US2092546A - Electric translating circuit - Google Patents

Description

ELECTRIC TRANSLATING CIRCUIT Original Filed Feb. 29, 1936 2 Sheets-Sheet l Pigl.

Inventor: Ernst F. W. Alexanderson,

by W 5.

H is Attorney.

Sept. 7, 1937. E. F. w. ALEXANDERSON 2,092,546

ELECTRIC TRANSLATING CIRCUIT Original Filed Feb. 29, 1936 2 Sheets-Sheet 2 Inventor Ernst F". WAlexanderson Hi Attorney.

Patented Sept. 7, 1937 UNITED STATES ELECTRIC TRANSIATING CIRCUIT Ernst F. W. Alexanderson,

Schenectady, N. Y.,

assignor to General Electric Company, a corporation of New York Original application February 29,

66,433. Divided and 1936, Serial No. this application November 21, 1936, Serial No. 112,042

7 Claim.

My invention relates to electric valve translating circuits and more particularly to electric valve circuits for dynamo-electric machines. I

This application is a division of my copend ing application, Serial No. 66,433, filed February 29, 1936, entitled Electric valve translating circuits, and assigned to the assignee of the present application.

Heretofore there have been devised many ar- 10 rangements for controlling the energization of electric valve apparatus in accordance with a combination of electrical conditions. For example, in electric valve frequency changing systems the auxiliary control apparatus has been combersome and complicated. In many electric valve translating systems employing electric valves to obtain a frequency transformation, the conductivity of the valves hasbeen controlled by mechanical means such as commutators or distributors acting in conjunction with electrical control means. While these systems have proved satisfactory in many applications, there has been evidenced a decided need for control apparatus entirely electrical in nature for controlling the conductivity of electric valve means in accordance with a number or combination oi electrical conditions. a

It is an object of my invention to provide a new and improved electric valve translating circuit.

It is another objector my invention to provide new and improved electric valve control circuits for controlling electric valve translating circuits.

It is a further object of my invention to provide improved circuits for controlling electric valve frequency changing circuits.

In accordance with the illustrated embodi-,

ments of my invention, I provide electric valve converting systems controlled by excitation circuits entirely electrical in nature and in operation for controlling the conductivity of associated electric valve means in accordance with a number of different predetermined electrical conditions. In accordance with one feature 01' my invention, I employ a control electronic discharge device having at least two control members or electrodes for controlling the conductivity of the main power electric valve means in accordance with a combination of electrical conditions. The control'members of the electronic discharge devices are energized in accordance with at least two separate electrical conditions of an associated circuit, or circuits, to control the conductivity of the control discharge device and hence to eifect control of the conductivity of the main electric valve means. .The control electronic discharge device is so constructed and arranged that the control members act conjointly to eilect control of the conductivity of the discharge device. That is, the discharge device remains non-conductive until voltages of predetermined minimum values are impressed upon the respective control members. The control discharge device may be maintained non-conductive by impressing a suitable negative potential upon either of the control members.

In accordance with another embodiment of my invention, I provide an improved excitation circuit entirely electrical in nature and operation for controlling the conductivity of electric valve translating apparatus for transmitting energy between alternating current circuits of the same or different frequencies. The excitation circuit may comprise a plurality of electronic discharge devices, each having a single control member, or it may comprise a single electronic discharge device having a plurality of control members. The conductivity of the control electronic device, and hence the conductivity of the main associated electric valve means, is controlled in accordance with the voltages and hence the frequencies oi the respective alternating current circuits which the electric valve translating circuit interconnects. By means of selective energization of the phase windings oi the interconnecting translating apparatus, I provide an improved system ior establishing electrical rotating fields for either stationary or rotary electrical apparatus.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

Fig. l of the drawings, diagrammatically represents an embodiment of my invention as applied to an electric valve translating circuit employing two main power electric valves. An excitation circuit is provided for each of the main electric valves and comprises an electronic discharge device having at least two control members for controlling the conductivity of the main power electric valve in accordance with two electrical conditions. Fig. 2 diagrammatically shows a modification of the embodiment of my invention illustrated in Fig. 1 as applied to a similar electric valve translating system in which the excitation circuit comprising two serially connected clectronic devices for each of the main power electric valves is energized in response to the voltage appearing across the anode and the cath- 'ionizable medium such as a gas or vapor.

ode of the associated main electric valve, and Fig. 3 shows a further embodiment of my invention as applied to an electric valve translating circuit for transmitting energy between an alterhating current circuit of constant frequency and an alternating current of variable frequency such as a dynamo-electric machine of the synchronous type.

Referring now to Fig. 1 of the accompanying drawings, my invention is diagrammatically illustrated as applied to electric valve converting apparatus for transmitting energy between a three phase alternating current circuit and a single phase alternating current circuit. For the purpose of explaining and illustrating my invention, I have shown electric valves I and 2 of the gaseous type having anodes 3 and d, mercury pool cathodes 5 and I5 and immersionignitor control members I and 8 for intercom necting a polyphase alternating current supply circuit 9 and a single phase alternating current load circuit I through a transformer II having a primary winding I2 and a secondary winding I3. The main power electric valves I and 2 are oppositely disposed or connected. That is, the cathode of electric valve I is connected to the anode l of electric valve 3 through a conductor I4, and the anode 3 of electric valve I and the cathode of electric valve 2 are connected to the same conductor of the polyphase supply circuit 9 through conductors I5 and IE, respectively. The cathode 5 of electric valve I and the anode 4 of electric valve 2 are connected to one side of the secondary winding I3 of transformer II through a conductor I'l, while the other terminal of the secondary winding I3 is connected to the supply circuit 9 through a conductor l8.

To provide means for controlling the conductivity of electric valves I and 2 in accordance with electrical conditions of the supply circuit 9 and the load circuit I0, I employ excitation circuits I9 and 29, respectively. The excitation circuits I9 and are energized from the supply circuit 9 by a transformer 2i having primary windings 22 and secondary windings 23 and 24 through any conventional phase shifting device, such as the rotary phase shifting arrangement 25. is energized from a suitable secondary winding of the transformer 2L For example, the excitation circuit I9 for electric valve I comprises the secondary winding 23 of transformer 2| for controlling the conductivity of the main electric valve l in response to an electrical condition of the supply circuit 9. A transformer 26, which may be of the type to supply a voltage of peaked wave form, having a primary winding 21 and a secondary winding 28, is employed to control the conductivity of electric valve I through an electronic discharge device 29, preferably of the gaseous type, in response to an electrical condition of the load circuit II). By the term electronic discharge device of the gaseous type I intend to include electric valves employing any The electronic discharge device 29 is provided with an anode 30, a cathode 3| and control members 32 and 33 and is employed to correlate the predetermined electrical conditions of the supply circuit 9 and the load circuit II] to effect the desired periodic energization of electric valve I through the control member I. The control members 32 and 33 of electronic discharge device 29 cooperate to control the conductivity of Each of the excitation circuits I9 and 20 the device 29 and when suitable voltages above predetermined minimum voltages are impressed upon the respective control members, the device 29 is rendered conductive. However, either or both of the control members 32 and 33 may maintain the electronic discharge device 29 nonconductive if a voltage below a predetermined minimum value is impressed upon either of the control members.

To obtain a voltage of suitable magnitude-and wave form for controlling the conductivity of the main electric valves I and 2, I employ circuits 33 in the excitation circuits l9 and 28, respectively, for impressing upon the immersionignitor control members 7 and 8 voltages in accordance with the desired sequence of operation. The circuits 33 each comprise a capacitance 35 which is periodically charged from the secondary winding 23 through a resistance 36 and a conductor 31 connected to an electrical neutral 38 of secondary winding 23. To impress upon the control member 32 of electronic discharge device 29 a potential of suitable magnitude and phase relation relative to the voltage of the supply circuit 9, I use a phase shifting circuit connected between the lower terminal of the secondary winding 23 and the neutral connection 38 comprising a capacitance 39 and resistance 49. A resistance M is connected in series with this phase shifting circuit and the control member 32 of electronic discharge device 23. The common connection between capacitance 35 and resistance '30 is connected to the cathode 3I of electronic discharge device 29 by a conductor 32. One terminal of the excitation circuit I9 for the electric valve I is connected to the immersion-ignitor control member I of electric valve I through a conductor 33, and the other terminal of the excitation circuit I9 is connected to the cathode 5 of electric valve I through a conductor ML'anode 39 and cathode 3| of electronic discharge device 29 and conductor 32. The right-hand terminal of the secondary winding 28 of transformer 26 is connected to the cathode 3| of electronic discharge device 29 and the left-hand terminal of secondary winding 28 is connected to the control member 33 through a current limiting resistor 35.

In explaining the operation of the embodiment of my invention diagrammatically shown in Fig. 1,

let it be assumed that the alternating current supply circuit 9 is of a higher frequency than the alternating current load circuit Ill and that current is being transferred between these two circuits by the interconnected electric valve means I and 2. Under the assumed conditions, the electric valve I should be rendered conductive, for example, during positive half cycles of the .alternating potential of the supply circuit 9 and concurrently during an interval corresponding to a positive half cycle of the potential of the load circuit I0. In other words, the electric valves I and 2 will be conductive alternately during alternate half cycles of a relatively higher frequency of the supply circuit 9. During a half cycle of predetermined sign of the potential of the lower frequency circuit I0, electric valves I and 2 will alternately conduct current in response to the higher frequency potential of the supply circuit 9 to supply current to the secondary winding I3 of transformer II.

Each of the electric valves l and 2 will be rendered conductive intermittently to effect transfer of current from the supply circuit 9 to the load circuit In during the half cycles of predetermined sign of the lower frequency potential of alternating current circuit III. For example, the excitation circuit l9 will operate to impress voltage of suitable wave form upon the control member 1 of electric valve I in predetermined phase relation with the voltage of the alternating current circuit 9. The capacitance 35 of the circuit34 will be charged during positive half cycles of alternating potential of circuit 9 by means of the secondary winding 23 of transformer 2|. When the electronic discharge device 29 is rendered conductive in response to suitable potentials being impressed upon the control members 32 and 33, the capacitance 35 will discharge through the circuit comprising conductor 43, control member I of electric valve l, conductor 44, electronic device 29, conductor 42, and the capacitance 35. The electronic discharge device 29 will be rendered conductive only during those intervals in which predetermined electrical conditions of the alternating current circuit 9 and the alternating current circuit l0 are satisfied. In this manner, the capacitance 35 will be charged during positive half cycles of the relatively higher frequency of the alternating current circuit 9 and will be discharged during the following half cycles of potential. The polarities of the potentials impressed on the control members 32 and 33 of electronic discharge device 29 by the phase shifting circuit comprising capacitance 39 and resistance 49 and'the secondary winding 28 of transformer 26, respectively, de-

termines the instant at which the device 29 isv rendered conductive. Since the control members 32 and 33 of device 29 must act conjointly to render the device 29 conductive, the electric valve I will be rendered conductive at only those intervals during which it is desired to transmit current from the alternating current circuit 9 to the alternating current circuit Hi.

It should be understood that the rotary phase shifting arrangement 25 may be employed to retard the phase of the control potential impressed upon control member 1 by excitation circuit I9 relative to the potential impressed on the anode 3 of electric valve I. While for the purpose of explaining my invention I have shown two electric valves interconnecting alternating current circuits, it should be understood that my invention in its broader aspects may be applied to electric valve translating circuits generally employing either a single electric valve or a plurality of electric valve means for interconnecting alternating current circuits and direct current circuits, or interconnecting alternating current circuits of the same or different frequencies.

Referring now to Fig. 2 of the drawings, my invention is dagrammatically respresented as applied to an electric valve translating circuit similar to the embodiment of my invention shown in Fig. 1 and corresponding elements have been assigned like reference numerals. Any suitable electric valve aggregate, such as electric valves l and 2 of the gaseous type employing an immersion-ignitor control member, is employed for transmitting energy between alternating current supply circuit 9 and alternating current load circuit H]. To control the conductivity of the electric valves l and 2 during predetermined intervals, I employ excitation circuits 46 and 41, respectively. Each of the excitation circuits 46 and 41 is energized in accordance with the voltage apearing across the anode and cathode of the respective main power electric valves l and 2 and in accordance with predetermined electrical conditions of the supply circuit 9 and the load circuit l0 and each comprises two serially-connected electronic devices, 48 and 49, preferably of the gaseous or vapor type, having anodes 50 and 5|, cathodes 52 and 53 and control members 54 and 55, respectively.

The conductivity of the electronic device 48 is controlled in accordance with an electrical condition, such as the voltage, of the load circuit l0 through a transformer 56 having a primary winding 5'! and a secondary winding 58, and the co'nductivity of the electronic device 49 is controlled in accordance with an electrical condition, such as the voltage, of supply circuit 9 through a transformer 59 having a primary winding 60 and a secondary winding 6|. The transformer 59 is energized from the supply circuit 9 through the rotary phase shifter 25, secondary winding 23 of transformer 2|, conductors 62 and 63 and unidirectional conducting device 64. A transformer 55 having secondary windings 66 and 61 is energized from any suitable auxiliary source of alternating potential to energize the cathodes 52 and 53 of electronic devices 48 and 49, through conductors 68 and 69, respectively. A potential which varies in accordance with an electrical condition of the load circuit l 9 is impressed across the control member 54 and cathode 52 of electronic device 48 by secondary winding 58 of transformer 55, through a conductor 19, a suitable negative voltage biasing means such as a battery H, and a current limiting resistance 72, conductors 58 and a conductor 13. A potential, which varies in accordance with an electrical condition of the supply circuit 9, is impressed across the control member 55 and cathode 53 of electronic device 49 by the secondary winding 6| of transformer 59, through a conductor 74 which is connected to the right-hand terminal of winding 6|, a current limiting resistance 15, and a conductor 15 which connects the cathode 53 to the left-hand terminal of the secondary winding SI of transformer 59. The left-hand terminal of the secondary winding 8| of transformer 59 is also connected to the control member I of electric valve l by a conductor 11. The anode 50 of electronic device 48 is connected to the anode 3 of electric valve I through a resistance 18 and any conventional current limiting device, such as a fuse l9.

As explained in connection with the operation of the embodiment of my invention diagrammatically shown in Fig. 1, the embodiment of my invention represented in Fig. 2 may be best explained by considering the operation of the system when thefrequency of the supply circuit 9 is greater than the frequency of the load circuit l0. To obtain the desired periodic energization of the electric valves I and 2, and hence to control the conductivity of the valves l and 2 at predetermined times relative to the polarities of the potentials of circuits 9 and ID, the electronic discharge devices 48 and 49 in each of the excitation circuits 48 and 41 act conjointly to effect energization at these predetermined intervals. Since the conductivity of the electronic device 49 is controlled in accordance with an electrical condition of the supply circuit 9 and since the conductlvity of the electronic device 48 is controlled in accordance with an electrical condition of the load circuit I 0, to obtain energization of the electric valve l and hence to render the associated valve conductive, the electronic devices 48 and 49 must both be conductive during predetermined intervals, or, in other words, these devices must be conductive concurrently to effect energization of the immersion-ignitor l by utilizing the potential appearing between anode 3 and cathode 5 of valve I. During those intervals in 48, electronic device 49, conductor I and conductor TI.

It should be understood that while I have described in detail the operation of the excitation circuit 46, the excitation circuit 91' operates in a similar manner to control the conductivity of electric valve 2 during alternate half cycles of the high frequency potential of the alternating current supply circuit 9. Furthermore, it should be understood that I may employ a group of valves similarly disposed in regard to the other phases of the alternating current supply circuit 9 to effect energy transfer between polyphase alternating current circuits.

Referring now to Fig. 3 of the accompanying drawings, a further embodiment of my invention is diagrammatically illustrated as applied to an electric valve translating system for transmitting energy between an alternating current circuit 80 and a dynamo-electric machine M of the synchronous type by means of any suitable electric valve aggregate such as the electric valves 02 to 87, inclusive, of the gaseous type having immersion-ignitor control members 88. The dynamoelectric machine BI is provided with a plurality of inductive phase windings 99, 90, and 9i, an

electrical neutral 92, a rotating member 93 and an inductive field winding 94. The electric valves 82-81, inclusive, are energized from the alternating current supply circuit 90 through a transformer 95 having a secondary winding 96 and an electrical neutral 9?. Electric valves 82 and 85, 83 and 86, and 84 and 81 serve to energize phase windings 89, 90 and 9i, respectively, of machine ill in a predetermined sequence to establish a-rotary field in the machine and to effect thereby rotation of the member 99. The unidirectional current which these groups of valves supply to the respective phase windings is returned from the electrical neutral 92 through the field winding 94 to the electrical neutral 97 of transformer 95 through a conductor 98. To control the conductivity of each of the electric valves 82-81 in accordance with an electrical condition of the supply circuit 80 and the machine 8|, such as the voltage of the supply circuit 80 and the voltage of the phase windings 89-9I, I employ a plurality of excitation circuits 99-I04 inclusive, each of which is associated with a predetermined different one of the electric valves 82-81. For example, the excitation circuit I04 is associated with the electric valve 8'1. The excitation circuits 99-l04, inclusive, are provided with electronic discharge devices I 05-IIO, respectively, preferably of the gaseous type, each having an anode III, a cathode H2 and control members I I3 and H4. Each of these excitation circuits is also arranged similar to the excitation circuits -I9 and 20 described in connection with the embodiment .of my invention diagrammatically shown in Fig. 1. Theexcitation circuits 99-I04 may be energized from the supply circuit 80 through any suitable phase shifting arrangement such as the rotary phase shifter H5.

To providemeans for controlling the conductivity of the electric valves 82 to 81 in accordance with an operating condition, such as the speed aooasae of the dynamo-electric machine 8I, a distributor mechanism II 6 is employed. This distributor may be of the electrical or mechanical type and as shown is of the mechanical type comprising a rotary conducting segment III which establishes contact successively with brushes H8, H9, and I20 to effect energization of the proper excitation circuit at a predetermined time relative to the speed and position of the rotating member 99. For example, the brush II 8 connects excitation circuits IN and I09 to the output of the phase shifter H5 through conductors I2I and I22 and unidirectional conducting devices I23 and I24. Since the potentials impressed between the anodes of electric valves 84 and 81 are opposite in phase, that is 180 electrical degrees out of phase, it is desirable toeifect energization of the associated excitation circuits IBI and I04 only during half cycles of predetermined sign. Since the unidirectional conducting devices I23 and I24 are oppositely disposed, the excitation circuits IUI and I04 are energized during half cycles of opposite polarity of the alternating potential supplied by the phase shifter H5. Similarly, brush H9 is connected toexcitation circuits 99 and I02 through a conductor I25 and conductor I'2I, and brush I20 connects excitation circuits I00 and I03 to the output of phase shifter II5 through a conductor I26 and conductor I2I.

In addition to the above mentioned means for controlling the conductivity of the electric valves 92-81 in accordance with an operating condition of the dynamo-electric machine 8I, I employ a transformer I27 having primary windings E28 energized in accordance with the voltage of phase windings 899I, and secondary windings I29-I34, inclusive. Secondary windings I29 and I30 of transformer I 21 are connected to control members N3 of the electronic devices I01 and II 0, respectively, through conductors I35 and I36 to control the energization of control members H3 and hence to control the conductivity of these valves in accordance with an electrical condition of the associated phase winding 9| of machine SI. Similarly, secondary windings I 3|, I 32 and I 33, I34 are associated with electronic devices I06, I09 and I 05, I00, respectively, through conductors I3'I-I40, respectively.

A switch I4! having stationary contacts I42 and I43 and a movable contact I44 may be ployed to render the distributor H6 inefiective by short circuiting the brushes II8-I20.

My copending patent application Serial No. 66,432, filed February 29, 1936, describes an electric valve translating system employing an electric valve means of the gaseous type having two control members for conjointly controlling th conductivity of the electric valve means in accordance with two independent electrical conditions; this application is assigned to the assignee of the present application. The electric valve circuits shown in Figs. 1, 2, and 3 are disclosed and broadly claimed in my copending application, Serial No. 66,433, filed February 29,1936, and the frequency changing systems are disclosed and claimed in my copending application, Serial No. 112,041, filed November 21, 1936, both applications being assigned to the assignee of the present application. The latter application is a division of the former. The present application is made to protect the further invention which the applicant believes to be present in the apparatus set forth in the claims hereof over and bevalves being supplied Yond the claims set forth applications.

The operation of the embodiment of my invention diagrammatically shown in Fig. 3 may be best explained by considering the operation of the electric translating apparatus when the supply circuit is energized from a source of suitable frequency, such as an ordinary commercial frequency, and the dynamo-electric machine I is not rotating. Let it be further assumed that contact I44 of switch I engages contact I43 and that the phase of the alternating voltages impressed upon the immersion-ignitor control member 88 of electric valves 82-81 is sufficiently retarded in phase relative to the voltage impressed upon the associated anodes so that the average voltage, and hence the average current, which these valves supply is relatively small and insufficient to cause rotation of the member 93. Under the assumed conditions, the distributor H6 is in a position so that the conducting segment II! is in contact with brush II8 to effect energization of excitation circuits IN and I04. Unidirectional current will, therefore, be supplied to phase winding 9| through electric valves 84 and 81, suitable excitation currents for these by excitation circuits IOI and I04 through electronic discharge devices I01 and II 0. If the phase of the excitation current supplied by the excitation circuits MI and I04 be advanced by means of phase shifter H5, the average voltage, and hence the average current, furnished by electric valves 84 and 81 will be increased and since the rotating member 93 of machine BI is in a torque producing position relative to the phase winding 9|, the member 93 will be caused to accelerate ata. rate dependent upon the connected load. Assuming that the interactions of the magnetomotive forces of the in the above mentioned phase winding'9l and field winding 94 of machine 8| are in the proper directions so that the member 83 rotates in a clockwise direction, the conducting segment II1 of distributor H6 will establish contact with brush II9 to effect energization of excitation circuits 99 and I02, which in turn will render electric valves 82 and 85 conductive to supply unidirectional current to the phase winding 89. In this manner, it will be understood that the distributor II6 effects energization of the proper excitation circuits to render electric valves 82-81 conductive in predetermined sequence to establish the desired periodic energization of the phase windings ,89-9I when the rotating member 93 is in a torque producing position relative to the respective pha se windings. It should also be noted that the distributor IIG effects transfer or commutation of unidirectional current between the phase windings 89-9 I, thereby producing the necessary rotating field.

The excitation circuits 99-I04 operate to furnish a voltage of suitable magnitude and wave form to the control members 88 of electric valves 82-81 in the proper sequence to render these valves conductive in accordance with the voltage of the supply circuit 80 and in accordance with an operating condition of the dynamo-electric machine 8|.

If it is desired to control the conductivity of the electric valves 82-81 by means entirely electrical in nature and operation, the movable member I44 of switch I may be placed in contact with stationary members I42 to render the distributor II6 ineifective. Since the transformer I21 is energized in accordance with the voltage of the phase windings 89-8I, the conductivity of 5 the electronic devices I05 to H0 will be controlled in accordance with an operating condition of the machine 8I and will also be controlled in accordance with the voltage of the supply circuit 80. The electronic devices I05-I I0, through the control members I I3 and H4, supply current to the immersion-ignitor control members those intervals in which these two satisfied.

Although in Fig. 3 of the accompanying drawings I have shown my invention as applied to an electric valve translating circuit for transmitting energy between a single phase alternating current circuit and a variable frequency load circuit, it should be understood that my invention in its broader aspects may be applied to electric valve translating circuits generally for transmitting energy between alternating and direct ourconditions are rent circuits or between alternating current circuits of variable frequency.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an alternating current supply gircuit, a dynamo-electric machine having a plurality of phase windings and a field winding 5 connected to be energized in series relation with said phase windings, a group of electric valves connected to transmit current to said phase windings, and electronic discharge means associated with each of said electric valve means for controlling the conductivity of said electric valve means conjointly in accordance with predetermined electrical conditions of said supply circuit and said phase windings.

2. An electric valve converting system comprising a source of alternating current, a dynamo-electric machine of the synchronous type including a plurality of phase windings, a group of electric valves connected to transmit current from said source to said windings in a predetermined sequence, an interconnection between said phase windings, and electronic discharge means for controlling the conductivity of said valves to effect sequential energization of said phase windings in accordance with a predetermined elec- I trical condition of said source and in accordance with a predetermined operating condition; of said machine.

3. In combination, an alternating current supply circuit, a dynamo-electric machine of the synchronous type having a plurality of armature phase windings and a field winding connected to be'energized in series relation with said phase windings, a plurality of electric valve means associated with each of said phase windings to transmit unidirectional current to said windings, and electronic discharge means associated with each of said valves for controlling the conductivity of said valves to effect selective energization of said phase windings in accordance with the position of said field winding relative to the respective phase windings.

4. In combination, an alternating current supply circuit, a dynamo-electric machine having a plurality of phase windings, a group of electric 84 of electric valves 828'Iv only during I valves connected to transmit current from said alternating current circuit to said phase windings, a plurality of electronic discharge means each associated with a difierent one of electric valve means for controlling the conductivity of said electric valve means conjointly in accordance with predetermined electrical conditions of said supply circuit and said phase windings, a plurality of excitation circuits each associated with a difierent one of said electronic discharge means, and a distributor for controlling said excitation circuits in accordance with an operating condition of said machine.

5. In combination, an alternating current supply circuit, a dynamo-electric machine having a plurality of phase windings, a plurality of electric valve means connected to transmit current to said phase windings, a plurality of electronic discharge means each having two control members for conjointly controlling the conductivity thereof and each being associated with a different one of said valve means, and a plurality of excitation circuits for impressing on said control members of each of said electronic discharge means voltages to render said electronic discharge means conductive to eflect energization of said phase windings in a predetermined sequence and in accordance with predetermined electrical conditions of said supply circuit and said phase windings.

6.'In combination an alternating current supply circuit, a dynamo-electric machine having a plurality of phase windings and a field winding connected to be energized in series relation with said phase windings, a plurality of electric valve means each associated with a difierent one of said phase windings to transmit current thereto, a plurality of electronic discharge means, each having two control members for conjointly controlling the conductivity thereof and each being associated with a difierent one of said electric valve means to efiect energization of said phase windings in a predetermined sequence, and a plurality of excitation circuits each associated with a different one of said electronic discharge means and each including means for impressing on one of said control members of the associated electronic discharge means a voltage which varies in accordance with an electrical condition of said supply circuit and means for impressing upon the other control member a voltage which varies in accordance with an electrical condition of the associated phase winding.

7. In combination an alternating current supply circuit, a dynamo-electric machine of the synchronous type having a plurality of phase windings and a field winding connected to be energized in series relation with said phase windings, a plurality of electric valve means connected to transmit current to said phase windings, a plurality of electronic discharge means each having two control members and each associated with a difierent one of said electric valve means for controlling the conductivity thereof, a plurality of excitation circuits each associated with a diiierent one of said electronic discharge means each including means for impressing on one of said control members a voltage which varies in accordance with an electrical condition of said supply circuit and for impressing on the other of said control members a voltage which varies in accordance with an operating condition of said machine for controlling the conductivity of the associated electric valve means conjointly in accordance with said electrical condition and said operating condition, and means comprising a distributor controlled in accordance with an operating condition of said machine to control said excitation circuits.

ERNST F. W. ALEXANDERSON.

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