CA2073164C - Adjustable-speed alternating current motor - Google Patents
Adjustable-speed alternating current motorInfo
- Publication number
- CA2073164C CA2073164C CA 2073164 CA2073164A CA2073164C CA 2073164 C CA2073164 C CA 2073164C CA 2073164 CA2073164 CA 2073164 CA 2073164 A CA2073164 A CA 2073164A CA 2073164 C CA2073164 C CA 2073164C
- Authority
- CA
- Canada
- Prior art keywords
- rotor
- direct current
- motor
- field
- intermediary
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000004804 winding Methods 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims description 4
- 241000239290 Araneae Species 0.000 claims description 2
- 239000004020 conductor Substances 0.000 claims 2
- 230000005540 biological transmission Effects 0.000 claims 1
- 230000006698 induction Effects 0.000 abstract 2
- 230000004075 alteration Effects 0.000 abstract 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- IVQOFBKHQCTVQV-UHFFFAOYSA-N 2-hydroxy-2,2-diphenylacetic acid 2-(diethylamino)ethyl ester Chemical compound C=1C=CC=CC=1C(O)(C(=O)OCCN(CC)CC)C1=CC=CC=C1 IVQOFBKHQCTVQV-UHFFFAOYSA-N 0.000 description 1
- 241001527806 Iti Species 0.000 description 1
- 229910000576 Laminated steel Inorganic materials 0.000 description 1
- 241000763212 Lype Species 0.000 description 1
- 241000282320 Panthera leo Species 0.000 description 1
- 102100034742 Rotatin Human genes 0.000 description 1
- 101710200213 Rotatin Proteins 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 101150087532 mitF gene Proteins 0.000 description 1
- GWUSZQUVEVMBPI-UHFFFAOYSA-N nimetazepam Chemical compound N=1CC(=O)N(C)C2=CC=C([N+]([O-])=O)C=C2C=1C1=CC=CC=C1 GWUSZQUVEVMBPI-UHFFFAOYSA-N 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K16/00—Machines with more than one rotor or stator
- H02K16/02—Machines with one stator and two or more rotors
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Multiple Motors (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
In an induction motor, which may be squirrel-cage or wound-rotor, it is known that the speed of the motor depends o the power supply frequency and the number of stator poles. Although the speed of a wound-rotor type can be controlled by external resistors, the speed depends mainly on the load.
In this invention the speed of an induction motor can be fully controlled - independent of the load - by applying a very small amount of direct current on the motor's field windings which interact with an intermediate rotor, without any alteration or change in the power supply.
In this invention the speed of an induction motor can be fully controlled - independent of the load - by applying a very small amount of direct current on the motor's field windings which interact with an intermediate rotor, without any alteration or change in the power supply.
Description
Adj~ ,d h1t~ tin~ C7~ent ~ t~
The present invention relates to electric motors and in paIticular to an electric motsr c~mbining an A1fP nAti~7 c~ure~t motor with a direct current motor, with the direct current motor housed inside the AltP~Ating current one.
In ~en~1, electric motors are used to convert elec~cal ener~y into ~1~PchAni~A1 energy. In simplest terms, an electric motor consists of a stator and a rotor keyed to the motor7s shaft. There are two ~pes of motors, categorized accol~i~ to the lype of source used to drive them~ thus, there are ~1tPrn~ting current aI~d direct current motors. EIowe~ ?
l0 most applications require Acc 1rAte control of the motor's speed and torque. Presently, this is achieved by clc~tl~ic means, with c~n,pl~Aily depenf1in~ on the type of motor used, i.e., A1t~rnAfin~ current motors require more complex c~ than their direct current counteIparts. A disadvantage, common to both classes of moto~s, is their ~bility to run effici~ntiy at low speeds. Some power is always ~ ipAt~d as heat7 however, at high speeds the wind produced by the ~otor is sllfficient to cool the motQr. Obviously this is not the case at low speeds, and ill~rt;ful~, the motors require cooling means. A disadvaIItage pa~ticular to the ~lt~ting current motors is the high start~g ~urrent re~ired for adequate sta~ng torque, particularly so when the shaft is loaded. Another disadvantage particular to the A1tP~fing current motor is the hi~h cost associated with hardware 20 required to control the speed of such motors. Tn the case of direct cu~rent m~tors, ~e more important drawback~ are the high cost and high ~ ;,,t~l~AI~re required to keep them .'-,, ~
-- 2073~ 64 One attempt to overcome some of the disadvantages mPntiQnPd above is embodied in t~e United ~tates Patent No. 3,07~,108 dated Tanuary 22, l~G3, granted to Fehn for a "Dl]f Rotor Electric Motor." However, the method outlined in t~e irvention is limited only to synchronous applications. A Lrr~t;lll constIuction is required to obtain a vaIiable speed motor. Moreover, the dual rotor motor proposed by Fe~n seems not tn be ~m~tiQn:~l This might be due to the desLucti.,e i,lk;lr~lt;.,ce of the ei~l~ n~n~tic fieds produced by the ~lt~fing and direct cu~rent field Cois of the stator. A~other prQblem writh the dual 30 rotor motor is outlined by Fehn.
"Bel¢w sy~.cl~ us speed a p~ ting torque, caled ~hlt~f~nL~ t~rque is developed by tbe m~ti~ flux cutting the ca~e bars. I~e stator rotatin~ ma~etic field will also add plll~tinn~ of a rninor level."
It seems that these problems have not yet been overcome, as the motor is not used in practice.
A ~ a.y object of the invention is to combine an ~lt~ tin~ cuTrent squi~el-cage motor with a direct current motor, housed by the squirrel-cage rotor to achieve the pu~pose of the invention. That is, to combine the versatiiity of the direct curren~ molor with the robustness of the ~lt~n~ting current motor. From another point of vievv, the motor can be 40 ~ ught of as comprising an ~lt~ current motor made up of a stator, a sq ~i~rel-ca~;e and an inf~rn~ ~ rotor, intel~ ed between the stator and squir~el-cage.
Another object of the invention is to provide for trAn~mi~inn of power to the direct current field coils of the int~- "~ te ~otor without the use of brushes or c~mmllt~tors A still fi~er o~ t of ~ invention is to pro~ide a motor wherein one of the rotQrs is started in-i~PntlPntiy of the load, and allows for the cooiing nP~essitiP~ of the motor lo be met, even at low output speeds.
A further object of the invention is to provide a low cost adjusta~le-speed alt~nAting current motor with improved torque and speed control7 as well as rel~tively lo~hr starhng current, regardless of motQr si~e.
Yet another object of the invention is to eliminatP the use of v~iable f~equen~ydrives used in the control of AltP~atin~ current motors. Usualiy, the drives are more expensive than the motor they contrfol. As well, the drive~ require coQling systems and are sensible to Op~ g t;llvi In general terms, the invP~ntion may be described as ~m~ ing an alt~rnatin~
current stator surroundin~ an int~"~.PAiate rotor, coll.~ ing a combination of a s~lirrel-cage assembled on the P~t~n~l side, and direct current field coils together with the l~S~Je ;iive field poles on the inner side of the intPrrnP~liary rotor. The second rotor is keyed to the shaft. The int.~ PAi:~tP rotor is free to rotate on the shaft ~nd fQll~w the r~tati~
forces in~11u~1 by the altPrnafing current coils of the housi~. The second squirrel-ca~e GO rotor will follow the i~ lediate rotor when linked to it by the mA~ Pti~ field produced when the direct current coils of the int ~- ",~llat~ rotor are activated.
~e invenfion alsQ provides for a ~rushless n~P~hAni.~tn to transmit power to thedirect current coils mounted on the inside of the i-~ iia1y rotor. This device is described fur~her below.
1~ the ~ wi~s which illustrate embo~ of the invention, Figure 1 is a cutaway view of the motor, -- 3~
- ~)73~ 64 Figure ~ is a cross-section ~iew of the motor, taken along line 1-1 of Figure 1,Figure 3 is a cross-section view of the motor, taken along line 2-2 of Figure 1, and shows the brushless device used in controlling the speed of the motQr, Figure 4 is the electric srh~ til~ showing the circuits used for speed contrQl.
The electric in-luctiQn motor ill~ l~ in the above mPntion~ drawin~s cl m~i~es a stator core 1 that is supported in a st~til~nA~ frame 2. The stator windings 3 are placed in the slots of the stator core 1. An int~n~liAtç annular rotor comprises a field yoke 4, a rotor core 5 constructed of lAminAted steel sheets, a squi~rel-ca~e 6, field pole cores 7, and field cQils 8. In this descli~lion and drawings there are four pole cores, and acollt;spolldin~ number of field coils. The rotor core 5 and the squirrel-cage ~ are moumed on the exterior side of the field yoke 4. The field pole cores 7, and field coils 8 are mounted on the interior side of the field yoke 4, with the field coils 8 placed around the said pole cores 7. The field coils 8 may be ct~nnPctçd in either series or parallel to form the in~iuctit~n field. The assembly forming the int~ rotor iS rotatably mounted in the said stator core 1 and supported at each end by one bearer frame ~ e said bearer fiames 9 have a ~iven number of openillgs 10 to allow the free muvt;~t of air in order to satis~
the cooling n~ceqs;~ i of the motor. A motor s~ft 14 is jQurnalled in the bearer frames ~, and is supported by the cc~v~ n~1 ball b~s enclQsed in the said bearer frames ~. A
second rotor is placed inside the said in~ tt? ann~lar rotQr, between the ~earer ~mes 9. The second rotor o~m~ g the siQtted lAminAt~ c~re 11, spider 1~, and a squirrel-ca~e 13 embedded in the surface ofthe said rotor core 11. The secQnd rotor is keyed to the motor shaft i4. The main puIpose of the said interm~ii~te annular rotor is th~t of controlling the amount of power tr~n~mitf,~1 to the said ~ tor gha~ t~u~ e second ~'3 r~tor. ~other p~pose of the int~nnPAi~e r~t~r is to ensure the cooling n~r~s~ities of the motor are met, independent of the speed at which the motor is operated.
In the embodiment shown in Figure 1, the brushless speed control dev~ce is mounted at one end ofthe said stator core 1. The device com~ es a field yoke 1~, pole cores 16, and the field coils 17 placed around the said pole cores 1~. ID addition, the speed control device c~mpri~es a slotted steel sheet l~min~tion rotor 18 having three windin~s lg. The said rotor 18 and its windinl3s 19 are mounted on the bearer fi~me 9 aligned with the pole cores 16. The windin~s 1~ are spaced 120 elY~fricAl de~rees apart and are wye-connected. As illll~tr~t~l in Figure 4, the cc~mmon cQnt1uctnr of the wye-conn~cted windings lg is c~nl-~t~1 to one wire ofthe said field coils 8. The other three end wires of 100 ~e said windi~gs lf are cnnn~t~l tn~P,thPr tl~r~ugh three diodes 20 to the secdnd wire of the said field coils 8. The said diodes 20, in number of three, are f~t~n~ on the said bearer ~ame 9.
To illll~tr~te the operation prin~iple of the motor, let us look first at a three phase wound-rotor motor, wye-conn~cte~l, and whose t~rn in~til~n wires are brought outside through the collector rings, and connected to t~ree variable resistors, also wye-coIme~ted to ensure the circuit is closed. Through the vari~ble resistors, the speed, and iml~licitly the torque, developed by the motor can be controlled over any range thr~ugh increasing or decr~sing the current flowin~ t~rough the rotor CQilS. If the tPrmin~tions to the collector rings are c~nn~t~ together, the rotor behaves like a squirrel-cage at startup and while 110 fim~.ti~nir~ Note that during operation the use of the variable rcsistors to control the torque and speed of the motor means that the energy ~ si~ted in the resistors is wasted as heat; this consists an importa~t loss.
- 2073 1 6~
In simple terms, my invention consists of an ~lt~n~tin~ current motor, whose rotQ~
houses a direct current motor. The ~qltt~ current motor com~ixes the stator 1 wifh itS
windings 3, and the squirrel-cage rotor 6. With the direct current field kept idle, i.e., no control voltage is ~li~ the ~ current motor can be started. Note that there is no load on the shaft, and that the i.. t.. PAi~fe rotor will rotate freely, tumed by the rotating m~P1ie field set up by the AltP n~tin~ current coils. The direct current motor c~m~ii~x the field poles 7 and their windings ~, and the squirrel-cage rotor 11.
120 Fis~.nfi~lly, the stator ofthe direct current motor is rotary, as it i~ part ofthe int~m~Ai~lv rQtor. Once the control voltage is activated, the field cQils S form a stationa~y magnetic field with respect to themselves. The rotor 14 will .^ollQw the fieid cQils 8 when linked to them by the said m~gnPti~. field. It is important to observe that the elecl~ gnPtie field produced by the direct current cQils ~ does not illL~lrc;lt; wi~ the rotating elecilol~.agnetic field produced ~y the t~ree phase ~lt~nAting current coils 3 of the stator 1.
Another important part of my invention is the device which tr~nxfiP~ the direct current used to control the torque and speed ofthe motor shaft 14. As well as elimin~tin~
any friction parts used in tr~nx....ll;.~ the control current, this device also Amplifi~s the direct current rectified by the diodes 20 sent to the field coils ~. To analyze its Opt~LtiOIl, 130 observe that the speed control device behaves as a genPrAtnr. The dire~t current applied to the coils 17 serves to xL,en~ n the m~gn~fir field set up. This in tum affects the amplitude of the .qlt~n~tin~ vo3tage in~ c~1 in the windings 19. The ~lt~rnAting voltage is then rectified by the diodes 20, i.e., converted to direct volt~e or cu~ t, And flows through the direct current coils 18. Finally, the mAgnifude of the cuITent t~rough the coiis 1~ affects the speed at ~,vh~ch the rotor 14 ~ rn.
T~ ~umm ~n7~ wheIl power is applied to the motor stator windings 3, the torque produced by the inf~r,fion ofthe said stator and said ;.~ f'd;51t~ Sl-st rotor causes the latter to tum and run as an infhlf~tiftn motor. As long ~s no col~t~ol ~ir~t current is applied to the said field cQils 17, no torque or power is ~ n!~ i to the second rotor and hence 140 no power is L~ f~l to the motor's shaft 14. A preferred of ~rcJlr~te speed control uses a speed mf~nitoring device, such as a t~rhn~en~ Qr7 together with an oppr~tion~l ~mplifier in a fi~l~hf I loop cnnfi~llratiQn. ~he amount of control direct current is esfitn~t~ to be anywhere from 0.01% to 0.05% ofthe full load p~ y current.
The present invention relates to electric motors and in paIticular to an electric motsr c~mbining an A1fP nAti~7 c~ure~t motor with a direct current motor, with the direct current motor housed inside the AltP~Ating current one.
In ~en~1, electric motors are used to convert elec~cal ener~y into ~1~PchAni~A1 energy. In simplest terms, an electric motor consists of a stator and a rotor keyed to the motor7s shaft. There are two ~pes of motors, categorized accol~i~ to the lype of source used to drive them~ thus, there are ~1tPrn~ting current aI~d direct current motors. EIowe~ ?
l0 most applications require Acc 1rAte control of the motor's speed and torque. Presently, this is achieved by clc~tl~ic means, with c~n,pl~Aily depenf1in~ on the type of motor used, i.e., A1t~rnAfin~ current motors require more complex c~ than their direct current counteIparts. A disadvantage, common to both classes of moto~s, is their ~bility to run effici~ntiy at low speeds. Some power is always ~ ipAt~d as heat7 however, at high speeds the wind produced by the ~otor is sllfficient to cool the motQr. Obviously this is not the case at low speeds, and ill~rt;ful~, the motors require cooling means. A disadvaIItage pa~ticular to the ~lt~ting current motors is the high start~g ~urrent re~ired for adequate sta~ng torque, particularly so when the shaft is loaded. Another disadvantage particular to the A1tP~fing current motor is the hi~h cost associated with hardware 20 required to control the speed of such motors. Tn the case of direct cu~rent m~tors, ~e more important drawback~ are the high cost and high ~ ;,,t~l~AI~re required to keep them .'-,, ~
-- 2073~ 64 One attempt to overcome some of the disadvantages mPntiQnPd above is embodied in t~e United ~tates Patent No. 3,07~,108 dated Tanuary 22, l~G3, granted to Fehn for a "Dl]f Rotor Electric Motor." However, the method outlined in t~e irvention is limited only to synchronous applications. A Lrr~t;lll constIuction is required to obtain a vaIiable speed motor. Moreover, the dual rotor motor proposed by Fe~n seems not tn be ~m~tiQn:~l This might be due to the desLucti.,e i,lk;lr~lt;.,ce of the ei~l~ n~n~tic fieds produced by the ~lt~fing and direct cu~rent field Cois of the stator. A~other prQblem writh the dual 30 rotor motor is outlined by Fehn.
"Bel¢w sy~.cl~ us speed a p~ ting torque, caled ~hlt~f~nL~ t~rque is developed by tbe m~ti~ flux cutting the ca~e bars. I~e stator rotatin~ ma~etic field will also add plll~tinn~ of a rninor level."
It seems that these problems have not yet been overcome, as the motor is not used in practice.
A ~ a.y object of the invention is to combine an ~lt~ tin~ cuTrent squi~el-cage motor with a direct current motor, housed by the squirrel-cage rotor to achieve the pu~pose of the invention. That is, to combine the versatiiity of the direct curren~ molor with the robustness of the ~lt~n~ting current motor. From another point of vievv, the motor can be 40 ~ ught of as comprising an ~lt~ current motor made up of a stator, a sq ~i~rel-ca~;e and an inf~rn~ ~ rotor, intel~ ed between the stator and squir~el-cage.
Another object of the invention is to provide for trAn~mi~inn of power to the direct current field coils of the int~- "~ te ~otor without the use of brushes or c~mmllt~tors A still fi~er o~ t of ~ invention is to pro~ide a motor wherein one of the rotQrs is started in-i~PntlPntiy of the load, and allows for the cooiing nP~essitiP~ of the motor lo be met, even at low output speeds.
A further object of the invention is to provide a low cost adjusta~le-speed alt~nAting current motor with improved torque and speed control7 as well as rel~tively lo~hr starhng current, regardless of motQr si~e.
Yet another object of the invention is to eliminatP the use of v~iable f~equen~ydrives used in the control of AltP~atin~ current motors. Usualiy, the drives are more expensive than the motor they contrfol. As well, the drive~ require coQling systems and are sensible to Op~ g t;llvi In general terms, the invP~ntion may be described as ~m~ ing an alt~rnatin~
current stator surroundin~ an int~"~.PAiate rotor, coll.~ ing a combination of a s~lirrel-cage assembled on the P~t~n~l side, and direct current field coils together with the l~S~Je ;iive field poles on the inner side of the intPrrnP~liary rotor. The second rotor is keyed to the shaft. The int.~ PAi:~tP rotor is free to rotate on the shaft ~nd fQll~w the r~tati~
forces in~11u~1 by the altPrnafing current coils of the housi~. The second squirrel-ca~e GO rotor will follow the i~ lediate rotor when linked to it by the mA~ Pti~ field produced when the direct current coils of the int ~- ",~llat~ rotor are activated.
~e invenfion alsQ provides for a ~rushless n~P~hAni.~tn to transmit power to thedirect current coils mounted on the inside of the i-~ iia1y rotor. This device is described fur~her below.
1~ the ~ wi~s which illustrate embo~ of the invention, Figure 1 is a cutaway view of the motor, -- 3~
- ~)73~ 64 Figure ~ is a cross-section ~iew of the motor, taken along line 1-1 of Figure 1,Figure 3 is a cross-section view of the motor, taken along line 2-2 of Figure 1, and shows the brushless device used in controlling the speed of the motQr, Figure 4 is the electric srh~ til~ showing the circuits used for speed contrQl.
The electric in-luctiQn motor ill~ l~ in the above mPntion~ drawin~s cl m~i~es a stator core 1 that is supported in a st~til~nA~ frame 2. The stator windings 3 are placed in the slots of the stator core 1. An int~n~liAtç annular rotor comprises a field yoke 4, a rotor core 5 constructed of lAminAted steel sheets, a squi~rel-ca~e 6, field pole cores 7, and field cQils 8. In this descli~lion and drawings there are four pole cores, and acollt;spolldin~ number of field coils. The rotor core 5 and the squirrel-cage ~ are moumed on the exterior side of the field yoke 4. The field pole cores 7, and field coils 8 are mounted on the interior side of the field yoke 4, with the field coils 8 placed around the said pole cores 7. The field coils 8 may be ct~nnPctçd in either series or parallel to form the in~iuctit~n field. The assembly forming the int~ rotor iS rotatably mounted in the said stator core 1 and supported at each end by one bearer frame ~ e said bearer fiames 9 have a ~iven number of openillgs 10 to allow the free muvt;~t of air in order to satis~
the cooling n~ceqs;~ i of the motor. A motor s~ft 14 is jQurnalled in the bearer frames ~, and is supported by the cc~v~ n~1 ball b~s enclQsed in the said bearer frames ~. A
second rotor is placed inside the said in~ tt? ann~lar rotQr, between the ~earer ~mes 9. The second rotor o~m~ g the siQtted lAminAt~ c~re 11, spider 1~, and a squirrel-ca~e 13 embedded in the surface ofthe said rotor core 11. The secQnd rotor is keyed to the motor shaft i4. The main puIpose of the said interm~ii~te annular rotor is th~t of controlling the amount of power tr~n~mitf,~1 to the said ~ tor gha~ t~u~ e second ~'3 r~tor. ~other p~pose of the int~nnPAi~e r~t~r is to ensure the cooling n~r~s~ities of the motor are met, independent of the speed at which the motor is operated.
In the embodiment shown in Figure 1, the brushless speed control dev~ce is mounted at one end ofthe said stator core 1. The device com~ es a field yoke 1~, pole cores 16, and the field coils 17 placed around the said pole cores 1~. ID addition, the speed control device c~mpri~es a slotted steel sheet l~min~tion rotor 18 having three windin~s lg. The said rotor 18 and its windinl3s 19 are mounted on the bearer fi~me 9 aligned with the pole cores 16. The windin~s 1~ are spaced 120 elY~fricAl de~rees apart and are wye-connected. As illll~tr~t~l in Figure 4, the cc~mmon cQnt1uctnr of the wye-conn~cted windings lg is c~nl-~t~1 to one wire ofthe said field coils 8. The other three end wires of 100 ~e said windi~gs lf are cnnn~t~l tn~P,thPr tl~r~ugh three diodes 20 to the secdnd wire of the said field coils 8. The said diodes 20, in number of three, are f~t~n~ on the said bearer ~ame 9.
To illll~tr~te the operation prin~iple of the motor, let us look first at a three phase wound-rotor motor, wye-conn~cte~l, and whose t~rn in~til~n wires are brought outside through the collector rings, and connected to t~ree variable resistors, also wye-coIme~ted to ensure the circuit is closed. Through the vari~ble resistors, the speed, and iml~licitly the torque, developed by the motor can be controlled over any range thr~ugh increasing or decr~sing the current flowin~ t~rough the rotor CQilS. If the tPrmin~tions to the collector rings are c~nn~t~ together, the rotor behaves like a squirrel-cage at startup and while 110 fim~.ti~nir~ Note that during operation the use of the variable rcsistors to control the torque and speed of the motor means that the energy ~ si~ted in the resistors is wasted as heat; this consists an importa~t loss.
- 2073 1 6~
In simple terms, my invention consists of an ~lt~n~tin~ current motor, whose rotQ~
houses a direct current motor. The ~qltt~ current motor com~ixes the stator 1 wifh itS
windings 3, and the squirrel-cage rotor 6. With the direct current field kept idle, i.e., no control voltage is ~li~ the ~ current motor can be started. Note that there is no load on the shaft, and that the i.. t.. PAi~fe rotor will rotate freely, tumed by the rotating m~P1ie field set up by the AltP n~tin~ current coils. The direct current motor c~m~ii~x the field poles 7 and their windings ~, and the squirrel-cage rotor 11.
120 Fis~.nfi~lly, the stator ofthe direct current motor is rotary, as it i~ part ofthe int~m~Ai~lv rQtor. Once the control voltage is activated, the field cQils S form a stationa~y magnetic field with respect to themselves. The rotor 14 will .^ollQw the fieid cQils 8 when linked to them by the said m~gnPti~. field. It is important to observe that the elecl~ gnPtie field produced by the direct current cQils ~ does not illL~lrc;lt; wi~ the rotating elecilol~.agnetic field produced ~y the t~ree phase ~lt~nAting current coils 3 of the stator 1.
Another important part of my invention is the device which tr~nxfiP~ the direct current used to control the torque and speed ofthe motor shaft 14. As well as elimin~tin~
any friction parts used in tr~nx....ll;.~ the control current, this device also Amplifi~s the direct current rectified by the diodes 20 sent to the field coils ~. To analyze its Opt~LtiOIl, 130 observe that the speed control device behaves as a genPrAtnr. The dire~t current applied to the coils 17 serves to xL,en~ n the m~gn~fir field set up. This in tum affects the amplitude of the .qlt~n~tin~ vo3tage in~ c~1 in the windings 19. The ~lt~rnAting voltage is then rectified by the diodes 20, i.e., converted to direct volt~e or cu~ t, And flows through the direct current coils 18. Finally, the mAgnifude of the cuITent t~rough the coiis 1~ affects the speed at ~,vh~ch the rotor 14 ~ rn.
T~ ~umm ~n7~ wheIl power is applied to the motor stator windings 3, the torque produced by the inf~r,fion ofthe said stator and said ;.~ f'd;51t~ Sl-st rotor causes the latter to tum and run as an infhlf~tiftn motor. As long ~s no col~t~ol ~ir~t current is applied to the said field cQils 17, no torque or power is ~ n!~ i to the second rotor and hence 140 no power is L~ f~l to the motor's shaft 14. A preferred of ~rcJlr~te speed control uses a speed mf~nitoring device, such as a t~rhn~en~ Qr7 together with an oppr~tion~l ~mplifier in a fi~l~hf I loop cnnfi~llratiQn. ~he amount of control direct current is esfitn~t~ to be anywhere from 0.01% to 0.05% ofthe full load p~ y current.
Claims (6)
1. An adjustable speed electric motor, comprising:
a stationary housing, a motor shaft journalled in the housing, a squirrel-cage cylindrical rotor fixed upon the shaft, an intermediary rotor rotatably journalled on the motor shaft and surrounding the squirrel-cage rotor, direct current field coils mounted on said intermediary rotor, another squirrel-cage mounted on said intermediary rotor, an alternating current stator fixed inside the housing, and alternating current field coils mounted on said alternating current stator; and a device comprising a field yoke, field poles, field coils and a wound rotor, said device allowing the transmittal of direct current from the outside of the housing to the direct current field coils mounted on the intermediary rotor, whereby the direct current field coils set up a magnetic field linking the intermediary rotor to the rotor fixed to the shaft, the speed of the rotor fixed to the shaft being proportional to the strength of the magnetic field set up by said direct current field coils.
a stationary housing, a motor shaft journalled in the housing, a squirrel-cage cylindrical rotor fixed upon the shaft, an intermediary rotor rotatably journalled on the motor shaft and surrounding the squirrel-cage rotor, direct current field coils mounted on said intermediary rotor, another squirrel-cage mounted on said intermediary rotor, an alternating current stator fixed inside the housing, and alternating current field coils mounted on said alternating current stator; and a device comprising a field yoke, field poles, field coils and a wound rotor, said device allowing the transmittal of direct current from the outside of the housing to the direct current field coils mounted on the intermediary rotor, whereby the direct current field coils set up a magnetic field linking the intermediary rotor to the rotor fixed to the shaft, the speed of the rotor fixed to the shaft being proportional to the strength of the magnetic field set up by said direct current field coils.
2. An adjustable speed electric motor as claimed in claim 1, wherein the intermediary rotor has an annular shape, the external surface of which comprises a squirrel-cage, and the internal surface comprises direct current field poles fixed upon the intermediary rotor, and direct current field coils located on said direct current poles.
3. An adjustable speed electric motor as claimed in claim 1, wherein the intermediary rotor is fastened to two bearer frames, one on either side, which bearer frames have openings in them to allow for the cooling of the motor, there being a gap between the intermediary rotor and the stationary alternating current stator, and another gap between the intermediary rotor and the rotor keyed to the shaft.
4. An adjustable speed electric motor as claimed in claim 1, wherein the direct current transmission device comprises a field yoke fixed to the housing to one side of the alternating current stator, pole cores fixed to the field yoke, and field coils placed around said pole cores, a wound-rotor mounted on one of the bearer frames, aligned with said field yoke.
5. An adjustable speed electric motor as claimed in claims 1, 3, or 4, wherein the windings on the rotor mounted on the bearer frames are spaced 120 electrical degrees apart, the common conductor of said three phase coils being connected to one end of the direct current field coils, the other three conductors of said three phase coils being connected to other end of the direct current field coils through rectifying diodes.
6. An adjustable speed electric motor as claimed in claim 1, wherein the squirrel-cage rotor is keyed to the motor shaft by means of a spider and is mounted between the bearer frames supporting the intermediary rotor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2073164 CA2073164C (en) | 1992-07-03 | 1992-07-03 | Adjustable-speed alternating current motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2073164 CA2073164C (en) | 1992-07-03 | 1992-07-03 | Adjustable-speed alternating current motor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2073164A1 CA2073164A1 (en) | 1994-01-04 |
| CA2073164C true CA2073164C (en) | 1997-01-28 |
Family
ID=4150108
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2073164 Expired - Fee Related CA2073164C (en) | 1992-07-03 | 1992-07-03 | Adjustable-speed alternating current motor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2073164C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ITMI20121339A1 (en) * | 2012-07-31 | 2014-02-01 | Emanuele Bisti | INTELLIGENT ELECTRIC MACHINE |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103001427A (en) * | 2012-12-19 | 2013-03-27 | 山西汾西重工有限责任公司 | High-power hybrid-excitation bi-rotor double-fed synchronous wind driven generator |
-
1992
- 1992-07-03 CA CA 2073164 patent/CA2073164C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ITMI20121339A1 (en) * | 2012-07-31 | 2014-02-01 | Emanuele Bisti | INTELLIGENT ELECTRIC MACHINE |
| WO2014020514A1 (en) * | 2012-07-31 | 2014-02-06 | Italconsul S.R.L. | Electrical machine |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2073164A1 (en) | 1994-01-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |