EP0045675B1 - Steuerschaltung und Regelung der Geschwindigkeit der Umdrehungszahl eines Läufers, insbesondere der drehenden Anode einer Röntgenröhre - Google Patents

Steuerschaltung und Regelung der Geschwindigkeit der Umdrehungszahl eines Läufers, insbesondere der drehenden Anode einer Röntgenröhre Download PDF

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Publication number
EP0045675B1
EP0045675B1 EP19810401155 EP81401155A EP0045675B1 EP 0045675 B1 EP0045675 B1 EP 0045675B1 EP 19810401155 EP19810401155 EP 19810401155 EP 81401155 A EP81401155 A EP 81401155A EP 0045675 B1 EP0045675 B1 EP 0045675B1
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Prior art keywords
voltage
circuit
terminals
fraction
phase
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French (fr)
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EP0045675A1 (de
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Raoul Setbon
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/66—Circuit arrangements for X-ray tubes with target movable relatively to the anode

Definitions

  • the invention relates to a circuit for controlling and regulating the speed of rotation of a drive rotor, in particular that of a rotating anode of an X-ray tube, intended to maintain a substantially constant speed and to allow, for example, the application of the very high voltage between the anode and the cathode of this tube, as soon as the speed of rotation has reached a preset reference value.
  • relays are often used which are sensitive to a threshold value of a current whose windings are inserted in series with the stator windings constituting respectively the main and auxiliary phases which generate orthogonal magnetic fields and which are supplied respectively by currents out of phase with each other by means of a capacitor in series with the winding of the auxiliary phase, for example, in order to generate a rotating magnetic field.
  • a voltage-sensitive relay which goes into the working position when the alternating voltage across the capacitor exceeds a predetermined threshold is connected in parallel with the phase-shifting capacitor supplying the auxiliary phase.
  • the contacts of three relays are inserted in series in an authorization circuit for energizing the X-ray tube. The disadvantage of this arrangement is that it gives no indication of the actual speed of rotation.
  • This increase in the voltage at the terminals of the winding of the auxiliary phase of the stator with that of the speed of rotation of the rotor is mainly due according to the aforementioned publication, to the increase in the apparent impedance of this winding which is caused by the variable reaction with the speed of the currents induced in the rotor on the stator.
  • the apparent impedance of the winding then has an increasing inductive component which is of opposite sign to that of the capacitive reactance of the phase shift capacitor, which leads to an increase in the current in the auxiliary phase.
  • the relay has a first threshold voltage for which it goes into the working position and a second threshold voltage lower than the first for which it returns to the rest position and which respectively correspond to two speeds of rotation of the low anode away from nominal speed.
  • the relay contact When in the working position, the relay contact authorizes energizing of the X-ray tube. This has the drawback of allowing the tube to be energized, when the voltage across the auxiliary phase winding exceeds a threshold which can also come from an increase in the voltage of the supply network, even with the rotor stopped, for example, because of a main phase cut. It will therefore be necessary to stabilize the stator supply voltage.
  • the circuit which is the subject of the invention not only makes it possible to alleviate the above drawbacks and to authorize the application of very high voltage only when a predetermined speed of rotation, close to its set value is reached and to inhibit this application or to stop it when this speed has not yet been reached or has fallen below this set speed, but also the regulation of this speed by putting in series with the supply of the two phases d '' a continuously variable ballast between two resistance values.
  • a circuit for controlling and regulating the speed of rotation of a rotor in particular that for driving a rotating anode of an X-ray tube of the type in which this rotor, disposed inside a glass envelope, is driven using a rotating magnetic field generated by means of a stator located outside the envelope and comprising at least two pairs of windings, the first of which constitutes the main phase and the second the auxiliary phase and whose respective axes of symmetry, normal to the axis of rotation of the rotor, are angularly offset relative to each other, these two phases being joined together by one of their terminals to constitute a common power supply terminal coupled to one of the terminals of a single-phase alternating voltage source, the other terminal of the main phase being connected directly and the other terminal of the auxiliary phase being connected by means of a capacitor phase shift, at the other terminal of the so single-phase urce, which circuit includes first comparison means providing a first signal which indicates that the voltage across the main phase has reached or exceeded a fixed and pre
  • FIG. 1 a schematic section of the rotor which carries the rotating anode of the X-ray tube and which is arranged inside the glass envelope 2, shown in dotted lines.
  • the stator 3 comprises two pairs of windings 4 and 5 wound on a magnetic circuit (not shown), intended to generate two alternating and orthogonal magnetic fields, passing through the rotor 1 composed, for example, of a hollow outer cylinder of conductive material , such as copper, and possibly an inner cylinder also made of ferromagnetic material, such as soft iron or an alloy with low remanence, fitted one on the other and supported by two bearings or bearings.
  • the first terminal 6 of the first pair of windings 4 which are connected in series and arranged on either side of the casing 2, which constitute the main phase, is connected to a first output terminal 11 of a source of single-phase alternating voltage 10, such as a cycloconverter (possibly static) or multiplier (doubler or tripler) of conventional frequency, whose inputs 12 are supplied by the single- or three-phase distribution network (50 or 60 Hz) and which provides a higher frequency alternating voltage (150 or 180 Hz, for example) than the network, making it possible to reach a rotation speed of between 8,000 and 10,000 rpm.
  • a source of single-phase alternating voltage 10 such as a cycloconverter (possibly static) or multiplier (doubler or tripler) of conventional frequency
  • the first terminal 7 of the second pair of windings 5, also connected in series and constituting the auxiliary phase, is joined to the first output terminal 11 of the source 10 by means of a phase-shifting element 8, constituted here by a capacitor 8, to produce a phase shift between the output 11 and the terminal 7.
  • the second respective terminals of the main 4 and auxiliary 5 phases of the stator 3 are connected together to form a common terminal 9 which is joined, by means of a variable ballast circuit 20, to the other output terminal 13 of the single-phase source 10.
  • This common terminal 9 constitutes for the control and regulation circuit of this figure the reference potential point (or isolated ground).
  • the ballast circuit 20 is a dipole comprising between its terminals 21 and 22 a first ballast resistor 23 (of a few hundred ohms, for example) and, in parallel with this first resistor 23, a bridge composed of four diodes 24, 25, 26 and 27.
  • the common point of the anode of the first diode 24 with the cathode of the second 25 constitutes the first terminal 21 of the ballast dipole 20 and that of the cathode of the third diode 26 with the anode of the fourth 27, its second terminal 21.
  • a power transistor 30 which constitutes a variable resistance element, low in the saturated state and very high in the blocked state, and which varies continuously between these two states.
  • the resistance of the collector-emitter path of transistor 30 constitutes the variable element of the ballast circuit 20 which is in parallel with the first resistance 23 of fixed value.
  • the power transistor 30, of high-voltage type (such as type BU 208 of SESCOSEM having a collector-emitter breakdown voltage V cEx of approximately 1,500 V), has its collector joined to its base by means of a second polarization resistor 31 (of a few kiloohms, for example) which forms with the phototransistor 32 of a first photocoupler 33 a voltage divider providing variable polarization to the transistor 30, when the light-emitting diode 34 whose photoemissive surface is optically coupled on the photosensitive surface of the phototransistor 32, is traversed a current in the direct direction.
  • the control of the ballast resistor 20 between terminals 21 and 22 will be described later.
  • the alternating voltage present between the terminal 6 of the main phase 4 and the common terminal 9 is rectified using a fifth diode 40 which feeds through a third 41 and a fourth resistor 42 in series, which serve to filter and to reduce the level of the rectified, a ⁇ -shaped filter cell composed of a second capacitor 43, a fifth resistor 44 and a third electrochemical capacitor 45.
  • One 46 of the armatures of the second capacitor 43 connected to the junction of the fourth 42 and the fifth 44 resistor is also connected to one of the terminals of a sixth resistor 47, the other terminal of which is connected to the cathode of a Zener diode 48 and to the positive armature of a fourth capacitor 49, for example, electrochemical.
  • the other armature of the second capacitor 43, the respective negative armatures of the third 45 and of the fourth capacitor 49 and the anode of the Zener diode 48 are connected to the common terminal 9.
  • the junction 50 of the cathode of the Zener diode 48 with the resistor 47 and the capacitor 49 provides a stabilized (and filtered) direct voltage, positive with respect to the reference potential of the terminal 9 (of 24 volts, for example) which makes it possible, on the one hand, to supply the five amplifiers operational equipping the circuit and, on the other hand, to develop a fixed reference voltage used for comparison.
  • a first resistive voltage divider composed of a seventh 51 and an eighth resistor 52 in series, is connected to the terminals of the Zener diode 48, their common point 53 joined to the non-inverting input of a first integrated operational amplifier 54 by means of a ninth resistor 55, supplies it with a reference voltage which this amplifier, used as a voltage comparator, compares to a predetermined fraction of the rectified and filtered voltage across the terminals of the third capacitor 45, the level is proportional to the peak value of the alternating voltage supplying the main phase 4.
  • This fraction is supplied by means of a second resistive voltage divider connected in parallel with the third capacitor 45 and comprising a tenth 56 and an eleventh 57 resistor in series whose common point 58 is united, by means of a twelfth resistor 59 (of the same value as the ninth 55), at the inverting input of the first amplifier 54.
  • the fate ie 60 of the first amplifier 54 therefore supplies a positive voltage substantially equal to its supply voltage (high logic state), when the reference voltage applied to its non-inverting input is greater than the fraction of the rectified main phase voltage, applied at its inverting input.
  • the output 60 provides a zero voltage (low state) relative to the reference potential of terminal 9 .
  • the alternating voltage present between the terminal 7 of the auxiliary phase 5 and the common terminal 9 is also rectified by means of a sixth diode 70 whose cathode is connected through a thirteenth 71 and a fourteenth 72 resistance to one of the armatures of a fifth capacitor 73, the other armature of which is connected to the common terminal 9.
  • the common point of the resistor 72 and of the capacitor 73 is also connected to one of the terminals of a fifteenth resistor 74, the l 'other terminal is connected to the positive armature of a sixth capacitor 75, for example, electrochemical whose negative armature is connected to the common terminal 9.
  • the elements 73 to 75 form a filter cell in ⁇ similar to that which is formed by elements 43 to 45.
  • the sixth capacitor 75 is connected in parallel with a third resistive voltage divider of adjustable division factor, which for this purpose is composed of a sixteenth resistor 76, a potentiometer 77 and a seventeenth resistor 78 connected in series.
  • the cursor 79 of the potentiometer 77 thus provides an adjustable fraction of a direct voltage proportional to the peak amplitude of the alternating voltage applied between the terminals 7 and 9 of the auxiliary phase 5.
  • a second operational amplifier 80 is used as a second comparator, the non-inverting input of which is connected, via an eighteenth resistor 81, to the cursor 79 of the potentiometer 77 and the inverting input of which is connected to the junction, one 58 of the second divider 56-57 providing a DC voltage proportional to the peak amplitude of the AC voltage across the main phase 4, via a nineteenth resistor 82.
  • the second operational amplifier 80 makes it possible to compare the peak amplitudes of the two main phases 4 and auxiliary 5.
  • the output 83 of the second comparator 80 is in its high state (where it provides a positive voltage substantially equal to its supply voltage), when the adjustable fraction of the voltage of the auxiliary phase rectified and filtered, taken from the cursor 79 of potentiometer 77, is greater than the fixed fraction of the voltage of the main phase rectified and filtered, on the common point 58 of the second divider 56-57. If the voltage at the terminals of the main phase 4 exceeds that at the terminals of the auxiliary phase 5, the output 83 of the second comparator 80 provides a zero voltage (relative to terminal 9), that is to say a logic state low.
  • the combination comprising the second voltage divider 56, 57 fixed, the third voltage divider 76, 77, 78 adjustable and the second comparator 80 constitutes a means for determining the ratio of the voltages at the respective terminals of the auxiliary 5 and main 4 phases which corresponds at the set speed. More precisely, when there are equality of the fractions of voltages applied to the respective inputs of the second comparator 80, the ratio of the voltage of the auxiliary phase 5 to the voltage of the main phase 4 is equal to the quotient of the division factors of the second and the first divider. This quotient being adjustable using the potentiometer 77, it makes it possible to signal by a change of state (switching) at the output 83 of the second comparator 80 when this voltage ratio has reached its chosen reference value.
  • the output 83 of the second comparator 80 is connected to the anode of a light-emitting diode 35 of a second photocoupler 36, the cathode of which is connected to the anode of a seventh diode 85 and which ensures the isolation between circuits.
  • the cathode of the seventh diode 85 is brought together by means of a twenty-first resistor 86 at the output 60 of the first comparator 54. This gives the light-emitting diode 35 of the second photocoupler 36 only being supplied with current when the output 83 of the second comparator 80 is in its high state and when, at the same time, the output 60 of the first comparator 54 is in the low state.
  • the light-emitting diode 35 only conducts when the peak amplitude of the voltage of the main phase V 4 exceeds a determined value, proportional to the continuous reference voltage V 53 and when the speed of rotation of the rotor 2 is sufficient to that the fraction adjustable as a function of the desired target speed, of the peak amplitude of the voltage of the auxiliary phase V5 exceeds the predetermined and constant fraction of the peak amplitude of the voltage of the main phase V 4 .
  • the light-emitting diode 35 of the second photocoupler 36 illuminates, when it is supplied with direct current, the photosensitive surface of a phototransistor of the NPN type 37, for example, the emitter of which is connected to the ground 38 of the radiological generator (not shown ), for example, and whose collector is connected, via the winding 39 of a relay or a contactor with electromagnetic control, to the positive pole 87 of a DC supply voltage source (+ V DC ).
  • the phototransistor 37 becomes saturated and the movable contacts 61, 62, 63 coupled together pass from their rest position to their working position.
  • the first movable contact 61 connects together two fixed contacts 64 and 65 which are inserted in the authorization circuit for energizing the X-ray tube, located in the X-ray generator, for example.
  • the speed regulation circuit includes a third operational amplifier 90, the non-inverting input of which is connected, via a twenty-second resistor 91, to the cursor 79 of the potentiometer 77 supplying the DC voltage V 79 of which the level represents the above adjustable voltage of the amplitude of the voltage across the auxiliary phase V 6 . It further comprises a fourth operational amplifier 92, the non-inverting input of which is brought together, via a twenty-third resistor 93, at the common point 58 of the second divider 56-57, which supplies the DC voltage V 58 whose level represents the constant fraction of the amplitude of the voltage across the main phase V 4 .
  • the outputs of amplifiers 90 and 92 are respectively connected by means of a twenty-fourth 94 and a twenty-fifth 95 feedback resistance, to their inverting inputs which are. joined together using a twenty-sixth resistor 96.
  • the stages comprising the amplifiers 90 and 92 constitute amplification stages without reverse polarity, with high input impedance. Their outputs supply respectively, via a twenty-seventh 97 and a twenty-eighth 98 resistor, the non-inverting and inverting inputs of a fifth operational amplifier 99.
  • the output 100 of the fifth operational amplifier 99 is joined to its inverting input by a threshold feedback circuit comprising a twenty-ninth resistor 101, an eighth 102, a ninth 103 and a tenth 104 diode in series.
  • a threshold feedback circuit comprising a twenty-ninth resistor 101, an eighth 102, a ninth 103 and a tenth 104 diode in series.
  • the output 100 of the amplifier 99 is joined, moreover, to the common terminal 9 via, on the one hand, a thirtieth resistor 105 and, on the other hand, by an eleventh diode 106 and a thirty and a first resistor 107 in series with the light-emitting diode 34 of the first photocoupler 33.
  • the light-emitting diode 34 of the first photocoupler 33 in series with the eleventh diode 106 have a predetermined conduction threshold which must be reached as soon as the set fraction V 79 of the rectified auxiliary phase voltage has exceeded the fixed fraction V 58 of the voltage main phase rectified.
  • the three diodes 102 to 104 in series with the feedback resistance 101 provide the amplifier 99 with a gain close to its open loop value until its output voltage has reached this conduction threshold. Thereafter its gain is determined by the feedback resistors 101 and input 98 so that the variation of the current in the light-emitting diode 34 is gradual.
  • the output 100 provides a zero voltage (since it is not supplied by a negative voltage with respect to terminal 9).
  • the light-emitting diode 34 of the first photocoupler 33 remains off and the phototransistor 32 remains blocked, so that the high-voltage power transistor 30 becomes saturated during almost all of the alternations of the alternating voltage supplying the windings 4, 5 by the common terminal 9.
  • This saturation occurs shortly after each zero crossing of the alternating voltage due to the conduction thresholds of the transistor 30 and the diodes 24 to 27 of the bridge, two of which are each conductor in series, through intermediary of the collector-emitter path of the transistor 30 which is only polarized through the resistor 31.
  • the residual voltage drop between the terminals 21 and 22 of the ballast circuit 20 is then low (approximately 7 volts) compared to the voltage (of approximately 1000 V peak) supplied by the cycloconverter 10. This allows the starting (starting) of the motor with high currents and voltages, that is to say at full power which is also nt applied during the acceleration phase.
  • the output 100 of the fifth amplifier 99 provides a positive voltage which causes a current through the diode light emitting 34 having the effect of making the phototransistor 32 conductive so that it reduces the bias voltage of the base-emitter junction of the power transistor 30.
  • the resistance of the collector-emitter path of this transistor 30 then increases with the increasing illumination of the phototransistor 32.
  • This increase in the resistance of the collector-emitter path of the power transistor 30 has the effect of reducing the voltage across the main and auxiliary phases by the voltage drop between the terminals 21 and 22 of the ballast circuit 20, so that the currents flowing through them are reduced to their values just necessary to maintain the desired speed of rotation.
  • the rectified and filtered voltages undergo a significant reduction.
  • the fixed contacts of the relay connected by its movable contacts 62 and 63 are respectively connected so as to short-circuit the third 41 and the thirteenth 71 resistance of the respective rectifier circuits of the voltages of the main and auxiliary phases.
  • the ballast circuit 20 can be inserted in the circuit of the primary bearings of a three-phase transformer equipping the cycloconverter 10 which is then a static tripler, whose cold terminals (not connected to the network phases) are then each connected to the junction of the cathode of a diode and the anode of another diode in series, the other electrodes of which are connected respectively to terminals 21 and 22 of the ballast circuit 20 which then appears as a variable resistor in series with the three primary windings.
  • This resistance has the effect of influencing the voltage appearing at the terminals of the series combination of the three secondary windings, which constitute the output terminals 11 and 13 of the cycloconverter 10 which is then of the type with saturable core.
  • NO logic inverter
  • capacitors 14, 15 and 16 of high capacity for example, of the electrochemical type, between the outputs 53, 58 and 79 respectively of the first (51, 52), second ( 56, 57) and third (76, 77, 78) voltage dividers in order to perfect the filtering of the fractions of DC voltages, respectively applied to the inputs of the operational amplifiers 54 and 80.

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Claims (11)

1. Schaltung zur Steuerung und Regelung der Drehgeschwindigkeit eines Rotors (1), insbesondere für den Antrieb einer Drehanode in einer Röntgenröhre, in welcher der im Inneren einer Glashülle (2) angeordnete Rotor (1) durch ein rotierendes Magnetfeld angetrieben wird, das durch einen Stator (3) erzeugt wird, der auf der Außenseite der Hülle (2) angeordnet ist und wenigstens zwei Paare von Wicklungen (4, 5) umfaßt, wovon das erste die Hauptphase (4) und das zweite die Hilfsphase (5) bildet und deren zugehörige, zur Rotationsachse des Rotors senkrechte Symmetrieachsen gegeneinander winkelversetzt sind, wobei diese beiden Phasen (4, 5) miteinander durch einen ihrer Anschlüsse verbunden sind, um einen gemeinsamen Versorgungsanschluß (9) zu bilden, der an einen der Anschlüsse (13) einer einphasigen Wechselspannungsquelle (10) angekoppelt ist, während der andere Anschluß (6) der Hauptphase (4) direkt und der andere Anschluß (7) der Hilfsphase (5) über einen Phasenverschiebungskondensator (8) mit dem anderen Anschluß (11) der einphasigen Quelle (10) verbunden ist, wobei die Schaltung erste Vergleichermittel (54) zum Vergleichen der Spannung der Hauptphase (4) mit einem festen und vorbestimmten Referenzpegel zum Liefern eines ersten Signals, wenn die Spannung der Hauptphase die Referenzspannung überschreitet, und zweite Vergleichermittel (80) zum Vergleichen der Spannung der Hauptphase (4) und der Hilfsphase (5) mit einem einstellbaren Wert enthält, dadurch gekennzeichnet, daß die zweiten Vergleichermittel (80) ein zweites Signal liefern, welches anzeigt, daß das Verhältnis der an den Anschlüssen (6-9, 7-9) der Hilfsphase (5) bzw. der Hauptphase (4) abgenommenen Spannungen einen einstellbaren Wert erreicht oder überschritten hat, der einer gewählten Sollgeschwindigkeit entspricht, und daß sie Kombiniermittel zum .Kombinieren des ersten mit dem zweiten Signal enthält, welche bei der gleichzeitigen Anwesenheit derselben ein drittes Signal liefern, das anzeigt, daß die beiden oben genannten Bedingungen erfüllt sind, insbesondere zur Freigabe des Anlegens der sehr hohen Spannung an den Elektroden der Röntgenröhre.
2. Schaltung nach Anspruch 1, dadurch gekennzeichnet, daß sie einen ersten Gleichrichter (40) und ein in Kaskade folgendes Filter (41-45) enthält, die eine erste Gleichspannung liefern, welche proportional zum Scheitelwert der Wechselspannung an den Anschlüssen (6, 9) der Hauptphase (4) ist ; eine erste, fest eingestellte Potentiometerschaltung (56, 57) umfaßt, die einen ersten vorbestimmten Bruchteil (V58) der ersten Gleichspannung liefert; eine Referenz-Gleichspannungsquelle (47-52) umfaßt ; einen ersten Spannungskomparator (54) enthält, welcher die ersten Vergleichermittel bildet und durch den ersten Bruchteil (Vsa) sowie die konstante Referenzspannung (V53) gespeist ist, um an seinem Ausgang (60) das erste Signal in Form eines ersten vorbestimmten Logikzustandes auszugeben, wenn erstere letztere erreicht oder überschreitet.
3. Schaltung nach Anspruch 2, dadurch gekennzeichnet, daß sie ferner einen zweiten Gleichrichter (70) und ein in Kaskade folgendes Filter (71-75) umfaßt, die eine zweite Gleichspannung liefern, welche proportional zum Scheitelwert der Wechselspannung an den Anschlüssen (7, 9) der Hilfsphase (5) ist ; eine zweite, einstellbare Potentiometerschaltung (76, 77, 78) umfaßt, die einen zweiten, einstellbaren Bruchteil (V79) der zweiten Gleichspannung liefert und Bestandteil der ersten, fest eingestellten Schaltung (56, 57) der zweiten Vergleichermittel ist, die ferner einen zweiten Spannungskomparator (80) enthalten, welcher den zweiten, einstellbaren Bruchteil (V79) mit dem ersten, vorbestimmten Bruchteil (V58) vergleicht, deren Gleichheit ein bestimmtes und einstellbares Verhältnis der Spannungen an den Anschlüssen der Hilfsphase (5) und der Hauptphase (4) darstellt, welches einer gewählten Sollgeschwindigkeit entspricht, wobei der Ausgang (83) des zweiten Komparators (80) das zweite Signal in Form eines zweiten vorbestimmten Logikzustandes liefert, wenn der zweite Bruchteil den ersten erreicht oder überschreitet.
4. Schaltung nach Anspruch 3, dadurch gekennzeichnet, daß die Kombiniermittel eine Schaltung enthalten, welche die Ausgangszustände der beiden Komparatoren miteinander kombiniert und das dritte bzw. Freigabesignal ansprechend auf das gleichzeitige Vorhandensein des ersten und des zweiten Signals an ihren Eingängen liefert.
5. Schaltung nach Anspruch 4, dadurch gekennzeichnet, daß die die Ausgangszustände der zwei Komparatoren (54, 80) kombinierende Schaltung einen Optokoppler (36) umfaßt, dessen Leuchtdiode (35) zwischen die Ausgänge (83, 60) derselben eingefügt und so angeschlossen ist, daß sie einen ausreichenden Strom zieht, damit die so erzeugte Strahlung den Fototransistor (37) dieses Optokopplers (36) nur dann in die Sättigung bringt, wenn einer (60) der Ausgänge einen niedrigen Logikzustand liefert, der anzeigt, daß der erste Bruchteil (Vss) die Referenzspannung (Vss) überschreitet, und wenn der andere Ausgang (83) einen hohen Logikzustand liefert, welcher anzeigt, daß das der Sollgeschwindigkeit entsprechende Verhältnis erreicht oder überschritten ist, wobei die Sättigung des Fototransistors (37) in der Steuerschaltung für das Anlegen der Spannung an die Röhre die kontinuierliche Freigabe ermöglicht und wobei der Optokoppler (36) eine Isolierung zwischen den Schaltungen gewährleistet.
6. Schaltung nach einem der Ansprüche 3 bis 5, dadurch gekennzeichnet, daß sie einen Operationsverstärker (99) enthält, dessen differenzielle Eingänge mit dem ersten (Vss) bzw. mit dem zweiten (V79) Bruchteil gespeist werden, und eine Ballastschaltung (20) in Form eines Zweipols umfaßt, dessen Anschlüsse (21, 22) in den Versorgungskreis der beiden Phasen (4, 5) zwischen ihren gemeinsamen Anschluß (9) und einen (13) der Anschlüsse der einphasigen Quelle (10) eingefügt sind, wobei diese Ballastschaltung (20) einen Widerstand bildet, der kontinuierlich veränderbar ist zwischen einem minimalen Wert, den er während des Anlaufens und der Beschleunigung des Rotors (2) aufweist, bis der zweite Bruchteil (V79) den ersten (V58) geringfügig überschritten hat, und einem maximalen Wert, der mittels eines ersten festen Widerstandes (23) bestimmt wird, welcher zwischen ihre Anschlüsse (21, 22) geschaltet ist.
7. Schaltung nach Anspruch 6, dadurch gekennzeichnet, daß die Ballastschaltung (20) eine Gleichrichterbrücke umfaßt, die aus vier Dioden (24 bis 27) zusammengesetzt ist, deren Eingangsdiagonale (21, 22) die Anschlüsse des Zweipols bildet und die ferner einen Leistungstransistor (30) enthält, der über seine Kollektor-Emitter-Strecke zwischen die Anschlüsse (28, 29) ihrer Ausgangsdiagonale geschaltet ist und dessen Basis mit seinem Kollektor über einen Polarisationswiderstand (31) verbunden ist, der bei Abwesenheit des Signals aus dem Operationsverstärker (99) die Sättigung des Transistors (30) nach jedem Nulldurchgang der Spannung hervorruft, die von der einphasigen Quelle (10) geliefert wird, so daß seine Kollektor-Emitter-Strecke den ersten Widerstand (23) überbrückt.
8. Schaltung nach Anspruch 7, dadurch gekennzeichnet, daß ein Element mit variablem Widerstand (32), dessen Widerstandswert so gesteuert ist, daß er mit zunehmender Differenz zwischen dem zweiten (V79) und dem ersten Bruchteil (V58) abnimmt, zwischen Basis und Emitter des Transistors (30) geschaltet ist, um die Polarisation des Transistors (30) zu vermindern und infolgedessen den Widerstand seiner Kollektor-Emitter-Strecke in Abhängigkeit von dieser Differenz zu vergrößern, wenn diese positiv ist.
9. Schaltung nach Anspruch 8, dadurch gekennzeichnet, daß das Element mit variablem Widerstand durch einen Fototransistor (32) eines weiteren Optokopplers (33) gebildet ist, dessen Kollektor-Emitter-Strecke zwischen die Basis und den Emitter des Leistungstransistors (30) geschaltet ist, während die Leuchtdiode (34) dieses weiteren Optokopplers (33) zwischen den Ausgang (100) des Differenzverstärkers (99) und den gemeinsamen Anschluß (9) eingefügt ist, so daß in ihr ein Strom fließt, der mit der Differenz zwischen dem zweiten (V79) und dem ersten Bruchteil (V58) variiert, sobald diese positiv geworden ist.
10. Schaltung nach den Ansprüchen 6 bis 9, dadurch gekennzeichnet, daß der Ausgang (100) des Operationsverstärkers (99) mit seinem invertierenden Eingang über eine einen Schwellwert aufweisende Gegenkopplungsschaltung (101, 102, 103, 104) verbunden ist, die einen Gegenkopplungswiderstand (101) enthält, der es ermöglicht, seine Verstärkung beträchtlich zu reduzieren, sobald eine Schwellspannung überschritten wird, die durch Elemente (102-104) bestimmt wird, welche einen Leitungs-Schwellwert aufweisen und in Reihe mit diesem Widerstand (101) geschaltet sind und den Leitungs-Schwellwert insbesondere der Leuchtdiode (34) des anderen Optokopplers (33) kompensieren.
11. Röntgenstrahlen-Generator mit einer eine Drehanode aufweisenden Röntgenröhre, dadurch gekennzeichnet, daß er eine Schaltung zur Steuerung und Regelung der Rotationsgeschwindigkeit der Anode nach einem der vorstehenden Ansprüche aufweist.
EP19810401155 1980-07-25 1981-07-21 Steuerschaltung und Regelung der Geschwindigkeit der Umdrehungszahl eines Läufers, insbesondere der drehenden Anode einer Röntgenröhre Expired EP0045675B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8016491 1980-07-25
FR8016491A FR2487540A1 (fr) 1980-07-25 1980-07-25 Circuit de controle et de regulation de la vitesse de rotation d'un rotor et notamment celui d'une anode tournante de tube radiogene

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EP0045675A1 EP0045675A1 (de) 1982-02-10
EP0045675B1 true EP0045675B1 (de) 1984-05-02

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EP19810401155 Expired EP0045675B1 (de) 1980-07-25 1981-07-21 Steuerschaltung und Regelung der Geschwindigkeit der Umdrehungszahl eines Läufers, insbesondere der drehenden Anode einer Röntgenröhre

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Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2185826A (en) * 1938-06-07 1940-01-02 Gen Electric X Ray Corp Rotatable anode x-ray tube
US3094618A (en) * 1961-05-23 1963-06-18 Picker X Ray Corp X-ray tube protection mechanism
FR1372570A (fr) * 1963-08-02 1964-09-18 Picker X Ray Corp Waite Mfg Perfectionnements aux appareils à rayons x
US3518434A (en) * 1968-03-13 1970-06-30 Picker Corp X-ray tube rotatable anode control circuit with means to sense and control anode motor current
US3564254A (en) * 1968-07-17 1971-02-16 Westinghouse Electric Corp Spin motor controller for a rotating anode motor of an x-ray generator tube
DE2356459C2 (de) * 1973-11-12 1983-08-25 Siemens AG, 1000 Berlin und 8000 München Röntgendiagnostikapparat für Durchleuchtung und Aufnahme mit einer Drehanoden- Röntgenröhre und einem Leistungssteller für den Übergang von Durchleutung auf Aufnahme
DE2815893A1 (de) * 1978-04-12 1979-10-18 Siemens Ag Roentgendiagnostikgenerator mit einem den hochspannungstransformator speisenden wechselrichter

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FR2487540A1 (fr) 1982-01-29
DE3163389D1 (en) 1984-06-07
FR2487540B1 (de) 1983-08-05
EP0045675A1 (de) 1982-02-10

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