Патент USA US2413033код для вставки
Dec. 24, 1946. J. A. POTTER 2,413,033 VOLTAGE REGULA'I‘ED RECTIFYING SYSTEM _ Filed July 29, 1942 THERMIJ m 9 /o 2 Sheets-Sheet 1 FIG. / -___ ‘13:11? I ,6 7 / I /5 - l 2 12¢] . ' - . L040 T. + \Jmmmur llvsuun'o con/74mm ” Mm [-76.2 /6‘ mam/s10» 7 2 _ _ QTHERMALLY INSULATED I ' LOAD , T + ' LOAD LOAD + INVENTOP J A. P0 TTEP ‘Walk-n“ ATTORNEY 1m.v 24, 1946. 2,413,033 J. A. POTTER . VOLTAGE REGULATED RECTIFYING’ SYSTEM Filed July 29, 1942 2 Sheets-Sheet 2 FIG. 5 LOAD 4T ' E27 [20 % ERMISTOR L042: \47 OPERATING RAN“ 4 mu: ; l g 1 I '1 1 i I I I i 1 FIG. 6 NVENTOR J A. POTTER 8Y6. Mum, ATTORNEV Patented Dec. 24, 1946 2,413,033 UNITED STATES PATENT OFFICE 2,413,033 YOLTAGE REGULATED RECTIFYING * SYSTEM James A. Potter, Rutherford, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 29, 1942, Serial No. 452,728 10 Claims. (Cl. 175-363) 1 This invention relates to voltage regulators for ' alternating current rectifying systems. An object of the invention is to provide an in expensive device for regulating the voltage of rec ti?ed current. An additional object of the invention is to cause the voltage supplied by a rectifying system to a load to be held substantially constant irrespec 2 current input lead to the main recti?er or in a di rect current output lead of that recti?er. The heat supplied to the thermistor by the auxiliary heating circuit may be controlled by a relay re sponsive to the recti?ed voltage impressed upon the unidirectional current load circuit in such a manner as to close the auxiliary circuit when that voltage is low and to open it when it is high. 4 The relay may thus supply intermittent heating Another object of the invention is to enable 10 effects to the thermistor which are smoothed out a thermistor employed in a voltage regulating by the thermal inertia of the thermistor. systems to be placed at a sensitive point in its \ Other features and aspects of the invention tive of variations in the load current. resistance thermal characteristic under the con dition of no load. will be apparent from a consideration of the fol which the rectifying system supplies unidirec regulating the voltage supplied to the load in ac lowing detailed speci?cation taken in connection In accordance with the invention there is in 15 with the accompanying drawings in which: terposed between an alternating current source Fig. 1 is a circuit diagram of an alternating of a rectifying system and the load circuit to current rectifying system with provisions for tional current a series impedance element the cordance with certain principles of this inven resistance of which is a function of the tempera 20 tion; ‘ . ture of the element. When the element is cold Fig. 2 is a circuit diagram of a modi?cation of its resistance is very high. When its temperature rises the resistance decreases and at a certain point in its characteristic the rate of fall of the resistance is extremely high.‘ Such elements, 25 known as thermistors, are described by Pearson the system of Fig. 1 in which the series thermistor element is connected in the alternating current input circuit of the recti?er; Fig. 3 is another modi?cation in which the aux iliary heating circuit of the thermistor ‘is provided with an auxiliary recti?er; Fig. 4 illustrates a modi?cation of the circuit of Fig. 3 in which the thermistor is connected tures associated with low load current is relative 30 between the current supply ?lter and the load; ly high.‘ As the load current rises the heating Fig. 5 is a circuit diagram of a voltage regu ' lated rectifying current supply system in which effect of the current upon the thermistor also rises reducing the thermistor resistance to com the series thermistor is provided with an addi pensate for the increased resistance of the rec tional indirect heating circuit; , Fig. 6 is a graph employed to explain the op ti?er and current supply circuit. Additional eration of the circuit of Fig. 5; and heating of the thermistor to accentuate the change in its resistance may be obtained by asso Fig. 7 is a circuit diagram of a system for ciating it inphysically close relation to the rec regulating the voltage of recti?ed current in ti?er or the current supply transformer to facili which the indirect heating circuit of the regulat tate heat transfer to the thermistor. The ther 40 ing thermistor is intermittently energized in re mistor may be initially brought to the proper sponse to the operation of a Wheatstone bridge point on its resistance temperature characteristic connected directly across the load circuit. at no load by a separate heating circuit connected Referring to Fig. 1 a source i of alternating to an auxiliary winding of the current supply current to be recti?ed is shown connected by a transformer. In order to prevent the introduc 45 current supply transformer 2 to a full wave rec tion of ripples by the auxiliary heating circuit in tifier 3 of well-known type the output leads 4 and the load current the heating circuit may include 5 of which conduct recti?ed current to the uni an auxiliary recti?er and ?lter or the thermistor directional current load 6 through a smoothing may be connected between the load current rec ?lter ‘I. The transformer 2 is provided with an ti?er and the load current ?lter. 50 auxiliary secondary winding 9 having a variable Since the function of the thermistor is to re tap l0 and variable resistor I l in series therewith duce the voltage derived from the alternating for supplying an alternating heating current di current source by an amount which varies in in rectly to thermistor 8. At the no load condition verse manner with the load current, the ther the only current in the thermistor 8 is alternat in the Bell Laboratories Record for December 1940. In the operation of the recti?er system the resistance of the thermistor at the low tempera mistorimay be placed either in an'alternating ing Current derived from the secondary winding 2,413,033 4 9 and the magnitude of which is determined by the position of variable tap l0 and the setting of IT through the shunt path two additional regu lating effects are brought about. The ?rst is variable resistor I l in order to ?x the temperature of thermistor 8 at a point for which the resistance of the thermistor lies within the required operat occasioned by the fact that the shunt current IT traverses the series thermistor 22 and therefore ing range. This is highly desirable for the reason changes the resistance of thermistor 22 and the consequent potential drop vacross the thermistor as does a change in the load current itself. In that the resistance temperature characteristic of the thermistor begins with a rapidly rising por the second place the current T1‘ of the shunt path tion reaching a point beyond which the resistance is caused to traverse an indirect heater 2i of the rapidly falls and it is desired to operate on the 10 thermistor 22 to produce an additional effect falling portion of the characteristic. At higher upon the resistance of that thermistor. It will therefore be apparent that very slight changes loads there is a potential drop in the current sup in the voltage applied by the system across l9 ply transformer, the recti?er and the circuit con ductors which tends to reduce the recti?ed volt and 20 to the load will set into action correcting age available at the load input terminals. Since, 15 factors which will tend to hold that potential very closely constant irrespective of changes in however, the temperature of the thermistor 8 rises rapidly with increased load current, the re the magnitude of the load current. It remains to consider the action of the shunt sistance of the thermistor consequently under path in drawing the shunt current IT which goes a large decrease, thus reducing the potential drop across the thermistor so that the unidirec 20 changes greatly for small changes in the voltage tional voltage applied to the load remains sub applied to the load terminals. Assume that the system is in operation with the relay 24 energized stantially constant. The initial setting of the as shown in Fig. 5 so that its armature 3| is with transformer tap and of the variable resistance may be changed from time to time to take care of drawn from the ?xed contact 30. The shunt path aging in the recti?er and to allow for operation 25 connecting points l9 and 20 comprises a ther in several ambient temperature ranges. mistor 27, a special resistor 26, winding of relay The ?lter ‘i not only smooths out the recti?ed 2d, variable resistor 23 and the heater 2! of ther ‘mistor 22. The characteristics of the elements current but also keeps the alternating current impressed directly upon the thermistor from of this shunt path are illustrated in Fig. 6, it being understood that the apparatus is designed reaching the load. The elements of the full wave for operation for shunt currents IT extending recti?er may be of the well-known copper oxide type. 'over a range of In to Im. The voltage current characteristic Er of thermistor 21 is such that In order to still further accentuate the resist the potential difference across the thermistor ance change of thermistor 8 with varying load the thermistor maybe mounted in close prox 35 falls rapidly and non-linearly from its magnitude at current Io to the magnitude which it assumes imity to the recti?er 3 to be subjected to the heat developed by the recti?er. If desired the recti?er at the larger current Im. In fact, the thermistor 21 considered alone is unstable since the greater 3 and thermistor 8 may be enclosed in a common thermally insulated enclosure or housing [2 to its current and internal heating becomes, the stabilize the thermal environment and reduce 40 less its resistance and the greater the current it will tend to accept. This large change in current extraneous effects. is conducive to e?ective regulation in its e?ect Fig.2 discloses a modi?cation of the system of upon the resistance of the series thermistor 22. Fig. 1 in which the thermistor i3 is connected in series in one of the alternating current input However, the fall in potential across the ther ’ leads to the recti?er 3. In this circuit the ther 45 mistor 21 of the shunt path would by itself be very detrimental to maintenance of a constant mistor l3 and the transformer 2 may be mounted in close proximity to each other to facilitate heat potential across the load terminals I9, 20. To reduce this potential variation across the shunt transfer from the transformer to the thermistor. If desired they may be enclosed within a ther mally insulated container or housing ill. path as a whole while retaining the feature of 50 large change in current characteristicof the The system of Fig. 3 is similar to that of Fig. 1 thermistor 27 there are introduced resistance ele but adds an auxiliary full wave recti?er l5 in the circuit connecting transformer winding 9 and ment 23 and the resistance of winding 26 of relay 25. These may be made substantially linear so that their aggregate potential drop as represented the thermistor l6. Accordingly the heating cur rent for the thermistor introduces into the output 55 by ER will be a straight line. It will be apparent ‘ circuit of the main recti?er 3 only a unidirec that adding the potentials ER. and ET will yield tional voltage accompanied by ripples which may a more nearly horizontal potential throughout be readily suppressed by the smoothing ?lter ‘i. the range of In to Im. However, since ET is far In the system of Fig. 4 the thermistor Ill is from linear the resultant obtained by adding ER supplied with unidirectional heating current over 60 and ET will have a corresponding non-linearity a path including the secondary winding 9 of the or curvature. This may be much reduced and current supply transformer, auxiliary full wave the total shunt path potential made more nearly recti?er l5, and an auxiliary smoothing ?lter Hi. horizontal with change in current by the intro It is accordingly possible to connect, the ther duction of a resistor 26 which preferably consists mistor l'i immediately adjacent the input ter 65 of some such material as silicon carbide which minals of the load 6 since the thermistor is not has a negative coe?icient of resistance with in subjected to heating current variations or ripples. creased current. The terminal potential E26 The system of Fig. 5 adds to the circuit of Fig. 1 which such a negative coe?icient resistance ele a shunt path connected directly across the input ment will support rises with current but less rap terminals [9 and 2D to the load. This shunt path, 70 idly than does the current. The addition of the as will be later explained in detail, is of such potential E28 to those of ER and ET yields a nearly character as to draw a current IT which changes horizontal electromotive force E1. throughout the enormously for small variations in the electro-_ range of shunt currents from In to Im. Thus, it motive force applied to the load input terminals. is possible to take advantage of the wide varia Because of this very great change in the current 75 tion in current characteristic of thermistor 21 5 2,418,083 without permitting the potential difference across the shunt path connected between points l9 and tential will exist between points 62 and 18. If the recti?ed voltage impressed between points 50 and 51 should rise the bridge will be unbal anced to send unidirectional current over the circuit 59, 66 in one direction. If the impressed 20 to vary more than a slight amount. In operation, the shunt current I'r stabilizes at some magnitude at which the three potentials ER, E26 and Er will add up to equal the load volt age Er. which is available after subtracting the series potential drops across the ?lter 1 and thermistor 22 from the voltage delivered at the output terminals of the recti?er. If the system be designed and the variable resistors adjusted to cause the apparatus to tend to operate at a point such that the shunt current I'r lies between I0 and Im, as the voltage supplied across terminals l8 and 20 to the load slightly decreases the cur voltage across points .50 and 51 should fall the bridge will be unbalanced to send current over the circuit 59, 63, in the opposite direction. The two-arm varistor valve includes an asym metrically conducting arm adjacent the termi nal 65 which is so poled as to permit current of rent I'r will greatly increase. Conversely, if the load voltage Er. increases the current Ir will de one polarity only to pass to the winding of relay 64. This, in effect, makes the relay 64 a polarized relay. Similarly current of opposite polarity only is permitted by the other asymmetric arm ad jacent terminal 68 to pass through the winding of relay 61, thus effectively making that relay crease. polarized but in an opposite manner from relay 64. The purpose of the third transformer winding With the apparatus in proper adjustment, as 28, the relay 25 and the variable resistor 29 is to 20 suming that the switches 33 and 44 have just been closed, the thermistors 52 and 54 of the shunt control bridge will be cold and the shunt provide, at the time the circuit is energized, a high enough voltage to thermistor 21 to bring it within its operating range. When this operat ing range of temperatures has been reached the control bridge will be unbalanced in such direc 7 current through the thermistor 21 becomes great - tion as to send current from the storage battery enough to operate marginal relay 25 thus actu ating its armature 3| to withdraw it from engage ment with the contact point 36. Fig. _'7 discloses a system for rectifying alter nating currents which is similar to that of Fig. 45 through the winding of the starting relay 64. The relay 64 thereupon energizes attracting its armature 1| and closing at its contact 12 a 30 5 in that it involves an L network comprising a shunt control arm to control indirect heating of a series thermistor arm. As shown the apparatus is in unenergized condition with its starting switches open and the various relays and control circuits in released or idle condition. In this circuit a source 32 may be connected through switch 33 with current supply transformer 34 from the secondary winding of which leads 35 and 36 extend to the full wave recti?er 31. Connected in series in the alternating current input lead 36 are ballast lamp 38 and a thermistor 39. The unidirectional output current leads 40 and 4| extend from the recti?er by way of the smoothing choke 42 and the charge fuses 43 and, the switch 44 to the terminals of a storage bat tery 45, and from these terminals through the discharge fuses 46 to the terminals of‘the uni directional current load 41. circuit extending through the heater windings 14 and 15 of thermistors 52 and 54, respectively. In a few seconds thermistors 52 and 54 have warmed to such a degree as to greatly reduce their resistance. Under these circumstances cur rent will traverse these thermistor elements 52 and 54 in su?lcient magnitude to maintain their temperature within the downward operating range of their resistance temperature character istic. In consequence of the reduction of resist ance of the thermistors 52 and 54 the shunt con trol bridge becomes unbalanced in the opposite direction causing the starting relay 64 to re lease and sending a current through the winding of relay 61. The release of relay 64 interrupts the heating current passing through heaters 14 and 15 of thermistors 52 and 54 but the current which now passes directly through these thermis tors is su?icient to maintain their operating tem perature. - At the time that switch 44 is closed in starting The ballast lamp 38 by abruptly changing its 50 the apparatus current is applied through the fuses 5| over leads 85 and 86, ?xed contact 16 resistance to a higher magnitude when the safe and armature 11v of relay 61 to operating winding recti?er current is exceeded prevents overload 18 and resistance winding 19 of relay 80. Relay ing of the recti?er. The resistance of the therm istor 39 varies in accordance with the series load 80 thereupon energizes and attracts its outer ar current therethrough. It is also indirectly af 65 mature 8| to close the circuit through heater 49 fected by an associated heater element 49 which , of series thermistor 39. At the same time it is intermittently operated in response to the op attracts inner armature 82, establishing a holding eration of a shunt control circuit. The shunt circuit for itself by an alternative path around control circuit leads from point 50 by way of the armature 11 so that a: momentary actuation of regulator fuses 5| to the four-arm Wheatstone 60 relay 61 to open the energizing circuit of relay bridge comprising thermistor 52, ?xed resistor 88 at contact 16, 11 will not cause relay 88 to 53, thermistor 54, variable tap resistor 55 and deene'rgize. It will be apparent, therefore, that resistor 56 to point 6| and by way of conductor as soon after the switch 44 is closed connecting 85 to point 51. From the conjugate point 58 a storage battery 45 to the terminals of the con variable tap 10 and lead 59 provide a path to 65 trol bridge and to the leads 85, 86 of the circuit junction point 60 of a two-arm varistor valve. of relay 80 as will afford su?icient time for relay From the other conjugate point 62 of the shunt 80 to energize heating of the thermistor 39 will control bridge a lead 63 connects the winding oi.‘ . relay 64 to' one terminal 65 of the valve while a path 66 connects the winding of relay 6'! to the 70 remaining terminal 68 of the varistor valve. If begin. It will continue until such a time as relay 61 is energized breaking the contact be tween its armature 11 and the ?xed contact 16 and moving armature 11 into engagement with the variable tap 16 be properly positioned at a contact 84, thus short-circuiting winding 18 and given temperature and a given applied load volt permitting the release of armature 8|. age between points 58 and 51 the shunt control ‘In one embodiment of the circuit of Fig. 7 bridge will be balanced and no difference of po 75 with a alternating current supply at the primary 2,413,033 7 8 winding of transformer 34? of 115 volts, 50 to 60 cycles, the apparatus was designed for battery charging service to supply a current varying the recti?er and a second secondary winding associated with the primary winding and con nected to the thermistor to supply heating energy thereto. 3. A regulating system for controlling the Volt from zero to one ampere at 17 volts. In this particular embodiment the resistance of element ' 53 was 700 ohms, element 55 was 400 ohms, and element 56 was 300 ohms. The heater windings ‘l4 and 15 of thermistors 52 and 54 were of 140 age of the energy supplied to a load comprising an alternating current transformer having input terminals and output terminals, a source of unin ohms resistance. Upon operation of relay 613 terrupted alternating current, a conductive cir these windings were subjected to an alternating 10 cuit continuously connecting terminals of the al ternating current source to the input terminals of voltage of 24 volts. With the control bridge‘ the transformer irrespective of load conditions, a balanced the potential di?erence between the conjugate points 58 and 62 is of course zero. load, a load circuit connecting the output ter minals of the transformer to the terminals of the When, however, the circuit is ?rst put into oper ation by closing switches 33 and M, since ther 15 load and including a series variable resistance thermistor through which the load energy passes, mistors 52 and 54! are cold and their resistance‘ is high, the bridge is very much unbalanced so said thermistor and said transformer windings being in intimate heat conducting relationship as to make the point ‘ill highly positive with whereby the heat generated in the transformer respect to the point 62. When in a few seconds the resistance of thermistors 52 and 553 has been 29 may control the resistance of the thermistor to reduced by the heating effect of heaters ‘Hi and ' vary the voltage supplied to the load terminals. 4. A regulating system for controlling the volt 15 the bridge becomes unbalanced in the opposite age of the-energy supplied from a source of voltage direction to make terminal 52 positive with ref erence to terminal 58. Thereafter in operation to a load comprising‘a translating device having the terminal 62 always remains positive with 25 input terminals, a conductive circuit for con tinuously connecting the terminals to a source of reference to terminal 58 so that current passes at all times through the winding of relay Bl. alternating current irrespective of conditions of Relay 6‘! is marginal in its operation and is the load, said translating device also having an sensitive enough to operate on an unbalanced output circuit including terminals for connection _ voltage such as is impressed upon it when the 30 to the load, said circuit being continuously closed, and said translating device operating to modify unidirectional voltage across points 50 and 51 the form of the energy transferred from the rises to 17.3 volts and releases when that im pressed electromotive force falls to 17.0 volts. source to facilitate its utilization by the load, said translating device presenting resistance whereby Accordingly, so long as the circuit remains in operation the thermistor 39 will begin to receive 35 heat is generated by the translating device, a thermistor connected in series relationship in a heat from its heater Q9 shortly after the load continuously energized circuit to one of the ter voltage falls to 17.0 volts and will continue to minals of the translating device so that energy receive heat until the load voltage rises to 1743 volts. The output voltage does not rapidly passed to the load traverses the thermistor where by the thermistor may impose a varying loss of change between the limiting values of 17.0 and potential to regulate the load voltage as the 173 volts since the thermistor 39 and its heating energy supplied to the load varies, the translating element have a» considerable thermal inertia. Accordingly, at the beginning of the heating op device and the thermistor being mounted in such intimate heat transfer relationship that heat gen eration heat is applied slowly and at the end of the heating operation heat is applied morev 45 erated by the translating device a?ects the tem slowly than in the middle of the heating period. perature of the thermistor and hence its resist ance. Moreover, after the heating current has been interrupted heat continues to be applied to the 5. In combination, a transformer having a pri mary winding, 9, main ‘secondary winding induc thermistor in decreasing degree. This tends to greatly smooth the regulating operation. 50 tively associated with the primary winding, an What is claimed is: auxiliary secondary winding also inductively as sociated with the primary winding, a full wave 1. In combination a recti?er having input ter recti?er having input terminals connected to the minals to which a source of alternating voltage main secondary winding and output terminals, a may be connected and output terminals, means for regulating the voltage of the recti?ed current 55 thermistor and a ?lter connected in tandem to the ‘output terminals of the recti?er to regulate delivered from the output terminals of the recti the voltage supplied to the load and to reduce rip ?er to a pair of load terminals including a ther mistor connected in series between one of the ples, and a heating circuit for the thermistor in output terminals and one of the load terminals cluding the thermistor and the auxiliary sec to set up a potential di?erence between the ter 60 ondary winding. minals which varies inversely with the load cur 6. A source of current, a load, a circuit con rent traversing the thermistor, and means en necting the source to the load, a shunt path across ergized by an external source to heat the ther the connecting circuit including a thermistor mistor to a sensitive point on its resistance temperature characteristic. whereby the shunt path diverts currentfrom the 65 load to regulate the terminal voltage applied to 2. A transformer having a primary winding on the load, means for initially heating the ther which an alternating voltage to be recti?ed may mistor to a temperature at which its resistance be impressed, a secondary winding inductively is suitable for regulating purposes and means re associated with the primary winding, a full wave sponsive to current passing through the shunt recti?er having input terminals connected to the 70 path for disconnecting the initial heating means secondary winding and having output terminals when the current in the shunt path attains a pre adapted to be connected to a load circuit through determined magnitude. _ . , a regulating system, said regulating system com '7. A source of voltage, a load, means comprising prising a thermistor and a ?lter connected in a series thermistor having a falling resistance tandem relationship to the output terminals of 75 temperature characteristic throughout a desired 2,413,083 range of temperatures connecting the source to the load to regulate the voltage supplied to the load in accordance with the current supplied to in which the thermistor exhibits the falling re sistance-temperature characteristic. 9. In combination, a source of alternating cur rent, a full wave recti?er, a regulating thermistor the load, an external heater for the thermistor to supplement the heat supplied by the series load current passing therethrough, a path connected in shunt to the load and having two points which and a load, all in series circuit relation whereby said source supplies unidirectional current energy to the load, a shunt circuit including a thermistor are at the same potential when the total output electromotive force across the shunt path is at a connected across said load and means controlled by the, thermistor of the shunt path to cause abrupt variations in the temperature of the normal desired value, a relay having a winding connected between said two points and having an thermistor in the series circuit. armature and a, contact therefor, and a circuit connected to said source to derive an electro 10. In combination, a source of electrical en ergy, a series impedor and a load, all connected motive force therefrom and including in series said external heater and said armature and con tact. in series circuit, a Wheatstone bridge path con nected in shunt to the load and having two points conjugate to the connection points so that for a predetermined terminal voltage no di?erence in - 8. In combination, a‘recti?er having input ter minals to which a source of alternating voltage may be connected and output terminals, means for regulating the voltage of the recti?ed current delivered from the output terminals of the rec ti?er to a pair of load terminals including a ther , potential exists between the conjugate points, two asymmetrically conducting paths connected between the conjugate points and each including 20 an individual relay, means whereby operation of one relay in response to unbalance potentials mistor having a falling resistance temperature serves to initiate a reversal of the direction of characteristic connected in series between one of unbalance of the bridge and means whereby op the output terminals and one of the load ter eration of the other relay in response to oppositely minals to set up a potential di?erence between the 25 directed unbalance potentials serves to regulate terminals which varies inversely with the load current traversing the thermistor, and means en ergized by an external source to heat the ther mistor to a sensitive point in the temperature zone the impedance of the series impedor to control the voltage impressed upon the load. 30 JAMES A. POTTER.