GB1587919A - Electrical motor windings - Google Patents
Electrical motor windings Download PDFInfo
- Publication number
- GB1587919A GB1587919A GB43376/77A GB4337677A GB1587919A GB 1587919 A GB1587919 A GB 1587919A GB 43376/77 A GB43376/77 A GB 43376/77A GB 4337677 A GB4337677 A GB 4337677A GB 1587919 A GB1587919 A GB 1587919A
- Authority
- GB
- United Kingdom
- Prior art keywords
- winding
- torque
- control
- current
- controllable
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/02—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using supply voltage with constant frequency and variable amplitude
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
- Cable Accessories (AREA)
- Discharging, Photosensitive Material Shape In Electrophotography (AREA)
- Connections Effected By Soldering, Adhesion, Or Permanent Deformation (AREA)
- Windings For Motors And Generators (AREA)
Description
(54) ELECTRICAL MOTOR WINDINGS
(71) We, SIEMENS AKTIENGESELLSCHAFT a German company of Berlin and Munich,
Germany (fed rep), do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
The invention relates to electrical motor windings.
According to the present invention there is provided a winding for an electric motor, the winding.comprising a plurality of single phases in each of which there is: a first winding portion having an end for connection to a respective phase of an electrical supply, the first winding portions being interconnected; and a second winding portion having an end connected to said end of the first winding portion and an opposite end connection to a neutral conductor; each second winding portion having in series with it a contrpllable device operable to vary the current in the second winding portion, there being control means operable to control the controllable devices such that the currents in the second winding portions vary in such a manner as to control in stepless manner the torque produced by the winding.
In asynchronous motors having squirrel-cage rotors for driving heavy loads, more particularly conveyor belts, it is advantageous for the dimensional proportions of the first and second winding portions to be so chosen that the torque can be kept constant during runningup to speed in the range from substantially rated torque to substantially 1.3 times the rated torque, and for the last-mentioned torque value not to be exceeded even during passage through the pull-out torque.
For this purpose, the first and second winding portions may be divided, for example in the case of a six-pole asynchronous machine, in the ratios of coil numbers 3:3, 4:2 or 5:1.
With first and second winding portions of equal sizes, the stator impedance has, for example during starting, twice the value which it has in normal operation at rated torque. The utilisation of the asychronous machine in rated operation with such stator windings remains substantially unchanged.
By stepless parallel operation of the second winding portions a stepless control of the torque is possible. Particúlarly, but not exclusively, where anti-parallel semi-conductor rectifier elements of semi-conductor rectifier means are provided, two modes of control may be provided: a. a mode of control in which the controllable
devices conduct variable portions of
current half-cylces; and b. a mode of control in which the controllable
devices conduct periodically only predeter
mined numbers of successive cycles of
current, these periods of conduction being
interspersed with periods of non-conduction.
One or each of the two above modes of control may be applied in respect of positive or negative current half cycles only.
Different modes of control may be applied simultaneously to different one of the controllable devices.
For a better understanding of the invention and to show how it may be carried into effect reference will now be made, by way of example, to the accompanying drawing in which:
Figure 1 illustrates a motor winding according to the invention having commonly controlled semi-conductor rectifier arrangements controlling the second winding parts;
Figure 2 illustrates a motor winding according to the invention having separately controlled semi-conductor rectifier arrangements, and
Figure 3 illustrates the variation of the torque with speed for variation of the current through the second winding parts.
In each of the embodiments first winding parts A of a three phase motor winding are on the one hand connected to a three phase supply system N, and on the other hand fixedly connected together in star. Second winding parts B are connected on the one hand also to the supply system N, but at their other ends they are connected to a neutral conductor
Mp through respective semi-conductor rectifier arrangements V1, V2 and V3. These consist of anti-parallel-connected semi-conductor rectifier elements such as diodes, thyristors, transistors or the like, which are controllable at least in one branch. They can be brought steplessly from the non-conducting state to the fully conducting state in the same manner by a common control device ST for all three phases.Since the semi-conductor rectifier elements are always at one side at the potential of the neutral conductor M during operation, they need be designed only to withstand the internal voltage drops of the motor, which are substantially one power of ten lower than the terminal voltage. Since in addition only the current of the winding parts B flows through them, their loading is often only about 5% of the motor loading and they can be designed accordingly.
By corresponding common control of the semi-conductor rectifier arrangements V1, V2 and V3, the torque according to the characteristic curve I of Figure 3 can be obtained with the winding parts B non-conducting, or the higher torque according to the characteristic curve II can be obtained with the winding parts B in the fully conducting condition.
With semi-conductor rectifier arrangements which are phase-angle-controlled in the partially conducting condition, any intermediate value of torque in the hatched region can be obtained in dependence upon the phase angle. The difference in torque between the characteristic curves II and I depends upon the coil number ratio of the winding parts A: B.
In the embodiment according to Figure 2, in which parts identical with parts of Figure 1 are denoted by the same references as in the latter figure, each semi-conductor rectifier arrangement V1, V2 and V3 is separately controllable by a separate control device STI, ST2 or ST3.
Thus, the braking torque indicated by a chain line in Figure 3 can be obtained by a control in accordance with the aforementioned possibility, i.e. by all the positive half-cycles being blocked and all the negative-half-cycles being fully conducted (for example by means of an uncontrolled diode) or partially conducted. Due to this unsymmetrical control, pulsating direct currents flow in the winding parts B. If the direct-current components of all the phases are of equal value and of like direction (zero system), a relatively weak braking torque of triple pole number is set up.
On the other hand, if all the direct-current components do not have the same direction, substantially stronger braking torques of single pole numbers are set up.
More particularly in the case of the symmetrically controlled arrangements, the connection indicated by a dash-dotted line in
Figure 2 may be provided to form a common star point of the winding parts A and B with the neutral conductor Mp. Then each winding part B is connected in parallel with its accociated winding part A.
The embodiments make it possible for the torque of an asynchronous motor having a squirrel-cage motor to be controlled in stepless manner so as to render possible both a gentle start with constant torque which is above the rated torque, and a stepless torque adjustment during continuous operation, while at the same time ensuring that the dimensional loading resulting from the current and voltage loading of the switching means amounts only to a fraction of the motor loading.
WHAT WE CLAIM IS:
1. A winding for an electric motor, the winding comprising a plurality of single phases in each of which there is: a first winding portion having an end for connection to a respective phase of an electrical supply, the first winding portions being interconnected; and a second winding portion having an end connected to said end of the first winding portion and an opposite end connected to a neutral conductor; each second winding portion having in series with it a controllable device operable to vary the current in the second winding portion, there being control means operable to control the controllable devices such that the currents in the second winding portions vary in such a manner as to control in stepless manner the torque produced by the winding.
2. A winding according to Claim 1, wherein each of said controllabe devices is a controllable semi-conductor rectifier arrangement.
3. A winding according to Claim 2, wherein each of said controllable devices is an arrange.
ment of controllable semiconductor rectifier elements connected in anti-parallel.
4. A winding according to Claim 1, 2 or 3, wherein each of said controllable devices is connected between the associated second winding portion and the neutral conductor.
5. A winding according to any one of the preceding claims, wherein said controllable devices have sufficient current carrying capacity to withstand substantially no greater than the maximum current carried by said second winding portions when the stator winding is in operation.
6. A winding according to any one of the preceding claims, wherein each controllable device has associated with it its own respective control device in said control means.
7. A winding according to any one of the preceding claims, wherein the interconnection of said first winding portions is connected to said neutral conductor.
8. A winding substantially as hereinbefore described with reference to Figure 1 or 2.
9. A winding according to any one of the preceding claims wherein the control means is operable to apply to the controllable devices a mode of control such that they conduct variable portions of current half-cycles.
10. A winding according to any one of the preceding claims, wherein the control means is operable to apply to the controllable devices a mode of control such that they conduct periodically only predetermined numbers of successive cycles of current, these periods of conduction being interspersed with periods of
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (12)
1. A winding for an electric motor, the winding comprising a plurality of single phases in each of which there is: a first winding portion having an end for connection to a respective phase of an electrical supply, the first winding portions being interconnected; and a second winding portion having an end connected to said end of the first winding portion and an opposite end connected to a neutral conductor; each second winding portion having in series with it a controllable device operable to vary the current in the second winding portion, there being control means operable to control the controllable devices such that the currents in the second winding portions vary in such a manner as to control in stepless manner the torque produced by the winding.
2. A winding according to Claim 1, wherein each of said controllabe devices is a controllable semi-conductor rectifier arrangement.
3. A winding according to Claim 2, wherein each of said controllable devices is an arrange.
ment of controllable semiconductor rectifier elements connected in anti-parallel.
4. A winding according to Claim 1, 2 or 3, wherein each of said controllable devices is connected between the associated second winding portion and the neutral conductor.
5. A winding according to any one of the preceding claims, wherein said controllable devices have sufficient current carrying capacity to withstand substantially no greater than the maximum current carried by said second winding portions when the stator winding is in operation.
6. A winding according to any one of the preceding claims, wherein each controllable device has associated with it its own respective control device in said control means.
7. A winding according to any one of the preceding claims, wherein the interconnection of said first winding portions is connected to said neutral conductor.
8. A winding substantially as hereinbefore described with reference to Figure 1 or 2.
9. A winding according to any one of the preceding claims wherein the control means is operable to apply to the controllable devices a mode of control such that they conduct variable portions of current half-cycles.
10. A winding according to any one of the preceding claims, wherein the control means is operable to apply to the controllable devices a mode of control such that they conduct periodically only predetermined numbers of successive cycles of current, these periods of conduction being interspersed with periods of
non-conduction.
11. A winding according to Claim 9 or 10, wherein the control means is operable to apply the or each said mode of control in respect of positive or negative current half-cylces only.
12. A winding according to Claim 9, 10 or 11, wherein the control means is operable to apply different modes of control simultaneously to different ones of said controllable devices.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2652217A DE2652217C3 (en) | 1976-11-16 | 1976-11-16 | Arrangement with a partial winding circuit for changing the torque of an asynchronous machine |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1587919A true GB1587919A (en) | 1981-04-15 |
Family
ID=5993304
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB43376/77A Expired GB1587919A (en) | 1976-11-16 | 1977-10-18 | Electrical motor windings |
Country Status (5)
Country | Link |
---|---|
BE (1) | BE860860A (en) |
DE (1) | DE2652217C3 (en) |
FR (1) | FR2371088A1 (en) |
GB (1) | GB1587919A (en) |
NO (1) | NO141531C (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2159352A (en) * | 1984-05-24 | 1985-11-27 | Elevator Gmbh | Arrangement for braking a motor having a short-circuited rotor |
GB2205458A (en) * | 1987-05-12 | 1988-12-07 | Kone Elevator Gmbh | Dynamically braking a squirrel-cage motor |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0352354A1 (en) * | 1985-01-22 | 1990-01-31 | Gregory Leibovich | Compound short-circuit induction machine and method of its control |
DE3641189A1 (en) * | 1986-12-03 | 1988-06-16 | Stromag Maschf | Drive unit |
DE19704504A1 (en) * | 1997-02-06 | 1998-08-13 | Krauss Maffei Ag | Electric motor with sub-divided windings e.g. for drive- or feed-motor in machine tools |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES358002A1 (en) * | 1967-09-15 | 1970-04-01 | Honsberg Geb | Three phase motor with a device for its maneuver without contacts. (Machine-translation by Google Translate, not legally binding) |
SE303362B (en) * | 1967-11-24 | 1968-08-26 | Asea Ab |
-
1976
- 1976-11-16 DE DE2652217A patent/DE2652217C3/en not_active Expired
-
1977
- 1977-10-18 GB GB43376/77A patent/GB1587919A/en not_active Expired
- 1977-11-07 NO NO773810A patent/NO141531C/en unknown
- 1977-11-09 FR FR7733812A patent/FR2371088A1/en active Granted
- 1977-11-16 BE BE182644A patent/BE860860A/en unknown
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2159352A (en) * | 1984-05-24 | 1985-11-27 | Elevator Gmbh | Arrangement for braking a motor having a short-circuited rotor |
GB2205458A (en) * | 1987-05-12 | 1988-12-07 | Kone Elevator Gmbh | Dynamically braking a squirrel-cage motor |
GB2205458B (en) * | 1987-05-12 | 1991-06-12 | Kone Elevator Gmbh | Method and device for braking a sqirrel-cage motor |
Also Published As
Publication number | Publication date |
---|---|
DE2652217B2 (en) | 1978-10-12 |
NO773810L (en) | 1978-05-18 |
NO141531B (en) | 1979-12-17 |
BE860860A (en) | 1978-03-16 |
NO141531C (en) | 1980-03-26 |
FR2371088A1 (en) | 1978-06-09 |
FR2371088B1 (en) | 1982-02-19 |
DE2652217A1 (en) | 1978-05-24 |
DE2652217C3 (en) | 1979-06-07 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |