GB2051494A - An asynchronous generator - Google Patents
An asynchronous generator Download PDFInfo
- Publication number
- GB2051494A GB2051494A GB7941021A GB7941021A GB2051494A GB 2051494 A GB2051494 A GB 2051494A GB 7941021 A GB7941021 A GB 7941021A GB 7941021 A GB7941021 A GB 7941021A GB 2051494 A GB2051494 A GB 2051494A
- Authority
- GB
- United Kingdom
- Prior art keywords
- rotor
- asynchronous generator
- voltage
- generator
- stator
- 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.)
- Granted
Links
- 239000000463 material Substances 0.000 claims description 6
- 230000000087 stabilizing effect Effects 0.000 claims description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052742 iron Inorganic materials 0.000 abstract description 4
- 229910001369 Brass Inorganic materials 0.000 abstract description 2
- 239000010951 brass Substances 0.000 abstract description 2
- 239000000696 magnetic material Substances 0.000 abstract description 2
- 239000003990 capacitor Substances 0.000 description 9
- 238000004804 winding Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K17/00—Asynchronous induction motors; Asynchronous induction generators
- H02K17/42—Asynchronous induction generators
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Synchronous Machinery (AREA)
- Iron Core Of Rotating Electric Machines (AREA)
Abstract
An asynchronous generator comprises a stator (1) and a rotor (2) and is characterised by the output voltage being stabilized by means of a reduction of the sectional area of the field-penetrable portion of the rotor (2) for example by having a large diameter shaft (3) of non-magnetic material such as brass. As a result, the iron loss is reduced as the rotating field is almost stationary relative to the rotor. <IMAGE>
Description
SPECIFICATION
An asynchronous generator
The invention relates to an asynchronous generator comprising a stator and a rotor coaxially located therewith as well as means for stabilizing the output voltage.
In a known generator of the above type, the means for stabilizing the voltage are a pair of choke coils shunting their respective stator windings.
The voltage may furthermore be stabilized by a saturation of the stator material, whereby, however, a not inconsiderable heating of the stator material takes place.
The object of the invention is to provide a manner of stabilizing the output voltage at the same time as the total "iron" loss is reduced.
The asynchronous generator according to the invention is characterised by the output voltage being stabilized by a reduction of the sectional area of the field-penetrable portion of the rotor. In this manner the "iron" loss is reduced as the rotor is almost stationary relative to the rotating field.
According to the invention it is preferred that the sectional area is reduced by using a shaft of nonmagnetic material.
According to an embodiment of the generator according to the invention the diameter of the shaft is more than half as large as the diameter of the rotor.
The invention will be described below with reference to the accompanying drawing, in which
Figure 1 is a sectional view through an asynchronous generator according to the invention,
Figure 2 is a diagrammatic view of a stator winding with outer blank-effect capacitors, and
Figure 3 illustrates the voltage at idle running as well as in loaded condition versus the blank current.
The asynchronous generator illustrated in
Fig. 1 comprises a stator 1 with a plurality of slots for the stator windings, and a rotor 2 coaxially arranged therewith and also provided with slots. Furthermore, the shaft 3 of the rotor is illustrated. The shaft is of a nonmagnetic material such as brass and has a diameter preferaby more than half as large as the diameter of the rotor 2. The object of the nonmagnetic material is to make the field lines run around the shaft 3, whereby the field-penetrable sectional area of the rotor 2 is reduced. An example of one of the field lines is illustrated in Fig. 1. The effect of reducing the field-penetrable sectional area is that the output voltage of the generator is stabilized when the rotor is saturated, cf. Fig. 3, said saturation, of course, involving a predetermined "iron" loss.The losses, however, depend primarily on the frequency, the hysteresis loss being proportional to the frequency and the eddy current losses being proportional to the square of the frequency.
According to the invention the circumstance that the rotating field is almost stationary relative to the rotor is utilized, the frequency relative to the rotor being the slip multiplied with the net frequency at connection to the mains, typically 2 Hz, and furthermore the circumstance that the frequency and the losses are thereby minimized by placing the saturation-voltage stability in the rotor.
When the generator being constructed as a conventional asynchronous machine apart from the shaft, is connected to a three-phase network, the capacitors illustrated in Fig. 2 may be saved. These capacitors are only necessary in case a blank effect is to be supplied.
Then the frequency is primarily intended for the number of revolutions. The load and thereby the slip only influences the frequency to a minor degree.
Fig. 3 illustrates how the voltage is stable irrespective of the blank current Iwl and the size of the capacitors C. The dotted line, however, illustrates where the shaft is made of magnetic material.
A particular advantage by the generator according to the invention is that it is very reliable and requires no maintenance, which renders it possible to use said generator in the developing countries. The diameter of the generator is in the range 95 to 220 mm. The effect is in the range 5 to 40 kVA. The capacitors C are of 20 IlF/kVA and are thus 300 ,uF at 1 5 kVA. The generator may have an arbitrary pole pitch and need not be exactly fourpole. It may for instance be bipolar.
The voltage may be variable by the individual stator winding comprising a main winding and an auxiliary winding. The main windings and the auxiliary windings may then be coupled in various star-delta combinations.
The voltage is, of course, proportional to the number of field lines intersected per second.
Fig. 3 illustrates how little the voltage depends on the size of the capacitor C, the voltage being determined by the intersection between the characteristics of the capacitor and the magnetizing characteristics of the asynchronous motor. The interesting feature is, however, that the voltage does not vary much (AV) with the load, which corresponds to a parallel displacement of the magnetizing curve of the known characteristic triangle, whereby one only slides down the characteristics of the capacitor to the next intersection with the parallelly displaced magnetizing characteristics. Had the magnetizing characteristics been steeper, cf. the dotted line, it is obvious that the voltage variation would have been many times greater, especially when the characteristics of the capacitor have almost the same inclination as the last portion of the characteristics of the magnetizing curve.
Claims (4)
1. An asynchronous generator comprising a stator (1) and a rotor (2) coaxially located therewith as well as means for stabilizing the output voltage, characterised by the output voltage being stabilized by a reduction of the sectional area of the field-penetrable portion of the rotor (2).
2. An asynchronous generator as claimed in claim 1, characterized by the sectional area reduction being obtained by using a shaft (3) of nonmagnetic material.
3. An asynchronous generator as claimed in claim 2, characterised by the diameter of the shaft (3) being more than half as large as the diameter of the rotor (2).
4. An asynchronous generator substantially as described above with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DK570678A DK143429C (en) | 1978-12-19 | 1978-12-19 | asynchronous |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2051494A true GB2051494A (en) | 1981-01-14 |
| GB2051494B GB2051494B (en) | 1983-04-07 |
Family
ID=8144643
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7941021A Expired GB2051494B (en) | 1978-12-19 | 1979-11-28 | A synchronous generator |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS55114170A (en) |
| DE (1) | DE2947701A1 (en) |
| DK (1) | DK143429C (en) |
| FR (1) | FR2445054A1 (en) |
| GB (1) | GB2051494B (en) |
| IT (1) | IT1125913B (en) |
| NL (1) | NL7908704A (en) |
| SE (1) | SE7910427L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5541463A (en) * | 1993-06-15 | 1996-07-30 | Eko Technologies, Inc. | Flex path and core loss reduction assembly |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB597633A (en) * | 1944-03-31 | 1948-01-30 | Gen Electric Co Ltd | Improvements in electric generators of the induction type |
| FR1078760A (en) * | 1953-06-12 | 1954-11-23 | New AC generator group | |
| US3229137A (en) * | 1962-12-03 | 1966-01-11 | Aerojet General Co | Induction machine rotor |
| GB1096822A (en) * | 1964-01-16 | 1967-12-29 | English Electric Co Ltd | Improvements in or relating to induction motors |
| GB1348485A (en) * | 1970-04-23 | 1974-03-20 | Nat Res Dev | Rotary electric machines |
-
1978
- 1978-12-19 DK DK570678A patent/DK143429C/en not_active IP Right Cessation
-
1979
- 1979-11-27 DE DE19792947701 patent/DE2947701A1/en not_active Withdrawn
- 1979-11-28 GB GB7941021A patent/GB2051494B/en not_active Expired
- 1979-11-30 NL NL7908704A patent/NL7908704A/en not_active Application Discontinuation
- 1979-12-07 IT IT27875/79A patent/IT1125913B/en active
- 1979-12-18 JP JP16368479A patent/JPS55114170A/en active Pending
- 1979-12-18 SE SE7910427A patent/SE7910427L/en unknown
- 1979-12-18 FR FR7930918A patent/FR2445054A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| SE7910427L (en) | 1980-06-20 |
| DK570678A (en) | 1980-06-20 |
| NL7908704A (en) | 1980-06-23 |
| FR2445054A1 (en) | 1980-07-18 |
| DK143429C (en) | 1981-12-21 |
| DK143429B (en) | 1981-08-17 |
| IT7927875A0 (en) | 1979-12-07 |
| JPS55114170A (en) | 1980-09-03 |
| IT1125913B (en) | 1986-05-14 |
| GB2051494B (en) | 1983-04-07 |
| DE2947701A1 (en) | 1980-07-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |