core coil and output circuits in Fig. 1 and these are unchanged for the waves shown in Figs. 2. 3 and 4.

Referring to curve B of Fig. 4, the inductance of the saturable-core coil is a maximum for the positive half-cycle of the fundamental current I: between the points G and H and again a maximum for the negative half-cycle between the points K and L. Thus in curve B the saturablecore coil attains minimum inductance in a positive direction sooner than'in curve A and in a negative direction later than in curve A. In

other words, according to curve B the condenser in curve A. Consequently, the positive pulse P of Fig. 3 occurs sooner than the corresponding pulse P of Fig. 2'and the negative pulse N of Fig. 3 occurs later than the corresponding pulse N of Fig. 2.

The direct current bias I) may be proportioned to suppress or accentuate a particular odd or even harmonic of the fundamental alternating cur- .rent wave I: as desired. That is, a particular odd harmonic is produced with maximum amplitude while the even harmonics lying adjacent thereto are suppressed or a particular even harmonic is produced with maximum amplitude while the odd harmonics lying adjacent thereto are suppressed. The amount of direct current bias b required to produce a preselected harmonic with maximum amplitude can be readily calculated from the following equations:

b r b {hp-5 tr" where r s b is the magnetizing force due to the biasing voltage, P is the amplitude of the magnetizing force of the wave 11 and n in Equation a is a particular even harmonic while 11 in Equation 1) is a particular odd harmonic. If

h l P 6 the above equations are approximately correct.

In Fig. 5 it is seen that when an even harmonic, say, for example, harmonic X has a maximum amplitude, the two odd harmonics lying adjacent thereto are suppressed and that when an odd harmonic, say, for example, harmonic Y has a maximum amplitude, the even harmonics lying adjacent thereto are suppressed. It is understood that the distribution of harmonics shown in Fig. 5 is an amplitude factor to be applied to the distribution of harmonics obtained by the wave shape of Fig. 2, which is produced in accordance with the copending application of L. R. Wrathall, supra. Thus the factor, whose maximum value is 1.0, must be multiplied by the harmonic amplitudes obtained in Wrathall's harmrmic distribution in order to ascertain the actual value of the amplitudes.

InFlg.5itisalsoseenthat for alimitedrange in the vicinity of the intersections of the odd and even factors, the amplitudes of both odd and even harmonics will be relatively large and substantially uniform, depending in an inverse manner on the width of the range of harmonics.

Having ascertained the amplitude of an accentuated harmonic in the manner indicated above,

the extent of the suppression of the adjacent harmonics can be determined as follows:

If the amplitude of an even harmonic n. is produced with maximum value, then the ratio of the amplitude of the odd harmonics mil to the even harmonic n. is

If, for example, the thirty-fifth harmonic of the fundamental wave I1 is produced with maximum value, the amplitudes of the thirty-fourth and thirty-sixth are suppressed 21.0 decibles relative to the amplitude of the thiry-fifth harmonic.

What is claimed is:

1. In a harmonic producer including a source of alternating current waves of fundamental frequency, a saturable-core coil connected to said alternating current source, and an output circuit for said coil having a condenser and a substantially resistive load proportioned to produce therein a series of relatively sharp pulses of current occuring in a predetermined time relation; means comprising a direct current source for biasing said saturable-core coil to change the time relation of the occurrence of said pulses of current such that successive pulses are shifted the same amount of time.

2. In a harmonic producer including a saturable-core. coil, a source for applying an alternating current wave of fundamental frequency thereto and an output circuit therefor, said output circuit including a condenser and a substantially resistive load proportioned to produce therein a series of relatively sharp positive and negative pulses occurring in a certain time relation; means comprising a direct current source for biasing said coil to vary the time relation of the occurrence of said pulses so that the positive and negative pulses are respectively advanced and delayed in predetermined equal amounts of time.

3. In a harmonic producer including a source of alternating current waves of fundamental frequency, a saturabIe-core inductance connected to said alternating current source, and an output circuit for said inductance and having a condenser and a substantially resistive load connected therein and proportioned to provide in the inductance a magnetization characteristic such that successive pulses of current have equal time spacings therebetween; and means comprising a unidirectional current source for biasing the inductance to shift the magnetization characteristic in a manner such that the successive pulses of current have unequal time spacings therebetween.

4. In a harmonic producer comprising a saturable-core inductance, a source for impressing thereon an alternating current wave of fundamental frequency and an output circuit for the inductance, said output circuit including acoudenser and a highly resistive load proportioned to produce therein a broad range of odd harmonic frequency currents having uniformly large amplitudes; means connected to the inductance and including a source of unidirectional current for producing a predetermined range of both odd and even harmonics, the current applied to the inductance from said source of undirectional current being proportioned so that the amplitude of a preselected harmonic is produced with a maximum value relative to the amplitudes of adjacent harmonics in the produced range of harmonics.

5. In a harmonic producer including a saturable-core inductance, a source for impressing thereon an alternating current wave of fundamental frequency and an output circuit for the inductance, said output circuit including a condenser and a highly resistive load proportioned to produce therein a broad range of odd harmonic frequency currents of uniformly large amplitudes; means connected to the inductance and including a source of unidirectional current for biasing the inductance to produce odd and even harmonics of a range substantially equal to the range of odd harmonics, the current applied to the inductance from said source of unidirectional current being so proportioned that the amplitude of a preselected odd harmonic is produced with a predetermined maximum value while the amplitudes of the even harmonics adjacent thereto are suppressed.

6. In the harmonic producer according to claim 5 in which the unidirectional current is so proportioned that the amplitude oi a. preselected even harmonic is produced with a predetermined maximum value while the amplitudes of the odd harmonics lying adjacent thereto are suppressed.

7. In a harmonic producer comprising a saturable-core inductance, a source for impressing thereon an alternating current wave of fundamental frequency and an output circuit for said inductance, said output circuit including a condenser and a highly resistive load proportioned to produce therein a broad range of odd harmonic frequency current having uniformly large amplitudes; means connected to the inductance and including a source of unidirectional current for producing a predetermined range of both odd and even harmonics, the current applied to the inductance from said source of unidirectional current being proportioned so that a preselected group of both odd and even harmonics is produced with substantially uniform amplitudes.

JACK M. MANLEY.

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