Electric machine

Abstract

The present invention relates to an electric machine (200) with a stator (100) comprising: a stator body (1) with several stator slots (1.1), a winding system (2) with multiple winding strands (2.1), wherein at least two winding strands (2.1) are arranged in each stator slot (1.1), several phase terminals (3) designed to be connected to different electrical phases (202.1) of a power supply device (202), and a switching device (4) by which at least one winding strand (2.1) per stator slot (1.1) can be selectively connected to two different phase connections (3), such that in a first switching state of the switching device (4) the winding strands (2.1) arranged in the same stator slot (1.1) are all connected to the same phase connection (3), and that in a second switching state of the switching device (4) the winding strands (2.1) arranged in the same stator slot (1.1) are connected to at least two different phase connections (3), and a control unit (204) configured to switch the switching device (4) between the first switching state and the second switching state, characterized by the fact that the control unit (204) is designed to select a switching state of the switching device (4) to be set in each case based on at least one current operating parameter (DM, DZ) of the electric machine (200).

Description

[0001] The present invention relates to an electric machine with a stator comprising: a stator body with several stator slots, a winding system with several winding strands, wherein at least two winding strands are arranged in each stator slot, and several phase terminals designed to be connected to different electrical phases of a power supply device.

[0002] From DE 10 2019 216 488 A1 an electrical machine according to the preamble of claim 1 is known.

[0003] From JP 2012 - 227 980 A, an electrical machine with a winding switching device is known, wherein the winding switching device allows winding strands of a winding system of the electrical machine to be connected to phase terminals in different ways.

[0004] From US patent 2004 / 0164636A1, an electrical machine is known which comprises several connection units through which winding strands of a winding system of the electrical machine can be connected to phase terminals in different ways. The connection units each comprise three pairs of terminals, which can be connected to each other, for example, via a soldered wire or via a switch arranged between them.

[0005] The present invention is based on the objective of enabling the realization of an efficient electrical machine.

[0006] This problem is solved according to the invention by an electrical machine having the features of claim 1.

[0007] The electrical machine according to the invention comprises a stator according to the invention as described below.

[0008] The stator according to the invention comprises a magnetizable, preferably ferromagnetic, stator body with several stator slots. The stator body is preferably formed by one or more laminated cores, but can also be designed as a monolithic solid body. The stator slots are typically substantially identical and arranged uniformly along the circumference of the stator body.

[0009] The stator according to the invention further comprises a multilayer winding system designed in a generally known manner, i.e., a winding system with several winding strands arranged in the stator slots of the stator body such that at least two winding strands are arranged in each stator slot of the stator body. Preferably, the winding strands are all electrically connected to a common star point via one of their two ends.

[0010] The stator according to the invention further comprises several, preferably three, phase connections which are designed to be connected in a generally known manner to different electrical phases of a multi-phase power supply device, such as a three-phase AC power network or a multi-phase inverter.

[0011] The stator according to the invention further comprises a switching device comprising several switches, by which at least one winding strand per stator slot, i.e., at least one of the winding strands arranged in the respective stator slot, can be selectively connected to two different phase connections. The switching device is designed such that in a first switching state of the switching device, the winding strands arranged in the same stator slot are all connected to the same phase connection, and that in a second switching state of the switching device, the winding strands arranged in the same stator slot are connected to at least two different phase connections.The first switching state of the switching device thus enables the realization of a so-called unstrained winding system, and the second switching state of the switching device thus enables the realization of a winding system that has a so-called strain. Preferably, the switching device comprises two switches per winding strand that can be connected with different phase terminals.

[0012] The switching device according to the invention makes it possible to operate the winding system either as an unstretched winding system or as a winding system having a chord, so that a particularly efficient electrical machine can be realized with the stator according to the invention.

[0013] In principle, the switching device can comprise any type of switch suitable for switching electrical currents. Preferably, however, the switching device comprises several semiconductor switches that can be easily controlled electronically. Particularly preferably, the switching device comprises several so-called MOSFETs.

[0014] The electrical machine according to the invention further comprises a control unit configured to switch the switching device between the first switching state and the second switching state. The control unit typically comprises a microcontroller or another type of processor or arithmetic unit. Furthermore, the control unit preferably comprises a so-called driver circuit, configured in a known manner, for controlling semiconductor switches of the switching device.

[0015] For the reasons mentioned above, the electrical machine according to the invention can be implemented particularly efficiently by using the stator according to the invention.

[0016] According to the invention, the control unit is configured to detect at least one current operating parameter of the electric machine by means of suitable detection means and / or to receive it from a suitably designed detection unit, and to select a switching state of the switching device based on at least one current operating parameter of the electric machine. The control unit is thus preferably configured to select, based on the at least one current operating parameter, whether the stator winding system is to be operated as an unstrained winding system or as a winding system with a strain. This enables the realization of a particularly efficient electric machine. Preferably, the control unit is configured to select the switching state of the switching device based on several current operating parameters of the electric machine.At least one operating parameter of the electric machine can, for example, include a current torque and / or a current speed of the electric machine.

[0017] Preferably, the control unit includes a characteristic map for selecting the switching state of the changeover device, in which the switching state of the changeover device is stored for different values ​​of at least one current operating parameter. This makes it possible to easily implement an operating parameter-dependent selection of the switching state of the changeover device.

[0018] An embodiment of the present invention is described below with reference to the accompanying figures. These show: Fig. 1 a schematic diagram of an electrical machine according to the invention with a stator according to the invention, Fig. 2 schematically an arrangement of winding strands of a winding system within stator slots of a pole of a stator body of the stator made of Fig. 1, and Fig. 3 a simplified circuit diagram of the stator Fig. 1.

[0019] Fig. Figure 1 shows an electrical machine 200 according to the invention with a stator 100 according to the invention, a rotor 201 cooperating with the stator in a known manner, a power supply device 202, a detection device 203 and a control unit 204.

[0020] In the present embodiment, the power supply device 202 is a three-phase inverter designed in a known manner, i.e., designed to provide an alternating voltage having three electrical phases 202.1.

[0021] The detection device 203 is designed in a known manner to detect or calculate the current rotational speed DZ and the current torque DM of the electric machine 200 as current operating parameters of the electric machine 200.

[0022] Fig. Figure 2 shows an example of a section of a so-called pole of the stator 100, and Fig. Figure 3 shows a simplified circuit diagram of the stator 100.

[0023] The stator 100 comprises a ferromagnetic stator body 1 having several stator slots 1.1, wherein in the present embodiment each pole of the stator 100 comprises three stator slots 1.1.

[0024] The stator 100 further comprises a winding system 2, which includes several winding strands 2.1, wherein all winding strands 2.1 are electrically connected via one of their ends to a common star point S.

[0025] In the present embodiment, a first winding strand 2.1a and a second winding strand 2.1b are arranged in a first stator slot 1.1a of each pole, a third winding strand 2.1c and a fourth winding strand 2.1d are arranged in a second stator slot 1.1b of each pole, and a fifth winding strand 2.1e and a sixth winding strand 2.1f are arranged in a third stator slot 1.1c of each pole.

[0026] The stator 100 further comprises three phase terminals 3, wherein a first phase terminal 3a is electrically connected to a first electrical phase 202.1a of the power supply device 202, wherein a second phase terminal 3b is electrically connected to a second electrical phase 202.1b of the power supply device 202, and wherein a third phase terminal 3c is electrically connected to a third electrical phase 202.1c of the power supply device 202.

[0027] The first phase connection 3a is additionally electrically connected to the first winding strand 2.1a, the second phase connection 3b is additionally electrically connected to the third winding strand 2.1c, and the third phase connection 3c is additionally electrically connected to the fifth winding strand 2.1e.

[0028] The stator 100 further comprises a switching device 4, which in the present embodiment comprises six semiconductor switches 4.1 designed as MOSFETs, wherein a first semiconductor switch 4.1a is arranged between the first phase terminal 3a and the second winding strand 2.1b, wherein a second semiconductor switch 4.1b is arranged between the first phase terminal 3a and the fourth winding strand 2.1d, wherein a third semiconductor switch 4.1c is arranged between the second phase terminal 3b and the fourth winding strand 2.1d, wherein a fourth semiconductor switch 4.1d is arranged between the second phase terminal 3b and the sixth winding strand 2.1f, wherein a fifth semiconductor switch 4.1e is arranged between the third phase terminal 3c and the sixth winding strand 2.1f, and wherein a sixth semiconductor switch 4.1f is arranged between the third phase terminal 3c and the second winding strand 2.1b.

[0029] The switching device 4 is configured to selectively realize either a first switching state or a second switching state, wherein in the first switching state the second winding strand 2.1b is electrically connected to the first phase terminal 3a via the first semiconductor switch 4.1a, the fourth winding strand 2.1d is electrically connected to the second phase terminal 3b via the third semiconductor switch 4.1c, and the sixth winding strand 2.1f is electrically connected to the third phase terminal 3c via the fifth semiconductor switch 4.1e, and wherein in the second switching state the second winding strand 2.1b is electrically connected to the third phase terminal 3c via the sixth semiconductor switch 4.1f, the fourth winding strand 2.1d is electrically connected to the first phase terminal 3a via the second semiconductor switch 4.1b, and the sixth winding strand 2.1f is electrically connected to the fourth semiconductor switch 4.1e.1d is electrically connected to the second phase connection 3b.

[0030] Consequently, in the first switching state of the switching device 4, the two winding strands 2.1 arranged in the same stator slot 1.1 are each electrically connected to the same phase connection 3, and in the second switching state of the switching device 4, the two winding strands 2.1 arranged in the same stator slot 1.1 are each electrically connected to two different phase connections 3.

[0031] During operation, the control unit 204 receives the current operating parameters, i.e., the current speed DZ and the current torque DM, of the electric machine 200 from the detection device 203.

[0032] The control unit 204 includes a characteristic map 204.1 in which a switching state to be set by the switching device 4 is stored for different combinations of current speed DZ and current torque DM, i.e. it is stored whether the first switching state or the second switching state of the switching device 4 is to be set.

[0033] The control unit 204 is designed to switch the switching device 4 between the first switching state and the second switching state by appropriately controlling the semiconductor switches 4.1.

[0034] In particular, the control unit 204 is designed to select the switching state to be set based on the current operating parameters of the electric machine 200 provided by the detection device 203, i.e. based on the current speed DZ and the current torque DM of the electric machine 200, using the characteristic map 204.1 and to control the semiconductor switches 4.1 of the switching device 4 in such a way that the respective switching state to be set is realized. Reference symbol list 200 electric machine 201 Rotor 202 Power supply unit 202.1 electrical phases 203 Recording device 204 Control unit 204.1 Characteristic map 100 Stator 1 Stator body 1.1 Stator slots 2 winding system 2.1 Winding strands 3 phase connections 4 Switching device 4.1 Semiconductor switches DM current torque Current RPM S star point

Claims

[1] Electric machine (200) with: comprising a stator (100): a stator body (1) with several stator slots (1.1), a winding system (2) with multiple winding strands (2.1), wherein at least two winding strands (2.1) are arranged in each stator slot (1.1), several phase terminals (3) designed to be connected to different electrical phases (202.1) of a power supply device (202), and a switching device (4) by which at least one winding strand (2.1) per stator slot (1.1) can be selectively connected to two different phase connections (3), such that in a first switching state of the switching device (4) the winding strands (2.1) arranged in the same stator slot (1.1) are all connected to the same phase connection (3), and that in a second switching state of the switching device (4) the winding strands (2.1) arranged in the same stator slot (1.1) are connected to at least two different phase connections (3), and a control unit (204) configured to switch the switching device (4) between the first switching state and the second switching state, characterized by , that the control unit (204) is designed to select a switching state of the switching device (4) to be set in each case based on at least one current operating parameter (DM, DZ) of the electric machine (200). [2] Electric machine (200) according to claim 1, wherein the switching device (4) comprises several semiconductor switches (4.1). [3] Electric machine (200) according to one of the preceding claims, wherein the control unit (204) comprises a characteristic map (204.1) for selecting the switching state to be set of the switching device (4).

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