WO2018083639A1 - Self-starting synchronous reluctance motor - Google Patents

Self-starting synchronous reluctance motor Download PDF

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Publication number
WO2018083639A1
WO2018083639A1 PCT/IB2017/056859 IB2017056859W WO2018083639A1 WO 2018083639 A1 WO2018083639 A1 WO 2018083639A1 IB 2017056859 W IB2017056859 W IB 2017056859W WO 2018083639 A1 WO2018083639 A1 WO 2018083639A1
Authority
WO
WIPO (PCT)
Prior art keywords
reluctance motor
openings
synchronous reluctance
self
7b
Prior art date
Application number
PCT/IB2017/056859
Other languages
French (fr)
Inventor
Francesco CIRULLI
Marco SANTECECCA
Original Assignee
Bonfiglioli Riduttori S.P.A.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to IT102016000110554A priority Critical patent/IT201600110554A1/en
Priority to IT102016000110554 priority
Application filed by Bonfiglioli Riduttori S.P.A. filed Critical Bonfiglioli Riduttori S.P.A.
Publication of WO2018083639A1 publication Critical patent/WO2018083639A1/en

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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K19/00Synchronous motors or generators
    • H02K19/02Synchronous motors
    • H02K19/14Synchronous motors having additional short-circuited windings for starting as asynchronous motors
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K1/00Details of the magnetic circuit
    • H02K1/06Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22Rotating parts of the magnetic circuit
    • H02K1/24Rotor cores with salient poles ; Variable reluctance rotors
    • H02K1/246Variable reluctance rotors

Abstract

The rotor (2) of a synchronous reluctance motor is defined by a plurality of superimposed laminations (6), each of which has two series of openings (7, 13) distributed within two mutually concentric circular crowns (8, 14); one series of the openings (7) having for each magnetic pole of the synchronous reluctance motor a respective central opening (7a) arranged between at least two side openings (7b), each of which opens outwards at an outer surface (12) of the respective lamination (6).

Description

SELF-STARTING SYNCHRONOUS RELUCTANCE MOTOR

TECHNICAL FIELD

The present invention relates to a self-starting synchronous reluctance motor.

In particular, the present invention relates to a synchronous reluctance motor comprising a rotor mounted to rotate about a rotation axis; and a stator mounted around the rotor, coaxial to the rotation axis.

BACKGROUND ART

The rotor and the stator comprise respective superimposed packs of ferromagnetic steel laminations.

Each rotor lamination has a plurality of first openings, which are distributed within a first circular crown coaxial to the rotation axis, and a plurality of second openings, which are distributed within a second circular crown concentric to the first circular crown, and are separated from the first openings.

The first openings of each rotor lamination comprise, for each magnetic pole of the synchronous reluctance motor, a central opening and at least two side openings arranged on the opposite sides of the central opening.

Each central opening has an area larger than each side opening, and is closed by an annular profile. Each side opening has a symmetry plane that does not contain the rotation axis of the rotor and is closed by an annular profile .

The first openings of each rotor lamination define, along with corresponding first openings of the other rotor laminations, a plurality of first slots of the rotor.

The rotor is further provided with a squirrel cage, which is made by means of an aluminium or copper die-casting process, and comprises a plurality of bars housed within the first slots and two end rings obtained on the opposite sides of the relative laminations, coaxially with respect to the rotation axis.

The second openings of each rotor lamination define, along with corresponding second openings of the other rotor laminations, a plurality of second slots of the rotor.

The second slots are empty, and define relative flow barriers, which generate a reluctance torque for rotating the rotor.

Since the side openings of each lamination are closed by an annular profile, the flow lines of the magnetic field generated by the electric current fed to the stator predominantly flow along the outer perimeter of the rotor and only secondarily around the first slots.

Consequently, known synchronous reluctance motors of the aforesaid type show some disadvantages, mainly resulting from the fact that the first slots and the squirrel cage are subjected to a relatively low magnetic field, and that therefore these motors are, on the one hand, capable of starting if connected directly to the power network but, on the other hand, incapable of handling loads with a relatively high inertia.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a self- starting synchronous reluctance motor that is free from the aforesaid drawbacks and is simple and inexpensive to implement .

The present invention provides a self-starting synchronous reluctance motor as claimed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings illustrating an example of a non-limiting embodiment, wherein:

Figure 1 is a schematic plan view, with parts removed for clarity's sake, of a preferred embodiment of the synchronous reluctance motor of the present invention;

Figure 2 is a schematic perspective view, with parts removed for clarity's sake, of a detail of the synchronous reluctance motor of Figure 1;

Figure 3 is a section along line III-III of Figure 2; and Figure 4 is a plan view of a detail of Figures 2 and 3. BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figures 1 and 2, 1 indicates, as a whole, a synchronous reluctance motor, in this case a synchronous reluctance motor with four magnetic poles, comprising a rotor 2 and a stator 3.

The rotor 2 has an annular shape, is mounted to rotate about its own longitudinal axis 4 and extends in a direction 5 parallel to the axis 4.

The rotor 2 comprises a plurality of annular laminations 6 (Figures 3 and 4), which are made of ferromagnetic steel, and are coaxially superimposed with respect to the axis 4. As shown in FIG. 4, each lamination 6 has a plurality of first openings 7, which are formed through the lamination 6 in the direction 5 and are distributed around the axis 4 within an outer circular crown 8 of the lamination 6.

Since the motor 1 comprises, in this case, four magnetic poles, each lamination 6 is divided into four substantially identical segments 9, separated from one another by two interpolar axes 10 substantially perpendicular to each other.

The openings 7 of each segment 9 comprise a central opening 7a and a plurality of side openings 7b (in this case six side openings 7b) tangentially arranged on the opposite sides of the central opening 7a.

The central opening 7a substantially has the shape of an isosceles trapezium, is limited by a closed-ring side profile and further has a radial symmetry plane PI containing the axis 4.

Each side opening 7b has a symmetry plane P2 not containing the axis 4 and parallel to the planes P2 of the other side openings 7b (in this case, the other two side openings 7b) arranged on the same side of the central opening 7a.

Each side opening 7b has a substantially rectangular shape and is tangentially limited by two side flanks 11 parallel to each other and to the relative plane P2. Moreover, it is open outwards at an outer surface 12 of the lamination 6. Each central opening 7a has an area that is larger, in particular at least three times larger, than the area of each side opening 7b.

Moreover, each lamination 6 has a plurality of second openings 13 which are formed through the lamination 6 in the direction 5 and are distributed around the axis 4 inside a circular inner crown 14 of the lamination 6.

The openings 13 of each segment 9 are equal to the half of the side openings 7b of the segment 9, have the symmetry plane PI of the respective central opening 7a and comprise, in this case, three radially aligned openings 13a, 13b, 13c starting from the axis 4.

The opening 13c extends around the axis 4, radially facing its central opening 7a, and has two free ends facing the free ends of two side openings 7b.

Each opening 13a, 13b comprises two end portions 15, each of which faces the free end of a relative side opening 7b and extends parallel to the plane P2 of its side opening 7b, and a central portion 16, which is formed between the two portions 15 and extends around the axis 4.

Due to the shape and the arrangement of the side openings 7b and of the openings 13a, 13b, 13c, the distance D between the free ends of the side openings 7b and the corresponding openings 13a, 13b, 13c, measured parallel to the corresponding symmetry planes P2, is substantially constant .

With reference to Figures 2 and 3, the openings 7a, 7b of each lamination 6 define, along with the corresponding openings 7a, 7b of the other laminations 6, a plurality of first slots 17 of the rotor 2.

The rotor 2 is further provided with a squirrel cage 18, which is made by means of an aluminium or copper die- casting process and comprises a plurality of bars 19, each housed within a respective slot 17, and two end rings 20 formed on the opposite sides of the laminations 6, coaxially with respect to the axis 4.

Each lamination 6 further has a plurality of cavities 21, which are equal in number to the number of magnetic poles of the motor 1, are evenly distributed around the axis 4 and are formed on the surface 12 of the lamination 6.

Each cavity 21 has a semicircular shape, has the symmetry plane PI of a relative opening 7a and defines, along with the corresponding cavities 21 of the other laminations 6, an elongated channel 22 having a semi-cylindrical shape and extending in the direction 5.

The channels 22 allow connecting the laminations 6 by means of a welding process so as to carry out properly the next die-casting process of the cage 18.

The openings 13a, 13b, 13c of each lamination 6 define, along with respective openings 13a, 13b, 13c of the other laminations 6, a plurality of second cavities 23 of the rotor 2.

The cavities 23 are empty to define respective flow barriers capable of generating a reluctance torque to rotate the rotor 2 around the axis 4.

The stator 3 comprises a plurality of annular laminations 24 of the known type (one of which is shown in FIG. 1) , which are made of ferromagnetic steel, are coaxially superimposed with respect to the axis 4 and extend around the rotor 2.

Each lamination 24 has a plurality of openings 25, which are formed through the lamination 24 in the direction 5 and are distributed around the axis 4.

The separation between the two crowns 8 and 14 makes the squirrel cage 18 relatively simple and inexpensive, requiring relatively low material consumption.

Since the drive torque for starting the engine 1 is largely generated by the currents induced in the bars 19 housed in the slots 17 defined by the central openings 7a, the central openings 7a guarantee a relatively high performance of the motor 1 in the start-up phase, thus allowing the motor 1 to start loads with a relatively high inertia.

Since the symmetry planes P2 of the bars 19 housed in the slots 17 defined by the side openings 7b are parallel to each other and do not contain the axis 4, the width of the laminations 6 between each side opening 7b and each adjacent side opening 7b is substantially constant and allows to maintain a constant flow density, thus increasing the running performance of the motor 1.

Since the side openings 7b of each lamination 6 are open at its outer surface 12 and closed at the free ends of the respective openings 13a, 13b, 13c, the flow lines run below the side openings 7b, thus increasing the flow linked to the bars 19 of the squirrel cage 18 and improving the startup performance of the motor 1.

Claims

1. A self-starting synchronous reluctance motor comprising a rotor (2), which is mounted so as to rotate around a rotation axis (4) ; and a stator (3) , which is mounted around the rotor (2) coaxial to the rotation axis (4); the rotor (2) comprising a plurality of superimposed laminations (6), each having a plurality of first openings
(7) , which are distributed inside a first circular crown
(8) coaxial to the rotation axis (4), and a plurality of second openings (13), which are distributed inside a second circular crown (14) concentric to the first circular crown (8) ; the first openings (7) of each lamination (6) comprising, for each magnetic pole of the synchronous reluctance motor, a central opening (7a) and at least two side openings (7b), which are arranged on opposite sides of the central opening (7a); each central opening (7a) having an area larger than each side opening (7b) ; and each side opening (7b) having a symmetry plane (P2) not containing the rotation axis (4) ; and characterized in that each side opening (7b) opens up outwards at an outer surface (12) of the relative lamination (6) .
2. A self-starting synchronous reluctance motor according to claim 1, wherein the first openings (7) of each lamination (6) define, together with corresponding first openings (7) of the other laminations (6), a plurality of first slots (17) of the rotor (2) ; the rotor (2) comprising a squirrel cage (18), which is at least partially housed inside the first slots (17) .
3. A self-starting synchronous reluctance motor according to claim 1 or 2, wherein each central opening
(7a) is closed by an annular profile.
4. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein each central opening (7a) has a radial symmetry plane (PI) containing the rotation axis (4) .
5. A self-starting synchronous reluctance motor according to claim 4, wherein each central opening (7a) has a substantially trapezoidal shape.
6. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein each side opening (7b) has a substantially rectangular shape and is limited by two side flanks (11), which are substantially parallel to the relative symmetry plane (P2) .
7. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein the symmetry plane (P2) of each side opening (7b) is substantially parallel to the symmetry plane (P2) of each adjacent side opening (7b) .
8. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein each second opening (13) of at least some of the second openings (13) has two end portions (15), which are substantially parallel to the symmetry planes (P2) of corresponding side openings (7b), and further comprises a central portion (16), which is obtained between said two end portions (15) and extends around the rotation axis (4) .
9. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein the second openings (13) of each lamination (6) comprise, for each magnetic pole of the synchronous reluctance motor, a number of second openings (13), whose number is equal to the half of the side openings (7b) of the magnetic pole.
10. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein each second opening (13) extends around the rotation axis (4) and has two free ends facing two corresponding side openings (7b) .
11. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein each second opening (13) has a radial symmetry plane (PI) containing the rotation axis (4) .
12. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein the second openings (13) of each lamination (6) define, together with corresponding second openings (13) of the other laminations (6), a plurality of second slots (23) of the rotor (2); the second slots (23) of the rotor (2) being empty so as to define respective flow barriers and generate a reluctance torque to rotate the rotor (2) around the rotation axis (4) .
13. A self-starting synchronous reluctance motor according to any one of the previous claims, wherein each lamination (6) has, for each magnetic pole of the synchronous reluctance motor, a respective cavity (21), which is formed on an outer surface (12) of the lamination (6) and has a radial symmetry plane (PI) coinciding with the symmetry plane (PI) of a relative central opening (7a) .
14. A self-starting synchronous reluctance motor according to claim 13, wherein each cavity (21) of each lamination (6) defines, together with corresponding cavities (21) of the other laminations (6), a welding channel (22) to connect the laminations (6) through welding .
PCT/IB2017/056859 2016-11-03 2017-11-03 Self-starting synchronous reluctance motor WO2018083639A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
IT102016000110554A IT201600110554A1 (en) 2016-11-03 2016-11-03 synchronous reluctance motor bootable
IT102016000110554 2016-11-03

Publications (1)

Publication Number Publication Date
WO2018083639A1 true WO2018083639A1 (en) 2018-05-11

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IT (1) IT201600110554A1 (en)
WO (1) WO2018083639A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3045135A (en) * 1959-12-31 1962-07-17 Allis Chalmers Mfg Co Synchronous induction motor
US3597646A (en) * 1970-01-26 1971-08-03 Peter John Lawrenson Dynamoelectric machines
GB1347561A (en) * 1970-01-30 1974-02-27 Nat Res Dev Dynamo-electric machines of the reluctance type
GB1422522A (en) * 1971-12-17 1976-01-28 Nat Res Dev Dynamo-electric machines of the relictance type
US20150372577A1 (en) * 2013-02-01 2015-12-24 Ksb Aktiengesellschaft Rotor, Reluctance Machine and Production Method for a Rotor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3045135A (en) * 1959-12-31 1962-07-17 Allis Chalmers Mfg Co Synchronous induction motor
US3597646A (en) * 1970-01-26 1971-08-03 Peter John Lawrenson Dynamoelectric machines
GB1347561A (en) * 1970-01-30 1974-02-27 Nat Res Dev Dynamo-electric machines of the reluctance type
GB1422522A (en) * 1971-12-17 1976-01-28 Nat Res Dev Dynamo-electric machines of the relictance type
US20150372577A1 (en) * 2013-02-01 2015-12-24 Ksb Aktiengesellschaft Rotor, Reluctance Machine and Production Method for a Rotor

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Publication number Publication date
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