CA1066361A - Probe for measurement of magnetic flux of alternating current polyphase electric machine - Google Patents
Probe for measurement of magnetic flux of alternating current polyphase electric machineInfo
- Publication number
- CA1066361A CA1066361A CA266,939A CA266939A CA1066361A CA 1066361 A CA1066361 A CA 1066361A CA 266939 A CA266939 A CA 266939A CA 1066361 A CA1066361 A CA 1066361A
- Authority
- CA
- Canada
- Prior art keywords
- probe
- measurement
- yoke
- machine
- core
- 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
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/343—Testing dynamo-electric machines in operation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Tests Of Circuit Breakers, Generators, And Electric Motors (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
- Measuring Magnetic Variables (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed is a probe which allows for real-time measurement and stabilization of the magnetic flux of a polyphase motor fed by a voltage of frequency controlled from zero. A magnetic core of the probe consists of laminations of shape similar in shape to this stator laminations. On a yoke of the core there is wound a measurement winding. The probe is embodied in a stack of stator laminations, and its measurement winding is fed by voltage of suitably high frequency. The impedance of the probe, depends on the magne-tizing magnetomotive force of the motor saturating the yoke of the probe through teeth integral therewith. Changes of the impedance can be converted into a direct voltage representing the value of magnetic flux of the motor.
Disclosed is a probe which allows for real-time measurement and stabilization of the magnetic flux of a polyphase motor fed by a voltage of frequency controlled from zero. A magnetic core of the probe consists of laminations of shape similar in shape to this stator laminations. On a yoke of the core there is wound a measurement winding. The probe is embodied in a stack of stator laminations, and its measurement winding is fed by voltage of suitably high frequency. The impedance of the probe, depends on the magne-tizing magnetomotive force of the motor saturating the yoke of the probe through teeth integral therewith. Changes of the impedance can be converted into a direct voltage representing the value of magnetic flux of the motor.
Description
~6~3~
Thls invention relates to a probe ~or measuring the magnetic flux o$ an alternating current polyphase electric machine, allowing a conversion of the average value of magnetic ~lux into a direct voltage independently of the frequency of the voltage feeding the machine.
Up to now measurement of magnetic flux in alternating current poly-phase machines was effected by measuring instantaneous values of induction by means of Hall generators arranged in some points of the magnetic circuit of the machine. The resulting alternating voltage, representing the flux, can-not be directly applied in the feed-back circuit for stabilization of the flux. Tt is necessary to convert the said voltage intD a constant signal, which is especially difficult at low frequency.
The invention is aimed at the creation of possibilities for the stabilization of the magnetic flux of a machine operating at controlled fre-quency e.g. the flux of an induction motor fed from a thyristor frequency converter.
Thus, in accordance with the invention, there is provided a probe for measurement of magnetic flux of an alternating current polyphase electric machine embodied in a stator core of the machine and provided with at least one magnetic measurement core formed from at least one lamination of a shape similar to laminations of said stator, said core having a yoke adapted to be saturated through teeth which are integral with said yoke by magnetiæing magnetomotive forces of the machine and having a uniformly wound measurement ` winding, fed by an alternating voltage of a frequency higher than the highest working frequency of the machine, encircling the yoke at at least a part ; ~ , .
corresponding to one pair of poles of the machlne.
The essence of the inventlon consists in that the probe is a part o~ the stator core and is composed of one or two measurement cores, the subs-tantial element of which it is at least one measurement lamination having an outs~de~d~a~eterslnaller than the outstide diameter of the stator laminations as well as ha~ing higher slots, with a uni~ormly wound measurement winding on ",.
-.
, , ~ . : :. . . : . . .
- ,, , . . :,. . : ,.: .
, . . . .. .
~0~
the yoke's circumference or its part corresponding to one pair of poles. A
probe comprising two measurement cores can be screened by a closed winding uniformly wound on the whole circumference of the yoke consisting of the yokes of two measurement cores, the measurement windings of which are counter connected and led into a conduit box of the motor.
The space between the laminations of the stator, in which the probe is arranged, is filled with spaced tooth portions of the probe and forming a chamber having the shape of a ring in which there is arranged the yoke of the probe with its windings~
An advantage of the probe according to the invention consists in that the voltage representing the magnetic flux of the machine reacts without delays upon its rapid variations and is independent of the frequency of the working voltage of the machine.
An embodiment of the invention is presented by way of example with reference to the accompanying drawings,in which:
Figure 1 shows a sector of a measurement core of a probe according to the invention, and Figure ~ shows a section of a dual probe according to the inven-tion. ;
Figure 1 shows a sec~or of a measurement core of the probe with ~oke 2 and teeth 3 with uniformly wound measurement winding 4 of the probe against a background of a sector of the stator core 1. In Figure 2 there is presented a section of a dual probe consisting of two measurement cores with wound measùrement windings 4, counter - connected into one measurement windings~ the ends 4a of which are led into the conduit box (not shown) of the machine. On the whole circumference of the yoke of the dual probe there is additionally wound a closed s~reening winding 5. The probe according to the invention is arranged in chamber 6~ formed in the space between stator lamina-tion adjacent to the probe~ filled with spaced sections 7 of the fixing teeth ' : , ~ ,. . ' ~ . ' .
~o~
3 of the probe.
Operation of the probe consists in utilization of the phenomenon of magnetic saturation in the yoke of the probe's core, which core forms a part of the stator core.
Magnetic flux excited in the yoke 2 of the measurement core of the probe by the magnetizing mmf of the machine does nok link ~ith the measure-ment winding 4 of the probe, but merely magnetizes the yoke of measurement core 2. Measurement wind~lg 4 of the probe is fed by an alternating voltage of a frequency higher than the highest working frequency of the motor and at the same time so high ~hat variations of ~he state of saturation of yoke 2 of the probe will result in distinct changes of its impedance. A voltage repre-senting the average value of the working magnetic flux of the machine is achieved by utilization of the relationship between the flux magnetizing the ` yoke of measurement core 2 of the probe and its impedance, since with an increase of saturation of yoke 2 of the measurement core of the probe there is a decrease of its impedance. Changes of probe impedance are converted into an alternating signal at the frequency of the measurement voltage. This signal, after rectifying and smoothing, can be utilized for stabilization of he magnetic flux of the machine. A probe composed of one measurement core , .
, requires cutting off by means of suitable insulating elements the electric ~; circuit consisting of statorframe bearing shields, bearingsand shaft. It `~ ~ counteracts generation in the said circuit of electric currents at the measure-ment frequency. In a probe of two measurement cores, measurement windings - 4 of which are counter connected, it is advisable to employ closed screening ; winding 5, uniformly wound on the whole circumference of the yoke 2 of both measurement coresO It is aimed at elimination of non-uniformity of magnetic ; characteristics of the measurement cores and allows application to a machine of normal construction without ins~lating elements.
,'",;, ' ~
; . : . . .: . .
. . . , , : . : : ::: : :
3~
, .
: A probe according to the invention is charac-terized by simple construction and resistance to thermal and mechanical influences~
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.
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., ~
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:, .
, . .
~ . .
. .
.-','~'; : ,' . ,,', :.
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. ,; . . ~
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... :. . . . . .
Thls invention relates to a probe ~or measuring the magnetic flux o$ an alternating current polyphase electric machine, allowing a conversion of the average value of magnetic ~lux into a direct voltage independently of the frequency of the voltage feeding the machine.
Up to now measurement of magnetic flux in alternating current poly-phase machines was effected by measuring instantaneous values of induction by means of Hall generators arranged in some points of the magnetic circuit of the machine. The resulting alternating voltage, representing the flux, can-not be directly applied in the feed-back circuit for stabilization of the flux. Tt is necessary to convert the said voltage intD a constant signal, which is especially difficult at low frequency.
The invention is aimed at the creation of possibilities for the stabilization of the magnetic flux of a machine operating at controlled fre-quency e.g. the flux of an induction motor fed from a thyristor frequency converter.
Thus, in accordance with the invention, there is provided a probe for measurement of magnetic flux of an alternating current polyphase electric machine embodied in a stator core of the machine and provided with at least one magnetic measurement core formed from at least one lamination of a shape similar to laminations of said stator, said core having a yoke adapted to be saturated through teeth which are integral with said yoke by magnetiæing magnetomotive forces of the machine and having a uniformly wound measurement ` winding, fed by an alternating voltage of a frequency higher than the highest working frequency of the machine, encircling the yoke at at least a part ; ~ , .
corresponding to one pair of poles of the machlne.
The essence of the inventlon consists in that the probe is a part o~ the stator core and is composed of one or two measurement cores, the subs-tantial element of which it is at least one measurement lamination having an outs~de~d~a~eterslnaller than the outstide diameter of the stator laminations as well as ha~ing higher slots, with a uni~ormly wound measurement winding on ",.
-.
, , ~ . : :. . . : . . .
- ,, , . . :,. . : ,.: .
, . . . .. .
~0~
the yoke's circumference or its part corresponding to one pair of poles. A
probe comprising two measurement cores can be screened by a closed winding uniformly wound on the whole circumference of the yoke consisting of the yokes of two measurement cores, the measurement windings of which are counter connected and led into a conduit box of the motor.
The space between the laminations of the stator, in which the probe is arranged, is filled with spaced tooth portions of the probe and forming a chamber having the shape of a ring in which there is arranged the yoke of the probe with its windings~
An advantage of the probe according to the invention consists in that the voltage representing the magnetic flux of the machine reacts without delays upon its rapid variations and is independent of the frequency of the working voltage of the machine.
An embodiment of the invention is presented by way of example with reference to the accompanying drawings,in which:
Figure 1 shows a sector of a measurement core of a probe according to the invention, and Figure ~ shows a section of a dual probe according to the inven-tion. ;
Figure 1 shows a sec~or of a measurement core of the probe with ~oke 2 and teeth 3 with uniformly wound measurement winding 4 of the probe against a background of a sector of the stator core 1. In Figure 2 there is presented a section of a dual probe consisting of two measurement cores with wound measùrement windings 4, counter - connected into one measurement windings~ the ends 4a of which are led into the conduit box (not shown) of the machine. On the whole circumference of the yoke of the dual probe there is additionally wound a closed s~reening winding 5. The probe according to the invention is arranged in chamber 6~ formed in the space between stator lamina-tion adjacent to the probe~ filled with spaced sections 7 of the fixing teeth ' : , ~ ,. . ' ~ . ' .
~o~
3 of the probe.
Operation of the probe consists in utilization of the phenomenon of magnetic saturation in the yoke of the probe's core, which core forms a part of the stator core.
Magnetic flux excited in the yoke 2 of the measurement core of the probe by the magnetizing mmf of the machine does nok link ~ith the measure-ment winding 4 of the probe, but merely magnetizes the yoke of measurement core 2. Measurement wind~lg 4 of the probe is fed by an alternating voltage of a frequency higher than the highest working frequency of the motor and at the same time so high ~hat variations of ~he state of saturation of yoke 2 of the probe will result in distinct changes of its impedance. A voltage repre-senting the average value of the working magnetic flux of the machine is achieved by utilization of the relationship between the flux magnetizing the ` yoke of measurement core 2 of the probe and its impedance, since with an increase of saturation of yoke 2 of the measurement core of the probe there is a decrease of its impedance. Changes of probe impedance are converted into an alternating signal at the frequency of the measurement voltage. This signal, after rectifying and smoothing, can be utilized for stabilization of he magnetic flux of the machine. A probe composed of one measurement core , .
, requires cutting off by means of suitable insulating elements the electric ~; circuit consisting of statorframe bearing shields, bearingsand shaft. It `~ ~ counteracts generation in the said circuit of electric currents at the measure-ment frequency. In a probe of two measurement cores, measurement windings - 4 of which are counter connected, it is advisable to employ closed screening ; winding 5, uniformly wound on the whole circumference of the yoke 2 of both measurement coresO It is aimed at elimination of non-uniformity of magnetic ; characteristics of the measurement cores and allows application to a machine of normal construction without ins~lating elements.
,'",;, ' ~
; . : . . .: . .
. . . , , : . : : ::: : :
3~
, .
: A probe according to the invention is charac-terized by simple construction and resistance to thermal and mechanical influences~
' :~
.
i . ~.
., ~
'~:
:, .
, . .
~ . .
. .
.-','~'; : ,' . ,,', :.
: . ~
:'i `` ' .
' i`
;'~ " ~.~' ' : ... .
, :~, :
,..
i .. :, . . . ,, - , . , . :
. ,; . . ~
: ' : . : ` . . : . ':
... :. . . . . .
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A probe for measurement of magnetic flux of an alternating current polyphase electric machine embodied in a stator core of the machine and provi-ded with at least one magnetic measurement core formed from at least one lami-nation of a shape similar to lamination of said stator, said core having a yoke adapted to be saturated through teeth which are integral with said yoke by magnetizing magnetomotive forces of the machine and having a uniformly wound measurement winding, fed by an alternating voltage of a frequency higher than the highest working frequency of the machine, encircling the yoke at at least a part corresponding to one pair of poles of the machine.
2. A probe according to claim 1, wherein the measurement core consists of laminations of outstide diameter smaller than outside diameter of stator laminations and teeth longer than teeth of the stator laminations.
3. A probe according to claim 1 provided with two measurement cores having measurement windings which are counter connected.
4. A probe according to claim 3 having on the yoke of both measure-ment cores an additional uniformly arranged closed screening winding, encir-cling the yoke at at least a part corresponding to one pair of poles of the machine.
5. A probe according to claim 1 or 3 provided with spaced sections filling a space between stator laminations adjacent to the probe and fixing teeth of the probe as well as forming a chamber in a shape of a ring, in which there is arranged a yoke of the probe.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PL18565775A PL105294B1 (en) | 1975-12-17 | 1975-12-17 | PROBE FOR MEASURING THE MAGNETIC FLOW OF A MULTIPHASE ELECTRIC MACHINE ALTERNATING CURRENT |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1066361A true CA1066361A (en) | 1979-11-13 |
Family
ID=19974773
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA266,939A Expired CA1066361A (en) | 1975-12-17 | 1976-12-01 | Probe for measurement of magnetic flux of alternating current polyphase electric machine |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5274375A (en) |
| CA (1) | CA1066361A (en) |
| DE (1) | DE2655464A1 (en) |
| PL (1) | PL105294B1 (en) |
| SU (1) | SU747443A3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4230961A (en) * | 1978-09-12 | 1980-10-28 | Westinghouse Electric Corp. | Magnetic flux sensor for laminated cores |
-
1975
- 1975-12-17 PL PL18565775A patent/PL105294B1/en unknown
-
1976
- 1976-12-01 CA CA266,939A patent/CA1066361A/en not_active Expired
- 1976-12-07 DE DE19762655464 patent/DE2655464A1/en not_active Ceased
- 1976-12-10 SU SU762426150A patent/SU747443A3/en active
- 1976-12-17 JP JP15101176A patent/JPS5274375A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5274375A (en) | 1977-06-22 |
| SU747443A3 (en) | 1980-07-23 |
| PL105294B1 (en) | 1979-10-31 |
| DE2655464A1 (en) | 1977-06-30 |
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