BE476143A - - Google Patents

Description

       

   <Desc / Clms Page number 1>
 



  Motor control.



   The invention relates to AC motor control systems and more particularly to the type of control system which gives the motor a desired "torque versus speed" characteristic, by unbalancing the polyphase supply to the motor primary by one. controlled quantity. Systems of this kind are well known.



   The invention a. mainly aimed at creating control systems for polyphase AC motors which, while having performances comparable to those obtained with known systems, are able to operate with a shorter time constant and / or have torque characteristics. particular speeds which heretofore could not be easily achieved with control systems of the same kind proposed heretofore.

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  The invention will become clear from the following description of several ex <$ c1Jtion pr ^ fres9 re1) forces rrsentres as an example, d.ans-accompanying drawings.



  Figure 1 gives the diagram of a control system conforming to the intention, of a three-phase motor of the rotor type
 EMI2.2
 coil;
 EMI2.3
 Figure 2 is a diagra.Tv; e "speed-cou1Jl.e engine !! giving a game of car2, characteristics of the engine specific to the control system such as that shown in, Figure 1
 EMI2.4
 Figure 3 gives the diagram of the control circuits of another embodiment of the invention operation
 EMI2.5
 will generate similar to that of the pl'fcÁd9nte eXPC1Jtion form;

   
 EMI2.6
 Figures 4, 7 and 8 are circuit diagrams of
 EMI2.7
 more cO execution forms. "lpliou: <es, capable of 'oror'inira the reversal of the motor torque at a selected speed known to the motor under control Figure 5 represents the, SC11'7? T'p of the circuit / ovÍ . 1r "" 1nt ôv 1) rim. "Iro of the engine intervening in the system dp in figure 4; Figure 6 gives a C2.r? CtrlStiC9t0 "engine speed-torque" corresponding to the function of the 1D system of the kind
 EMI2.8
 Figures 4 and 5;
 EMI2.9
 Figure 9 gives a motor speed-torque diagram !!
 EMI2.10
 could not be obtained. with systems of the type shown in Figures 7 and 8.
 EMI2.11
 



  Referring to figure 7¯a the terminals of the primary Ti, Tua and TG of a three-phase motor? 'I of the tvpe î rotor 1 "' o'f; Ünf are supplied by the respective extifl4; -iitls of line 11 'L2, 1Z' by 1-'interr? ,, dipir-- d3un switch rrîncin7¯ 1. The secondary of the motor M includes rsisl. ^ Nces 2, 3 and 4, the value of which can be adjusted in the usual way. reason of s5-.T = nl¯5-cit ;, this resistance variation is reY1r / scnt6G z, 1r figure 1 by three brushes connected to each other, qll0i011 'it is l1'1.bitucle nr ± 1 ± reb 'The to have a main com, 11Rl1de with corresponding relays shorting different sections of the rnsis-

 <Desc / Clms Page number 3>

 tances, 2, 3 and 4 depending on the chosen position or condition of the main control.



  The motor M shown controls a hoisting winch 5 and its characteristics will be studied with reference to the raising and lowering operations of a crane or of a lifting device, but it is obvious that the invention is not not limited to this particular application case.



   A switch '6 is inserted between the end of the line L2 and the terminal T2 of the motor. When the switch 1 and the pusher 6 are closed, for example, during lifting operations, the motor M is supplied by means of a balanced three-phase voltage and therefore has a three-phase "motor speed-torque" characteristic. The control of the motor torque as a function of the speed can then be done by adjusting the resistance of the secondary motor circuit.



   Two electronic discharge tubes V1 and V2 are connected to the terminals of the switch 6. These tubes are put in parallel and inverted with respect to each other, and their assembly is put in series between the. end of line L2 and terminal T2 of the motor. The plates of the tubes V1 and V2 are biased by the voltage drop between the line end and the motor terminal, so that these tubes function practically, in the main order, as an adjustable impedance. Note that when the two tubes have infinite resistance and when switch 6 is open, there will effectively be no current flowing from the end of line L2 to terminal T2 of the motor, so that the motor M is thus supplied in single phase.

   It follows that the motor will have a bahtual single-phase characteristic with zero torque at zero speed. When the tubes V1 and V2 are maximum conductors and therefore have a minimum impedance, the motor M is supplied under practically balanced three-phase conditions and therefore has a high torque at zero speed.

   When the resulting impedance of tubes V1 and V2
AT

 <Desc / Clms Page number 4>

 
 EMI4.1
 has an intermediate value between the above-mentioned Unit conditions, for example, when the tubes are conductive only during a free interval of each period of 1 <1 voltage, the motor is supplied in three-phase but with a. rr '.- o-2rtition of fold,? is asymmetrical or unbalanced due to the fact that the inductor winding of the motor connected between terminals T1 and T3 is traversed by the total excitation current, while the excitation current of the two other inductor windings a lower value because of the impedance of the soft tubes.
 EMI4.2
 



  The Vl and Vagi tubes are preferably gas type discharge devices, such as those known as thyratron or ignitron. The tubes shown in the drawings are assumed to be thyratrons.
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  The COTm8nde circuit of the tube Vi connects 8 12 grid 7 comprises a secondary winding 8 of a tr "1ns forO '' '. T0ur T put in series with part of a rheostat 9 d.:'tei;..in6e by an intermediate tap. From 1110111e the grid 10 of the tube i13 is re-read 1 a CO circuit! 1l {'18ncle conpr8n8n t a secondary winding II of the transformer T connected with an adjustable part of a rheostat 13. L 'primary winding of the tra2sf.or? ni; esr T is connected to the extr4> rit,' s lines Li and L3 by the interiT '"diary of the aforementioned main switch 1. The transformer T still has three other secondary windings 14, 15 and 16 of which
 EMI4.4
 roles and circuit connections will be ex-1î, u-s later.

   The rheostat 9 is connected to the output terminals of a re-
 EMI4.5
 trainer 17 bridged by a filtering capacitor te1Jr 18. This rectifier is supplied by the secondary of a tré1n sfor ", lo t81.1r 19. The rheostat t 1- ',, in parallel with a filter capacitor 20, is connected at the output terminals of a rectifier 21 (Üi1 "1.ent by the secondary of a transformer 22.

   The primaries of
 EMI4.6
 transformers 19 and 22 are connected to the aforementioned secondafir'Ù 'winding 14 of transformer T, in series with the alternating current windings 23 of a saturation inductor 24. This

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 choke may be of the three branch type, as shown in the figure, and comprises a DC regulating winding 25 which allows the core of the choke to be magnetized in an adjustable manner. The degree of magnetization determines the actual reactance of the AC windings 23.

   The core of the choke remains, during the normal period of control of the system, magnetized below saturation so that the reactance of the windings 23 is substantially proportional to the DC voltage applied to the regulating winding 25. Therefore, the alternating current flowing through the primary windings of transformers 19 and 22 is also dependent on the energization of the control winding 25 with the result that the rectified voltages applied to the rheostats 9 and 12 respectively are also dependent. of the excitation of the winding 25. The. The operation of the choke and its associated circuits is that of an amplifier.

   That is, small variations in the voltage across the control winding 25 result in large proportional variations in the voltages applied to the rheostats 9 and 12.



   The excitation circuit of the control winding 25 of the saturation inductor is connected to a generator-tachometer G whose armature 26 is mechanically joined to the shaft of the motor 'M, so that the voltage created for a any given excitation of the inductor winding 27 of the. associated generator, is practically proportional to the speed of the motor. The inductor coil 27 is connected to the secondary 16 of the transformer through a rectifier 28 and a rheostat 29 provided, preferably, with a filter capacitor 30. A change in the setting of the rheostat 29 has the effect of changing the value of the control voltage created by the generator G, any given speed of the motor M.

   As will be seen below, such a change results in a corresponding variation in the operating characteristic of the engine.

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  The circuit of the enron1e '> 11en t' 5 co "'prC-'no a CO'r1111JtD tenr 51 which, in the position shown in the figure, - ,, and -a rectifier 32 in series with Ilindiiît 36 of the g / n (r :: sort.c8-t'1cl1Y'neter.



  The rectifier S3 is e1inent0 by the seconél'1ira 15 of the transformer T and its output terminals are pre-f / rC-'l'lce C011rt-circ, with a capacitor 55. If the switch is p '' 11recontact with a terminal 34, the output circuit of the rectifier 32 is opened and the pilot generator G is then the only source
 EMI6.2
 coil excitation 25.



  The main switch 1, the push-button 6, the switch 31 and the variable taps of the resistors 8, 3, 4 of the rhostt '9 force the '14 ..Gents of cO'0F <mde [11'pn091 .1 Watch to adjust and vary cOAne 013 system conditions. The first step of all these clients is, of course, to prevent a main con8nde (not shown) so that the operator does not have to worry about of the sequence of r '::> i! oe1.1VreS to do.



   Referring to the grid circuits of the imperial tubes
 EMI6.3
 daces Vl and V, it should be noted that C11E1, Cl111 of these circuits comprises two co! "'plér'entires grid voltage sources. By c7, e, ple, the grid voltage of the tube Vl is the resultant of an AC component created in the secondary 8 of the transformer T and of a unidirectional component which corresponds to the potential difference existing between the points P1 and P2 of the rheostat 9.

   The AC component a constant amplitude
 EMI6.4
 and is in a phase relation dpterl "inr with the voltage at the terminals of the plate circuit of the tube V1- The component at the terminals of the part of the rheostat 9 is variable and depends on the exci-
 EMI6.5
 station of the coil :: ent of cQ11ho28.nde bzz of the self. Nobody is unaware that, in a grid circuit of this type, the Tf10r'lents of;:. Rorç8.ge of the tube during the period of the plate voltage 1 's¯o% t function of the value of the . unidirectional component of the gate voltage. The grid circuit of tube V2 behaves similarly

 <Desc / Clms Page number 7>

 identically, except that this tube is conductive during the i periods when the other tube is not.



   When switch 31 is in the position shown in the figure, the rectified voltage across rectifier 32 is in opposition to the voltage created in induction 26. Consequently, the resulting excitation of the winding 25 then corresponds to the; difference between the two DC voltages applied to the winding. When switch 31 is in contact with terminal 34, only the voltage created by generator G is applied to the winding.



   When the main switch 1 and the push-button 6 are closed and when the motor M is stopped and therefore the voltage of the generator G is zero, the switch 31 being in the position shown in the figure, control winding
25 is powered by rectifier 32 and magnetizes inductor core 24 so that the reactance of AC winding 23 is very low. Consequently, transformers 19 and 22 have a relatively large excitation current through their primaries and rectifiers 17 and
21 apply respectively to the rheostats 9 and 12 a corresponding high direct voltage. Under these conditions, the gates 7 and 10 are negatively polarized and the two tubes V1 and V2 cannot be ignited.

   When the motor speed is other than zero, with the control system in the position defined above, the voltage of the generator G opposes that of the rectifier 32 'and the excitation current of the winding 25 decreases accordingly. Since the core 24 is less magnetized, the reactance of the windings 23 increases. The excitation current in the primaries of transformers 19 and 22 is reduced as well as the DC voltage across parts of rheostats 9 and 12, respectively. It follows that the polarization of the grids becomes less negative, and the tubes are ignited at every second half-period for an interval which is all the longer as the speed of the motor M increases.

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  It is assumed that for the connections of circuits represented at 1 ?. figure Z., with l9in terrtzt: nr 1 and pusher 6 ierinûs, motor ï .., turned J ū = ¯s 7th direction r'I '3V:> YlCe "" ent or
 EMI8.2
 lifting.



  So one way to make the system work was
 EMI8.3
 vage is to maintain contact 6 1'er, "" \ throughout the +; have "e and to adjust the actuator sblple'nent by varying the secondary circuit of the motor. The motor will have a torque or lifting to because ) three-phase ctristiou with tri excitation ;; h:; s. <e Faus¯1îbJ = <e.



  The engine cST2ctÓristirues thus obtained are similar to the. c8ractrristiCl.'LJe 'motor speed-torque "repT4sent: 4th in Hg
 EMI8.4
 µ figure 2.
 EMI8.5
 



  However, the system makes it possible to obtain the .won.t4e other characteristics of the type of the Hi and ilg curves. of FIG. 2. They are obtained when, z 1- "i-bridge ,, e, the switch 31 is in contact with the terminal S4 while the push-button 6 is kept open. The two tubes TTl and V2 of the motor 1.1 are then placed in series in a phase of the motor circuit and their angle of co'ort-circuit is comm8nd mar 1? Motor speed. At zero speed, the i "npp.d211ce of the winding 18 "flent of sÚ1 'P3 is high (e because due to the entrainment of CO] 1T"' F1l1 of C5 is not
 EMI8.6
 not excited. It follows that the negative polarization of the grids
 EMI8.7
 is ? its minimum and that the tubes will be conductive during the maximum time.

   The motor 1.i is therefore pr2tiollC'i'10nt. "'LientR in three-phase 5; j;: 2atZ'ïC ..' Ue and therefore develops a torque of Y! 1prr8, in the direction of the clock. When the speed of the motor 2 lJgo> ente, the voltage of the tacbyY1let generator G correspondingly increases the, magnetization of in, inductance R and therefore reduces 18 the activity of the winding 25 25. Hence the polarization of the windings. tubes Vl and V become more negative and the angle of arcing is reduced, possibly up to:; this bare the tubes no longer start for a given speed, o (teri <line "'9'2, 1 'the adjustment of the rheostat 29.

   This adjustment can be made by e'1-lo-oé, rator as described above., For example, for L - # .- "

 <Desc / Clms Page number 9>

 an adjustment of the rheostat 29, the "speed-motor torque" curve of the actuator M can correspond to the lifting characteristic H1 of FIG. 2. By way of comparison, FIG. 2 also gives a curve H in broken lines representing the characteristic of motor which would be obtained with the same resistance in the secondary circuit of the motor as that used to obtain the curve Hl, but with a symmetrical three-phase supply of the primary circuit of the motor. The part of the curve H1 between points C and S is like a single phase motor characteristic with the desired resistance in the secondary circuit of the motor.

   This means that, during the part of the curve between points S and C, the tubes V1 and V2 are virtually non-conductive. The part of the curve between points C and A shows how the conductance of the tubes gradually increases. The motor torque at point A is approximately the same as that obtained with a balanced three-phase excitation.



   The characteristic represented by the curve H2 differs. of the curve H1 in that the resistance in the secondary circuit of the motor is smaller. A change in the setting of the rheostat 29 has the effect of raising or lowering point C, approximately the point of transition between single-phase operation and three-phase operation.



   Lifting characteristics as represented by the curves H2 and H3 are advantageous, for example, in the case where the control system is applied to drawbridges which require a starting torque upon lifting or opening of the bridge. powerful which will decrease rapidly once the load is set in motion and especially sharply just before reaching the highest point.



   One way of carrying out lowering operations with lifting gear control systems in accordance with the invention and illustrated in FIG. 1, is to keep contact - 6 open and to completely remove resistors 2, 3 and, = 4

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 in the secondary motor circuit during the entire descent.



    The. The descent control is then performed by changing the setting of the rheostat 29, the switch 31 being located
 EMI10.1
 in the position shown in the drawings.



  Under these conditions winding 25 receives tm strong current from the rectifier 32 as long as the motor M is
 EMI10.2
 at rest. The reactance of the 2S windings is then low and the tubes V1 and V2 are polarized very negatively. These are
 EMI10.3
 therefore infinitely resistant. The motor is thus 8liel.ent in single phase and therefore has no starting torque. When an overload drives the motor in the downward direction, the generator G produces an increasing voltage which opposes that of the rectifier 32 and the tubes V1 and V2 are conductive for
 EMI10.4
 an interval of time which lengthens c'1'PLlt'1nt more than the speed of the mateur: nlgI1'8nte.

   Consequently, the motor is now supplied in three-phase and produces motor torque in the direction of. lifting. The opposing couple slows down the downward movement of the
 EMI10.5
 charge. This opposite torque increases by ± lutent as the speed of the descent increases and its power can be variable according to the setting of the rheostat 29. FIG. 2 'gives a group of characteristics.
 EMI10.6
 "engine speed-torque" teristisues representative of this operation; they are designated respectively by D1, D2 and D3.



  These curves son.t characterized by a torque nvl speed znro and by a passage â. equine tri-phase characteristics, 1ior> çes with increasing descent speeds.



  Because the devices at Ülp '; d "nces Vl and V2 are electronic, the control system just described has a very small time constant. Although the chokes and transformers used involve time constants, these elements do not. lead -in case of currents as high and are more
 EMI10.7
 small from the triple spatial point of view electrical and (<1.?, g'1.: ti0ue, than the elements which should withstand the charging currents and voltages which must be controlled.

   We can however

 <Desc / Clms Page number 11>

 get an even faster control reaction by using. electronic amplifying devices instead of the amplifying devices - - -tifs used in the preceding description. This will emerge clearly from the embodiment described in. present and illustrated in Figure 3.



     Referring to figure 5 the primary terminals T1,
T2, T3 of a wound rotor motor M are respectively connected to the line ends L1, L2, L3 by means of an inverter to the contactor 41 which makes it possible to rotate, depending on its position, the motor in the line. 'one or the other way. The secondary circuit of the motor contains the resistors 42, 43 and 44 ', the actual value of which can vary as explained in the description of the embodiment of figure 1. A 4: 6 switch is used. inserted between terminals L2 and T2; when it is open it is in parallel with two discharge tubes Vl and
V2 connected between them back to back as in the embodiment of Figure 1.



   The grid circuits of the tubes V1 and V2 pass, in the embodiment of FIG. 3, through a switch 47. The grid circuit of the tube V1 comprises a transformer winding 48 providing an AC component of the voltage. gate and a rheostat 49 giving a variable DC component of the gate voltage.

   Another rheostat 50, in series with winding 48 and rheostat 49, serves as a source of constant, unidirectional gate polarization, when switch 47 is in the position shown in the figure. The grid circuit of tube V2 contains a secondary transformer winding 51, a rheostat 52, and a rheostat 53 to provide a constant amplitude gate voltage AC component, a variable unidirectional gate voltage and a constant gate bias, respectively. The windings 48 and 51 form part of a transformer TR, the primary of which is connected between the line ends L1 and L3. This

 <Desc / Clms Page number 12>

 
 EMI12.1
 transformer has three other windings: 1 secondary teeth ri ,, signGs respectively by 55, 56 and 57.

   The secondary bzz5 feeds
 EMI12.2
 a rectifier 58 applying a constant voltage across the
 EMI12.3
 rheostat 50 inserts the grid circuit of the tube Vl. Likewise, the enrro1.eeJ, 'ent d.e transformer 56 supplies a rectifier 59 applying a constant voltage to the terminals of the rheostat 53 inserted in the grid circuit of the tube V2-
 EMI12.4
 The rheostat 49 is relayed: to a rectifier 60, the input terminals of which are joined to the secondary 61 of a transformer.
 EMI12.5
 TRl tower.
 EMI12.6
 The primary 62 of this transformer is supplied by the
 EMI12.7
 output of a 6x electronic amplifier. The transformer TR1 has another secondary winding bzz cuti supplies its rectifier 65 serving to apply a direct voltage to the rehostat 5n located in the grid circuit of the tube V2.

   The ente. üion of 2.1 '' 'lJlific8, tor 63 is taken from the secondary coil 57 of the Top transformer. The input terminals of 1' # ... <. nlîfîcr.tevr are connected to the second windings .aires of three tï2n.sfor "" "'te1Jrs
 EMI12.8
 designated as 66, 67 and 68, respectively. The primaries of these
 EMI12.9
 transformers have one of their respective exti 1; Titls together. 7¯'one to uter while cl1f), orne of the three e; atr, 1 ... it "s res-
 EMI12.10
 aunts is reread to one of the three connections of the secondary circuit.
 EMI12.11
 of the motor, by the inten'di2ire of one of the capacitors designated respectively by 69, 70 and 71.

   The transformers 66P 67 and 68 have been calculated from '' 'aniero to be r,' gntirjlernent saturated to a high degreeS 41 in normal service, so that the 2'rJplitude of their respective output voltages does not eYcÈ, the :: 'has in a way i -.> pTé.cialJle a given value c; u (-ls "' I be the changes of? -r15 the voltage C'e2ltrea These tr'è1, sforh", .. t. el; rs are, moreover, such Cue their output voltages have a sharp strength "'8 c" ol10.e. The CO; èr :: ens8't811rs 69, 7C and 71 sex> il - ;: it Î. ±; ire increase the tension (1 'ontr "r'uand the frc \ rï1JellCe,", up "lsnt8.

   It follows that the resulting voltage is applied., Ux terminals el 'at the input of 2)]' - <

 <Desc / Clms Page number 13>

 plifier 65 is practically a function of the frequency .de .tension induced in the secondary circuit of the motor? and not variations in the amplitude of the. secondary voltage of the motor. Like the, frequency of the voltage induced in the secondary circuit, of a wound rotor motor depends on .113. slip frequency and is therefore an accurate measure of motor speed, the resulting voltage applied to amplifier 63 also changes with motor speed. It follows that the voltages applied to the rheostats 49 and 52 forming part of the grid circuits of the tubes V1 and V2 respectively, also vary according to the speed of the motor.

   The rectifiers 58 and 59 are connected to the related rheostats 50 and 53 with a polarity such that the direct voltages applied to the rheostats oppose the unidirectional variable voltage components applied to the respective rheostats 49 and 52 and determine, for the tubes V1 and V2 , a cut-off bias when the motor is at rest, the voltage at the terminals of the rheostats 49 and 52 being, therefore, at a minimum. When the motor starts to move and increases its speed, the direct speed measurement voltages at the terminals of the rheostats 49 and 52 increase accordingly and cause the tubes V1 and V2 to ignite. for increasing intervals during each period of the cycle.

   Under these conditions, the operation of the system of Figure 3 is similar to the operation. the descent described about the. embodiment of Figure 1. When, in the system of Figure 3, the switch 47 is placed in its other position, the es rheostats 50 and 53 are separated from the grid circuits of the tubes V1 and V2, so that these tubes are then only controlled by the control devices using the voltage as a function of the. speed. The tubes V1 and V2 will then be conducting for the maximum time as long as the motor is at rest and the firing interval will decrease as the speed of the motor increases.

   Thus, the system works

 <Desc / Clms Page number 14>

 
 EMI14.1
 will work pratiq1Jerrent in the same way as in the case of the watch movement of the system of figure 1 J1101JV8 ": ent characterized by the" speed-motor torque curves !! H1 or H2 in figure 2.
In the embodiments of the type represented by
 EMI14.2
 figures 1 and 3, the C01IlèNH1de 8.utomati0ue, realism by means of the discharge tubes, allows to vary the c, r, -ct, 2ristin-Lies '' motor speed- torque !! between the limit characteristics of balanced three-phase power supply and single-phase power supply (zero torque at zero speed)

   of the engine but does not allow the
 EMI14.3
 engine torque without the use of CO''TL '' '' 'nrle [1cldi- tional devices such as the inverter 41 of FIG. 3. However, it is also possible to develop control systems in accordance with.
 EMI14.4
 the invention of such a nature as inaction of co-m ,, ande of the tubes 8 discharge produces a reversal of the torque rotelac a selected speed of the engine. One such embodiment is now described with reference to Figures 9: 9 5 and 6.



  Referring to the figure. 4, a 'r "ot"' the r rotor wound its primary terminals T ,, T2, Tg connected 'es res) 8ctively to eytr wït = s of line LI' L2, L3 and its secondary contains resistors 10, 10Z "104. A switch 106, inserted in the part of line Bzz L is open nund the electronic tubes designated below are in service.



   A pair of tubes at. Vi and V2 discharge is I take
 EMI14.5
 parallel on the interriipte-Lir 106 and is arranged in the r4éYne way (read the pair of tubes Vi and Vi3 of figure 1. The grid circuits and the correlating devices:? l1'12 of the tubes V1 and V2 of Figure 4 are also similar to the corresponding circuits and devices of Figure 1.

   In the
 EMI14.6
 aim to bring out this similarity and ds allow an easy comparison, the elements of cQ} 'rl1': '' '') nde of the tubes Vl and V2 of figure 4 carry the 1'neJ11es numbers of r "f" cznce inn the corresponding il) ments of 1 ;. Figure 1, except that we have at. la -ligure 4, added to these numbers the number hie !! or Tt] -Ti depending on whether

 <Desc / Clms Page number 15>

      the corresponding number in Figure 1 is one or two digits, respectively. For example, the grid 107, the winding, -of transformer 108, the rheostat 109, shown in figure
4, respectively correspond to clients 7, 8 and 9 of figure 1, and the grid 110, transformer winding 111 and rheostat 112 of figure 4 correspond respectively to elements 10, 11 and 12 of figure 1.

   From the same point of view of similarity, the transformer windings 108 and 111 of FIG. 4 belong to a transformer TR2 whose primary 113 is connected between the line ends L1 and L3.



  This transformer has other secondary windings among which the 114 and 115 corresponding to the windings 15 and 16 of the transformer T of figure 1. The rheostat 109 forming part of the grid circuit of the tube V1 (figure 4) receives a direct voltage. variable coming from a rectifier 117 supplied by a transformer 119, while the rheostat 112 inserted in the grid circuit of the tube V2 receives a variable direct voltage coming from a. rectifier 121 supplied by a transformer 122.



  The primaries of transformers 119 and 122 are powered by the transformer winding 114 controlled by the choke winding 123 of a saturation choke R1 whose direct current control winding 125 is fed by two opposing voltage sources. 'one to the other, one of the sources being the input 126 of a generator-tachometer G and the other being a rectifier 132 supplied by a secondary winding 116 of the transformer TR2. The voltage component coming from the rectifier 132 is adjustable by means of a rheostat 100. The inductor winding 127 of the generator-tachometer G is supplied by a rectifier 128 also supplied by a winding: ment of transformer 115, a calibration rheostat 129 being provided in this embodiment.



   It should be noted that the tubes V1 and V2 of figure 4 are ordered practically under the same conditions as the

 <Desc / Clms Page number 16>

 
 EMI16.1
 tubes V1 and V2 of figure 1, during operation the
 EMI16.2
 descent of the system shown in the latter figure. This is-
 EMI16.3
 that is, when the 'C1Otor, 1, in the figure, is at rest and the voltage of the generator-tachometer practically zero ;, the voltage applied to the saturation choke Ri by the rectifier 1PH magnetizes the core quite strongly of the self Rl so bare the. reactance of the coil "ent 122 ', is low and C11.1'1..111. cour *; t quite high runs through the primary of transformers 119 and 123.

   Consequently the voltage components n, pÜÍ <: ll..1f "es at the variable parts of the rheostats 109 and 122 are sufficient to polarize the tubes jI- and V2 beyond the cut-off. These tubes are therefore infinitely resistant. at zero speed and CO starts to become conductive during longer intervals when the motor is running at higher speed * The system of figure 4 includes in alum a use of Vg and IS tubes ,. These tubes are ", é" i'ls'l'3: 1.t "'lont0s" back to back "so as to be able to conduct the current during the successive (1" ": 1- 9 /' rio0.83 of the voltage wave.

   However, these tubes are connected to 311X connections of the thief r1 <ms of conditions such as, when they are conductive ;, 1 ::, voltage applied to, this iJxii tubes is out of phase with the voltage applied to. the pair VI and Vg. In this block, one end of the V3 Vtl pair is connected to the motor terminal Tg while the other end is fixed, at the end, 11it /, of line 11, so the secondary '. ^ 0 of a transformer Tlb whose primary is p12c' between the endings of lines Li and T, ij, The arrangement of the circuit d!, nl1Bseur of the two gr011DeS of tubes will emerge more c12ir2P8nt from l.'r ' tlJr12 of ClZ'CV: It t'r11v31ent of the primary of -; otecr re; cr, lsent6 to 7¯ ^ figure 5.



  In figure 5, the terminals of the 'Ot8tll' and the extr.tr1itr's of lines bear the number rings of ia "f'e1-ce C'lJ 'in figure 4, and the three motor windings between the terminals" "i, T2 and T3 are denoted respectively by '.1,' 2 and W3 'The 1" \

 <Desc / Clms Page number 17>

 Windings 240 and 241 of transformer T4 are shown separately in Figure 5. Assuming flood alone. the pair of tubes V1, V2 is conductive and that the phase rotation of the voltage applied to the motor terminals is such that the latter produces a rising or advancing torque, it is bare, if the tubes V1 and V2 are kept non-conductive while the tubes V3 and V4 allow current to pass, the phase rotation of the voltages at the terminals of the windings W1, W2 and W3 is reversed.

   Such reverse control is performed automatically by the grill control devices which will be described below.



  Referring to Figure 4, it can be seen that the anointed grid circuits of tubes V3 and V4 are technically similar to those of tubes V1 and V2. The grid circuit 207 of tube V3 includes a transformer secondary 208 and a rheostat 209 in series. The grid circuit 210 of tube V4 includes a transformer secondary 211 and a rheostat 212 in series. The rheostat 209 receives a direct voltage 217 supplied by a transformer 219. Likewise, the rheostat 212 is supplied (,, by a rectifier 221 connected to a transformer 222. The transformers 219 and 222 are connected to the secondary 214 of a transformer TR3 in series with an inductive winding 223 of a saturation inductor R2.

   The control winding 225 of this saturation inductor is connected to the terminals of the armature 126 of the generator G in series, with an adjustment rheostat 200.



  The operation of the tubes V2 and V4 is similar to that of the tubes V1 and V2, except that the excitation of the control winding 225 of the saturation choke R2 is controlled only by the variable voltage of the generator G and does not depend of the voltage drop produced across the rheostat 100 by the rectifier 132. Consequently, when the motor and the generator are at rest, there is no voltage

 <Desc / Clms Page number 18>

 
 EMI18.1
 at the terminals of the control winding 225, so that the power of the winding 22S is 12xim1.1! "1. The windings of the transformers 219 and 322 are traversed for low currents so that the polarization of the 207 and RIO grids make the V and V tubes 4 conductors at most.

   When the engine has
 EMI18.2
 a finite speed, and, for example, increasing, the self at saturation
 EMI18.3
 ration R2 is more and more magnetized and sees its reactpnce decrease so that the time of B.1TIorcage 'of the tubes il "and T4 decreases until naked, at a given speed of the engine ;, both
 EMI18.4
 tubes become and remain non-conductive.
 EMI18.5
 



  The two pairs of tubes operate from tp.l1e 1 -;>? Iére Cl'U 'at, at a given moment, a single pair of tubes lets the coiirant pass, and that, when the speed varies, we "' .ttein01 ' 2, a point of the characteristic where 1'1-Ine of the pulses ceases to occur while the other pair causes its ma.¯rcjps, fi C1'2 (1) 8 change of operation, the interval d '2'morcoge of 1 first jjcice of tubes is gradually pxnenf to. 2. ^ ro and then that of the other pair is gradually f1l1gment / j, .s¯17'? 7, ni # imxî <11.tmo The speed at which the feed of vne is fried, the area of tubes at the meter depends on the regulation of the potential sources of cOr <1.ynande.



  Assuming that the field winding 137 of 1. n'¯r, trice receives a constant excitation, the value of the. speed can be chosen by adjusting the set of rh'osi, ^ ts 100 and 200.



  These two rheostats are preferably single-ended or interconnected d.'vne harm way, cOTi1, YJe 1, * dashed line 220 shows. This adjustment can be made in stages, for example, in spite of the fact that the push-button 106 and the T4sistors 103,: L are not represented. ' 104 placed in the secondary motor circuit. If desired, the system can include an invesor, COE} JJ1.e celtli indicated in 141, so bare 1.'iiJversion, of the couple, obtained by means of the tubes, can be f "ire 8) very well at the ascent or 1, before going down or back.

 <Desc / Clms Page number 19>

 



   The inverter 141 can also be controlled by the aforementioned main control.



   FIG. 6 gives a very characteristic "speed-engine torque" diagram of the system, representing the operation on lowering of a crane or hoist motor. Three different characteristics are respectively designated by D4, D5 and D6 a la. figure 6. Let, for example, the. characteristic D5.



   One of the pairs of tubes will be conductive as long as the operating conditions correspond to the part of the curve between points B and E. At point B corresponds the maximum priming time. As we approach point E, the interval decreases, and, at point E, the pair of tubes ceases to prime while the other pair begins to conduct the current for a time which lengthens d the more so as the operating conditions of the engine approach point F on curve D5. During operation between points B and E, the motor torque drives at. lowering.

   At the speed, defined by point E, the torque is reversed due to the reversal of the phase rotation of the voltage of the motor so that the latter undergoes an opposite or lifting torque that is all the greater as the conditions approach zero speed (point F). The speed corresponding to point 15 can be chosen by adjusting the layout of the control system, for example, by adjusting the two rheostats 100 and 200. In this way the operator can determine whether the motor characteristic will follow. the. curve D4, D5 or D6. Likewise, such a system can produce a torque reversal when driving up or forward at a desired determined speed, for example for the control of drawbridges.



   While the embodiments of the invention described so far still make use of electronic discharge tubes, the plate circuits of which are inserted into the power supply. of the motor and which practically play the role of impedances

 <Desc / Clms Page number 20>

 
 EMI20.1
 adjustable, the invention includes' "'cheerfully electronic motor control systems which can give similar performances without having to insert charging tubes <1pias ie motor charging circuit this avi allows the eYl1') law of more;

  these tubes and simplification of the "1iXil.Í" l.J'N1 circuits and accessories, compared to those required for tubes of larger capacity. Such control systems are shown in Figures 7 and 8 and the following description will clearly show.
 EMI20.2
 That this kind of electronic motor control system Il.'1J uses only a small number of tubes and. ^ 1;

   - related control teeth, while or / it allows a continuous and gradual CO ': "1r1pnde continuous and gradual over a large rlt (- number of speed values - and torque, so that this system lends itself easily to various applications, for example, orders for lifting equipment, lifting
 EMI20.3
 screws, reversible motors for machine tools and other manufacturing mechanisms.



  In figure 7, -a motor? .L with alternating current with rotor coil4 has its primary terminals Tl, l and fJ connected to the ends of lines L1, L2 and L3 by 11 ire d.'v: 1 circuit t supply including a reed el 'iY "1J /' dpnces d./'sign6 as a whole by N.



   The secondary circuit or motor rotor comprises
 EMI20.4
 resistors a01 C) and; Z, 03 which can be CQurt-circnitees by, t8.pes by the intervention of oj; 4r; tevi cui has, preferably, at its disposal a main command (not re - presented).



   The network. N includes primary windings 304,
 EMI20.5
 505, 506 and z07 of four trûnsfor: n'lte1.1rS Rl, 2, R3 and R4. The secondaries of these transformers are dpsÍFJ1f: s respectively by 70s,: 309p ..10 and 311. The four primary <:, 04,? 05, 506, 307 are all in series so that they form the branched bolts. of a bridge.

 <Desc / Clms Page number 21>

 



   These primary windings 304, 305, 306 and 307 act as variable impedances, and the magnitude of these impedances is controlled by the corresponding secondary windings depending on whether they have low or high impedance. If, for example, the impedance values of the four primary transformer windings are equal so that the reed N is balanced, then the three-phase supply to the motor is maximally unbalanced and the motor is supplied approximately single-phase. Under these conditions, the engine has zero torque at the start. If the primaries 304 and 306 have a minimum impedance while the primaries 305 and 307 have a maximum, the motor is roughly powered as if the terminal T1 were connected directly to the line end L1, and the. terminal T2 to line L2.

   The phase rotation of the voltages applied to the terminals T1-T2. T2-T3, T3-T1 is then in the same direction as the phase rotation of the polyphase voltage between the ends of lines L1-L2, L2-L3, L3-L1. Therefore, the motor will produce torque at all speeds, for example, in the forward or upward direction.



   Conversely, if windings 304 and 306 have high impedance and windings 305 and 506 have low impedance, the motor will be powered approximately as if terminal T1 was connected directly to line end L2 and terminal T2 to line L1. The phase rotation of the voltages applied to the terminals of the motor is opposed to that of the line voltage and the motor develops a three-phase torque directed in the opposite direction, that is to say on the descent or the return.

   It can therefore be seen that by gradually adjusting and varying the impedance of the circuits of the secondary windings of the transformers, the motor can be made to operate according to different ca.ractéristics included between the above-mentioned limit conditions.

 <Desc / Clms Page number 22>

 
 EMI22.1
 In order to achieve such a C017l.m: = mc1 e, the secondary erlroulements 308 and 310 are connected in series in the plate circuit of a discharge tube E1, for example ;, of the gas type known under the thyratron number. Likewise, the secondary windings
 EMI22.2
 Transformer units 309 and 311 are wired into the plate circuit of another similar electron tube designated 8.

   During the operation of the CO''11) 11pnde device, the secondary voltages induced in the transformer windings 303 and 310 serve as voltage p180V8 pu tube El; and likewise, the secondary voltages induced in the windings 70 and t11 supply the voltage at 1. <1 'the plate of the tube 82. The tubes E1 and E2 operate practically as variable impndance devices whose instantaneous value can be varied by means of the associated control or gate circuits.



   The grid 316 of the tube El and the grid 317 of the tube E2 are interconnected by means of a group of resistors
 EMI22.3
 series 318, 519, S20 and il; 21. The SO @ 118 of resistors 318 and if ± has a value equal to the. sum of resistors 720 and 521 so that point C represents the electrical midpoint of the voltage drop across the grid resistors placed in series. The variable part of a rheostat 022 is connected between point C and the common cathode connection of the tubes.



  This rheostat receives a variable direct voltage coming from a
 EMI22.4
 -ipprodriée voltage source, represented here by a rectifier supplied by an auxiliary transformer, the primary of which can be connected between the lines Li and L3 estreits. The voltage drop in the variable part of the rheostat 322 applies a constant bias to the tubes E1 and E2 which can be of such direction and value as to tend to hold both tubes at. their maximum conductance, so that the tubes prime for their longest intervals.

   We
 EMI22.5
 can however work with polarization conditions given by the rheostat 322, such as the tubes E1 and E2

 <Desc / Clms Page number 23>

   normally remain infinitely resistant; well, the grid polarization may still have a value between the two aforementioned limits, for example, so that the tubes operate with medium strike and medium conductance.



   An auxiliary circuit 325 is connected to points A and B, to the group of series resistors; it comprises two control voltage sources linked together. One of these sources consists of a pilot generator 326 mechanically joined to the rotor of the motor M, as shown schematically by the dashed line 327. The pilot generator 326 is of the tachometer type and therefore produces a continuous voltage practically proportional to the speed of the motor. , and of polarity determined by the direction of rotation of the motor.

   The second voltage source of circuit 325 is represented by a potentiometer 328 supplied by a suitable DC voltage source, embodied here by a rectifier 329 itself supplied by a transformer 330 whose primary winding can also be connected between the ends of lines L1 and L3. The rheostat 328 is provided with a number of sockets including one at the. times is connected to point A of the aforementioned group of resistors. The intermediate tap of the rheostat 328 can be selected by the operator, for example, by means of a main control (not shown) which at the same time adjusts the aforementioned resistances 301, 302 and 303 of the secondary circuit of the motor.

   The polarity in which the pilot generator 326 and the rheostat 328 are connected is such that the adjustable voltage drop across the variable part of the rheostat 328 is opposite to the variable voltage of the generator. When these two voltages are equal, only the constant bias voltage supplied by the rheostat 322 influences the gate circuits of the control tubes.



  This case corresponds to the moment when the motor M rotates at a single determined speed, the value of which is defined by a chosen setting of the rheostat 328. When the motor rotates at a speed

 <Desc / Clms Page number 24>

 
 EMI24.1
 different, the circuit 525 applies a voltage, resulting determined between the points A and B of the group of resistors ;, and the polarity of this voltage depends on whether the speed of the motor is below or above a given value. Such a tendency
 EMI24.2
 sion defined ouelconcue s' p joute to the bias voltage of the rheostat 322 in the gate circuit of one of the tubes and is subtracted from the. bias voltage of the gate circuit of the other tube.

   Therefore, when the motor is running at a different speed than above, one of the tubes becomes more
 EMI24.3
 driver and otter is less so. That is -? -> - to say that in the case of use of thyratrons, the firing angle or the conductivity interval of a tube is increased during the stripping angle or the conductivity interval of the other tube decreases. This brings about a change in the load of the two groups of secondary transformer slow windings and the distribution.
 EMI24.4
 of the impedances between the coils P04 '505 a06 and? 07 of the network N is modified.

   The voltage distribution between the motor terminals is also changed correspondingly, so
 EMI24.5
 The command for the "speed-torque" operation of the motor varies accordingly.



  The description of an application: '1p.rtj cll1ip.re du. control system, 1 lift and. the descei-itp, of a hoist motor will be given now.



   It is assumed that ;, for the operations to be described ;, the bias voltage supplied by the rheostat 322 a value
 EMI24.6
 such that the tubes El and S2 are conductors ¯end. ^ - n an average interval, so that the transformer windings vr >> -. res of the network have a value of imp / 'd2J "lCe The distribution of the impedances of the reed is? when equilibra and the motor is 8.) '; Jroxirr2ti'lTe "ent 11'Ti6'i2tr 2n single-phase so that it 8. a torque lîr2, ti" îJe'r: zero mt at speed 7 ,, - 'ro, as long as the grids of tubes E1 and E2 receive only the bias voltage of rheostat 322.

 <Desc / Clms Page number 25>

 



   To obtain descent operation, 'the rheostat
328 is set so that the socket D'1 is connected to point A -, of the tube grid circuit, as shown in figure 7.



  With this setting, the rheostat 328 is outside the auxiliary circuit 325 and has no effect on the operation of the cathode. When the engine? is off, the control voltage component from generator 326 is zero. Therefore, the circuit 325 does not create a voltage between the points A and B of the gate circuit, and there is always as a bias only the voltage supplied by the rheostat 322. As seen above. ,. the motor torque is zero at zero speed. This case corresponds to point F1 of the "speed-torque" diagram in figure 9.



   If an overload weighs on the motor M, it will make the motor run in the direction of descent. As the engine speed increases, generator 326 develops a correspondingly increasing voltage of defined polarity. The resulting voltage drop across the group of resistors between points A and B is opposed to the constant gate bias coming from rheostat 322 which is part of the E1 tube grid circuit while it is additive with respect to bias constant grid of tube E2. It follows that the tube E1 is made to work with a greater firing angle and is therefore conductive during increasing intervals.



  Conversely, the tube E2 decreases its priming time and therefore has a lower resulting conductance. The resulting decrease in the impedance of the tube E1 increases the load on the secondary transformer windings 508 and 310 and decreases the impedance of the associated primary windings 304 and 306. At the same time and for similar reasons, the resulting impedance of the transformer. primary windings 305 and 307. Consequently, the distribution of voltages between the motor terminals gradually tends towards a symmetrical three-phase supply, the phase rotation of

 <Desc / Clms Page number 26>

 these voltages being identical to that of the voltages between the ends of lines L1, L and L3.

   With this phase rotation, the motor develops a lifting torque which counteracts the downward thrust of the overload. This mode of operation of the
 EMI26.1
 engine corresponds to the. characteristic Dl of counter-torque on the descent, of figure 9.



   If the system is set to the second position of
 EMI26.2
 descent, the tap D'2 of the tliéostzt bzz'8 is read again at point A, so that there is now between the points D 'and D'z of the rheostat 338 a relatively low voltage drop coming from the rectifier S29. When the: 1 = otevr 'ia zero speed, .the control voltage component due q 18 g>' nr.% Tx "1, ce., I lote K36 is equal to. Zero so that only the drop 1 -; voltage D'1-D'N is applied between points A and B of the own gate circuits, by circuit 325. This voltage drop
 EMI26.3
 is added to the. constant grid polarization provided ner rhost ^ t t ;: 22 for tube Eg and subtracted for tube Dl.



    The resulting grid polarization of tube E1 is therefore smaller and the latter becomes less conductive, while tube E2, whose resulting grid polarization is larger, conducts - making longer intervals. It follows
 EMI26.4
 That i> 1,, j.; Ô, nce of windings 304 and s 06 is i'1i ':(' 11entpe and that of windings 105 and zozo di '' '1inll / e.

   The motor terminals now receive a voltage, tZ'2J1'L ^ See eissy ",, / triC'l.J8 in a bare 1; phase rotation of the voltages between these terminals is or.posed to that of the voltage of line between the e, - ,: t1 "mits L1, Li. and L 3 'The motor thus produces a desceY1sional torque E1, L2 3
 EMI26.5
 8, corresponding zero speed, for example, "'11 point G :: of curve D2 in FIG. 9.



  When the speed of the motor drops -u-7.e-nte, 1 generator 320 provides an increasing voltage yes s / qppDse at the voltage drop D 'ID' 2 'We will therefore reach a position where the voltage of the generator balances it exactly. fall

 <Desc / Clms Page number 27>

 voltage taken from the rheostat 328. Under these conditions, the fixed grid bias supplied by the rheostat 322 acts alone, and the impedance of the network N is distributed equally so that the motor is supplied so as to have a torque no. The speed at which this occurs is given at point F2 in Figure 9. When the motor speed increases beyond this value F2, the motor torque is reversed and the motor opposes the downward movement of the overload.

   This happens in the lower part of the. characteristic D2 beyond the poirtF2. When point D'3 of rheostat 328 (fig. 7) is connected to point A (third lowering position), the operation is similar to that described last except that, at zero speed, the torque at descent is increased until having the value indicated in G3 of figure 9, and the reversal of the engine torque occurs at a higher descent rate than before, as can be seen at point F3 of characteristic D3. It is therefore clear that the speed at which the counter-torque begins to act is determined by the adjustment of the rheostat 328.

   It has been assumed that during these different operations of the motor on the descent, the resistance of the secondary circuit of the motor M remained fixed, so. that the resistors 301, 302 and 303 (fig. 7) intervene entirely at maximum resistance.



   If you want to use the control system in question for lifting operations, the rheostat is set so as to, for example, connect point H'2 to point A. In this case, there is a voltage drop relatively large between the points D'1 and H'2 of the rheostat 328 which is applied between the points A and B, when the engine is stopped and the voltage of the generator 326 is zero. This voltage applied between the points A and B by the rheostat 328 is of opposite polarity to that which had been obtained by the rheostat 28 during operation at A downhill.

   This high voltage of reverse polarity is opposite '

 <Desc / Clms Page number 28>

 
 EMI28.1
 to the. gate bias provided by the ri'7rpSt ^ i; 52P in the grid circuit of tube 1 and is so deep that tube E1 grows for its interval of t "'1'1'r; s: 1J8xi"' uln. Similarly, the angle of orifice of the tube C2 is "'Menf at the mini- .rovfv ov at zero .. With this rr <, glpge, the windings 04 and? 06 of the rc-bucket IIi have their 1 < Tp * d? Nce Y1Üli '(d'M and the e111'oule,; r; nts? 05 and, 07 their irr'padance (1J, "' xi"; lJ.: ', 1.

   Therefore, the! 'LimeY.1t; :: tion of the motor is three-phase with the minimum of d.rscizi.irre, that is to say with a distribution of' 0112se p, 1) ,; rozim: "tiv8Clent sjTn trirue and a rotation of pnpse of the voltages between the terminals of the motor identical to that existing between exti À .. 5t's of lines LI 'L8 and L3 "P2T therefore, at zero speed, the motor develops a C01.J-, pie power re ; * r. "scnti, p ^ r exe, -, nle-, by noint K8 of 1? c ^ ractristi.i? e They of 1? figure 9. If the lifting speed increases, the tension produced by the lifting speed becomes more and more effective.

   This voltage has.; * Intein..m: reverse polarity. n a certain speed this tension. de, l.8, s! n ;; r? trice balances the voltage drop relatively /1.ev'e between points D'1 and H'8 of rheostat 388 so rr1.1'9. this noifent the imped-nce of the network N is distributed from f2con / 3le and I bare the rooter is? li3'n2nt ^ with a dn'sr - ', n, uilibre "() l-'xj:' T1um In (l '21Jtres' words, at this speed, the motor torque is zero. This CD is represented ps.r the point P2 on 12. curve H2 in figure 9.



  When 1F motor speed exceeds 1. '' P0 speed, the motor torque is reversed and therefore acts CO, 1JI e counter-torque.



  When the rheostat 3É? S is 8jUSt / do so that the point ri'8 (fig.7) is connected to the painted 3., the C;? I '? Ct ..!. D, stl011e of the motor follows the given conditions by lux curve 1-T in figure 9. That is, at zero speed the torque of è ''; 1p, rr "-1ge, reprp.sent2 by K3, is r4dui-t, thus than 1 "speed P3 to 18 than 1
 EMI28.2
 the motor torque is reversed .. ¯ Another lifting characteristic is shown at
 EMI28.3
 Figure 9 by. curve Hl. This c8.rpct: risti0ue gives a:

 <Desc / Clms Page number 29>

 zero torque at 100% lifting speed and corresponds, from a gender point of view, to a "motor speed-torque !!" diagram, with fully balanced three-phase power supply.

   Such a power supply can be obtained in the system of FIG. 7 by removing the network N in the power supply circuit and connecting the ends of lines L1 and L2 directly to the respective motor terminals T1 and T2. The device making these connections is not shown in Figure 7 but may be similar to that of Figure 8 consisting of an RC contactor described below.



   Although, in the previous description of the engine operating modes, no allusion was made to a change in the setting of the resistors of the secondary 301, 302 and 303, it is understood that the "engine speed-torque" characteristics can still be observed. modified by changing in addition the value of these resistances between the maximum and zero.



   In the system shown in figure 7, each tube and its associated transformer only operate during each second half period. Such a half wave control is sufficient for certain applications. If, however, a two-wave control is desired, it suffices to add a second to each tube. overturned tube. The grid circuits of these additional tubes can be similar to the circuits of the tubes E1 and E2. But there is another way to achieve a two-wave command, which will be explained in the. description of the following embodiment.



   Referring to Figure 8, it can be seen that the terminals T1, T2, T of a wound rotor motor are connected to the ends of respective lines L1, L2, L3 by means of inverters, shown as part of a Single RC reversing contactor, although it is understood that separate contactors or other reversing devices may be used instead. Between the terminals T1 and T2 and the ends L1 and L2.

 <Desc / Clms Page number 30>

 
 EMI30.1
 There is also a network 11 composed of c, utre chokes Si, Sp, 8;) and 84 .. Each choke a winding of i ^, d "nce 404, 405 406 or 9¯O07 and a control winding 408, 409, 47¯0 01- '411.

   The i ';] pedance of the self windings is maximum when the con? Llcde windings are not supplied and dev "1nW d¯'17t71t more than the exci t8, tion of the coelent coil? , i - nc3e increases.



  As we know, the salt ± îq1Je enr01Üerlent of a? such a saturation choke is composed of two parts whose effects of 5.l1 <: 11Jction on the winding of CO''11l11nIl (3e are r'cuuil3.br ^ s of f "con due the cot.rc. AC nt yes through them does not induce any voltage d8ll.s 1 'etRro vl e #; = at t of cOnL'I1.8nde. The connection of the inductive windings to each other and to the motor terminals thus C1U'i'llX extrpY11itÂs of lines, and the connection of the coils 408, 409, 410 and 411 to each other, are similar to the corresponding chords of Figure 7 and therefore <4t ± described above.



  When the changeover contactor RC is in nnns 1 .'- 'position indicated at. in the figure, the network dirp (', dnnces is cormecV between the line ends and the motor terminals of If JT1yre Banière than the network N of figure 7. When the contactor RC is in its other position, the rRS8? A is disconnected, in figure 8, from the power supply circuit and the ends of lines Li and L2 are connected directly to the respective terminals
 EMI30.2
 of the engine Tl and T2.
 EMI30.3
 



  The control windings 408 and 410 are inserted into the plate circuit of the tube II and the control windings 409 and 411 are also placed in the plate circuit of the tube Ep.
 EMI30.4
 The plate circuits of these two tubes are supplied by the
 EMI30.5
 secondary 431 of a transformer Tn whose primary 433 is connected between the line ends Txg and L3. The grid 416 of the tube '1 and the grid 417 of the tube E2 are interconnected by 1 -interr. (Edi, ire of a group of resistors series 418j 1.1, g :;
 EMI30.6
 
 EMI30.7
 420 and 421. A grid voltage transformer Lj, 37i is piled to the electrical center of the group of resistors and is supplied to it.

 <Desc / Clms Page number 31>

 by the secondary winding 434 of the transformer TR through a phase shifter circuit.

   The midpoint C 'of the secondary of transformer 433 is connected to rheostat 422. This rheostat acts as a voltage divider and is supplied by a rectifier.
423 itself driven by another secondary 424 of transformer TR. The variable part of the rheostat 422 gives a constant grid polarization, for example of a magnitude such as to keep the two tubes E1 and E2 moderately conductive.



   An auxiliary circuit 425, which includes two rheostats
428 and 435 in series, is connected to points A and B in the grid circuits of tubes E1 and E2. The rheostat 428 receives a DC voltage from a rectifier 429 supplied by a transformer winding 430. This rheosta.t corresponds to the rheostat 328 of FIG. 7 and makes it possible to. adjust the motor characteristics in the manner described previously with reference to figures 7 and 9.



   The 'reostat 435' receives a variable direct voltage corresponding substantially to the speed of the motor M, this voltage being derived from the secondary circuit of this motor in the following manner.



   Three transformers 436, 437 and 438 are connected in series with respective capacitors 439, 440 and 441 to the three phases of the secondary circuit of the motor. Rectifiers 442, 443 and 444 are respectively connected to the terminals of the secondaries of these transformers. The rectifier output circuits are all connected in parallel across the terminals of the rheostat 435. A capacitor 445 may be provided to filter the rectified voltage. Transformers 436, 437 and 438 are highly saturated so that the magnitude of their respective output voltages does not significantly exceed a given value regardless of variations in the input voltage. The capacitors 439,
440 and 441 are advanced devices.

   The resulting output voltage across rheostat 435 is nearly proportional

 <Desc / Clms Page number 32>

 
 EMI32.1
 tional to the frequency of the voltage induced in the secondary circuit of the motor and therefore to the speed of the latter. This circuit
 EMI32.2
 therefore plays an analogous role o. In generator nīlote? '' '6 of the form of ex4ciitio.a of Ip figure 7. When the reed N is inserted into a system of the kind in figure 8, the operation is very similar to the descending operations described above with reference to. figure 7.

   It should be noted however that
 EMI32.3
 the angle of 8: TlOrç2ge of the tubes Ei and En is co.rrt: r "'J1r'J, 8 by a resulting grid voltage comprising an alternating CO' '' '' 0os2ntA derived from the transformer 433. Consequently a Voltage variation in circuit 425 results in a phase shift of the AC gate voltage from transformer 433 relative to the blade voltage supplied by transformer 431.



   A diode or rectifier valve 446 is connected to the terminals of the control windings 408 and 410 of the saturation inductors. A similar 417 straightener is in parallel on
 EMI32.4
 cow ^ .nde 409 and 411 enrollees.



   These straighteners are preferably gas discharge tubes. The polarity of their connections is such that they do not allow any current to pass during the intervals in which the tubes El and E2 are respectively conductors. At the end of a
 EMI32.5
 interval of n110rça, age of. tube L19 for example; the reverse current due to the self-induction of windings 408 and 410 passes through tube 446.

   Consequently the time during which the windings 408 and 410 are supplied is prolonged beyond the inter-
 EMI32.6
 during this time the tube E1 is conductive and may comprise a large part of a complete period. The tube 447 also allows the passage of the reverse current coming from the windings 409 and 411.
 EMI32.7
 



  In figure 8, the rheostat 438 served by the opf; Í'2, tor has three chosen taps D'19 D'2 and D'3 for the downhill operations illustrated by the curves, Dl> D2 or D3

 <Desc / Clms Page number 33>

 of figure 9. For lifting operations, the contactor, RC is inverted so that the control of the saturation chokes is disconnected, and to vary a characteristic of the motor there is nothing else to do but to change the total resistance of the motor secondary circuit.


    

Claims (1)

R E V E N D I C A T I O N S 1) Control system -for polyphase motors comprising variable impedance devices serving to unbalance by an adjustable amount the distribution of the energy applied to the motor, in which these variable impedance devices include electronic tubes whose Control circuits are connected to a voltage source, the latter having a value dependent on the speed of the motor. 2) System according to 'claim 1, wherein at least one of the adjustable discharge tubes a. its plate circuit placed in series in a phase of the supply circuit of the motor and has a control circuit serving to vary the intervals of conductivity of the tube during the voltage periods of the aforementioned supply circuit. 3) System according to. claim 1 or 2, in which two tubes with adjustable discharge are placed in parallel with each other and back-to-back and their assembly placed in series in one phase of the motor supply circuit, each of these tubes having a control circuit serving to vary the intervals of conductivity of the tube during periods of tension of this supply circuit. 4) System according to claim 1, 2 or 3, comprising a variable control voltage source connected to the motor for the purpose of producing a control voltage varying as a function of the speed of the motor, a voltage source of fixed control, these two voltage sources being connected to each other and connected together to the control circuit of the one or more <Desc / Clms Page number 34> electron tubes in order to adjust it according to EMI34.1 of the combined effect of these two voltages of co: ^; nd.e9 and a control device to be operated manually associated with one of these sources to choose by adjustment the respective values of the fixed control voltage and of the control voltage va- EMI34.2 riable in such a way: '3, obtain a given control r? ct4ristiç1Je of the prrci control circuit t'3 for a motor speed defined by the prec1 setting: ter!' 1in (of the prRCÍ t4 control device. 5) System according to claim 4, in which this variable control voltage source is a generator EMI34.3 tachometer in which the armature is joined to the motor so as to be driven by it and in which this manually operated control device is connected to this generator. EMI34.4 way to be determined by this predetermined setting, 1.'p: Tplituôe of. voltage supplied by this generator at a given engine speed. 6) System according to claim 4, wherein said motor is of the coil rotor type comprising a secondary circuit EMI34.5 daire with resistors, and in leouel this source of variable voltage includes transformers with strong smt1Jr-tion whose primary is connected to this secondary circuit of the motor and whose secondary is connected: to this control circuit so that EMI34.6 this variable control voltage is obtained prnticuernent as a function of the value of the induced voltage o <on8 this coil rotor * EMI34.7 7) System according to 7.'une C] lJelc01.wue of claims lJr (cc1entes, comprising a motor%, current "Iternatif trin112sÉ :, a circuit trir1Îl" sr 'rrlif to this motor and serving .q -ener 1.? voltage and comprising two dcb tubes; 'rg8., (1.octrcni01JP adjustable connected to at least two phases of this circuit do not fTcon 8, dJtrc #, -' iner phase rotation do this voltage Sl1ÎV'1 '(1t, the respective conductance conditions of these two tubes; , each of these tubes having a control circuit to adjust this con- <Desc / Clms Page number 35> conductance output, a voltage regulator connected to the motor and serving to produce a variable control voltage, almost a function of the motor speed, and a circuit device coupling this voltage regulator to these two gate circuits so that a variation in the control voltages changes these conductance conditions in opposite directions for the two tubes, whereby the motor is caused to reverse its torque at a given motor speed. 8) System according to claim 7, comprising two pairs of adjustable electronic discharge tubes, the tubes of each pair being placed in parallel and back-to-back with respect to each other and these two pairs! connected to at least two phases of the circuit. above. 9) System according to claim 7 or 8, wherein said voltage adjustment device is / coupled with these two gate circuits such that a gradual variation of the control voltage decreases the intervals during which a tube of one pair of tubes conducts practically to zero before making the other tube of the same bar conductive for progressively increasing intervals. 10) System according to any one of claims 1, 4, 5 or 6, in which an inductive impedance device, having an inductive coil connected in the supply circuit of the motor and serving to control the motor in part, comprises a control winding in inductive relation with this choke winding in order to adjust the value of the impedance thereof, and in, in which an electronic discharge tube is connected by its plate to this control winding and comprises a control circuit for gradually varying the real conductance of this tube as a function of the speed of the motor. 11) System according to claim 10, comprising a group of impedance devices arranged in two phases of the motor supply circuit and having their circuits' secon- <Desc / Clms Page number 36> EMI36.1 daires ordered by au. at least two electron tubes so that the values of these impedances included in these two phases vary in opposite directions 1.'ime with respect to 1 'avt.re 12) System according to claim 11, comprising four impedance devices having their primary windings connected in bridge, the input terminals thereof ^ both connected to two phases of the supply circuit and its output terminals being connected to, two phases of the primary winding of the motor. 13) System according to claim 12 wherein the control windings of each naare of impedance devices placed in opposite branches of the bridge, are connected in series with each other and with an adjustable electron tube. 14) System according to any one of claims 10 to 13 wherein the impedance devices are saturation core inductors and the control winding circuits include an AC voltage source in addition to the tubes EMI36.2 These electronic devices cause a unidirectional current of a controlled magnitude to circulate in the control windings. 15) Control system of 1J1ote1Jr, C01 "nT '' '' nnt vn polyphase alternating current motor one circuit \ J01y" h '-' sÓ: <Day alim811ter ce nlOtel.1r, a control device Pn asymmetric relation with this circuit for varying the distribution -, o7.v- 'based on this power supply in order to adjust the tar2ctrÍsti (, vG "speed-torque" of this)! Iotel1r, this control device cO' (1 ') rcn '-' Dt a transformer including 7 ', W "C'11.9-'ctlt Y?' i" 111? '11r'-'. 3, impedance is inserted 'in this circuit and ^' ^ 11'i a el, .rnlÜe '.. ,,' J ':: 1t 5eC0Cld! A.1.7 e, hn Electronic tube rC: 7¯l nor S " l¯ ^ r, 7C this secondary winding to be pillent '' 'j? c the C011l'P: lt in (hJi t in this secondary and 2T'nt 1T17 circuit do CO "' '' '' 1'1.d '':. 'proi = fl vai-ler im6dpnce 1'1 \ 13118 due to this tube 8' (1 function of this Cn ', oi "Y'i', J '' t. iii-i adjustment device of ē2sio, 2 ral¯ia this circuit of zôr <:. i #: nde <Desc / Clms Page number 37> and associates with the motor for the purpose of applying to this control circuit a variable voltage whose value depends on the speed of the motor. 16) Control systems for polyphase motors, in substance as described above and shown in the accompanying drawings.