Single-phase synchronous motor and pump comprising synchronous motor

Abstract

The utility model relates to a single-phase synchronous electric motor comprising at least one stator winding, a U-shaped laminated stator core with two poles and a rotor, the rotor being arranged between the two poles and the rotor comprising rotor permanent magnets wherein the electric motor comprises a magnetic device support wherein the magnetic device support comprises at least a first part and a second part, the first and second portions are located between the two poles in diametrically opposite positions with respect to the axis of rotation of the rotor and radially away from the rotor permanent magnets, the first portion being implemented or configured to implement a first magnetic moment, the second portion being implemented or configured to implement a second magnetic moment, the first and second magnetic moments being oriented parallel to each other.

Description

Technical Field

[0001] The present invention relates to a single-phase synchronous motor, which includes at least one stator winding, a U-shaped laminated stator core with two poles, and a rotor, where the rotor is arranged between the two poles and the rotor includes rotor permanent magnets.

[0002] Furthermore, the present invention relates to a pump, which includes the synchronous motor according to the present invention. Background Art

[0003] Single-phase synchronous motors are well known and are now especially used as drives, for example, for pumps, especially water pumps.

[0004] When the same number of magnetic poles are formed in the stator and the rotor, a force is exerted on the rotor, resulting in torque fluctuations during one rotation of the rotor. This causes unstable operation, especially at low speeds. In a single-phase bipolar motor, there are two positions during one rotation of the rotor where no electric torque is generated, that is, no torque acts on the permanent magnet rotor, which is the result of the current flowing through the stator winding and the resulting magnetic field force. These two positions correspond to the angular positions where the north and south poles of the rotor are aligned with the pole legs and pole shoes, that is, "in a straight line" with them. This is the case for the angular positions of 90° and 270°. These angular positions represent stationary positions, also known as locked positions, because no torque acts on the rotor at these positions. After power-off, the motor remains in one of these two stationary positions.

[0005] Therefore, it is difficult to start the motor from one of these positions because at these angular positions, the electrical activation of the stator winding does not generate torque, that is, no starting torque is generated, so the rotor cannot accelerate and thus the motor does not start. The same is true if the rotor is close to one of the locked or stationary positions in the angular position, and if the static friction torque is greater than the starting torque, no starting will occur.

[0006] To ensure starting, it is known to use a synchronous motor with laminated part asymmetry in the form of arcuate recesses on the pole arcs of the pole legs or pole shoes. In particular, these recesses are diametrically opposite and are offset by a certain angle from the plane of symmetry where the stator poles are located. In addition, it is well known to use a single magnetic device or multiple magnetic devices that are not diametrically opposite to each other (therefore, in the case where the number of magnetic devices is even, these magnetic devices are not symmetrically distributed along the circumference of the motor bore). This arrangement results in a change in the cogging torque such that in the case of power-off, the rotor remains in a stationary position that can generate sufficient electric torque when restarting the rotor.

[0007] The arrangement of a single magnetic device, or the arrangement of a plurality of magnetic devices that are not diametrically opposed, is asymmetrically distributed along the circumference of the motor bore in the case where the magnetic devices are even in number, resulting in a change in cogging torque such that it no longer has a half-cycle of electrical torque relative to the rotation of the complete rotor, but has the same period as the electrical torque. This is achieved by moving the zero point of the cogging torque in opposite directions in the rotor position regions corresponding to the natural rest positions of the lower and upper halves of the rotor circumference. Furthermore, such an effect is that when power is cut off, the rotor remains in the rest position, and this position can generate sufficient electrical torque when the rotor is restarted.

[0008] However, the use of an asymmetric arrangement or setting of magnetic devices (using a single magnetic device or a plurality of magnetic devices that are not diametrically opposed) results in severe wear of the bearing system. Summary of the Invention

[0009] The object of the present invention is to provide a technically simple, effective and cost-saving solution to provide a single-phase synchronous motor such that when power is cut off, the rotor remains in the rest position, and sufficient electrical torque can be generated when the rotor is restarted at this position. Another object of the present invention is to provide a pump including the synchronous motor according to the present invention, especially for a hydraulic system, especially for pumping water.

[0010] The object of the present invention is achieved by a single-phase synchronous motor, which includes at least one stator winding, a U-shaped laminated stator core with two poles, and a rotor arranged between the two poles, and the rotor includes rotor permanent magnets. Among them, the motor includes a magnetic device support, and the magnetic device support includes at least a first part and a second part. The first and second parts are located between the two poles at positions diametrically opposed with respect to the rotor rotation axis and are radially spaced from the rotor permanent magnets. The first part realizes or is configured to realize a first magnetic moment, and the second part realizes or is configured to realize a second magnetic moment, and the first and second magnetic moments are oriented parallel to each other.

[0011] Therefore, according to the present invention, it is advantageously possible to both reduce the wear of the bearing system, that is, to provide an increased product life, while still achieving a relatively high electrical starting torque of the motor. Therefore, it is advantageously possible to provide torque improvement by introducing additional radial forces (unbalanced loads) due to the asymmetrically distributed magnetic devices without endangering the product life of the motor.

[0012] According to the present invention, the single-phase synchronous motor includes at least one stator winding, a U-shaped laminated stator core with two poles, and a rotor. The rotor is arranged between the two poles and includes rotor permanent magnets.

[0013] The electric motor according to the invention comprises a magnetic device support which comprises at least a first part and a second part, wherein the first and second parts are located

[0014] -- between two poles,

[0015] -- in positions opposite to each other with respect to a diameter of the rotor rotation axis, and

[0016] -- at a radial distance from the rotor permanent magnets,

[0017] wherein the first part implements or is configured to implement a first magnetic moment and the second part implements or is configured to implement a second magnetic moment, wherein the first and second magnetic moments are oriented parallel to each other, i.e., aligned and in the same direction.

[0018] In particular, the magnetic device uses two permanent magnets (e.g., sintered ferrite, anisotropic) embedded in a molded part (magnetic device support) to ensure the correct positioning of the magnets with respect to the rotor (since any misalignment would create some unbalanced load).

[0019] By implementing the magnetic device support as an axially mountable element of the electric motor, in particular as a stator construction of the electric motor, according to the invention, an electric motor can advantageously be provided for easy assembly and production.

[0020] In addition to using two permanent magnets embedded in a molded part (magnetic device support), according to the invention, other devices can also be and preferably are provided, such as auxiliary windings (i.e., the magnetic device support comprises a first coil which is in or as part of the first part of the magnetic device support and a second coil which is in or as part of the second part of the magnetic device support), which auxiliary windings are energized particularly only during the starting phase of the electric motor, or a single magnet remote from the rotor which is removed once full speed is reached.

[0021] According to the invention, furthermore, advantageously the absolute values of the first and second magnetic moments can be and preferably are equal,

[0022] wherein, in particular, the absolute values of the first and second magnetic moments correspond to between 10% and 30%, preferably between 15% and 25%, of the magnetic moment of the rotor permanent magnets.

[0023] Therefore, the method according to the invention can advantageously be implemented and carried out in a relatively simple and effective manner.

[0024] According to the invention, it is also advantageously possible and preferably that the magnetic device support includes a first permanent magnet having a first magnetic moment, the first permanent magnet being in or as part of a first part of the magnetic device support, and a second permanent magnet having a second magnetic moment, the second permanent magnet being in or as part of a second part of the magnetic device support

[0025] wherein, in particular, the first and second permanent magnets and / or the first and second parts are configured

[0026] -- to have a height in the axial direction approximately equivalent to the length of the rotor permanent magnet, and / or

[0027] -- to have an angular direction width of at most 60 degrees, preferably at most 45 degrees, more preferably at most 30 degrees

[0028] and / or wherein, in particular, the first and second permanent magnets and / or the first and second parts are made of or include sintered hard ferrite

[0029] Thus, the method of the present invention can be advantageously implemented and carried out in a relatively simple and effective manner

[0030] According to the invention, it is also advantageously and preferably that the magnetic device support includes a first coil, the first coil being in or as part of a first part of the magnetic device support, and the magnetic device support includes a second coil, the second coil being in or as part of a second part of the magnetic device support, wherein the electric motor includes or is assigned control means such that the first coil can be controlled to achieve the first magnetic moment and the second coil can be controlled to achieve the second magnetic moment

[0031] Thus, the method of the present invention can be advantageously implemented and carried out in a relatively simple and effective manner

[0032] Furthermore, according to the invention, it is advantageously possible and preferably that the magnetic device support is a molded part, wherein the first and second permanent magnets and / or the first and second coils are arranged, in particular, by overmolding and / or by insert molding as parts of the magnetic device support

[0033] Thus, the method of the present invention can be advantageously implemented and carried out in a relatively simple and effective manner

[0034] Furthermore, according to the invention, it is advantageously possible and preferably that the magnetic device support is a molded part

[0035] -- made of a material having magnetic properties, or

[0036] -- made of a material including particles having magnetic properties

[0037] Therefore, the method of the present invention can be advantageously implemented and carried out in a relatively simple and effective manner.

[0038] Furthermore, according to the present invention, it is advantageously possible and preferably that, with respect to the stator core, the electric motor has at least one angular position with a minimum motor torque, wherein the electric motor is configured such that any stationary position of the rotor is at least 20 degrees, preferably at least 30 degrees, more preferably at least 40 degrees angularly spaced from any angular position of the minimum motor torque.

[0039] Therefore, it is advantageously possible to implement and carry out the method of the present invention in a relatively simple and effective manner.

[0040] Furthermore, the present invention relates to a pump that includes a synchronous motor according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] These and other features, characteristics, and advantages of the present invention will become apparent from the following detailed description in conjunction with the accompanying drawings, which illustrate the principles of the present invention by way of example. This description is given for illustrative purposes only and does not limit the scope of the present invention. The reference figures cited below refer to the accompanying drawings.

[0042] Figure 1 The electric motor of the present invention is schematically shown in perspective as a single-phase synchronous motor that is part of an assembly with a pump or a pump element.

[0043] Figure 2 More details of the electric motor of the present invention are also schematically shown in perspective, particularly showing the two poles, the rotor, and the magnetic device support.

[0044] Figure 3 and Figure 4 Two identical representations of the magnetic device support are schematically shown, particularly a magnetic device support including a first part and a second part, with the first and second parts located between the two poles and at diametrically opposite positions with respect to the axis of rotation.

[0045] Figure 5 A top view (or, more precisely, a cross-sectional view with a sectional plane perpendicular to the axis of rotation) of the electric motor of the present invention is schematically shown.

[0046] Figure 6 The variation of the electric torque and the variation of the cogging torque of the electric motor according to the present invention are schematically shown, depending on the angle of rotation about the axis of rotation. DETAILED DESCRIPTION

[0047] The present invention will be described with reference to specific embodiments and with reference to certain drawings, but the present invention is not limited thereto, but is only limited by the claims. The described drawings are only schematic and not restrictive. In the drawings, for purposes of illustration, the dimensions of some elements may be exaggerated and not drawn to scale.

[0048] When referring to a singular noun, the indefinite or definite article is used, such as "a", "an", "the", which includes the plural of the noun, unless otherwise expressly stated.

[0049] Furthermore, the terms first, second, third, etc. used in the description and claims are used to distinguish similar elements and are not necessarily used to describe an order or a chronological order. It should be understood that the terms so used are interchangeable under appropriate circumstances, and the embodiments of the present invention described herein are capable of operating in other orders different from those described or illustrated herein.

[0050] Figure 1 The electric motor of the present invention is schematically shown in a perspective view - as a single-phase synchronous motor. Figure 1 The electric motor of the present invention is shown as part of a pump or a pump element assembly: in <6> Figure 1 the upper part, the electric motor 100 is schematically shown, while in Figure 1 the lower part, the pump 200 (or the pump unit 200) is schematically shown. In particular, the electric motor 100 has a rotational axis, while the pump 200 (as a rotary pump, i.e., also having a rotational axis) is aligned along the rotational axis of the electric motor 100 in Figure 1 the lower part.

[0051] Figure 2 More details of the electric motor of the present invention are also schematically shown in a perspective view.

[0052] Generally, single-phase synchronous motors are well known, and the electric motor 100 includes a stator and a rotor 120.

[0053] In particular according to the present invention, the stator has a U-shaped laminated stator core with two poles 111, 112, and the laminated stator core has or is arranged with at least one stator winding. The rotor 120 has or defines a rotational axis 121, the rotor 120 is arranged between the two poles 111, 112 of the stator core, and the rotor 120 includes rotor permanent magnets (not specifically shown in Figure 2 ).

[0054] Figure 2Further shown is the magnetic device support 130. The magnetic device support 130 is shown as being fixed (or attached) to the stator (or stator core, particularly in the regions of the two poles 111, 112 of the stator core). In particular, by means of axial mounting along the rotation axis 121, the magnetic device support 130 is fixed or attached to the stator.

[0055] Figure 3 and Figure 4 Two identical representations (perspective views) of the magnetic device support 130 are schematically shown: According to the invention, the magnetic device support 130 comprises a first part 131 and a second part 132 (see Figure 3 ).

[0056] In the assembled state of the magnetic device support 130, the first and second parts 131, 132 are located between the two poles 111, 112 of the stator core (however, the stator core is not shown in Figure 3 ). In addition, the first and second parts 131, 132 of the magnetic device support 130 are located in diametrically opposite positions with respect to the rotation axis 121. In addition, the first and second parts 131, 132 of the magnetic device support 130 are radially remote from the rotor permanent magnets (which are also not shown in Figure 3 ).

[0057] As Figure 4 can be seen, the first part 131 of the magnetic device support 130 implements (or is configured to implement) a first magnetic moment m1, and the second part 132 implements (or is configured to implement) a second magnetic moment m2, where the first and second magnetic moments m1, m2 are oriented parallel to each other, i.e., aligned and directed in the same direction; this is schematically shown by the vector representation of the magnetic moments m1 and m2 in Figure 4 .

[0058] Figure 5 A top view (or, more precisely, a cross-sectional view with a cross-sectional plane perpendicular to the rotation axis 121) of the motor according to the invention is schematically shown. From the Figure 5 cross-sectional view, the U-shaped laminated stator core 110 can be seen. The U-shaped laminated stator core 110 comprises two legs, and the respective ends (or respective end portions) thereof form the two poles 111, 112 of the stator 110 or stator core 110.

[0059] The U-shaped laminated stator core 110 (in the part remote from the two poles 111, 112) is provided with one or more stator windings 110'.

[0060] Figure 5 Also shown, as part of the shown cross-sectional plane, is the rotor 120 of the motor; the rotor 120 is located between the two poles 111, 112 of the stator core 110.

[0061] In a generally known manner, the two poles 111, 112 include (or the laminated stator core 110 includes) recesses 115 to increase the starting torque of the electric motor 100. The recesses 115 create a small asymmetry in the sheet metal portion of the laminated stator core 110, thereby generating an angular change of the cogging torque relative to the electric torque, thus improving (or enabling) the starting of the electric motor. In particular, these recesses 115 are diametrically opposite to each other with respect to the rotation axis 121, and their connecting line (not shown) is offset by an angle (indicated by "0°" in Figure 5 ) with respect to the connecting line (not shown) passing through the rotation axis 121 between the two poles 111 and 112. This offset angle (the central connecting line between the recesses 115 with respect to the connecting line between the two poles 111, 112 passing through the rotation axis 121) approximately corresponds to 30 to 45 degrees.

[0062] In addition, Figure 5 the first and second portions 131, 132 of the magnetic device support 130 and their respective magnetic moments m1, m2 are shown (also in the shown cross-section or as part of the shown cross-section), schematically shown as being directed downward in the Figure 5 representation.

[0063] The two poles 111, 112 and the rotor 120 are shown in Figure 5 as arranged horizontally, while the first and second portions 131, 132 and the rotor 120 are shown in Figure 5 as arranged vertically - that is, in the cross-sectional plane shown in Figure 5 , the central connecting line (not shown) between the first and second portions 131, 132 of the magnetic device support 130 is substantially vertically oriented, and the central connecting line (not shown) between the two poles 111, 112 is substantially horizontally oriented (indicated by "0°" in Figure 5 ), so an angle of substantially 90 degrees is achieved between these two connecting lines.

[0064] From the Figure 5 representation, it can be seen that the first and second portions 131, 132 of the magnetic device support 130 are radially spaced from the rotor, and thus also radially spaced from the rotor permanent magnets (schematically indicated or represented in Figure 5 by the indication "N" and "S" of the two poles of the rotor permanent magnets).

[0065] In Figure 6 , the variation of the electric torque and the variation of the cogging torque of the electric motor according to the present invention are schematically represented, which vary depending on the rotation angle (in degrees on the abscissa) around the rotation axis 121. The electric torque - also called the starting torque or starting torque (in Figure 6is represented by reference numeral 128, and the cogging torque is represented by reference numeral 129. On the vertical axis, the corresponding torque values (in Nm) are indicated respectively. From the variation of the cogging torque 129, it can be seen that the rotor 120 has a plurality of stationary (angular) positions (in Figure 6 which are represented by reference numerals 122 and 123), that is, at these angular positions of the rotor 120, the cogging torque 129 corresponds to or is almost zero (Nm). In addition, from the variation of the electric torque (or starting torque), it can be seen that there are also a plurality of (angular) positions of the minimum (electric) torque of the motor (in Figure 6 which are represented by reference numerals 125 and 126), that is, at these angular positions of the rotor 120, the electric (or starting or starting) torque 128 corresponds to or is almost zero (Nm).

[0066] Preferably, according to the present invention, any stationary positions 122 and 123 of the rotor 120 are at least 20 degrees, preferably at least 30 degrees, more preferably at least 40 degrees angularly spaced from any angular positions 125 and 126 of the minimum torque of the motor 100. In this way, a relatively high electric starting torque of the motor can be advantageously achieved. In addition, by arranging the first and second parts 131 and 132 of the magnetic device support 130 in a symmetric manner, thereby avoiding unbalanced loads, it is also possible to advantageously avoid the asymmetric distribution of the magnetic device, and thus increase the life of the motor, especially the life of its bearings.

[0067] According to the present invention, preferably, the absolute values of the first magnetic moment m1 and the second magnetic moment m2 are equal, and / or the absolute values of the first and second magnetic moments m1 and m2 correspond to between 10% and 30% of the magnetic moment of the rotor permanent magnet, preferably between 15% and 25%.

[0068] According to different embodiments of the present invention, the first and second parts 131 and 132 can be made of a magnetic material (the magnetic material itself) (that is, the first and second parts 131 and 132 have their respective magnetic moments m1 and m2, in particular, the first and second parts 131 and 132 are realized or included by sintered hard ferrite). Therefore, the magnetic device support 130 may be a molded part

[0069] -- made of a material having magnetic properties, or

[0070] -- made of a material including particles having magnetic properties.

[0071] According to other embodiments of the present invention, the magnetic device support 130 includes (in its first part 131 or as a part of its first part 131) a first permanent magnet 131' having a first magnetic moment m1, and in or as a part of its second part 132, a second permanent magnet 132' having a second magnetic moment m2.

[0072] In particular, the first and second permanent magnets 131', 132' and / or the first and second parts 131, 132 are realized by or include sintered hard ferrite.

[0073] Thus, the magnetic device support 130 may be a molded part, wherein the first and second permanent magnets 131', 132' are arranged, in particular, by overmolding and / or by means of a device or insert molding as part of the magnetic device support 130.

[0074] Regarding the (magnetic) extension of the first and second parts 131, 132, it is also preferred that the first and second permanent magnets 131', 132' and / or the first and second parts 131, 132 are configured to

[0075] -- have a height in the axial direction that approximately corresponds to the length of the rotor permanent magnet (rotor 120), and / or

[0076] -- have a width in the angular direction of at most 60 degrees, preferably at most 45 degrees, more preferably at most 30 degrees.

[0077] According to a further embodiment of the invention, and alternatively or cumulatively using two permanent magnets 131', 132' embedded in an overmolded part (i.e., the magnetic device support 130), according to the invention, an auxiliary winding that is only powered during the motor starting phase can also and preferably be provided. According to such an embodiment, the magnetic device support 130 includes (in its first part 131 or as part of its first part 131) a first coil, and in or as part of its second part 132, a second coil, wherein the motor 100 includes or is assigned to a control device such that the first coil can be controlled to achieve a first magnetic moment m1 and the second coil can be controlled to achieve a second magnetic moment m2 (only during the motor starting phase). Again, the magnetic device support 130 may be a molded part, wherein, in particular, the first and second coils are provided as part of the magnetic device support 130 by overmolding and / or by means of a device or insert molding.

Claims

1. A single-phase synchronous motor (100) includes at least one stator winding, a U-shaped laminated stator core (110) with two poles (111, 112), and a rotor (120). The rotor (120) is arranged between the two poles (111, 112), and the rotor (120) includes rotor permanent magnets. It is characterized in that The motor (100) includes a magnetic device support (130). Among them, the magnetic device support (130) includes at least a first part (131) and a second part (132). The first part and the second part (131, 132) are located between the two poles (111, 112), at diametrically opposite positions with respect to the rotational axis (121) of the rotor (120), and are radially spaced apart from the rotor permanent magnets by a distance. Among them, the first part (131) realizes or is configured to realize a first magnetic moment (m1), and the second part (132) realizes or is configured to realize a second magnetic moment (m2). Among them, the first magnetic moment and the second magnetic moment (m1, m2) are oriented parallel to each other.

2. The single-phase synchronous motor (100) according to claim 1, characterized in that, The absolute values of the first magnetic moment (m1) and the second magnetic moment (m2) are equal. Among them, the absolute values of the first magnetic moment and the second magnetic moment (m1, m2) correspond to between 10% and 30% of the magnetic moment of the rotor permanent magnets.

3. The single-phase synchronous motor (100) according to claim 2, characterized in that, The absolute values of the first magnetic moment and the second magnetic moment (m1, m2) correspond to between 15% and 25% of the magnetic moment of the rotor permanent magnets.

4. The single-phase synchronous motor (100) according to claim 1, characterized in that, In the first part (131) of the magnetic device support (130) or as a part of the first part (131), the magnetic device support (130) includes a first permanent magnet (131') having the first magnetic moment (m1), and in the second part (132) of the magnetic device support (130) or as a part of the second part (132), a second permanent magnet (132') having the second magnetic moment (m2). Among them, the first permanent magnet and the second permanent magnet (131', 132') and / or the first part and the second part (131, 132) are configured to -- have a height that is approximately corresponding to the length of the rotor permanent magnets in the axial direction, and / or -- have a width with an angular direction of at most 60 degrees. And / or among them, the first and second permanent magnets (131', 132') and / or the first and second parts (131, 132) are realized by sintered hard ferrite or include sintered hard ferrite.

5. The single-phase synchronous motor (100) according to claim 4, characterized in that, The first permanent magnet and the second permanent magnet (131', 132') and / or the first part and the second part (131, 132) are configured to have a width with an angular direction of at most 45 degrees.

6. The single-phase synchronous motor (100) according to claim 4, characterized in that, The first permanent magnet and the second permanent magnet (131', 132') and / or the first part and the second part (131, 132) are configured to have a width with an angular direction of at most 30 degrees.

7. The single-phase synchronous motor (100) according to claim 1, characterized in that, The magnetic device support (130) includes a first coil, which is in or as part of a first part (131) of the magnetic device support (130), and the magnetic device support (130) includes a second coil, which is in or as part of a second part (132) of the magnetic device support (130), wherein the electric motor (100) includes or is assigned to a control device such that the first coil can be controlled to achieve a first magnetic moment (m1) and the second coil can be controlled to achieve a second magnetic moment (m2).

8. The single-phase synchronous motor (100) according to claim 4, characterized in that, The magnetic device support (130) is a molded part, wherein the first permanent magnet and the second permanent magnet (131', 132') are arranged by overmolding and / or by means of a device or insert molding as part of the magnetic device support (130).

9. The single-phase synchronous motor (100) according to claim 7, characterized in that, The first coil and the second coil are arranged by overmolding and / or by means of a device or insert molding as part of the magnetic device support (130).

10. The single-phase synchronous motor (100) according to claim 1, characterized in that, The magnetic device support (130) is a molded part -- made of a material having magnetic properties, or -- made of a material including particles having magnetic properties.

11. The single-phase synchronous motor (100) according to claim 1, characterized in that, The rotor (120) has an angular position of at least a minimum torque (125, 126) of the electric motor (100) relative to the stator core (110), wherein the electric motor (100) is configured such that any stationary position (122, 123) of the rotor (120) is at least angularly spaced 20 degrees from any angular position of the minimum torque (125, 126) of the electric motor (100).

12. The single-phase synchronous motor (100) according to claim 11, characterized in that, The electric motor (100) is configured such that any stationary position (122, 123) of the rotor (120) is at least angularly spaced 30 degrees from any angular position of the minimum torque (125, 126) of the electric motor (100).

13. The single-phase synchronous motor (100) according to claim 11, characterized in that, The electric motor (100) is configured such that any stationary position (122, 123) of the rotor (120) is at least angularly spaced 40 degrees from any angular position of the minimum torque (125, 126) of the electric motor (100).

14. A pump (200), characterized in that, The pump (200) includes a synchronous electric motor (100) according to any one of claims 1 to 13.

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