NO125023B

NO125023B -

Info

Publication number: NO125023B
Application number: NO4659/69A
Authority: NO
Inventors: J Milavec
Original assignee: Bbc Brown Boveri & Cie
Priority date: 1968-11-26
Filing date: 1969-11-24
Publication date: 1972-07-03
Also published as: BE742114A; NL6917643A; AT291396B; FR2024243A6

Description

Innretning for regulering av en likestrømelektromotors turtall samt feltsvekningsområde. Device for regulating a direct current electric motor's speed and field weakening range.

Oppfinnelsen vedrorer en innretning for regulering av turtall samt feltsvekningsområde for en kollektormotor som mates av en likestromkilde via en likestromregulator, som er innkoblet mellom likestromkilden og rotoren og hvor feltviklingen i serie med en forste diode er parallellkoblet rotoren på en slik måte at strora-mene fra likestromregulatoren og denne seriekobling gjennomflyter rotoren i samme retning, og feltviklingen er parallellkoblet en andre diode slik at de to dioder er forbundet med feltviklingen med samme polaritet. The invention relates to a device for regulating speed and field weakening range for a collector motor which is fed by a direct current source via a direct current regulator, which is connected between the direct current source and the rotor and where the field winding in series with a first diode is connected parallel to the rotor in such a way that the currents from the direct current regulator and this series connection flow through the rotor in the same direction, and the field winding is connected in parallel with a second diode so that the two diodes are connected to the field winding with the same polarity.

En slik innretning er kjent fra norsk patent nr. 121.907 Such a device is known from Norwegian patent no. 121,907

og er vist skjematisk i fig. 1. Denne innretnings funksjon skal and is shown schematically in fig. 1. The function of this facility shall

beskrives kort nedenfor. Ved avbrytning av strommen gjennom regulatoren St kommuterer rotorstrommen I 3 på feltviklingen F og frilopdioden Dl. Hvis regulatoren igjen kobler inn, kommuterer feltstrommen på feltfrilopdioden D2. Som det fremgår, skjer en svek-ning av feltstrommen relativt rotorstrommen når avfolingsforhold-et T^nn/T (innkoblingstid/periodetid) går mot 1. Strommen gjennom regulatoren St er null når Dl begynner å fore en strom. Begynnelsen av strommen j FD gjennom frilopdioden Dl registreres med en "anodestrbmomformer" T. For nå å garantere det nodvendige og minimalt tillatelige magnetiseringsfelt kobler man samtidig med begynnelsen av strommen J„_. inn et tids ledd (f. eks. en monostabil multivibrator) som er avhengig av motorturtallet eller rotorstrommen, og utloser forst etter dettes forlop den neste tennpuls i regulatoren St. is briefly described below. When the current is interrupted through the regulator St, the rotor current I 3 commutes on the field winding F and the free-wheeling diode Dl. If the regulator switches on again, the field current on the field free-op diode D2 commutes. As can be seen, a weakening of the field current relative to the rotor current occurs when the winding ratio T^nn/T (switch-on time/period time) goes towards 1. The current through the regulator St is zero when Dl starts to conduct a current. The beginning of the current j FD through the free-loop diode Dl is registered with an "anode current transformer" T. In order to now guarantee the necessary and minimally permissible magnetizing field, one connects at the same time as the beginning of the current J„_. into a period of time (e.g. a monostable multivibrator) which is dependent on the engine speed or the rotor current, and only triggers the next ignition pulse in the regulator St.

Med denne metode er det imidlertid ikke helt enkelt å oppnå en stor noyaktighet, for på den ene side er den noyaktige bestemmelse av begynnelsen av strommen Jpjj med hensyn på forstyrrelse av strom-okningen på grunn av koblingskapasiteten meget vanskelig å virke-liggjøre i praksis, og på den annen side er tidsleddets forsinkel-sestid liten i forhold til periodetiden, og selv små tidsforand-ringer bevirker store feltstyrkeforandringer. Dessuten krever dette tidsleddets avhengighet av rotorstrommen eller turtallet en hensyntagen til motorkarakteristikken. With this method, however, it is not entirely easy to achieve great accuracy, because on the one hand, the precise determination of the beginning of the current Jpjj with regard to disturbance of the current increase due to the switching capacity is very difficult to realize in practice, and on the other hand, the delay time of the time link is small compared to the period time, and even small time changes cause large field strength changes. Moreover, the dependence of this timing element on the rotor current or speed requires consideration of the motor characteristics.

Formålet med oppfinnelsen er å tilveiebringe en innretning av den innledningsvis nevnte art som muliggjor en mer noyaktig regulering av den automatiske feltsvekning av en likestromregulator. The purpose of the invention is to provide a device of the type mentioned at the outset which enables a more precise regulation of the automatic field weakening of a direct current regulator.

Innretningen kjennetegnes ved en direkte måling av rotorstrommen og feltstrommen og en regulert begrensning av forholdet rotorstrom/ feltstrom til en på forhånd bestemt verdi på en slik måte at det til onskerotorstrommen svarende analogsignal som av en forste diodeekstremverdikobling begrenses til en av en konstant spenning bestemt maksimalverdi, over en forste blandemotstand tilfores et forste blandepunkt, hvilket blandepunkt samtidig også over en andre blandemotstand av samme storrelse tilfores det fra en likestromomformer leverte analogsignal for realrotorstrommen, at dette real-rotorstrbm-analogsignal videre over en blandemotstand av samme storrelse tilfores et andre blandepunkt, hvilket blandepunkt samtidig også over en ytterligere blandemotstand hvis storrelse er f ganger storre enn den for den andre blandemotstand - hvorved f betyr den minimalt tillatelige magnetiseringsgrad - tilfores det fra en ytterligere likestrbmomformer leverte med hensyn på real-rotorstromsignalet motsatte analogsignal for feltstrommen, at det forste blandepunkt og det andre blandepunkt på utgangssiden er direkte tilkoblet inngangen på hhv. en forste og en andre reguleringsforsterker, hver av hvilke er forsynt med et stabiliseringsledd, og at de negative utgangsspenninger fra de to reguleringsforsterkere tilfores en andre diodeekstremverdikobling som utvelger den storre av de to spenninger og tilforer regulator-styresettet denne negative regulatorspenning. The device is characterized by a direct measurement of the rotor current and the field current and a regulated limitation of the ratio rotor current/field current to a predetermined value in such a way that the analog signal corresponding to the desired rotor current is limited by a first diode extreme value circuit to a maximum value determined by a constant voltage, across a first mixing resistor, a first mixing point is fed, which mixing point is simultaneously also fed across a second mixing resistor of the same size, the analog signal for the real rotor drum delivered from a direct current converter is fed, that this real-rotorstrbm analog signal is further fed across a mixing resistor of the same size to a second mixing point, which mixing point at the same time also across a further mixing resistance whose size is f times greater than that of the other mixing resistance - whereby f means the minimum permissible degree of magnetisation - it is supplied from a further direct current converter supplied with regard to the real rotor current signal opposite e analog signal for the field current, that the first mixing point and the second mixing point on the output side are directly connected to the input of a first and a second control amplifier, each of which is provided with a stabilization link, and that the negative output voltages from the two control amplifiers are fed to a second diode extreme value switch which selects the larger of the two voltages and supplies the regulator control set with this negative regulator voltage.

Oppfinnelsen skal nærmere beskrives nedenfor under henvisning til fig. 2. Rotorstrommens onske-verdi angis av et dertil proporsjonalt positivt spenningssignal i form av en regulerbar likespenn-ing C. Den positive spenning D tilsvarer den maksimalt tillatelige rotorstrom. Denne begrenser spenningen C oppad ved hjelp av en av dioder G,. og G, bestående ekstremverdikobling hvis felles kob-lingspunkter er tilkoblet en p^ ositiv konstantstromkilde I const. og hvilken på kjent måte påtrykker den mindre av de to spenninger C og D dette koblingspunkt. The invention will be described in more detail below with reference to fig. 2. The rotor current's desired value is indicated by a proportional positive voltage signal in the form of an adjustable DC voltage C. The positive voltage D corresponds to the maximum permissible rotor current. This limits the voltage C upwards by means of one of the diodes G,. and G, existing extreme value connection whose common connection points are connected to a positive constant current source I const. and which, in a known manner, applies the smaller of the two voltages C and D to this connection point.

Dette signal som er proporsjonalt med den oppad begrensede bnske-rotorstrom I . blir over en forste blandemotstand R tilfort et This signal is proportional to the upwardly limited Swedish rotor current I . is added across a first mixing resistor R

as as

forste blandepunkt Ml som samtidig over en andre blandemotstand av samme storrelse R tilfores et andre signal i form av en nega-tiv spenning som er proporsjonal med rotorstrommens real-verdi I ax.. Denne spenning leveres av en likestromomformer A som på primaersiden er innkoblet i rotorstromkretsen (fig. 1) . Ved addi-tiv blanding av de to signaler oppstår således i blandepunktet Ml et reguleringsavvikningssignal som er proporsjonalt med diffe-ransen mellom rotorstrommens onske-verdi og real-verdi. Dette signal tilfores inngangen på en reguleringsoperasjonsforsterker first mixing point Ml which at the same time via a second mixing resistance of the same size R is supplied with a second signal in the form of a negative voltage which is proportional to the real value of the rotor current I ax.. This voltage is supplied by a direct current converter A which on the primary side is connected in the rotor current circuit (fig. 1) . By additive mixing of the two signals, a control deviation signal is thus produced at the mixing point Ml which is proportional to the difference between the rotor current's desired value and actual value. This signal is fed to the input of a control operational amplifier

E. E.

En andre reguleringsforsterker F mottar et reguleringssignal fra et andre blandepunkt M2. På inngangssiden blir dette blandepunkt for det forste - og vel å merke igjen over en blandemotstand av storrelsen R - tilfort nevnte signal som er proporsjonalt med rotorstrom-realverdien I . og for det andre - over en f ganger storre blandemotstand (f.R) hvorved f er den minimalt tillatelige magnetiseringsgrad - tilfort et signal som er proporsjonalt med feltstrom-realverdien (If). Dette signal leveres av en andre likestromomformer B som på primærsiden er innkoblet i magnetiserings-feltstromkretsen (fig. 1). A second regulation amplifier F receives a regulation signal from a second mixing point M2. On the input side, this mixing point is firstly - and again, again above a mixing resistance of the size R - added to said signal which is proportional to the rotor current real value I . and secondly - across an f times greater mixing resistance (f.R) whereby f is the minimally permissible degree of magnetisation - a signal is added which is proportional to the field current real value (If). This signal is supplied by a second direct current converter B which is connected on the primary side to the magnetizing field current circuit (fig. 1).

De to reguleringsforsterkere E og F er tilkoblet med tilsvarende stabiliseringsledd T a hhv. Tf,.. The two control amplifiers E and F are connected with corresponding stabilization links T a respectively. Tf..

Så lenge feltstrommens og rotorstrommens kvotient er storre enn f, forblir reguleringsforsterkerens F utgang i den negative begrensning. Hvis imidlertid kvotienten forsoker å underskride verdien f, blir utgangsspenningen fra reguleringsforsterkeren F akk-urat så positiv at kvotienten ikke kan underskride verdien f for-di den negative reguleringsspenning V blir tilsvarende positiv. As long as the quotient of the field current and the rotor current is greater than f, the control amplifier's F output remains in the negative limitation. If, however, the quotient tries to fall below the value f, the output voltage from the regulation amplifier F becomes precisely so positive that the quotient cannot fall below the value f because the negative regulation voltage V becomes correspondingly positive.

Reguleringsforsterkerenes E.og F utganger tilfores en andre diode-ekstremverdikobling som består av diodene Gj og Gg. Denne koblings stjernepunkt er forbundet med en ytterligere positiv konstantstromkilde Iconst 0<3 leverer den negative reguleringsspenning V. Diodene G7 og Gq er slik polet av V tilsvarer maksimum for de to negative reguleringsforsterkerutganger. The regulation amplifiers' E. and F outputs are fed to a second diode-extreme value circuit consisting of the diodes Gj and Gg. The star point of this link is connected to a further positive constant current source Iconst 0<3 supplies the negative regulation voltage V. The diodes G7 and Gq are such that the pole of V corresponds to the maximum of the two negative regulation amplifier outputs.

Stabiliseringsleddene Ta og Tf er koblet etter diodene G^ resp. Gq. Derved unngås metningseffekter og overforingsvanskeligheter mellom de to reguleringsforsterkere. The stabilization links Ta and Tf are connected after the diodes G^ resp. Gq. This avoids saturation effects and transfer difficulties between the two control amplifiers.

Ved en "vanskelig" start med maksimal strom er altså til å begyn-ne med kun regulatorforsterkeren E i drift og sorger for maksimal strom ved stigende rotorspenning. Etter oppnåelse av den maksimalt mulige driftspenning over rotoren, holder reguleringsforsterkeren E rotorstrommen konstant. Nå reduseres imidlertid magnetiserings-feltet, og således tiltar feltsvekningen. In the case of a "difficult" start with maximum current, it is therefore possible to start with only the regulator amplifier E in operation and ensures maximum current when the rotor voltage rises. After reaching the maximum possible operating voltage across the rotor, the regulation amplifier E keeps the rotor current constant. Now, however, the magnetizing field is reduced, and thus the field weakening increases.

Når den maksimale feltsvekning oppnår (I.e/I_ = f) , trer reguleringsforsterkeren F i aksjon, og de strammer 1^ og Ig reduseres, hvorved fremdeles gjelder x a = f. When the maximum field weakening is achieved (I.e/I_ = f) , the regulation amplifier F comes into action, and they tighten 1^ and Ig is reduced, whereby x a = f still applies.

Utgangen på reguleringsforsterkeren E er over en diode G, koblet tilbake til sin inngang. Denne diode hindrer at utgangen fra forsterkeren E blir mer positiv enn 0 volt. The output of the regulation amplifier E is across a diode G, connected back to its input. This diode prevents the output from amplifier E from becoming more positive than 0 volts.

Reguleringsforsterkerens F utgang er over seriekobling av diodene G^, G^ (i sperreretning) og G. (i gjennomslipningsretning) tilbake-koblet til sin inngang. De med hverandre forbundne anoder på de to dioder G^ og G^ tilfores over en motstand en positiv spenning. Disse tre dioder forhindrer at utgangen fra F blir mer positiv The output of the control amplifier F is connected back to its input via the series connection of the diodes G^, G^ (in the blocking direction) and G. (in the pass-through direction). The interconnected anodes of the two diodes G^ and G^ are supplied with a positive voltage via a resistor. These three diodes prevent the output from F from becoming more positive

enn -1 U"D (terskelspenning) og muliggjor således start av anord-ningen, for ellers ville forholdet I a /Ir_ = 0/0 være udefinert, og forsterkeren F kunne hindre start. than -1 U"D (threshold voltage) and thus enables start of the device, because otherwise the ratio I a /Ir_ = 0/0 would be undefined, and the amplifier F could prevent start.

Innretningen ifolge oppfinnelsen muliggjor en virkelig noyaktig regulering av den automatiske feltsvekning ved maksimal rotorstrom. Derved oppnås en betraktelig forbedring av ydelsesevnen uten nev-neverdige ekstra foranstaltninger. The device according to the invention enables a really precise regulation of the automatic field weakening at maximum rotor current. Thereby, a considerable improvement in performance is achieved without significant additional measures.

Claims

1. device for regulating speed and field weakening range for a collector motor which is fed by a direct current source via a direct current regulator, which is connected between the direct current source and the rotor and where the field winding in series with a first diode is connected parallel to the rotor in such a way that the currents from the direct current regulator and this series connection flows through the rotor in the same direction, and the field winding is connected in parallel with a second diode so that the two diodes are connected to the field winding with the same polarity, characterized by a direct measurement of the rotor current (I ) and the field current (I ) and a regulated limitation of the ratio rotor current/field strbm to a predetermined value in such a way that the analog signal corresponding to the desired rotor current (I as) is limited by a first diode-extreme value coupling (G5, G6) to a maximum value determined by a constant voltage (D), across a first mixing resistor (R) a first mixing point (M^) is supplied, which mixing point at the same time "also via a second mixing resistor of the same size, the analogue signal supplied from a direct current converter (A) for the real rotor current (I .) is supplied, that this real -rotor current analog signal further across a mixing resistor of the same size (R) is fed to a second mixing point (M2), which mixing point is simultaneously also across a further mixing resistor whose size (f.R) is f times greater than that of the second mixing resistor - whereby f means the minimally permissible degree of magnetization - it is supplied from a further direct current converter (B) supplied with regard to the real rotor current signal opposite analog signal for the field current (1^), that the first mixing point (M^) and the second mixing point (M2) on the output side are directly connected to the input of the respective . a first and a second control amplifier (E or F), each of which is provided with a stabilizing element (Tg or T^), and that the negative output voltage from the two control amplifiers, a second diode-extreme value coupling (G_, GQ) is supplied which selects the larger of the two voltages and supplies this negative regulator voltage (V) to the regulator control set.

2. Device as stated in claim 1, characterized in that each stabilization link (T_, TV) is connected to the input of the corresponding control amplifier (E or F) and the star point for the second diode extreme value connection (G^, Gg).

3. Device as specified in claim 2, characterized in that the output of the first control amplifier (E) is connected back to the input of this amplifier via a diode (G-^) which allows current to pass through in the direction from the amplifier output towards the amplifier input.

4. Device as specified in claim 3, characterized in that the output of the second control amplifier is connected to the input of this via a series connection of three diodes (G^, G^, G2) of which the first two (<G>^, < G>^), seen from the amplifier output, the pole is in the blocking direction and the third (G2) in the forward direction, and that the connection point between the second diode (G^) and the third diode (G2) is applied a positive voltage across a resistor.