US1963021A - Rectifier control system - Google Patents

Description

June 12, 1934. E. KERN RECTIFIER CONTROL SYSTEM Filed Oct. 15, 1932 QAMWWCM 2 W Patented June 12, 1934 UNITED STATES PATENT OFFICE RECTIFIER CONTROL SYSTEM Switzerland Application October 15, 1932, Serial No. 637,881 In Germany October 21, 1931 3 Claims.

This invention relates to improvements in electric rectifying systems and more particularly to means for controlling the flow of current within electron discharge devices utilized in such sys- 5 tems.

It is well known in a rectifying system to utilize an electron discharge device in which the flow of current is controlled by successive energization of control electrodes at different potentials from sources of alternating current or from a direct current source through the segments of a distributor. Each such control electrode associated with an anode of the device is repeatedly energized at intervals equal to one cycle of the supply line alternating current voltage and, after each period of energization, the current drawn by the control electrode must be interrupted by the distributor. The brushes and the segments of the distributor are thereby subject to continuously repeated sparking which causes a rapid deterioration thereof and may result in faulty operation of the system.

By using a source of alternating current of a frequency considerably higher than the frequency of the supply line voltage as one of the sources of current supply to the control electrodes, the distributor will frequently open the circuits of the control electrodes, while not carrying current and any arcing present will not extend over more than one cycle of the high frequency voltage so that the duty of the distributor will be very much reduced.

It is accordingly one of the objects of the present invention to provide a rectifying system ineluding an electron discharge device having control electrodes sequentially energized through a distributor.

Another object of the present invention is to provide a rectifying system including an electron discharge device having control electrodes energized at potentials obtained from different sources of which at least one source is a source of high frequency alternating current.

Another object of the present invention is to provide a rectifying system including an electron discharge device having control electrodes and providing means for reducing sparking at the distributor associated therewith for controlling the connection of sources of potential with the control electrodes.

Objects and advantages, other than those above set forth, will be apparent from the following description when read in connection with the accompanying drawing forming a part of the present disclosure which diagrammatically illustrates one embodiment of the present invention in which the source of high frequency potential supplied to the control electrodes of an electron discharge device is an electric generator driven by a motor energized from the alternating current supply line of the system.

Referring more particularly to the drawing by characters of reference, reference numeral 6 designates a polyphase alternating current supply line herein shown as a three-phase line as '65 such type of line is the type most frequently utilized in practice. The direct current output circuit of the system includes a positive conductor '7 and a negative conductor 8. The system includes a transformer having a primary winding 9 energized from line 6 and a secondary winding 11 having the several portions thereof severally connected with anodes as at 12 of an electron discharge device 13 herein shown as being of the metallic vapor arcing type and having a cathode 15. Rectifier 13 is also provided with control electrodes as at 14 severally associated with each of the anodes and arranged to be energized at a negative potential with respect to cathode 15 from a battery 16 through banks of resistances so 17 and 18. The control electrodes may also be energized, through a distributor 19 driven by a synchronous motor 21 energized from line 6, from a source of high frequency current herein shown as consisting of a synchronous generator 22 driven 5 by a motor 23 energized from line 6. It will be understood that generator 22 may be replaced by any other means for producing currents of a frequency considerably higher than the frequency of the voltages in line 6. It will also be understood that other energizing means may be utilized in series with generator 22 and in particular that such generator may be connected in series with the secondary winding of a transformer energized from line 6 if so desired.

In operation, assuming that line 6 is energized, transformer primary winding 9 will receive alternating current voltages therefrom and will induce voltages in the several portions of transformer secondary winding 11. The anodes of rectifier 13 energized from the transformer 9, 11 will then sequentially carry current as is well known in the art of electric current rectification. During such operation the control electrodes of rectifier 13 are generally maintained at a negative potential with respect to cathode 15 from battery 16 through resistances 17 and 18. During the time of the supply line voltage cycle when an anode 12 of rectifier 13 receives a positive potential with respect to cathode 15 from the associated portion of winding 11, the associated control electrode 14 receives a high frequency alternating current potential from generator 22 through distributor 19 and resistance 18. Due to the rectifying action of control electrode 14, such current is reduced to its positive half wave portions and is accordingly of a pulsating nature. When the brush of distributor 19 leaves the segment with which it was in contact, such brush opens the circuit of control electrode 14 and it will frequently occur that such opening of the con trol electrode circuit takes place during the negative half wave of the voltage of g nerator 22, at which time control electrode 14 does not draw current therefrom. If such opening occurs during the positive half wave of the voltage of generator 22 the interruption of the current drawn by control electrode 14 from he generator will not continue beyond one-half cycle of the voltage of the generator 22, such period being reduced in duration in proportion to the frequency of the voltage of generator Distributor 19 also carries current flowin from generator through distributor l9, resistance 17 and battery 16. If the peak value of the voltage of generator 22 is less than the voltage or" battery 15, such current will be undulating, but when the voltage peak value of generator 22 is higher than he voltage of battery 16 such current becomes alternating with unsymmetrical half waves and will ire uently be interrupted without any arcing. Under the most unfavorable conditions, such control current will be interrupted with the production of an arc extending over a period not longer than one cycle of the alternating current voltage of generator 22. The process of energization above described, is repeated sequentially for all anodes and control electrodes of rectifier 13 during each cycle of the alternating current voltage of line 6 as is well known in the of electric current rectifica ion. In particul the conditions of current interruption described above for one segment of dis-- tributor l9 sequentially obtains for every segment thereof during each cycle of the voltage or" line 6. Although but one embodiment of the present invention has been illustrated and descr1 it will be apparent to hose skilled in the art that es and 1, ions may be made therein without depar the spirit of the invention or from the i tne appended claims.

It is claimed and desired to secure by Letters Patent:

1. In an electric current rectifying system, an alternating current supply line, an el-ctron discharge device having anodes with associated. control electror es t id a cathode, a transformer hav ing a winding d1 ded into a plurality of sections severally connecting the anodes with said line,

a source of direct current at a potential negative relative to the potential of the cathode and connected with the control electrodes, a source of a1- ternating current at a frequency higher than the frequency of said line and of an amplitude greater than that of the potential of the said direct current source, and means operating in synchronism with the potential of said line to sequentially connect said source of alternating current with the control electrodes 2. In an electric current rectifying system, an alternating current supply line, an electron dis charge device having a cathode, a plurality of anodes and a plurality of control electrodes severally associated with said anodes, a transformer having a winding divided into a plurality of phase displaced sections severally connecting the said anodes with said line, a source of electrornotive force connected with said control electrodes operable to impress potential thereon more negative than the potential of said cathode, a source of alternating current electromotive force having a frequency greater than the voltage currency of said supply line and of voltage amplitude greater than the amplitude of the first said electromotive force, and distributor switch means having connections and operable in such manner as to impress potential of the second said source of electromotive force on said control electrodes during such recurring periods relative to the voltage frequency of said line as to permit "flow of current sequentially through the respective said winding sections by way of said anodes and cathode.

3. In an electric current rectifying system, an

alternating current supply line, an electron discharge device having a cathode, plurality of anodes and a plurality of control electrodes severally associated with said anodes, a transformer having a winding divided into a plurality of phase displaced sections severally connecting said anodes with said line, a source of electroniotive force connected with said control electrodes and continuously impressing potential thereon of such sign and magnitude as to prevent new of current through said device by way of said anodes, a source of alternating current electromotive force having a frequency greater than the voltage frequency of said line and of magnitude greater ban the magnitude of the first said electromotivc force, and means having connections with the second said electromotive force and with said control electrodes operable to impress potential on the latter of such sign and magnitude and at such recurring periods as to permit flow of current from said line sequentially through the respective sections of said winding by way of said anodes and cathode.

ERWIN KERN.

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