US2727159A

US2727159A - Switching apparatus

Info

Publication number: US2727159A
Application number: US436419A
Authority: US
Inventors: Joseph E Sunderlin
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1954-06-14
Filing date: 1954-06-14
Publication date: 1955-12-13
Anticipated expiration: 1972-12-13

Description

Dec. 13, 1955 J. E. SUNDERLIN 2,727,159

I SWITCHING APPARATUS Filed June 14, 1954 2 Sheets-Sheet l Fig.l. 20

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SWITCHING APPARATUS Filed June 14, 1954 2 Sheets-Sheet 2 Fig. 6.

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90 IIIIHIHIHIF W IAImmmIm United States Patent SWITCHING APPARATUS Application June 14, 1954, Serial No. 436,419 7 Claims. (Cl. 307-106) This invention relates to switching apparatus, and more particularly to magnetic switching apparatus for supplying recurring pulses to a load that appears resistive during the time of the output, such as a magnetron.

The pulses that are utilized for pulsing a magnetron are generally high power recurrent pulses of very short duration compared to the interval between pulses. A prior art device for producing recurrent pulses operates on the principle of the periodic storage of energy in an inductive system, the transfer of that energy to a storage capacitor and finally the discharge of that energy to the load circuit. The building up of energy 'in th e inductive system is initiated by the periodic conduction of a control tube whose conduction is regulated by a pulsating voltage supplied to the grid of the control tube.

It is an object of my invention to provide an improved switching apparatus for supplyingrecurring pulses to a load.

It is another object of my invention to provide a magnetic switching apparatus in which no, electron discharge devices are employed and hence the apparatus is quite m s a It is an additional object to provide a magneticjswitching apparatus in which saturablereactors, having cores of a material which exhibits a rectangular'hysteresisloop, are employed in a relatively simple circuit for pulse forming. I

' It is still another object to provide a magnetic switching apparatus in which the rate of pulses supplied to a load by the apparatus is twice the frequency of the input to the apparatus, without the use of rotating equipment to produce the frequency doubling. 7 i

It is a still further object of my invention to'provide a magnetic switching apparatus in which the rate of pulses supplied to a load by the apparatus is triple" the frequency of the three-phase input signal to the apparatus.

These and other objects of the invention are effected as will be apparent from the following description, taken inaccordance with the accompanying drawings, which form a part of this application and'in' which like numerals are employed to designate like parts throughout the same:

Figure 1 is a schematic diagram of a magnetic switching apparatus in accordance with a first; embodiment of my invention;

Fig. 2 graphically illustrates the output .voltage wave of the embodiment of my invention shown in Fig. 1;

Fig. 3 is a schematic diagram of a magnetic switching apparatus in accordancewith a second embodiment of my invention in which a multiplex pulse shaping network isemployed;

Fig. 4 graphically illustratesthe output voltage wave of the embodiment of .my invention shown in Fig. 3;

Fig. 5 is a schematic diagram ofla magnetic switching apparatus in accordance with a third embodiment of my invention, in which a saturating centertap transformeris utilized; r

Fig. 6 graphically illustrates the output voltage wave of the embodiment of my invention shown in Fig. 5;

Fig. 7 is a schematic diagram of an equivalent circuit of the circuit illustrated in Figure 5, with a conventional centertap transformer being utilized in the equivalent circuit;

Fig. 8 is a schematic diagram of a magnetic switching apparatus in accordance with a fourth embodiment of my invention with the apparatus being adaptable for operation from a three-phase power supply to effect a pulse tripping of the frequency of the input power.

In Fig. 1, there is shown a schematic diagram of a circuit of a magnetic switching apparatus in accordance with one embodiment of the present invention in which an inductor 16 is serially connected with capacitor 18 and this series combinationforms a charging circuit which is placed in parallel with an alternating signal source 10, with source 10 being connected to the circuit through the connecting means 11 and 12. This connecting means may be of any known prior art type. Inductor 16 has a fixed inductance and is utilized to isolate capacitor 18 from the source 10 when the capacitor is discharged. The various combinations of diiferent values of inductance and capacitance will determine the shape of the charging voltage on the capacitor 18, i. e., the input charging circuit may be resonant or non-resonant. A saturating reactor 20 is connected in a series arrangement with load 15 and this series arrangement is shunted by capacitor 18. Load 15 is connected with the output of the magnetic switching circuit through connecting means 13 and 14. Saturating reactor 20 is preferably wound on a core of a material which exhibits a rectangular hysteresis loop, more commonly known as a square loop material. Materials of this type when used in the form of cores for reactors or transformers exhibit a very large change in impedance, e. g., 1000 to 1, when driven from the unsaturated condition into saturation. The circuit may be grounded at junction 17. I

The combined impedance of the reactor 20 when it. is unsaturated and load 15 should be much greater than the impedance of capacitor 18. This is necessary in order that there is very little shunting of the capacitor 18 during the charging cycle. The impedance of the reactor 20 when it is unsaturated should be much greater than the impedance of the load 15. This effectively causes all of the charging voltage on capacitor 18 to appear across the reactor 20. The. type of reactor 20 should be so chosen that when it becomes saturated its impedance should drop to a value that is much less than the impedance of the load 15. The combination of the impedances of the load 15, the capacitor 18, and the reactor 20 when saturated, should be such that the discharge of capacitor 18 takes place in a short time compared with the time of the input cycle. This allows the charging circuit to operate in a stable manner- In Fig. 3 there is shown a schematic diagram of a circuit of a magnetic switching apparatus in accordance with a second embodiment of the present invention by which pulses of one polarity are. produced. Inductor 36 is serially connected with capacitor 38 and this series combination forms a charging circuit which is placed in parallel with an alternating signal source 30, which source to the respective reactor across 30 being connected to the circuit through the connecting

means

32 and 33. A saturating reactor 40 is connected in series arrangement with capacitor 41 and this series arrangement is shunted by capacitor 38. Reactor 40 is provided with an auxiliary winding'47 which may be connected to a source of direct voltage through impedance 111. Impedance 111, aswell as all the impedances 112 116 used in the bias windings in thecircuits in accordance with my invention, has a high A. CL impedance relative which it 'is connected.

A pulse shaping network having

input connectors

101 and 102 and

output connectors

103 and 104 is provided in this circuit with the network consisting of a plurality of serially connected saturating reactors, such as

reactors

42, 44 and 46, with the saturating reactors being shunted by a plurality of parallel capacitors, such as 41, 43 and 45. One or more of the

reactors

42, 44 and 46 may require a means for supplying a D. C. bias potential to the reactor such as winding 106 with impedance 110 on the reactor 42. A pulse transformer 48. serially connected with the last reactor 46, is provided to inductively couple the output of the pulse shaping network with the

connectors

34 and 35 for connecting a load to the circuit. The circuit may be grounded at junction 39. In selecting the inductor 36, capacitor 38 and saturating reactor 40, relative values of the latter elements of the circuit should be similar to the ones suggested for the inductor 16, capacitor 18 and saturating reactor 20 in the circuit shown in Fig. l. Saturating

reactors

40, 42, 44 and 46 should have cores made of a thin square loop core material to minimize eddy current effects. It should be understood that the number of serially connected reactors and parallel shunt capacitors utilized in the circuit is determined by the amount of pulse narrowing that is desired to be produced by the circuit.

In Fig. 5, there is shown a schematic diagram of a circuit of a magnetic switching apparatus in accordance with a third embodiment of the present invention in which a saturating transformer 63 is utilized with the transformer having a primary winding, which is divided into two

portions

65 and 66 by centertap 64, and a secondary winding 67. A bias winding 62 including the impedance 49 may be provided for supplying a D. C. potential to saturating transformer 63 for biasing the transformer. An inductor 55 is serially connected with capacitor 56 to form a charging circuit and this charging circuit is connected in parallel with an alternating signal source 50 by means of

connectors

51 and 52. Two loop discharge paths are provided for capacitor 56. One path includes a saturating reactor 60, provided with an auxiliary winding 61, including the impedance 113, which winding may be connected to a source of direct current with the reactor 60 being connected in series with the first portion 65 of the primary winding of the transformer 63. The second path for the discharge of the capacitor 56 includes a saturating reactor 58, provided with an auxiliary winding 59, including the impedance 112, which winding may be connected to a source of direct current, with the reactor 58 being connected in series with the second portion 66 of the primary winding of the transformer 63.

Reactors

58 and 60 should be so biased by the flux from

windings

59 and 61, respectively, that reactor 58 will become saturated only during one half of the cycle of the input signal to the circuit and reactor 60 will become saturated only during the other half of the cycle of the input signal to the circuit. The secondary winding 67 of the transformer 63 is connected with capacitor 68 and load 57 in a series arrangement, with load 57 being connected to the capacitor 68 and Winding 67 by means of

connectors

53 and 54.

Reactors

58 and 60 and saturating centertap transformer 63 should contain cores of magnetic material having a rectangular hysteresis loop.

In Figure 7 is shown a circuit that is similar to the circuit shown in Figure 5. However, in the circuit shown in Figure 7, a conventional centertap transformer 63 is used instead of a saturating centertap transformer. The secondary winding 67 of the transformer 63' is shunted by capacitor 68' and is connected in a series arrangement with saturating reactor 69 and load 57, with load 57 being connected to the reactor 69 and winding 67 by means of

connectors

53 and 54.

In Figure 8 is shown a schematic diagram of a magnetic switching apparatus in accordance with a fourth embodiment of my invention which is operable with a three-phase power supply. Three separate charging circuits are provided. Each charging circuit consists of an inductor and capacitor in series arrangement with one end of the capacitor grounded. In the embodiment shown, the three charging circuits comprise inductor 76 and capacitor 80, inductor 77 and capacitor 81, and inductor 78 and capacitor 82, respectively. Each of the three charging circuits is connected to a three-phase power supply 70 by means of

connectors

71, 72 and 73.

Saturable reactors

85, 86 and 87 are provided with respective

main windings

91, 92 and 93 on each of which windings are two end connector members. The respective

auxiliary windings

95, 96 and 97, including the

respective impedances

114, 115 and 116, are adaptable for connection to a direct-current source for biasing. One end connector member of each of the reactors is connected to the respective charging circuits at the junctions where the respective capacitors and inductors are connected in such a manner that the

capacitors

80, 81 and 82 may facilitate the saturating of

reactors

85, 86 and 87, respectively. The other end connector member of the main windings of the reactors are connected together in a common junction 88. Reactor and connector 74 are connected in a series arrangement with this junction 88. Connector 74 is provided as means for applying a load 75 to the circuit. Load 75 should be grounded as shown in the diagram. Also connected to common junction 88 and being in parallel arrangement with the above series arrangement is capacitive member 89. Member 89 is also grounded as shown in the schematic diagram.

In accordance with the first embodiment of my invention shown in Fig. 1, an alternating signal from signal source 10 is supplied to the circuit through connectors 11 and 12. Initially there is no voltage on capacitor 18 and reactor 20 is unsaturated. As the voltage of the capacitor rises, a change of flux occurs in the core of the reactor 20. The reactor is designed so that when the voltage on the capacitor 18 has reached its peak, the core of the reactor will become saturated. The saturation of the core of reactor 20 causes a very great drop in the impedance of the reactor. Consequently, the capacitor 18 is now shunted by a low impedance path and discharges its energy into the load 15. The shape of the output voltage wave to the load is illustrated in Fig. 2.

In accordance with the second embodiment of my invention shown in Fig. 3, an alternating signal from signal source 30 is supplied to the circuit through

connectors

32 and 33. Similar to the operation of the circuit illustrated in Fig. l, the voltage across capacitor 38 tends to saturate the core of reactor 40. However, the core of the reactor 40 is so biased that it will become saturated during only one half of the cycle of the input signal. Hence pulses of one polarity will be produced. A resonant circuit is formed when reactor 40 saturates. The resonant circuit consists of

capacitors

38 and 41 and the reactor 40 which has become saturated. The voltage on capacitor 41 will appear as a pulse considerably reduced in width when compared with the voltage wave form on capacitor 38. The wave form then passes through the rest of the pulse shaping network including serially connected

reactors

42, 44, 46 and

parallel capacitors

43 and 45, and is inductively coupled by means of a pulse transformer to the

connectors

34 and 35 to which a load may be applied. 'lghe iutput voltage wave of the circuit is illustrated in In accordance with the third embodiment of my invention shown in Fig. 5, an alternating signal from signal source 50 is supplied to the circuit through

connectors

51 and 52. A suitable D. C. bias potential may be supplied to the winding 62 of the saturating transformer 63. Inductor 55 and capacitor 56 are provided as an alternatingcurrent resonant charging circuit with the capacitor 56 being discharged every half cycle of the input signal. This results in positive and negative pulses.

Reactors

58 and 60 are so biased by direct current being supplied to their

auxiliary windings

59 and 61, respectively, that onereactor saturates when the voltage on capacitor 56 reaches its positive peak and the other reactor saturates on the reverse peak polarity. By feeding these pulses into the satu rating centertap transformer 63 through winding 65 when reactor 60 is saturated and then through winding 66 during the other half of the cycle of the input signal when reactor 58 is saturated, the flux in the core of transformer 63 is caused to fluctuate in magnitude in one direction only and hence output pulses of one polarity will result and these pulses will occur at a rate which is twice the fre quency of the input signal to the circuit.

It should be pointed out at this time why a saturating centertap transformer 63 is utilized in this circuit rather than a conventional centertap transformer. When capacitor 56 is discharged, it forms a resonant circuit with capacitor 68 and the saturated inductance of reactor 58 or reactor 60, depending on which reactor is in the saturated state. The values of these circuit components,

capacitors

56 and 68 and

reactors

58 or 60, are so chosen in order that some pulse sharpening occurs. During the time capacitor 56 is discharging into capacitor 68, the transformer 63 operates as a conventional transformer. The transformer 63 should be so chosen that it will become saturated when the voltage on capacitor 68 reaches its maximum value. A new resonant circuit is now formed which comprises capacitor 68, the transformer 63 which has become saturated and the load 57. Consequently, more pulse sharpening occurs and in the circuit shown in Fig. the narrowed pulses are dissipated into the load 57. However, the pulses could be passed through an additional pulse sharpening network before supplying them to a load. In Fig. 6 is illustrated the output voltage wave supplied to the load 57 in the circuit shown in Fig. 5.

By referring to Fig. 7, it can be seen that an additional component, saturating reactor 69, must be added to the circuit in accordance with the third embodiment of my invention when a conventional centertap transformer 63 is used instead of a saturating centertap transformer, if it is desired to obtain the same amount of pulse sharpening as was obtained from the circuit illustrated in Fig. 5. In other words, Fig. 7 is an equivalent circuit of Fig 5 when a conventional centertap transformer 63' is used instead of the saturating centertap transformer 63. The circuit shown in Fig. 7 operates in the same manner as the circuit shown in Fig. 5 up until the time when capacitor 68 is receiving the charging voltage. The saturable reactor 69 should be so chosen that it will become saturated when the voltage on capacitor 68' reaches its maximum value. A new resonant circuit is formed which comprises capacitor 68, the reactor 69 which has become saturated and the load 57. Consequently, pulse sharpening occurs as is the case in the circuit illustrated in Fig. 5.

It can be seen from the above description that by utilizing a saturating centertap transformer in this particular embodiment of my invention, additional pulse sharpening can be obtained which could otherwise be brought about only by use of an additional component, namely, a saturable reactor. The elimination of the necessity of utilizing the additional saturable reactor for obtaining the desired pulse sharpening will result in a savings in space and weight which is quite a factor when the circuit in accordance with this embodiment of my invention is utilized in equipment for the military.

In accordance with the fourth embodiment of my invention as shown in Fig. 5, a three-phase alternating signal comprising phases A, B and C is supplied to the circuit through

connectors

71, 72 and 73. Let us first consider phase A. With a proper bias on winding 95 of reactor 91 so that the reactor can become saturated during only one-half of a cycle of phase A, capacitor 80 will charge up to some peak value. At this point reactor 91 becomes saturated and capacitor 80 discharges into capacitive member 89. When the charge on capacitive member 89 reaches its peak value, reactor 90 becomes saturated and member 89 discharges into the load 75. Each time a discharge takes place, some pulse sharpening occurs. Phase B and phase C cause similar charging and discharging of capacitors and 81 respectively, with the aid of reactors 86 and 87 in a manner as described above for phase A. Capacitive member 89 receives pulses at a rate which is three times the input frequency and supplies them to load 75. is within the scope of this embodiment of the invention to remove capacitive member 89 and reactor 90 from the circuit and connect the load 75 through connector 74 directly to junction 88. However, the pulses would lack the desirable pulse sharpening which is effected by the charging and discharging of capacitive member 89.

While I have shown the use of my invention in several embodiments, it will be obvious to those skilled in the art that it is not so limited but is susceptible to various changes and modifications without departing from the spirit thereof. For example, in all of the suggested embodiments of my invention, additional pulse sharpening components, including additional capacitors and reactors with cores of a material having a rectangular hysteresis loop, could be added to the circuits of the disclosed embodiments without departing from the scope of my invention. Further, the load may be of any type which appears resistive during the time of output.

I claim as my invention:

1. A magnetic switching circuit for applying recurring pulses to a load, said circuit comprising first means for applying a signal to said circuit, second means for connecting a load to said circuit, an inductor, a capacitor and a saturable reactor, said saturable reactor being serially connected with said second means, said inductor and said capacitor being connected in a series circuit, with said series circuit being connected in parallel arrangement with said first means, said serially connected saturable reactor and second means being shunted by said capacitor in such an arrangement that the voltage across the capacitor saturates the saturable reactor, said saturable reactor after being saturated thereby forming a low impedance path for the discharge of the capacitor into said load.

2. A switching circuit for applying recurring pulses to a load, said circuit comprising first means for applying a signal to said circuit, an inductor and a capacitor serially connected, said serially connected inductor and capacitor being connected in a parallel arrangement with said first means, a saturable reactor provided with a biasing winding, a pulse shaping network, said saturable reactor being serially connected with said pulse shaping network, said serially connected saturable reactor and pulse shaping network being connected in a parallel arrangement with said first capacitor, and second means for connecting a load to said circuit, said second means being inductively coupled to said pulse shaping network.

3. A switching circuit for applying recurring pulses to a load and adapted to be connected between a signal supply and a load, said circuit comprising an inductor and a first capacitor, said inductor being in a series circuit arrangement with said first capacitor, said series circuit arrangement being adapted for connection in parallel with said signal supply, a saturable reactor member provided With a biasing winding, a pulse shaping network including a plurality of branches, with each of said branches including a serially connected saturating reactor and capacitor member, said saturable reactor member being provided in a series circuit arrangement with the capacitor member of one of said branches, said latter series circuit arrangement being shunted by said first capacitor, and an inductive coupling member, said inductive coupling member providing a coupling between the saturating reactor of one of said branches and said load.

4. A magnetic switching circuit for applying recurring pulses to a load at twice the frequency of the alternating input signal to the circuit, said switching circuit Hence pulse tripling is achieved. It

including a serially connected inductor and capacitor, and first means for connecting said input signal to said circuit, with said serially connected inductor and capacitor being connected in parallel with said first means, a first and a second loop conductive path, with each of said paths being shunted by said capacitor, first and second saturable reactors respectively provided with biasing windings, a saturable transformer having a primary winding and a secondary winding, said primary winding having a center tap and a first portion and a second portion, said first loop conductive path including said first saturable reactor serially connected with said first portion of the primary winding of said saturating transformer, said first saturable reactor being biased such that it will become saturated during only one half of each cycle of the alternating input signal, said second loop conductive path including said second saturable reactor serially connected with the second portion of said primary winding, said second saturable reactor being biased such that it will become saturated during the other half of each cycle of the alternating input signal, a second capacitor, and second means for connecting a load to said circuit, said second capacitor being connected in a series circuit arrangement with said secondary winding of said saturating transformer, with said series circuit arrangement being connected in a parallel circuit arrangement with said second means.

5. A magnetic switching circuit for applying recurring pulses of one polarity to a load at a rate which is twice that of the frequency of the alternating input signal to be supplied to the circuit, said switching circuit including a saturating transformer having a center tap, said transformer having a primary winding including first and second portions and a secondary winding, a first conductive loop and a second conductive loop, said loops being connected in a parallel circuit, each of said loops being shunted by first means for supplying an alternating charging voltage to said loops, said first loop consisting of a first saturable reactor and said first portion of the primary winding, said first saturable reactor having second means for biasing said first reactor, said second loop consisting of a second saturable reactor and said second portion of the primary winding, said second saturable reactor having third means for biasing said second reactor with said first and second saturable reactors being so biased that they will alternately become saturated by said alternating charging voltage, said charging voltage thereby effecting the passage of a peaked fluctuating unidirectional flux in the core of said saturating transformer, fourth means for connecting a load to said circuit, a capacitor, said fourth means and said capacitor and said secondary winding being serially connected, with said capacitor being operative to saturate said saturating transformer to thereby sharpen the pulses supplied to said load.

6. A magnetic switching circuit for applying pulses to a load at a rate which is three times that of the frequency of a three phase alternating input signal to be supplied to the circuit, said switching circuit including means for applying a three-phase supply signal to said circuit, first, second, third and fourth charging circuits, first, second, third and fourth saturable reactors, with said first charging circuit being connected in a first series circuit arrangement with said means and said first saturable reactor, said second charging circuit being connected in a second series circuit arrangement with said means and said second saturable reactor, said third charging circuit being connected in a third series circuit arrangement with said means and said third saturable reactor, said first, second and third series circuit arrangements being connected at a common point, said fourth charging circuit being connected to said common point, and said fourth charging circuit being connected in a fourth series circuit arrangement with said fourth saturable reactor and said load.

7. A magnetic switching circuit for applying pulses to a load at a rate which is three times that of the frequency of the alternating input signal to be supplied to the switching circuit, said switching circuit including first, second, and third connectors adaptable for receiving said input signal, first, second and third pulse forming circuits, each of said pulse forming circuits including an inductor member and a saturable reactor connected in series circuit arrangement to provide a point of connection therebetween, a grounded capacitive member connected to said point of connection, said respective first, second and third pulse forming circuits being serially connected with respectively the first, second, and third connectors, a fourth pulse forming circuit comprising a series circuit arrangement of a capacitive member and a saturable reactor member, connector members adapted for connecting said load to the switching circuit, said first, second and third pulse forming circuits being respectively connected to said fourth pulse forming circuit at a common point in such an arrangement that the pulses produced by the first, second, and third pulse forming circuits produce a charging voltage on the capacitive member of said fourth pulse forming circuit, said charging voltage thereby effecting the saturation of the saturable reactor of said fourth pulse forming circuit.

References Cited in the file of this patent UNITED STATES PATENTS