DE2053077B2 - CIRCUIT ARRANGEMENT FOR SUPPLYING THE DRIVE MOTOR OF THE ROTATING ANODE OF A ROENTINE TUBE - Google Patents

Description

The invention relates to a circuit arrangement for supplying the from an asynchronous motor existing drive motor of the rotating anode of an X-ray tube with at least one converter, the the frequency of the supply voltage during the rotary node start-up the grid frequency increased.

It is known (Siemens prospectus T 40/046 d [7 a] Kinopulsröhren BIANGULIX-RAPID 8500 U / min), a single-phase asynchronous motor with a To use auxiliary winding, which is fed by a converter that has an output voltage a frequency of 150H / higher than the mains frequency. At the transition from x-ray fluoroscopy The drive motor is switched on for an X-ray exposure and the rotating anode runs at a speed of around after it has started up Revolutions per minute. The X-ray tube is because of this high, through the frequency conversion Relatively high load capacity due to the anode speed.

The start-up time, after which the anode reaches its final speed when using a certain drive motor has reached. in the known arrangement depends on the one on the drive motor! Tension off. Because this tension from isolatiotiitechnischen For reasons that cannot be increased at will, the start-up time is limited.

ίο With that from one fluoroscopy to one quickly Admission can be skipped, one strives to to keep the starting time of the rotating anode as short as possible. Start-up times below a lower one However, with the known arrangement, the limit value of about 0.8 seconds is reasonable not reachable.

Through the magazine PROCIEE. Vol. 113. No. 10. 1966. pp. 1617 to 1623. it is known that This reduces the start-up time of an induction machine can be that the frequency during de Start-up of the induction machine is increased. In this reference are abe; no indications given according to which function the frequency must be increased during start-up. so that the smallest possible Start-up time results.

It is the object of the invention. a circuit arrangement of the type mentioned at the beginning, in which with relatively little circuitry] Effort, especially with a relatively low supply voltage of the drive motor, the The smallest possible starting time of the rotating anode can be achieved.

According to the invention, this object is achieved in that control means are assigned to the converter are, through which the frequency of the supply voltage during ces anode start-up the breakdown torque curve can be increased accordingly to a value above the final value and then to the final value is lowerable. The torque of the drive motor then has at every point in time during start-up its maximum value when the supply frequency and the rotor speed at any point in time during start-up is just that big. that there is a tilting moment. The invention makes use of this knowledge. As a result of the change in the frequency of the supply voltage according to the invention, at every point in time the maximum possible torque and thus the shortest possible start-up time.

Further details of the invention emerge from the following description of an exemplary embodiment in connection with the drawing.

In Fig. 1, the course of the torque is dependent on the speed of an asynchronous motor shown for different frequencies of the supply voltage,

Curve 1 applies, for example, to a frequency of 50 Hz, curve 2 to a frequency of 150 Hz and curve 3 for a frequency of approximately 180 Hz. From FIG. 1 clearly shows that The lower the frequency of the supply voltage, the greater the initial torque of an asynchronous motor is.

Therefore, according to the invention, the drive motor consisting of an asynchronous motor for The rotating anode of an X-ray tube is initially operated at a low frequency of 50 Hz, for example and the frequency during start-up

After the Uberg an ν on

ierlich according to the increase in the speed of the drive motor until the desired one is reached Final value increased. This way, the lead time can compared to an operation in which the drive motor is already switched on, with a supply voltage is fed by the end frequency, can be shortened significantly.

An optimal start-up time is achieved when de ζ ^

Frequency of the supply voltage corresponding to the £; ^ '^ V.,. _{15 "EÖ} opened and the time 2s again Kippmomentverlauf _{Swiss cooperative} aut io Schalterpaa · ι = _e offscale _{and the} switch is increased a value which is a start-up of the S'halterpa · _o ^ _{hMerte z, klus}

Asynchronous motor until it reaches the final rotation J """ ^e ! °" ^ idh

ilf d h t

H ie at

p ^^ Sung to an A ™ consecutively in

^ fT, pair of switches 17 resolved and punW21 the & * £ Φ _{iffl Zeilpunkt 22} ^

SchaUerpa. * » _{And the} switch pair 16 Zritpunkt 23 the switch pair 17 open-switch pair 18» closed. "closed and _15" in the witnesses, _fire lterpaar ^ _EÖ opened and re ι at the time 2s = _{ed the} switch

Asynchronous motor up to the E

number according to the breakdown torque curve, ie with the breakdown torque corresponding to the respective feed frequency, guaranteed. When the final speed is reached. So acceleration is no longer required. In this case, the feed frequency is reduced to its final value. In FIG. 1 is the uie torque characteristic of the drive motor like curve 4, which is shown for this case gil '. Curve 4 is based on an initial frequency of 50Hz (curve 1), a highest frequency of about 80Hz, curve 3), corresponding to the breakdown torque curve, and an end frequency of b Hz (Kune2) of the supply voltage. With Ml, V / 2 and M 3 in FIG. 3 denotes the breakdown moments occurring at the Spe.sefrequenzen of 50 Hz, 150 Hz and 180 Hz. The tilting moment therefore runs as a function of the supply frequency in accordance with curve 4.

In FIG. 2 is the block diagram of an exemplary embodiment of the subject matter of the invention. The drive motor for the rotating anode de X-ray tube is a single-phase asynchronous motor with a rotor =, a main winding6 and e.ner Auxiliary winding 7. The windings 6 and 7 are fed by converters 8 and 9, which are at the output a rectifier 10 are connected. The rectifier 10 is connected to the lb

d wechseInd! ° "^ _sc h repeated.

J ₁ ^ actuation of the switch pairs I _{3 in the} ° distributor 14 controlled.

«Te control oscillator 12 from _{g to the} j _that ^ _dw

^a " ^S

Rectifier
Three-phase network can be connected.

The frequency of the output voltages of the stirrers and9, i.e. the frequency of the supply voltage for windings 6 and 7 is adjustable. A control oscillator 12, the frequency of which g

by means of an arrangement ₃ 13 during the start-up time 45 ^we ™ J ™; of the rotor 5 from an initial value to an end Be, ^d J [P ^r

υm ^^ ^

^^, ₆ flowing through stream opposite

™ " ^ρ ί £"? _F " _windlun " 7 durchflieb: nden Strom phadem de auxiliarysw, cUun ₌

^ of the control oscillator 12 must. like ^^ ^ ^ to _be ^

di supply voltage of the winding

^^^ t ^ mi. dawn from that to educate6 and 7 ..aL oen Rotors _£ . ^ _Fri _

tion of a tendon Hen ^ ¹⁸ " _{5Q f 180 Hz increased [} quenzder Sp ^ Ρ ™ | ^ _{voli 150} Hz lowered and Jann? ut the tna 4 _{the output voltage} .

™ ^ ° \ Z ™ ^ s 12 the area between

»""«>"Can cross over _QR. Through the 200 and 7-0 Hz ud _{the pf des}

Schaj "arrangement" _{shooting of the} ^ _x

increased and lowered from 200 to 720Hz. The function after the ^^ ^ J _{olt and the} time within the «^^^^", j J _et , _who the dabe. once tube, ie for a particular one

^ SS SiSne of achieving an optima- Ar.tneb >

F ^ has aezHet that through the inventive

achieved bs change "the frequency of the supply voltage ^" 5 ^{a "d"} ^ _{a, the rotary anode} ⁴ a Verkürde Antrieb.mo ^ ^ ^ r ors ₀ ** _{5 seconds} of wetting Anlautzeit aui

Execution of the FIG. ^S _l Shle

50

and a pair of contacts 16 which the main leakage alternately apply DC voltage. In the same way, the converter contains 9 pairs of contacts 17 and 18, which the auxiliary winding 7 alternately to DC voltage, d. H. to the output voltage of the

sem rough _three- phase output voltage

r provided that by means of a

^r ^ ^, _d ^ its output ^

S? The rotor itself starts is the tension on the main winding 6, the course of which is the curve in FIG. 4 against the voltage

and 7 roughly rectangular tensions 60 _νν ° ^ _3β ^εΐ ^ _η £ ^ ί _η ^ϋη _ε ! _{η6Γη of the} two Umrich ^erS S? ^ h ^ v ^ dnjpr seconds ^ e-

^^^ torwickg connected to DC voltage speaking Motorw g ^^ _{dne Abb} remsung

^{Make 5} blotors and the rotating anode.

1 sheet of drawings

Claims (5)

Patent claims: 1. Circuit arrangement for feeding the off an asynchronous motor existing drive motor of the rotating anode of an X-ray tube with at least a converter that adjusts the frequency of the supply voltage during the starting of the rotating anode increased compared to the mains frequency, thereby characterized in that the converter (8. 9} Control means (12 to 14) are assigned by which the frequency of the supply voltage during of the anode start-up to a value above the final value corresponding to the breakdown moment The value can be increased and then reduced to the final value. 2. Circuit arrangement according to claim 1. with eini-m single-phase motor with main and auxiliary windings as a drive motor, characterized in that that a converter (8. 9) is connected to each of the main and auxiliary windings (6. 7) and the control means (12 to 14) for the converters (6, 7) include an arrangement (14;) which is the supply voltage for the auxiliary winding (7) compared to the supply voltage for the main winding (6) can be moved by 9 (). 3. Circuit arrangement according to claim 2, characterized in that the converter (8, 9) are powered by a DC voltage Umpoischaiter from a StciierosLillator (12) with variable frequency are controllable. 4. Circuit arrangement according to Ai.ipruch 3. characterized in that between the control oscillator (12) and the converter (8. 9) a pulse distributor (14) is connected. through which the output pulses of the control oscillator (12) alternately in each case one of the converters (8, 9) for its switchover are supplied. 5. Circuit arrangement according to claim 2, characterized in that for braking the Drive motor and the rotating anode at least one of the motor windings (6. 7) during some Seconds can be applied to DC voltage.